Quench! Higher Compression with Less Detonation (A key to making more HP)

[@stuartbuckley8720]

I have ran 355s with 0 deck height and Chevrolet steel shim gaskets we painted with cheap paint and a solid flat tappet cam without checking anything but valve clearances and it ran like a scalded dog. Old roundy round racing. We ran Sunoco 260 or aviation fuel and 36 to 38° total timing or until it pinged then backed it down just enough to stop the spark knock with cold plugs. We had lead in the gas back then. Good old Ethel. Yep, I am old.

[@cuttersperformance]

Haha thats why I said that about you crazy circle track guys! You guys often have great luck with pushing the limits hahaha but I guess some blow up first lap hahaha. I guess you can't find the limits without pushing them! Cheers!

[@michaelvrooman5681]

I knew one guy bringing his pistons .003 out of the hole for engines running in " stock class" engines. He had to run 72 cc heads so he had to get compression somewhere.

[@Doug-b4p]

This clown doesn't understand quench at all

[@larryburns7094]

.032 to .034 is real world safe BUT CHECK PISTON TO VALVE CLEARANCE is a must . Good info .

[@flyfaen1]

Just some practical info for those that don't live in the US (except California perhaps), that actually have to meet emissions, and run a catalytic converter etc.... A very tight squish will indeed increase TDC turbulence (any increasing amount of squish exit velocity will) and prevent end gas detonation, and thus increase power due to less pumping loss by lower burn time, and at the same time be more knock resistant so MBT timing (or closer to it) can be achieved. Mostly the increase in detonation/"knock" resistance is due to the fact that gasoline mixes don't burn closer to cooled surfaces than ~3 mm or ~1/8", having the quish very tight delays the point of sufficient squish opening at a ignitable distance from cooling faces and exposure to the main combustion event happens after peak pressure, preventing end gas detonation... However (there is ALWAYS a "but") not all fuel/air mix escapes the quench, regardless of how tight it is, this is what would otherwise detonate if exposed to the main combustion at too early of a time (like with a larger gap), but in a very tight squish where it won't be able to detonate, and where the squish opens later it is often a very rich mix, which due to all the cool faces the fuel is not vaporized (air escapes the quench much easier than the fuel) it will burn late and "cold" causing oxygen deprived secondary combustion and some of will also polymerize, causing excessive CO and HC by-products, making it hard to pass emissions. You can still have a bit of both worlds tho, if you have smaller squish areas, but more distributed along the chamber. Which by being shallower allows for faster progression of the flame front at squish open not giving time for end gas detontation to happen, giving opportunity to get heat in early enough (more gradual increase in heat in the qench/squish area) for the end gas mix to contribute in a normal combustion just slightly later on, instead of the trapped gasses being pig-rich, and hard to combust. That's why modern 2v engines has squish on both sides of the chamber, but smaller (unlike the old CI heads in this video, with just one large squish area on one side), or why in general 4v heads are basicly "mainstream" by OEM's these days, which lends itself the benefit of still having good squish induced turbulence, without needing to run the squish so tight that it makes alot of CO and HC, that makes one fail emissions (well, fails emissions in the most of the "developed" world, anyway)

[@pizzandoughnutspage7817]

I learned this lesson the hard way a long time ago, had know idea the pistons were rebuilder specials. They had a comp. height of 1.540, causing a quench of about.060 though it was for a basic rebuild it ran and detonated under a load. Cause all kinds of problems such as overheating, burnt exhaust valves and poor performance. It’s important to pay close attention to what your purchasing, a deal that’s to good to be true really is!

[@flinch622]

Yep: 0.060" is trouble, not a quench motor. Close it down or move to a dish/switch cams. Gotta check installed numbers when mocking up/degreeing the cam. It's a bummer pulling a motor because of bad math.

[@brandonkanthack]

I'm running my 383 with the pistons .018 in the hole and a .015 head shim. At 10.75:1 compression, i run on 87 octane in the winter and 89 in the summer with no detonation. 33 degrees total timing. It does work and work well.

[@jacobjarvis2545]

What cc where the heads you have on that 383

[@brandonkanthack]

@@jacobjarvis2545 67cc

[@jacobjarvis2545]

@@brandonkanthack thanks for the reply back i appreciate it.

[@cfmechanic]

Dish piston?

[@brandonkanthack]

2 valve relief flat top

[@martintodd5542]

Why's that important you might ask. In every video. Great videos. GREAT information.

[@truethought369]

The old way of measuring the quench was by using plasticine or blue-tack, this only works if you know beforehand what the measurement should be! Once you have this info, all you have to do is the Math, so as to alter the head gasket thickness. This has always been a tricky subject, but you have explained it well. Thanks for your explanation.

[@302hobronco]

Thank you. Your art work for a visual explanation was much better than that Steve guy lol

[@BrentFrancis-h8o]

Very good. Thank you. I am planning a sbf stroker for the street at 11.0:1 so this was crucial informations. Have a good weekend.

[@vg23air]

9 months later and I get a rec to watch this video from another video and rediscover what I already watched, and it prompts major redesign in my project, for better or worse, we will see :)

[@robking9857]

One oversight I'd like to mention about "piston rock" is that a hyper piston will run "HOTTER" and be more likely to detonate although tighter in the bore and nothing I'd use with any compression ratio over 10.5:1. They are cast pistons with a coating that heats up more that is "budget" friendly. Forged pistons or billet pistons are "sloppier" when cold, and are known for piston slap, but they like aluminum rods expand once up to temp and the "slap" tends to dissipate. Thus, a little expansion is expected, so running a slightly thicker MLS head gasket is a safer bet just as a margin of expansion. And if you are running NOS in a high-compression street motor of, say 11.5:1, you'd never run a hyper piston, and the rings need to be "loose".

[@lukepokrajac1057]

I just installed 440 source heads on my 68 Hp 383 engine. True zero deck engine from factory…piston tops right even with deck. All original bottom end in engine including pistons. I have .039 clearance from head gasket. Engine now runs well on 89 octane gas. Heads made a huge difference over original 906 open chamber heads

[@406MenaceRacecar]

68

[@mikes.1882]

​@@406MenaceRacecar 1968 Hi Performance

[@406MenaceRacecar]

@@mikes.1882 is there actually a brand name called high performance? This seems odd and I'm not trying to be difficult here but honestly it seems like a moot point to claim a 383 is high performance, you've customized a V8 engine to have more power. There's no "low performance" lol

[@b.c4066]

It's all relative to bore size, I built a Yamaha blaster years ago with extensive porting, peak power at around 8700 rpm, quench was a verified .016" and that was an air cooled single that spent it's entire life being beat like it owed me money. A full hemispherical chamber and the piston crown matched it. I'd have to look at my old notes but squish band was around 35% of the bore, it seemed to break all the rules. But never failed and for a 198cc air cooled twin it would run with piped banshees up to 45-55 mph, in tight trails they couldn't keep up with it. Never ran hot, actually ran cooler than it did when stock. Guys with 383/385 sbc are running 4132 forged slugs around .028 - .035 no problems at all on na street stuff. The tighter piston to bore. Clearance, and small lt1/lt4 chambers and a flat top allow them to get away with it, I'm sure the reverse cooling doesn't hurt either. And they get revved to 6500-6700 rpm. I think .040 is kind of an old general rule of thumb. Have seen turbo LS engines tore down where the owner didn't know better and assembled with .025-.028 quench and never had a problem. Most in the know tend to agree for 4" -4.040 bore stuff .039-.041 is fine and not really any more power or detonation resistant going any tighter.

[@cuttersperformance]

I have to agree with you for the most part. Bore size is for sure will play a part as it contributes to the rock of the piston as well as the weight. As mentioned in the video I know guys will run under the recommend amount but you have to know what your doing and good parts are key. I can't suggest to guys to run under .036 for two reasons. Mostly becuase it gives a safety net and secondly you won't really see a benefit under that. (All risk not much reward sort of thing)

[@b.c4066]

@@cuttersperformance oh I agree brother, just sharing some personal experiences and observations. I set my engine up at .041" spent a significant amount of time making sure the sharp edges of the valve reliefs, around the plug threads etc were softened I was advised that would do more for detonation resistance than ultra tight quench with the afr eliminator heads I used. Love your vids bro, have a set of ultra low mileage original 906 castings without the hardened seats, and will be throwing them on a flat top long rod 355 plan to push comp to 11.5-12.1 and run e-85. I get a lot out of your videos, and enjoy watching them with my dad. I'd like to contact you about some vortec specific parts I'm sure you have laying around from all the heads you've found cracked and experimented with. Do you have a website for your spring kits with some contact info dude?

[@cuttersperformance]

Thank you i appreciate that! Yeah man shoot me a email at [e-mail]

[@jrdmotorsports9718]

Although anything in .040's is fine in most applications, it is certainly not bore size specific. However the bigger the bore, the tighter it needs to be, as they are more prone to detonation. A lot more to it than just quench distance.

[@jjmccloud]

@@jrdmotorsports9718 Right, thats basically what he was explaining in his comment 😆

[@goldsgarage8236]

Great video on an important subject. I mentioned you in my presentation at Forsyth College, the video should be out soon. AG

[@cuttersperformance]

I appreciate that AG! Feel free to email me if you want to chat. [e-mail]

[@Grooty79]

Good video, biggest overlooked measurement in engine building

[@regdor8187]

When the piston approaches the head it Squishes the air from the closing gap into the remaining cylinder space.....When the piston approaches the head it can Quench any flame propagating between the two cold surfaces of the Squish Zone....

[@bdugle1]

If I remember correctly, David Vizard says you can go down to 0.029” piston to head clearance. I’m running an LS with pistons coming 0.005” out of the hole and an 0.040” head gasket. Not running yet but we’ll see. Turns over fine by hand, anyway!

[@cuttersperformance]

I know he has done testing with very tight quench but I'd be surprised if he recommended .029" piston to head clearance. I'm not saying that guys don't run under .030" but it can be risky thats for sure. Lots of checks and really good parts are key!

[@albertgaspar627]

sometimes an aluminum head can trick you, expanding later than the block and a valve gets friendly with the slug. the question is, are you turning over by hand when the engine is cold or after it's gotten to operating temp and everything's as expanded as its going to get (and you have no valve float, flutter from pushrods bending and unbending, etc)

[@bdugle1]

@@albertgaspar627 All good points. Valve train should be good, BTR dual springs. The cam is a relatively short overlap, so flat top pistons should not be a problem.

[@albertgaspar627]

@@bdugle1 and the nice thing about short overlap, relatively speaking, is that you can run a lower mechanical compression but it'll raise up by not getting blown out the exhaust. That gives you more room inside the chamber for valve clearance if you go with a dished piston. I prefer that over a large combustion chamber--let the combustion expand against the piston, not the cylinder head which isn't going anyplace.

[@StabyMcStabsFace]

Hondas go that tight and more, but they don't have the piston rock problems of sbc/ls

[@brentonk461]

Amusing reading the comments. I spend way to much time watching KZbin, No one even watches my KZbin 379ci Chevy build, otherwise I'd do more.depending on how I feel, might show my 2bolt main small block Chevy, has stock rods, JEGs cam, shift it @8500rpm yeah, it has cast flat top 4 eye brow pistons. Yes, and Street drivable. Actually it was my daily driver. I'll keep watching, see how you go with your build. 👍

[@cuttersperformance]

Wow 8500 on stock rods and cast pistons! thats wild! I know some guys that turn in the 7k rpm but the rods are carefully selected, mag test ect and then the engine is very well balanced. I can't say I ever seen 8500 on a combo like that....well not 8500 rpm on purpose hahaha I will be sure to check out your channel man! Cheers

[@bobg3034]

I made 422 HP with a Holley 500 2 barrel carb on a Vortec headed 355 dirt track engine! The engine made 486 HP with a HP 750 4 barrel Holley.

[@cuttersperformance]

The magic of vortecs!

[@trtony-xe4cl]

Ive seen some race head shops shave off around 5 k from this quench area,they angle it towards the exhaust valve,it helps to prevent detonation while ruining higher compression

[@scotthultin7769]

You still need a minimum of three to six thousands clearance in the quench area to stop the vacuum from the Piston jerking away from the head happening there and pulling the flame away from the spark plug

[@Faolan161]

If you understood an engine, you would understand how the combustion is creating pressure inside the chamber, where it's impossible for vacuum to happen between the piston and head... even furthest away from the valves

[@jrdmotorsports9718]

All well and good, but keep in mind, this all being measured cold. Watch what happens when the piston sees heat. Then watch what happens when you hit a certain rpm. It's a lot tighter than you think. Don't forget piston rock. Even with a steel rod and especially with an iron block. Aluminum blocks have that safety factor built in at 0, because the block grows taller giving more distance with heat, unlike iron. You only need enough quench distance to keep the carbon off the tops of the pistons under the quench pad without it actually hitting. Unfortunately, no way of knowing what that is, unless you run the same exact combo and rpm, and creep up on it. Point is tighter the better except in big power adder stuff. You actually need as much as you can get while keeping the desired compression ratio. Many factors are involved, but general rule of thumb in most is .036"- .045" will work on anything with a steel rod. After .049", the ability to help suppress detonation diminishes, and. 060" and over, or no quench distance. Does nothing. This is all provided you have the correct cam profile, compression, desired cylinder pressure, piston design and heads that actually have enough quench pad.

[@flinch622]

Gaskets only do so much, which is to say you will select pistons/machine deck to suit gaskets that fit the head and are suitable to both combustion chamber size and the bore size in arriving at desired compression ratio. A gasket diameter 0.020" bigger than the bore is damn close - you don't want to risk fire ring sitting on the chamfer, which is not flat. Often, +0.030" is a minimum margin, but check machine shops work: they must put some in to allow for easy piston install. Last build, I had to go with +0.070" on account of combustion chamber casting dimensions. Perfect? No, but fire ring was properly clamped in place and not going to squish out of place.

[@edpetrocelli2633]

On all my circle track motors I run as close to .035 deck ht. as I can. Some turn in excess of 8000rpm and when I refresh them they show signs of being very close to the head. The burn on the quench of one of the heads I could read .030 that transferred from the piston, it was written in carbon. I don`t believe the engine would have survived for 1800 laps if it was any tighter. That was 20 some years ago now I leave em .007 in the hole and use the gasket to get .035. In the hole helps with the rocking situation too. Little light shiny valve smiles with no deformation in the pockets are OK

[@cuttersperformance]

Thats awesome man! .036 is the tightest I like to go but I dont do circle track stuff. I often get told by guys that they have had good luck with like .025 on circle track engines and I can't quite figure out how they get away with that haha maybe not a true .025? Who knows Cheers!

[@muftifaizan1964]

I got away with 0.015 on a 1.6L 12.7:1 engine but with 6.5k rpm limit only.

[@edpetrocelli2633]

@@muftifaizan1964 Rule of thumb is .040 and .now I know I can go a little closer, I would have fattened the head gasket if I got a .015

[@davenkaren2572]

Love all your vids ! Very easy to understand and follow!!!

[@cuttersperformance]

Thank you, I really appreciate that

[@academaciated7466]

The simple answer is always BOOST 💪🏻

[@kylestephenson3004]

Nitrous is even simpler

[@KingJT80]

power breaks other things.like pistons if you dont gap the rings the right way for power adders. there are simple solutions. but in the end theres no substitute for just building it the right way for the application

[@jeffjarquin5600]

Again like you said not recommended, I've build several will piston .010 in the hole with a steel shim gasket. They are great performers. Much more throttle response than a unmilled block. The best was a flattop 350 pro top line 200cc runner 49cc chamber heads with a 285b6 comp cam. Shifted at 6700 in a 79 malibu with 4.30 gear ran 11.36 in a quarter

[@cuttersperformance]

Haha Risky business running that tight but you are right, there are some good benefits of tight quench. Did you ever tear down that engine? I would imagine at that tight you may see some signs of the piston getting pretty close to the head especially shifting past 6500

[@jeffjarquin5600]

@@cuttersperformance I did have the heads off it once. The flat part of the piston under the quench stayed very clean, but showed no signs of contact. I ran that engine for 2 years and sold it it so I could build a 400

[@hotrodray6802]

Quench is the result of squish. Crevice volume is a trapped area. Singh grooves relieve the areas and produce swirl.

[@imnotahealthandsafetyperso4889]

We go piston to valve clearance sometimes put cutouts in the pistons for the valves to allow for high lift Camshafts

[@cuttersperformance]

Yeah fly cutting is great for high lift cams, typically only needed in racing profiles Cheers!

[@imnotahealthandsafetyperso4889]

@@cuttersperformance yes oval track race engines is what we do

[@jessechronister2452]

The less gap you have between your Pistons and head the higher your compression will go . In short the longer the rod the torq will rise . Asking everyone 13-5to 1 compression 512 cui flat top Pistons static is there boost can I run is .?

[@The340king]

We ran a 305 sprint car engine at 0.027” piston to head clearance. It survived and ran for two season like that.

[@6.liter-beater]

Great video! Good info as always!

[@mikes.1882]

The stock quench on the sbc LT1/LT4 is .025 if I remember right. Pretty sure it has a 10.5 to 10.89:1 compression. Maybe their pistons are made of super secret alloy blends. Heck I don't know

[@Greybuiltracing]

Bro you explain on video like I do ! I know what I want to say but my brain processes other ways to say it . We know what we want to say but our thoughts aren’t in order . I recommend for our selfs to practice what we want to say and say it . I pause a lot and say huh or I repeat words . You don’t repeat words that much but I do . And I say huh a lot or pause and then continue. It’s all good though ! Keep going ! We’ll get better !

[@FourbrrlGrabber]

Check out Alameda racing… he cuts strategic v grooves in the quench area for a more complete burn !!

[@brodyturney1500]

Have you, or are you still going to do the "quench" or "squish" video for the dome top pistons? If you've done this video already, which one is it? Love the info, just wanting to learn a bit more if possible! Keep at it man!

[@mantullera6652]

huge insight i learn from you, thanks

[@FreeSwimmer]

Wouldnt a high voltage ignition make for better burn of hiding gases under the head ? Im building a .040 350/357 ci right now. The deck was cleaned when I got the block. The piston to deck measure is .020 and running .028 head gaskets. New Eagle rods with Icon flattop pistons. ( 4 valve relef ) Heads are milled to 59cc, so compression is 10.25-1..

[@JohnDoe-du6yi]

With decking the head, what about intake ports aligning between the heads and intake.

[@rafatrill]

so this came up the other day and I was talking to my tuner and I asked him where should compression be for a e85 boost engine. tuner said around 10/11 :1 he told me that u should sand the heads after u have them machined or have a machine shop do it if they have a cnc to avoid quenching the pistons and heads. he then showed me his high dollar performance heads and he said it's very little to nothing. if ur having doubts just look at the aftermarket heads they do especially when the chamber is smaller then factory

[@b.c4066]

How much life are you getting out of the speedpro hypereutectic pistons, and how hard are you working them, what sort of scr/dcr and cranking compression?

[@cuttersperformance]

I've pushed a few sets pretty hard lol one engine I have out there in a chevelle is almost 10:1 and running a torqstorm supercharger with 6 psi of boost. It took some careful tuning to get this thing to run "safely". The engine wasn't built for boost but he really wanted to boost it and see what happens. Typically I use them for most 10:1 street builds and have had great luck with them

[@charlesroyal2357]

Exalent life street and circle track pulled motor apart with 5seasons at 6400 to 7000 depending track pistons all looked and micrometer perfect replacing just for cheap insurence tight quench of 34 .

[@bill2178]

you nailed it excellent vidy question what kind of gains Would you expect to see you from no other changes then tightening up the quench from stock to 35 on a small block Chevy something like a Vortech 350

[@raygonzales1113]

Which video is the one to check you deck height ,thanks for videos I'm learning so much this next build from you.

[@jjmccloud]

Deck height and piston compression height will make or break an engine, no way around it. Something you gotta know to know the outcome, of there's tons of lucky people that it just always works out for and they never even know how easy it could've went the other way lol my luck doesn't work like that 🤣

[@jakewade7388]

Can you recommend a good valve spring upgrade for stock 062 GM Vortec heads? Lift at valve will be .474. Hydraulic roller.

[@jjmccloud]

Ls3 or ls6 stock beehive springs (blue or yellow) work great for the vortecs, its a drop in replacement without having to do any machining at all and with the matching comp cams spring retainers. I believe you can use stock vortec keepers on those retainers. Just Google the upgrade for the retainer and spring part numbers. If money or budget allows comp cams makes a nice beehive spring thats the same size as the ls springs and they're a little better spring just double the cost. The Ls springs will be just fine though , its a very easy swap and allows alot more lift for hardly any work

[@jessechronister2452]

My theory is that with the compression being higher vac and suction will be higher if boost is equal to that will this work ?

[@jasonconaway69]

Professional opinion please. Had my SBC done at a local machine shop. 350 bored .040 over. New Eagle bottom end. Cast crank and rods. Block not decked. Rebuilder pistons. Which the machinists wasn’t aware of the lower compression height. So he ordered +6.0 flat 4 valence relief hypereutectic pistons. I measured deck height as best as possible without a bridge. I’m getting around .040-.045 height. With the thinnest .015 head gasket this puts me at a .055-.060 quench. Compression around 9.2:1. Dynamic compression around 8.10:1. I’m running Profiler as cast aluminum 70cc heads. I was hoping for higher compression, especially with aluminum heads. But I wasn’t going to pay him tho tear it down again to deck the block. You thoughts on this compression and quench combo. Cam is a Howard’s Rattler. Thanks!

[@cuttersperformance]

I am assuming your running a fairly mild cam given that dynamic compression..so what are your goals with the engine? The reason i ask, if you are just building a cruiser engine and dont want to pay to have the engine torn down again and decked or piston swapped, you could run it at .055 quench and probably not notice a difference. A tight quench is always a good idea but if your doing a mild build then you will probably notice any seat of the pants difference You could also mill those heads abit to bring up your static compression Cheers!

[@jasonconaway69]

yea, it’s just a hot rod street truck. I was intending on reusing the stock rods and crank but they were no good. Only reason I bought a new bottom end. The Howard’s cam is a .488 lift. Duration 227/235 @.050 LSA 109. It’s their rattler cam. Guess similar to Comps Thumper. What scared me was reading so many people online talking about detonation with a quench over .040.

[@mannmadesbc]

Enjoyed the content!

[@Faolan161]

What you're describing is two different concepts wrapped into one. Quench used to be the distance from piston to cylinder head, not just piston to cylinder head surface distance. The term 'quench' means to extinguish flame, so your definition has no relation. Squish was the term for piston to head clearance. What you're describing that creates the lack of pinging is combustion shape as well as atomization created by tighter squish as it creates a far more efficient combustion, lessening the need for to start the combustion sooner. Quench is, or at least used to be, the term used to describe the shape of the ball of air-fuel mixture, not piston to head surface clearance. Making a word mean two nearly opposite principles is improper use of language... It confuses people, even if your concept is correct. Quench can't mean the distance needed to properly design the combustion to eliminate pre-ignition, as it's a very different concept to putting out a fire or eliminating thirst... quench is about the combustion itself.

[@croomsracingengines9265]

Will you make CNC files of your heads specifically the vortec ports

[@jjmccloud]

Very nice job explaining it all

[@jorgesalcedo5614]

No se exactamente en que te enfocas, pero debes saber qu las formas, materiales,la relación de compresión el tipo de cámaras, combustible calidad de refrigeración,los grados de apertura del termostato,el grado termico de la bujía insideden en la temperatura de la combstion y la posibilidad de detonaciones. Yo personalmente trabajo con medidas de proximidad de las válvulas con el pistón y luego cúbico todo el conjunto para no pasarme de 11 a 1 luego trabajo la culata eliminado puntos calientes y filos agudos y rebajando la superficie y trabaja super .Los octanos los compenso co los grados de avance del distribuidor si lo tiene hasta el punto que no cascabelee con el motor caliente.

[@gingersquatch9844]

Would you have some time and ideas for a D16Y7 with a Y8 head that is being massively modified in the port bowls and the quench pads champhered to deshroud the valves for a turbo build?? I'm literally cutting into the cooling chamber and plan to weld the "low flow" bowl to create an even flow between the two intake ports/bowls.

[@thedobermangang3503]

hey got a question for you i got 1990 blazer 5.7 tbi had engine rebuild about month ago got a few up grades bigger cam so i had to get my computer chip tune to raise fuel and timing on the chip i change pressure regulator and adjust that the cam i have in there is xe 262 h comp cam the block was 30 over.and i still have the factory swirl port heads i should had put some vortec heads on there...but for some reason cant get it to run right just dont have no power and im getting a ping sound from engine and #6 had oil on spark plug threads only the rest of plugs are fine i dont no where im getting the ping sound dont no if the oil on the spark plug have anything to do with it or something with the fuel and timing is not right..

[@cuttersperformance]

When you say no power? Is it less than it was when it was stock? Have you verified the actual ignition timing with a timing light? (Set base timing) With stock tbi heads the truck won't have a ton of power but with those upgrades and a tune it should for sure have more power than before. Years back I did alot of tuning with the TPI (not tbi but same era) stuff and I found most issues guys were having were no properly setting up the base timing/base settings. Check into the ignition timing and let me know how it goes and if you have any more questions Cheers!

[@nashvilleoutlaw]

On piston rock. Are you saying the rock would be .009 from the lowest to the highest point when mesuring from the same side or would it be the total rock divided by two, to get the piston height?

[@cuttersperformance]

You can go off the center of the piston, or divide the rock of it by 2

[@thedobermangang3503]

my block was 30 over and the cam i use was xe 262 h comp cam

[@jamyers121]

I bought a L31 out of a 99 2500HD Suburban to build and to replace the 2-bolt main L31 in my 96 Silverado std cab Short bed. I noticed that the Rods are different in the 96 L31 vs 99 L31. I assume the 96 still had the forged rods and maybe the 99 4-bolt L31 are using powder metal rods? Wondering if the 99 L31 4-bolt had stronger rods? Also what Flat-Top piston Choice is a good recommendation for the build? I want to go as much compression as possible using High octane 91/93 fuel only @ the pumps. I am going to reuse whichever one of the connecting rods thats best from one of the L31 with ARP bolts, ARP main cap Bolts, mid length headers with 2.5" exhaust, Lt4 Hotcam with 1.6 roller rockers, and upgraded fuelpump and the 36lbs "improved spider injection system I found on eBay and finally a Tune from a reputable tuner for the combination. As for tranny build, its a 4L60E with all the upgrades and heavy duty rebuild kit, maybe a 2500 stall or something around. Rear end is a limited slip posi unit with a 3.73 or 3.90 gear/pinion. What do you think about both connecting rods and which would be best? And what type flat top hyper .30 over piston? And compression? Ive been studying your videos and LOVE ALL YOUR INFO, but trying to figure this out. I trust your recommendations. Keep posting vids! I am hoping my standard cab, short bed truck can run in the 12's after all this, maybe. Lol and of course , removing some weight to lighten up some. Its been a project for some time now.

[@cuttersperformance]

Im thinking your right that the 96 has regular rods as ive seen some early vortecs engines have non PM rods. If the 99 has the PM rods then those are for sure the ones you want to use. Add some ARP bolts, resized and you got yourself a nice set of rods. I currently have a engine out there running 550+ hp (355 sbc supercharged) with those rods and the Summit Racing Hyper flat top pistons, 2 bolt mains with studs and vortec heads. Thanks for checking out my channel and let me know if you have any more questions

[@tlstanbro3193]

That rocking of the piston and I’m sure you know this is called piston slap Subaru motors are famous for it I had to have two pistons replaced thank God it was under warranty at 90,000 miles I bought the extended warranty sometimes it pays when you buy the extended warranty I only paid 1500 bucks for that warranty they pull the motor out to replace yPistons it would have costed me 4 thousand dollars

[@cuttersperformance]

I call it Subie Slap haha yes very common on Subies and actually some v6 gms engines aswell

[@paulz2641]

Always bring the piston to TDC and open the valve as far as it can go minus 40 th an inch and you'll know the highest lift cam you can use.

[@AR_420]

Another AWESOME video! Love to hear some recommendations on a head gasket bore?..... # 683 TBI 4blt roller 350, 0 deck, 908's, stock rotating assembly. Waiting on dial gauge and bridge to arrive, but, assuming average "in the hole" numbers, what gasket bore diameter do you recommend? You and the masses say quench @ .035"-.070", so if i can get close to that i was wondering, hypothetically, why can't i un-shroud a valve to a 4.060 bore gasket, then install a 4.080-4.100...or proportionally larger. Scribe out a 4.080 gasket to grind to, then install a 4.120? Or do you alwaus want to un-shroud to the line/gasket? I hope that made sense. Plenty of gasket thickness selections out there and 3x as many bore sizes. If not, im sorry I wasted your time. 😊✌

[@cuttersperformance]

Not sure your compression goals but you'll find if your using the stock pistons that usually have a 12cc dish to them you will want to shoot for that .040 quench to keep up the compression. If you want to unshroud the valves a bit i would just run a 4.100 bore head gasket. Just be sure not to unshroud too far into the sealing ring of the head gasket. Cheers!

[@AR_420]

@@cuttersperformance 10:1+, looks like im screwed for getting that number with buckets for dish pistons😞 Back to drawing board. Was hoping to keep it budget as much as possible. If i want 10:1, ill need aftermarket 6cc or less valve relief pistons with NO dish. I COMPLETELY forgot factory Vortec pistons have 4 valve reliefs AND that pesky dish DOH! Sorry i wasted your time brotato chip 👍✌

[@N-Lee]

I wonder how much quench really matters in a Supercharged engine, If it does have dished pistons - which changes quench a lot.

[@cuttersperformance]

The best dished pistons are the D shaped dish. They still have a great quench pad and are only dished under the combustion chamber

[@racerd9669]

I like your explanation of Quench, but you do have to understand wet flow of the intake port and why a tight quench makes better power. All factory style cylinder heads have all the wet flow coming around the short turn radius, and then the fuel collects on the quench pad, this is raw fuel in droplet size and not very burnable. Like you explained the tight quench helps force the fuel across the chamber toward the spark plug, and reduce the need for spark timing. But if you study the carbon in the chamber you will see where fuel is and where is is not. So if you look at the area around the intake valve , you will see very little carbon build up there. This is because there is no fuel there to burn. If you remember about 20 years ago AFR was experimenting with golf ball dimples on that portion of the chamber, thinking this was fuel wash. The real fact is that there was no fuel ther to build up any carbon. They did not understand wet flow either.

[@StabyMcStabsFace]

Or was it more clean there because the burn was better? I remember the thinking you're talking about in the 80s and 90s; Dirty is where the burn is. Around 2005 (I believe it was Darin Morgan) it was shown the clean part of the chamber is where the burn is best.

[@racerd9669]

@@StabyMcStabsFace Unless you are burning straight methanol you will get carbon build up. Just get a look at a NASCAR engine after a race. The pistons and chambers are the same color ever where. That is fine tuning on E95

[@JDMCARSCIVIC]

Did you ever do the video about the dome pistons?

[@ericuncapher9922]

The zz4 is a perfect example of to much quench.

[@t-roy3438]

Thanks

[@fbbc6495]

Cool video thanks

[@akramdastager45]

I have a Honda k20 engine. I have 1mm oversized dished valves on the intake and I have stock size flat faced valves on exhaust side. Is this a good set up?

[@6.8SuperDutyDriver]

Good show!

[@jeremys924]

this makes a lot of sense. my 360 would start pinging once it gets to temp, i thought it was too much advance. i cant tell you how many times i put the timing light on it and moved the distributor... i used the 4.060 kit from jegs and thought it was good. the CR calculator said it was like 9.4 to 1. Maybe i should get a cooler plug, it has autolight 45 tapered seat. it spends its whole life at 2000 feet elevation and over 100F degrease ambient air temp. would you recommend a better spark plug?

[@jeremys924]

i did a bit of googling and ive purchased some autolight R44ts to replace the R45ts. hopefully it helps with detonation.

[@paulz2641]

We delt with all this back in the early 80s

[@chickenfoundation9323]

Building a 383 0 deck with the eBay aluminum heads assuming that it’s 68cc I’ll be needing a .06 gasket for 10.1 compression and 10.9 with a .03 , It will be a street engine with pump gas , what do you suggest either port the chamber to get more cc and a thinner gasket or leave the head alone and get a .03 or .04 gasket and run pump gas and 10.5+ compression

[@cuttersperformance]

91+ octane? What cam are you running? I think you'll be asking for trouble at zero deck and .030 for piston ti head clearance. Id shoot for .040 to .045 make sure your cam choice will keep the fuel sensitivity in check

[@chickenfoundation9323]

@@cuttersperformance I don’t have a cam yet , it will be going in a jimmy lifted on 35 inch tires so would like to get as much low to mid rpm torque as possible and would like to stay on pump

[@chrisd078]

Why won’t domed Hyper pistons work with Vortec heads? Only flattops or forged I hear. Any insight?

[@cuttersperformance]

Video coming up on pop ups with vortecs! You dont need to run forged with vortecs 95% of the vortec builds I do are hypers

[@chrisd078]

@@cuttersperformance I agree I want to run domed hypers but the mfg says it won’t clear the vortec. My guess is the spark plug area contacts the dome. That’s why it’s a must to run icon forged domed if you use a vortec head. Flat hypers are fine.

[@cuttersperformance]

@@chrisd078 o yeah sorry I thought you meant hypers in general. You'll for sure want to check out my next video then on running pop up hypers with vortecs

[@jjmccloud]

@@chrisd078 it can be done, your only real clearance issue is on the spark plug hole on deck surface side, you can shave off what you need to make it work out no problem

[@martyengland1964]

Great video thanks! I’m using a 4.4” piston with a 15cc dish to get a 9.8:1 compression ratio. I have 0.045 quench height but with the dish the quench pad is only about 1/4 inch wide - is that enough quench? I would have preferred a flat top piston but I’m limited with head choice.

[@cuttersperformance]

When it comes to dished pistons getting that ideal quench is a hard to achieve. They have D style dished pistons that leave you with a quench pad work well but not every dished piston is designed that way. Your not running a ton of compression and if you have a good combustion chamber I don't think you'll have any issues. A large bore engine like that (Ford 460?) Will need a decent amount of ignition timing so you may have to play abit with timing vs detonation vs max power.

[@martyengland1964]

@@cuttersperformance thanks very much, it’s a 8.1 GM gen 7, I have a round dish not a D dish. I would have preferred to run a flat top with higher compression but the gas where I live is only around 89 so that’s why I dropped the compression a bit.

[@cuttersperformance]

Badass! The vortec 8100 Work horse! How are you getting a 4.400 bore? Merlin block or something?

[@martyengland1964]

@@cuttersperformance PSI block with a stroke crank - 4.4 bore 4.75 stroke 577 cu all up, going in my 2003 Avalanche 2500 HD. There are not many aftermarket head options, only one is aluminium which is Raylar 107cc chambers which is what I have. I live in New Zealand and our gas here is not as good octane as US.

[@cuttersperformance]

@@martyengland1964 thats fricken awesome man Torque monster for sure

[@sirtnfol8476]

Who put BBs in my intake?? Thats detonation friend

[@curtthompson2787]

Unfortunately I have dished pistons. Im pretty sure I know the answer to this but do you treat dished pustons the same as flat top pistons as far as the ridge all the way around the dish. The top of the outer ridge or ring on top of a dished piston is where you measure quench and that needs to be the same as flat top?

[@cuttersperformance]

Yeah thats correct. Unfortunately a full dished piston has little to no quench

[@sweetness34km]

I have a 355 with 11.7-1 tips on using pump gas and 91 through 93 octane

[@cuttersperformance]

What cam are you running?

[@jjmccloud]

Has to be the wrong 1 🤣

[@DaveMcKnight-e6h]

Yea just asking for a leaking head gasket I know it happened to me get the good gaskets

[@jonschwartz9669]

I have a 305 vortec 98 silverado daily driver needs more power hauling trailer for my job would it be better to get new heads with behive springs and cam to match or keep vortec heads and just change rockers for more lift

[@cuttersperformance]

a little more lift with 1.6 rocker arms would help but a mild/torque cam would for sure be better. Just remember though most cams worth swapping will require the ecm to be tuned

[@jonschwartz9669]

@@cuttersperformance cool thank you keep up the good work

[@jonschwartz9669]

@@cuttersperformance my 98 obd2 so a dyno tune after cam upgrade is best or what about black bear tuning or a wait for me tune dyno shops cost alot

[@Drunken_Hamster]

So if you run a dished piston for lower compression, should you only dish the side on the combustion chamber in order to preserve quench? Or should you primarily adjust the combustion chamber size to change compression?

[@cuttersperformance]

D Shape dished pistons are the best choice for dished pistons. The same tight quench with a lower static compression, but a larger chamber will do the same

[@Drunken_Hamster]

@@cuttersperformance Wellll, the D-shape, in particular, might only apply to single-angle 2V heads like the ones on your bench, there. There are also multi-angle 2V heads like Trickflow's 2V 4.6 Mustang heads, and then there are of course 3V heads for Mustangs and some Mercedes, and 4V heads for a myriad of enthusiast engines like VQs, J35s, K series, B series, UZ, JZ, etc. What should you do in those cases?

[@nathanaelpedroza]

What mild Cam can I put on a 5.7 l out of a 98 suburban without interference ?

[@JB-ro3sz]

could quench be measured on an assembled engine? maybe with some solder through the spark plug hole?

[@cuttersperformance]

Never tried on an assembled engine, but solder could work. I just might have to try that

[@paulz2641]

Fact, composite gaskets blow at high boost vs copper

[@nickortega9987]

hey pat I have a question I just installed 8803 cam AFR vortec heads on a l31 block I have a sniper with timing control and it idles great I went on a test drive and it's popping like the timing is off any advice would be highly appreciated thanks

[@cuttersperformance]

Hey Nick, did you get your issue sorted out? Email me at [e-mail] if you still are having issues. Ive done alot of holley snipers and might be able to point you in the right direction

[@roncoburn7771]

Iam running 2.5 thou in the hole on my Harley m8 street bike

[@karlvanboxel561]

Not sure about v8s etc but many motorcycles run at .027”

[@andy347495]

Would the .060 max piston to head clearance apply to a 454 also? I have a 454 short block that the pistons are .045 in the hole and the thinnest gasket I can get for a 4.350 bore is .039 thick.

[@andy347495]

Am I asking for detination issues?

[@nakedshorts6784]

That sure sounds like a lot of gap. Maybe look for pistons with higher tops or get block decked. Sounds like allot of pain, I know. I don't think it's that much different from small block to big block engines. I could be wrong. I'm doing a 350 sbc build with every piston checked in it's place .004 out of the hole and .0028 head gasket. AND I"M SCARED...But I hear you can get as much as one whole point higher compression. ie. 9:1 / 10:1 before detonation. Just gotta remember age/ware also ads to the equation .

[@cuttersperformance]

Yeah even will a big ole bbc piston. Steel Rod you wouldn't want more than .060"

[@cuttersperformance]

Your going to go for .024" piston to head? Damn son! Some circle track guys do it because of class requirements part restrictions but they want to get the compression up. I will not advise that though

[@nakedshorts6784]

@@cuttersperformance The detonation that occurs in this area is in the last few thousands of an inch of piston travel to tdc. Thus the amount of ready to burn gasses that are trapped in this area that are detonating is crucial ,I believe this happens totally independent of ignition timing or flame front propagation. So where do we go from here, if it isn't exactly right and you have some fuel/air still in this area? Especially if you have a bit of piston rock in that direction. I have run those old deep dish piston with the narrow outer band right up to 195 psi cylinder pressure with small chamber heads and didn't give a care about deck ht. or gasket thickness. No problems. Seems to be the biggest problem for these flat tops is the surface area of the quench pad. That's why we are seeing these guys doing cnc chamber softening (who can afford that)Though.

[@pingpong9656]

Is it normal for new piston rings to make a slight scraping noise when turning crank by hand? I just put some in and was surprised to hear anything, but it seems to be the rings riding on the newly deglazed cyclinder wall. I even uninstalled the piston to check the rings and cylinder wall, and it was all good.... Just a bit confused with noise - just hope it is normal... crank turns quite effortlessly. Any wisdom from experience rebuilder would be most welcome!

[@cuttersperformance]

A bit of noise is normal on a freshly honed cylinder. Did you make sure add some lube to the rings and cylinder wall on assembly?

[@pingpong9656]

@@cuttersperformance I dipped piston in oil and lubed cylinder walls - after a few turns the noise quietened down and the assembly rotates quiet nicely... I think it's fine now - it was just probably noise from the rings contacting the new hone surface... even after a few turns it's much quieter.

[@pingpong9656]

@@cuttersperformance Yes - fully lubed. After a few rotations it's already sounding more normal and turning nicely. Good to hear many people experience same thing - so I feel good now, and can proceed with piece of mind. Thanks!

[@kevinclancy.]

great info thank you

[@sandycurrie5453]

Building a sbc 383 with vortec heads and using a COMP Cams 12-242-2. Been trying to order an Eagle rotating assembly but all I can find is with flat top pistons with 5cc pistons. From what I read this will give me 10.1 CR. Would the 10-12cc dished pistons be a better choice to achieve 9.5 CR. Or can I get to 9.5 CR with the 5cc pistons with a thicker gasket. What are peoples recommendations here. 🤔

[@cuttersperformance]

Shoot for a combination that will give you atleast 9.5:1 and have a tight quench of around .040"

[@williamquire2115]

Call as you won't but all the area inside the cylender head is a combustion area

[@williamquire2115]

If not the cops of the head would have no matter, that is why there are different cc heads which in reference to the area where the valves are I beleave

[@Meatwad.Baggins]

If the piston were to hit the head what would happen? Break the piston? Break the crank? Or would it just stop and quit running? Would it damage the head? I had my heads shaved on an old carbureted 360 bored 40 over and I think that could have happened. My mechanic replaced a piston head but I dont think that really fixed that motor. Also I had it reringed after that and we found what was probably a screw or something laying on the piston head. It was beat up. This experience is what kept me from getting into motor building. I let it get to me too much I guess. 😕. Apparently it runs now but it is in better hands.

[@cuttersperformance]

The piston would probably be the weakest link, then probably a bent rod, damaged head. It would depend on how bad its hitting. Often times it's just kissing the head and causes damage to the piston only

[@gregleenyit]

@@cuttersperformance If the piston is just kissing the head it will usually beat the daylights out of the rad bearings...ask me how i know

[@cuttersperformance]

@@gregleenyit haha makes sense! Got a story?

[@AreaThirteenThirteen]

@@cuttersperformance I have a strange story...I had a .40 over 350 with 305 heads and flat top pistons with valve reliefs and a mild RV cam, I didn't take any measurements or even know what size the chambers were, this was back in the mid 80's, I was young and broke and we didn't have the head selections like we do now I just used what I had laying around but it pulled hard and ran good for what it was. I know the compression was pretty high from the way it turned over and it would ping with the vacuum advance hooked up but I daily drove it for about 80K miles and it developed a noise where it sounded like there was a small piece of metal in the number 8 cylinder. I tried pulling the plug and rotating the engine by hand with a hose stuck down in there hooked up to a shop vac to remove it and it still made the noise afterwards. I ended up pulling the head and there were small dents in the piston but no damage to the valves etc. I never found the object in question then put it back together and the noise was gone, drove it for about another year and one day I parked it at work and it was running perfect then when I went to leave work it acted like it was hung up when I went to start it. I kept bumping the starter and when it fired up it sounded like someone was inside having a field day beating some pots and pans together. I shut if off and had it towed home, and when I got around to pulling the engine and tearing it down I found the number 8 rod bent and twisted in such a way that it shrunk the piston straight down to where the skirt was contacting the crank counterweight just enough to where was making the loud knocking sound there was no other damage to that cylinder or any of the others including the rod and main bearings or pistons at all, to this day it is still a mystery to me.

[@joeyjojojr.shabadoo915]

So, are we talking about the possibility of an 11:1 carb or port injection engine on 93 ? or is this more to keep the average 9.6:1 engine from pinging on 87 ?

[@cuttersperformance]

Both haha I've done 11:1+ on 94 and 10:1 on 87. My vortec headed daily is almost 10:1 and runs on 87. Full timing and no detonation

[@joeyjojojr.shabadoo915]

@@cuttersperformance With the current fuel prices, the world needs to see more semi-performance street builds dedicated to 87 octane.

[@cuttersperformance]

@@joeyjojojr.shabadoo915 soo true 🤣🤘

[@joeyjojojr.shabadoo915]

@@cuttersperformance There is still hope in the coming years. Direct Injection junkyard Chevy LT engines. All that compression and happy with 87 octane.

[@cuttersperformance]

@@joeyjojojr.shabadoo915 i had this exact conversation with a guy at the shop today haha LTs are badass

[@SuperTambo69]

Could the bowl be redesigned to have a quench area flow into chamber better?

[@jjmccloud]

Nah

[@Airman..]

Personal experience: wide quench, deep exhaust note Tight quench: crisp/sharper note NA/NOS engine: run as tight as possible Boosted engine: quench is not important matter of fact there is a chamber mode intended to delete the quench pad called "chamber softening" it allows to run additional timing without knocking and it is perfect for a full blown race engine that give no 2F about MPG

[@williamklibinski3475]

So I am building a engine that I have been trying to learn from you. I'm also a roundy round stock class. Not wanting to blow up my engine in the first round either. 😂 really don't think someone will have that much of an advantage over me to be pushing the limits on the engine next to having a good suspension setup. So are you saying that if I have my block 0'd out and use a regular head gasket I will be in a safe zone? Also if I do that and ran into ever needing to get new pistons, could I run into a problem with it pushing past my zero deck height? Thank u again for your channel.

[@cuttersperformance]

Thats exactly it, Zero deck with a .035 to .040 head gaskets puts you right in the sweet zone. Guys will run less that, but obviously, it is not recommended for engines that will see lots of rpm. Thanks for checking out my videos, I appreciate the positive feedback

[@Faolan161]

It's worth noting that when guys run less clearance, they always feel the positive results.

[@100amps]

Do dished pistons impact the quench area, or do they usually dish them only under the combustion area?

[@cuttersperformance]

The best dished pistons are only dished in the combustion chamber and have nice quench pad. Stock style dished pistons have a center dish and only have a small quench band

[@100amps]

@@cuttersperformance Thanks! Just found me an 880 block, 4bm, fuel pump ready. Starting a 383 stroker build this winter. Stoked! Hey Pat have you ever used Performance World heads. They're not too far from me, here in the Vancouver area. They look good, but...

[@Rodeshion]

I guess you never made the video explaining the humped pistons or dome pistons and what has to be done to use them?

[@victoroneill7924]

No wonder hemi heads with the spark plug in the middle run so good. Little to no quench area

[@cuttersperformance]

You'll actually notice on a new style hemi head the small quench pads at each side, rather the the full round early hemi heads. Helps promote turbulence in the chamber, mix that will the amazing flow of those heads and you can make some great power

[@TheFARM2019]

This is the same idea that im going for on my inline 300 build… i have a CNC head with bigger valves where the valves have been unshrouded… and im going with a set of round dished pistons (hypers) to maximize the surface area that the combustion is pushing down on… i know its not going to make big power with 8 to 1 cr and mild cam, but im hoping for a higher flowing engine and with more air/fuel in bowl and plenty of advance it may just perk it up a bit… 🤷🏽‍♂️ but i guess ill find out

[@tahcogunworks]

The old hemi heads had little to no quench and pinged like crazy.

[@braydenmeals9311]

Im building a 99 ls1 5.7l with stock short block, double cut valves in a set of 862 heads. 61cc combustion chamber i believe. I think 10.7 to 1 compression rn. I want to run a thinner head gasket to get to 11 to 1. I know pistons rock a little in the hole rn. Its still being built. Pistons go .003 out of the hole at tdc. Any advice?

[@motorkraftautomotive6492]

Depends on the gasket thickness at that point, .030" thickness is what i would go for, David Vizard recomends .025 to.035" you be fine< buck check your piston to valve clearance.

[@paulz2641]

With an aluminum rod I'd go 60 th inch clearence of valve to piston clearence