The Affects Of The Combustion Chamber

[@aishayana4298]

I so hope you talk about deck heights. Tight decks make turbulence and the combustion process is much more efficient.😊

[@baims8367]

Love that you’re willing to “help”. You have great “Instructor” like delivery about you .

[@WesAdams-HillsideAuto]

Thank you Sir! You brought some light in that I have been thinking about. I also look at old FE heads (1958-60) and wondered why they got rid of the kidney shape combustion chambers.

[@equipewilliansmecanicawell3476]

Hey ... from Brazil i loved this vídeo...thanks you make me think different things.

[@MsKatjie]

Mr. Salter, I very much appreciate the time you take to explain the chamber. Thank you for addressing one of the most crucial parts of it all. I have noticed a change in volume, as in smaller, in more modern designs, well Oz Clevo heads. So, less time to bring the pressure system up, before it starts working. I got a 318 shaved head, with a consistent colour. Maybe not as bad as one thought. You goto come to the Great Southern Land, one of these days.

[@mikebrown4429]

I’m building an amc 360 . This engine is a real pain in the neck. It was supposed to be a budget rebuild of locked up motor . It spiraled out control (money) very quickly. The knowledge that you and other utubers has helped me understand the engine very clearly. Thank you .

[@stuartwall8212]

I heard it explained by Ben Alameda that a faster burning chamber will allow you to place more of the burn pressure in the optimum position of crankshaft degrees ATDC to drive the piston down. Spark plug locations more near the center of the chamber as I recall. Burn rate gets affected by many other things too. fascinating stuff. Thanks for sharing!

[@TimothyArnott-m7z]

Hey Brian, Tim here.....ur Poncho sub'r nerd......yea, my '68 heads gave me 11.5:1, and wanted 38°......years ago i put Kauffman Racing Al heads on it, that have a modern LS heart shaped chamber.....lost almost a full point in comp, but gained SERIOUS flow!!....i now run 31° of timing, and the loss of comp is moot......i had the idiots tell me i was gonna lose pwr, cuz i was loosing comp.....i knew what i was doin, gee went from 12.0's to 11:30's...LOOSING ALMOST A FULL POINT OF COMP!!!....less timing, pump gas, LOTS of flow........PLS dont get bogged down with the idiots, us engine nerds know better......LOVED the vid!!...i'm a happy sub'r!!....keep ROCKIN my brother!!

[@gisaac3779]

Great information on WHY things work. I was told years ago (early 80’s) by my engine mentor that when designing an engine milling the head and using a flat top would be better than using a dome with the same or near same compression. I just used it as a “rule of thumb” and never really thought much about the “why” other than the dome acting like a wall to the process of combustion. The burning field analogy is a perfect picture for this. Back then I was running a stock class 9/1 compression deal little Chevy 265 engine. I can tell you a simple spark plug trick we did netted 10hp on a 260hp 2bbl engine which made all the difference in winning and competing. 😉

[@kennyrmurray]

Hey Brian (I think I got your name right) lol. I’m glad I found your channel, I love it! I watch all of you guys. There wasn’t much out there when I built my first engine since about 95 or so. I couldn’t afford it after I had kids but now they’re grown and I’m self employed as a plumber making more money. I built a sbc for an 84 Monte SS. It was supposed to be just a respectable street car with around 550-575 HP but of course that wasn’t enough. I pulled the motor and since rebuilt it to handle 1,200HP and added an F1R Pro Charger. I’m almost finished tuning it with a carb that I converted first to E85 and now for boost. I almost nailed it so I’m ready to max it out with a pulley change. It’s my first time playing with boost so I started small. Anyway I did my own old school Dart Pro1’s. I bought a valve grinder, own a Bridgeport and a Clausing 13X40 lathe. I loved the port matching and setting spring pressures etc. I wish I could experiment these days with a flow bench and dyno 24/7! I’m sick of plumbing and Long Island NY!! Anyway enough babbling. Great channel, I love it and I’m binge watching since I found you. And good luck to you on Eric’s cam challenge! Somehow I found him when he put out his first video.

[@biastv1234]

In Australia, an engine developer Larry Perkins designed a twin cam 350 , very high crown piston. Never performed that well . Went back to it several years later and fitted twin spark plugs. Picked up over 100 horsepower, the flame had to travel too far and needed two spark plugs

[@Twogreenfeet]

I remember an aftermarket 32 valve head small block chevy.

[@leekavanagh6549]

I don’t think Larry built twin cam Chevy, he developed a twin throttle body, Frank Duggan built a OHC 32 valve sb Chevy for Bryan Thompson’s VW sport sedan

[@biastv1234]

@@leekavanagh6549 might have been Duggan , I was in Cambelfield Victoria ( Australia) when it happened. It used Porsche rockers on overhead shafts wth a high crown piston and raced in sports sedans, along with Peter Brock , Leo Geoghegan, Alan Moffat . It was belt driven .

[@MsKatjie]

Jesus, didn't know that.

[@brianwolgamot7076]

Thank you for explaining this. I really like your method of teaching.

[@BustersFabShop]

Thank you, once again for your insight and experience explaining technical theory that all engine builders will appreciate. I have a 23 degree SBC with flat top pistons and AFR 220 CNC ported heads. My intent is to run 11.8 compression ration with 93 octane pump gas and roll the timing back, when it’s show time I want to add some 110 race gas and adjust the timing accordingly. Small cubic inch… lots of rpm!👍

[@Redneckairflow]

I love the theory behind it. Alot of people don't want to learn to apply they learn to copy. If you understand the theory you can apply it to anything from a yugo to a hemi. Thank you for this

[@richardoliver1303]

You said it perfectly

[@dondotterer24]

I learned my lesson a long time ago. I put the 193 TBI Swirl port heads on my 79 2wd Blazer. Stock 350. Alot of work on the 800 Quadrajet and distributor. It knocked. Had to back off the timing about 4 degrees. It screamed and would do a burnout both tires 3.08 gear. I couldn't believe it.

[@Shademax4273]

I remember reading that it is optimal to try set your engine up so that the timing advance requirement is as low as possible.

[@danielmauter1737]

Wow!!!... excellent as always!!. Back in the day we run huge domes in 283's.. Had to learn fast to be competitive.. Alot of dome learning quick... 13 to 1 and get it to work!!..😊

[@reevesautomotivefarm9614]

Thank you so much for your insight That's a fantastic video. Your video and others like you have really helped me through the years and designing engines for my more or less daily drivers and my pickup truck I tow with. Incorporating things like this into your engine build not only increases horsepower but reliability and efficiency / gas mileage. Keep up the good work

[@larrythompson7802]

Very informative. You have expanded my knowledge further. Thank you.

[@stewarth8390]

Thanks for another great video. I won’t be racing out to design my own chambers anytime soon but I do find it fascinating and it helps understand my own engine with what it needs and also why. 350 sbc with Brodix track one heads out of the box and bolted on. Built 12 years ago, never been apart and still runs 11.4@120 in a 3600lb car. Keep up the great work 👍🇦🇺🇺🇸

[@kellyjones841]

Really helped with that drawing of cylinder stroke length and crank degrees. Also field burning analogy is very helpful. Thanks, this is down to earth explanations I can understand!

[@edpetrocelli2633]

I never went to school for high output engines cause they didn`t exist but I couldn`t stay away from them. There wasn`t much of an aftermarket parts industry for it eithter, I did drag race my car for about 10yrs and thats how I educated myself. It would have been alot easier had some one took me under their wing so to speak. I had a job offer from Bruce Crower in 1981 and I didn`t take it cause of the economy and second gas shortage raised hell in the racing industry. A bunch of tracks closed down Nascar was thinking about shortning the races. The job could saved me alot of time figuring this stuff out and you know volumes more than me and I`m 20yrs older. I damn sure enjoy your videos

[@HaHaHa-TRUMPSYOMAN]

I understood it all personally. Although I’ve never thought about it but now I won’t stop thinking about it Thanks man !

[@mdfrtech]

Makes total sense. Thank you for the knowledge! 🇺🇸

[@charlielathrop8465]

Great video Brian very informative

[@JuniorHenderson-i6q]

I have a two valve air cooled cg250 engined motorcycle here in Jamaica and I'm soaking up all his videos. 🚦🏁🇯🇲✊🏾

[@PeggyParrow]

Great vid. But i know some of it but still learned more, Thanks !

[@terrybagatella3898]

Very insightful. Thank you. I'm now thinking spark plug placement as the flame will start right there. 🙏

[@jeppakongur]

Wow🎉 best explanation of combustion chamber ❤ thank you

[@4xsilverado]

Mr Salter, I appreciate your videos and teaching the everyday guy more about this stuff

[@johnholland4776]

Brilliant info, such a lot to think about. It appears that everything coming out of a box has to be questioned and scrutinised.

[@Red9GearHeads]

I appreciate all the clear and well presented info Brian. It’s a big help to us fellas that don’t already know it all. Lol

[@LEETIGER-v8y]

Would have liked to hear you discuss quench and its impact on flame propagation

[@billlittle4285]

Great video Brian,spark plug placement is a big deal, as well as thick valve margins, keep up the good Videos!!

[@beardedgamer8416]

Been a long time.... Hungry Tiger Eating Dragon.... learned soo much from this man years ago

[@robertfontaine3650]

Nice tip on the burn marks in the chamber. Nice thoughts. I need to walk through the progression of chamber design through the last 30 years or so.

[@RussellCompton-fh3gr]

great stuff,,,helps explain how GOOD atomization will help with timing and power,,,Keep it coming,,Please

[@cjespers]

Great video, thanks for posting. Lots if things to think about. Well done.

[@keithtobin5369]

man do I love your explanations thank you for sharing this wisdom

[@rksg2003]

Now I understand how ignition timing works. I never really thought about why it changed so much from idle to higher rpm’s just knew it was a requirement. Thanks for the video!

[@anthonylorek8847]

Thank you for sharing your helpful knowledge.

[@peanut7105]

Nice seeing you pay tribute to the person who taught you about combustion chamber designs he must have been a great mentor and knowledge is a big key to success thanks for sharing awesome videos

[@jimkillen1065]

I appreciate your advice. I only know what i been told . I often wondered why certain cylinder head chamber designs make power better at certain timing levels. Way back when i was told aluminum cylinder heads would allow me to run a bit more compression on my street engine, pump gas build with around 200 ccp psi ..The only thing i found in my opinion is cylinder heads is a place not to skimp on a NA build . The good cylinder heads seem to make a mild cam carry out farther..

[@TerryBall-v8l]

How in the hell did you learn so much? Great video!

[@SalterRacingEngines]

@@TerryBall-v8l well thank you LOL

[@jamesandannschmitt6835]

You are the first guy I have heard touch on this topic. Thank you

[@peanut7105]

Great video I've always believed when you are around the old timers that have tried many ways of doing things it's best to listen that's why God gave us 2 ears and 1 mouth we should do twice as much listening as talking that's how you learn thanks for sharing your knowledge,if a person is seeking knowledge try to learn from someone who is successful at what they do and willing to share their knowledge because a lot of successful people want tell you anything they will take it to their grave

[@bobbymenzie9853]

I always enjoy your videos very good process explaining things

[@blueridgemountainprepper2166]

Every video you put out I learn something, can't wait to get into this 1

[@jcnpresser]

That’s some great information, I like videos like this. They’re nice to listen to when driving. I like Ben alameda to listen to when I’m driving as well.

[@kyleandrewburgess]

Great insight. Thank you

[@teagreen2220]

Great thought provoking video! Good info!

[@Rob-m9s]

Had a 402 BBC block, took it 0.30 over (408), the engine's original design was to be iron head oval port closed chamber 11:1 domed piston. My buddy (master-level engine builder) ported a set of second generation Chevy aluminum heads before deciding on a 6-71 instead of nitrous. Yep, couldn't run nearly enough valve spring pressure for a blower on those heads. He sold them to me at the cost that he paid for the new castings. Couldn't afford another set of forged pistons. So, open chamber BIG port heads (2.19/1.88) with closed chamber pistons. Ran like a dog . . . I got desperate and kept increasing the timing, and that engine woke up BIG TIME. I was scared, not gonna lie, but I got it up to 46 degrees and left it there. I believe it was at 9.8:1 and it ran on Sunoco 94. I built that engine for a '65 Malibu daily driver. I patterned it off of a circle track engine (3500 - 6500). Crower 0.615 lift 107 lobe separation solid lift circle track cam, 830 cfm annular-discharge Holley (drilled a hole in each throttle plate) with a Holley Strip dominator manifold reworked by the late, great Lee Shepherd. Engine pulled very little vacuum, had to ditch the brake booster (discs off '70 Monte Carlo) and shift in neutral at every stop. 10" 3500 stall TCI converter, turbo 400 kevlar bands/clutches (BFH in the tunnel to fit that), TCI valve body mods. 4:10 posi Mark Williams axles. MSD 6AL with electronic advance curve kit, timing master adjustment, wires, cap, coil. Hooker Super Comp headers (one tube through wheel well) into 3" duals exiting before the rear wheels. I had the engine for 6 years as my daily driver, even through harsh winters, because of protection and maintenance. A temp gauge in each head, temp for engine oil and trans fluid. My oil pressure was taken at the end of the oil galley to measure the pressure that was left over. I had a Pro Light with a 30 lb. Hobbs switch right over the oil pump. Get a good 7000 rpm pull and you emptied out the 7 quart Moroso oil pan. It might light the Pro Light, so you'd lift and shift and it'd go out. Never harmed the engine.

[@bigdog2024]

Really good stuff! To me, avoiding all the chemistry and physics of the fuel itself which all burns much the same when you get it right, this is common sense. I had an uncle way back in the 1970s who built some successful engines for dirt racing in the Carolinas and I learned a lot just asking him question. He was nice enough to tolerate an 8-10 yr old kid trying to learn. You are doing the same thing for adults and I think you have found a new passion for sharing your knowledge. Can you do something on plugs? One thing I’ve never got my head wrapped around is spark plug heat ranges and the length of time the spark itself is active. I’ve heard some engines like a longer spark time maybe to ignite a larger volume of charge in the cylinder (bigger displacement) the spark needs to be hotter or longer in duration? The older hemi’s way back in the 60’s had two plugs, was that to ignite the charge on both sides of a domed piston at the same time or we just had crap ignition so if we had two pretty sure one would fire! Thanks again and good luck on the cam challenge that’s going to spawn some videos I am sure!

[@rocknraptor3195]

Enjoy your videos bud, keep em coming!

[@wayneskelly4297]

Great video. Going to look at the pics of one I just tore down a few weeks ago. LOL

[@adamhayler8105]

Awsum Brian, to say I think it's great that guys that have been there done that and are willing to share is an understatement... I have a 408 windsor, all the modern goodies, cnc aluminium heads... 11.6.1 comp, 220psi cylinder pressure. Runs on premium pump fuel. Only wants 28° timing. Makes 560ftlbs @ 4300 570hp @ 6200 duel plane intake. What's you're saying is I have a good efficient combustion chamber design with minimal nooks and crannies? Most others say oh 28 that's to low, to much cylinder pressure need race fuel & more timing.... Would be interested to hear your take on it.🍻 mate. Adam

[@MsKatjie]

Nice what cam? No Clevland heads?

[@keithbarron3654]

The tuning school took a Corvette race car they had, tested various fuels, adjusted volume of fuel and timing on chassis dyno. It showed the variation of fuels . Some burn fast/slow and density. Was good video series.

[@bengibson8778]

Id love to see your dome design!

[@Jeffery-yo4vk]

On point Brian. 😊

[@dondotterer24]

Thank you for the valuable information. Well explained! I have alot of questions about chamber modifications but maybe you will make more videos in them . I don't want to bug you. Thanks!

[@blueyhis.zarsoff1147]

Spark plug location is also very important. if it runs with less advance then its a good chamber

[@stephennelson6041]

loving your channel,thankyou!

[@4speed3pedals]

I had never seen the shape of the SB 2.2 heads from Chevrolet until you talked about them. I had to search to find a pic of the bottom of the head. To me, it looked quite similar to the 409 head with deeper valves. That W series had an odd chamber, with or without a compression dome.

[@timothyfalkowski6007]

the best chamber shape is found in heads like used on 2 stroke race motocycles, they are not restricted by valves, so are a true centered dome cavity and centered spark plug.

[@peterfairlane2065]

SB2 and R07 nice chambers . I'm running N351 on my street car. Seems to work well

[@ronaldlingle8766]

Well I thought it was very informative myself keep up the good work

[@robbyposey9128]

Man I am so fascinated with your videos.. I’m currently building a 4 cylinder Honda engine… I’m gaining so much from your sharing of knowledge and alternate way of thinking really helps me understand or at least I think I am understanding things that I never took into consideration.. I would honestly love to know your thoughts and tell me if I have gone in a good or bad path with my setup if you would possibly recommend anything different ? So if you read this comment and can spare the time to msg me I’m just a guy trying to do his first engine build and found out I think I have a passion for it truly the correct way not the most popular or most sought after..

[@GrandPitoVic]

Great information brother!!! Keep em coming.

[@gtrider316]

Great information, thank you sir!

[@chriszucker7500]

Very informative...thank you!

[@waynetoneseekerandersen2213]

Great discussion

[@jeffcreel5508]

Outstanding video Brian,at least I know I'm on the right track

[@michaelgiglio1571]

Good breakdown Eric. For those reasons, I think the early fords with a centred closed chamber, got it right, 5o yrs ago while everyone else went the wrong way, eg. Chevy, Holden, FE wedge, Hemi. All wrong. Mike

[@gskjr01]

Thanks great explanation

[@scottosborne8735]

It occurs to me that modern engines are very well engineered. Ford 5.0l is 12:1 and will run on lawnmower swill.

[@mattharrod5362]

Bryan, some follow up questions on spark plug placement within the cylinder head: in theory with a flat top piston and perfectly symetrical domed combustion chamber the ideal spark plug placement would be dead center of the dome, correct? That way the flame front / pressure wave hits all areas of the piston top at the same time and is very burn time efficient. Does it then follow that in a wedge shaped combustion chamber that the spark plug needs to be offset towards the larger/wider part of the chamber in order to achieve the same same burn time efficiency? That said, the whole point of your video is these many relationships are highly dynamic and so a flame front that does not hit the piston top perfectly symetrical might not always be ideal?

[@SalterRacingEngines]

@@mattharrod5362 great comment great thought and great question. In a wedge head design, I personally like the spark plug canted towards the exhaust valve going away from the intake valve what this does is open up the line of sight from the electrode to the incoming air fuel and if everything is done correctly the fuel and air will flow towards the exhaust side due to the port and chamber design therefore causing a swirling effect as it is ignited which would for sure speed up the ignition process and seemingly cause a complete combustion burn in the cylinder. Would you think less of me if I told you I just don't know all the answers. All I can say is I've tried so many things I don't even remember them all and I can tell you a lot of the scientists are wrong. But for now I know when our engine makes more power than the other guys you have to be doing something right. And of course that's not always the case but we do pretty well. As far as the hemispherical chamber in the center spark plug yeah ideally you would think that would be the absolute best way to go about it. And I think the only drawbacks is mechanical limitations due to the size of the head when you start to really open that thing up it can become a pretty large piece of aluminum. But honestly what I have found is a lot of these pro mod engine builders have adopted the NASCAR combustion Chambers to their very very high flowing cylinder heads and the power of people are making these days it's just unbelievable. And they're not using hemi heads to do it well I should say a lot of them are not using hemi heads but a lot of them are so it's tit for tat. I think the only real way to measure is to make them all have the same cubic inch make them all run the same fuel and make them all be naturally aspirated to see which chamber could possibly come out on top. There would be a lot more to it than that but you know I think you get my point

[@mattharrod5362]

@@SalterRacingEngines Thanks for taking the time to reply. Cetainly don't think less of you for admitting you don't know it all. If only more people were so humble. Don't pay any attention to the haters; when you skeewer peoples sacred cows they can either step back and rethink, put forward a better argument, or sling mud at the other guy. Lastly a video suggestion: if you haven't done so already, maybe a video about the NASCAR comustion chamber and the history behind it.

[@Shademax4273]

How about the afr does much affect on burn speed? Thank you for illustrating this. Mind blown.😮

[@SalterRacingEngines]

@@Shademax4273 yes but that's why I said in the video whatever air fuel ratio you have whether it's lean or rich or perfect it will burn at a set speed but your piston speed changes with RPM so you have to change your timing to match that. That's why at idle you don't need that much timing but you need more timing at high RPM.

[@Shademax4273]

@@SalterRacingEngines Ok I see what your saying.

[@russelltripp9313]

Remember, at 6000 rpms each piston reaches TDC 100 times per second. Which is why the plug needs to fire prior to the piston reaching the top or the burn of fuel will happen after the piston starts down

[@bigdog2024]

The difference between good timing and bad timing is a matter of a few milliseconds!

[@ryanlindley6476]

THE SPARK PLUG HAS TO FIRE DURING THE COMPRESSION STROKE FOR THE FLAME FRONT TO APPLY PRESSURE TO THE TOP OF THE PISTON DURING THE POWER STROKE.

[@craig8187]

The poor old combustion chamber has a big job. It serves as the end of the intake port, it is the beginning of the exhaust port, must efficiently control overlap scavenge flow and efficiently manipulate combustion flame front. The more you learn about combustion chambers, the more you relalise how much you dont know about combustion chambers.

[@PaulCTownsend]

Very interesting info thank you. But what I want to know is how do I know how much timing my engine needs I don't have no dino.

[@Twogreenfeet]

Try a few different setups with a drag strip app. If the engine pings back ignition timing off 2 degrees.

[@stephenaslinger818]

Not only that the timing required will be different from cylinder to cylinder on the same heads same piston so add another variable I think the intake runner fuel distribution and firing order effect it

[@georgedreisch2662]

Regarding shape charges, the explosive is outside the v-shaped cavity, and the ignition point is at the base of the V. The propagation starts at the base of the V, and moves forward up the legs of the V, impinging on each other. Think pinching a melon seed between your thumb and forefinger, till it shoots out. The copper liner becomes a jet of plasma, shooting out of the V, that does the cutting. Got any information or experience with the passive pre-combustion chamber spark plugs, like they’re using in F-1, to deal with lean mixtures?

[@SalterRacingEngines]

@@georgedreisch2662 those plugs were designed for extreme at the most extremes cylinder temps and pressures. In addition they're in a corrosive environment. like I said in the video the fuel Burns at the same rate and it's getting to the point to where the F1 engine is out running the fuel burn. I don't have all the answers to that question but that's an interesting technology.

[@stevenhobbs709]

More of this please.

[@hughobrien4139]

I would like to hear your thoughts on valve margin thickness in these cases. Ive flow tested valves back to back with the only difference being margin thickness. The thinner valve margin around .050”-.060” always flow a slight bit less than a valve margin that is .080” and up. Valve weight aside. Often I see engines with enough piston to valve clearance to accommodate a thicker margin that flows more with the added benefit of increasing static compression without milling a ton off of a casting. I’ve got a scenario brew on my own engine. Stock LS3 heads. Need more compression. Just don’t feel good about milling .085” off of the deck surface when I can suffer the cost of a 2.165” titanium intake with a much thicker margin than I can control with the likes of a hollow stem stainless steel valve. It’s a question that I think I know the answer to but it’s based solely from flow tests. Listening to your design parameters surrounding a dome piston being in the mix makes me wonder if I’m chasing myself into less so far as ignition timing is concerned.

[@SalterRacingEngines]

@@hughobrien4139 hey man I will tell you this margins are extremely and I emphasize extremely important. I was going to get to that at some point. I was just a little concerned about how much I wanted to actually talk about because there are some hidden secrets right there. Especially with getting your low and high lift flow numbers. And just because you really seem to be on the right track I'll tell you this not only is Margin thickness important but the angle of the margin is important as well. You don't always have to be 90° with your margin.

[@seanbrown8269]

Do you flow in reverse with the different margins? I'm always trying to optimize forward flow without picking up reverse flow, though I don't have enough correlating dyno info yet to say for certain what is best.

[@hughobrien4139]

It’s really a case of flying blind when you’re limited to a flow bench. Even more so when you have witnessed first hand what wet flow modifications can bring to the table. Years ago I was working with a set of spread port BBC heads. Big Chief type. 14 degree big valves big air flow. 480+ which was big back then. We had issues during two annual freshen ups with this engine. The gussets that support the wrist pins in the pistons were cracking. The tops of the pistons and the combustion chambers had a very defined carbon streak right down the middle about an inch and half wide. Outside of that carbon the parts looked new. Engine ran very well. Just couldn’t keep replacing pistons every freshen up. With some outside the shop influences the decision was made to send the heads off for modifications based off of wet flow testing. When the heads got back that 480 cfm was gone. 460 cfm was about all they would flow test. This will always drive anxieties in a performance shop with limited resolutions. In short that lost cfm was never realized at any level. Can’t say the car ran faster but no power loss what so ever and more importantly when the engine came back in for its annual freshen up the entire combustion chamber and top of the piston had a nice even coat of carbon distributed all across. The pistons lived well. Everyone was happy except me and my flow numbers. (Later on I figured out a new valve seat angle combination and the airflow went well over 515 cfm but the limits of the Super Flow 600 began showing when we couldn’t hold 28” of test pressure.) In any event those valve job improvements came by means of a 50 degree seat vs the original 45 degree seating angle. I for one have never witnessed any head to flow more by reducing the seat angle from say 45 degrees down. Not to say it doesn’t happen or that it does not aide towards improving wet flow characteristics. It’s just what my flow testing has directed me in my efforts have shown. Similarly as you mentioned the radius work I’ve done to exhaust valve margins has shown nothing on the flow bench. This has been tried several times in years passed with no clear indication to justify any additional costs to both static compression figures or flow numbers. Yet again it’s lack of resolution without a wet flow bench. So you’re at the mercy of what a reputable engine builder has to share. No different than doctors advice. When you know they’re educated on the subject and they offer free advice, you take it.

[@SalterRacingEngines]

@@hughobrien4139 great comment

[@MsKatjie]

@@hughobrien4139 Very interesting.

[@shawnmcatee895]

Listening to the way you analyze things, sometimes I wonder if we're related. The amount of time Ive just sat an pondered, looking at a piece, wondering what was going through an engineer's head when they did XY or Z, I could probably have a Phd. A great demonstration of a cylinder head that works is the Honda CRF450R. It's practically flat. There's only enough peak in it to make room for the 2 intakes and 2 exhausts. At 12.9:1 they're making 1.06hp per cubic in. Right off the showroom floor. on pump gas. Do that math on a 358. The bore stroke ratios are wildly over bore. Almost 2;1. But looking at that combusion chamber, and what they call a "dome"...completely flat plateau that gives way to a perfect squish that gives you that perfect burn witness. The only washed place is the squish.

[@dannylee9138]

Your videos make a guy look at the hole picture that's what I like about your video and knowledge

[@CJ5EVOLUTION]

I wondering if that is part why a very small CI import 4cyl makes more power per CI than the V8, beside the higher flowing heads the flame travel is better because the spark plugs are in the middle of the chamber, so even with a higher dome piston the flame front and pressure wave distributes more equal.

[@SalterRacingEngines]

@@CJ5EVOLUTION one thing is for sure on something like that especially if it's a dual overhead cam And what people often forget is that with a dual overhead cam you've got the high flow of a big valve head with the velocity of a small Port head. So you have the best of both worlds. Plus the spark plug is in the center which helps the combustion process so yeah it's a combination of all of it.

[@MsKatjie]

NA?

[@CJ5EVOLUTION]

@@MsKatjie NA or Boosted, look at Honda engines, Porsche, Ferrari, any of these 4 valve per cylinder with center spark plug, will bit a 2 valve cylinder head in HP per CI. You have 4 cyl making 210 HP stock engine of 2L, there are 4L 6 Cyl making 465hp stock, all of them, 4 valve per cylinder DOHC.

[@richardmoerke9329]

Nice. No magic pill. Every head is different. Then you put on the aluminum head. Just have to find a master like you. Any fast tips to help? I know I’m f cause I like the mopar LA small block but any help to what I should look for would be nice. Thank you for a great video.

[@Twogreenfeet]

I'm thinking magnum heads.

[@MsKatjie]

Working on two myself. Nothing sounds as good as a cammed, compted up LA. Not even a clevo. Blasphemy, on my part. I paid a shit ton of money for some Edelbrock victors. Lovley but, different intake, rockers and fuck knows what else. So at the moment just shaved the buggery on some 1976 318 heads and put some 0 deck height .060' KBs in it. Measuring clearance at the moment and will check chamber volume but it aint much. Solid 238 at 0.050 and 244 for exhaust. 1.94 ' intake and 1.6' ex. Blended bowls. Get the best valve job and it should hammer. Single plan intake and it will get a VRS on it. Cheers.

[@ericanderson6671]

I was always told, the smaller the chamber the better, or more efficient the burn. Why Ferrari makes 12 cylinders with tiny little bores. Same with Ford and Dodge 10 cylinders.

[@paulfrantizek102]

I recall reading this is why everyone in F1 eventually settled on V10s during the 3.0 and 3.5L formulas, optimal combustion chamber size.

[@truthboomertruthbomber5125]

Also makes it easier to have highly efficient port flow and cylinder filling.

[@flyfaen1]

Absolutely correct. I deal mostly with "computerized" stuff, and in that regard, even tho ignition tables still are in degrees, much like in the fuel table with injector millisecond open time where the injection time is fairly flat across rpm for each absolute pressure cell, only varying with cylinder filling... aka if the engine magicly had 100 % VE at any RPM, all cells at 101.3kPa absolute would be the same millisecond value, and all say 50.6 kPa would be half. Same goes for ignition. if one "reverse-engineer" ignition advance in degrees vs. rpm into millisecond burn time, the actual burn rate in milliseconds for two points in the table with 100 % VE would be basicly identical, regardless of rpm 😉 But, speaking of burnrate/burn time, you could allways go down a deeeeeeep rabithole and make a video on the effects of turbulence on burn time caused by squench-pad action, and swirl (and/or tumble) 😂

[@MsKatjie]

Far out. i will stick to VRS's. Nice info.

[@jesseduke694]

I think about chambers & efficient combustion all the time. There are so many variables & only so much I can do to change some things it's hard to pin point what might be "best". Wich is up for grabs also? If best is the most power? And at what level? All my engines I work on are my personal street engines, not racing competition engines. It's only a hobby for me but I love the science behind this stuff & chambers are what I wonder about alot. I run alot of big ford 4x4s so I work with 390 FEs & 460s alot. Somtimes I will unshroud some valves & maybey layback a quench pad alil. I know when I had a set of heads flow tested I saw big gains by unshrouding. But I am tempted to try other things that I'm just not sure of yet & I don't have the R & D to be trying some stuff out. Just using a different head with a different chamber might perform different but they usually have more differences than just chamber design so how can I know what is really making the differences?. Ya know.

[@hectorsalazar5584]

👌you doing a fine job bro. 🏁

[@mcwbadass]

Great information!!

[@SalterRacingEngines]

@@mcwbadass what do you mean

[@mcwbadass]

@SalterRacingEngines having a platform like KZbin where you've got thousands of eyeballs can have a real impact on people's decisions as to what and who they buy from. 15+ years ago, that piston company could have just ignored Powell machine with minimal consequences compared with what we've seen here today.

[@mcwbadass]

Oh shit dude I just realized I thought I was commenting on a different video!! My apologies, your content is fantastic brother, keep it up!

[@SalterRacingEngines]

@@mcwbadass no worries

[@kenwatts5410]

I like to check the timing mark on the plug as you creep up on the timing, street motor I'm talking about.

[@inscoredbz]

I figured part of tge timing being advanced was also due to tge time it takes for the spark to basically start at the distributor and it takes time for it to reach the plug to actually spark and ignite the fuel. Also part of it geing chamber shape that controls how fast the burn spreads. A shitty chamber needed more timing. That was always my take on it.

[@MsKatjie]

Induction leads current or visa versa? Not very helpfull, me. But hysteresis is the time for initial flux build up and it is finite, not instant. I think from memory, no guggle. Cheers.

[@arturozarate1752]

Salter....good video. I'm a firm believer in the combustion chamber and its necessity for controlled flame travel. I've got an issue with off the shelf dished pistons. If I'm wrong correct me please. I feel like the full dish piston renders the chamber of aftermarket heads useless. Then the half dished piston is side loaded with the quench area on half the piston only. If I've had to use a dish I've pushed my clients to a custom piston that mirrors the combustion chamber. Your thoughts....or maybe discuss in a future video. Also v-grooves shaped and aimed properly do work man. By the way I meant this to agree with you on a comment you left to another's question.

[@SalterRacingEngines]

@@arturozarate1752 yes they do and yes you are correct. There is such a thing as a perfect dish piston but it's hard to accomplish that when you're trying to have valve clearance and compression ratio. It's just always robbing Peter to pay Paul. If you make something great over here it hurts something over there

[@superstockamx9064]

I believe you are referencing “Singh Grooves”? @salterracingengines I wanted to see if you could discuss this. I know of a fellow racer that has a similar engine as mine (similar, but not the same) and he has used Singh Grooves, noticed no power increase but optimum timing dropped from 40° to 32°. That in itself should be worth something. Right?

[@SalterRacingEngines]

@@superstockamx9064 yes they work in that way. It aids in igniting fuel that can be slower to ignite due to poor chamber shape. Helps Prevent detonation and spark knock as well

[@arturozarate1752]

@@superstockamx9064 of course it's worth something. Glad you commented here. Thanks Salter. I've speculated and tested from time to time, but having a known winning veteran to get some quick and awesome feedback makes flowers grow in the snow for me.

[@arturozarate1752]

@@superstockamx9064 btw, I do mention more about them in another comment on this very video. I'll try not to do that again. Had me thinking, "Shit did I say something wrong and my comments got deleted?"

[@StevenBowron]

Very informative

[@gabrieldimarco9646]

Great video Brian. You must have been reading my mind as I have been thinking about why some engines require less ignition timing than others and I was thinking about combustion chamber design but I didn't know what makes a good design. Thank you for clarifying. Would straight plug or angle plug make a difference as well for burn efficiency?

[@SalterRacingEngines]

Yes absolutely spark plug placement has a lot to do with it

[@gabrieldimarco9646]

@@SalterRacingEngines Thank you

[@billshiff2060]

A good design is one that puts the spark electrodes in the center of where the charge is most concentrated. If you could put the electrodes in the center of a ball shaped chamber that would burn the best but we can't have that so we have to do all we can to approach that shape. You want to minimize the surface area of the piston/chamber as far as possible. That is for unlimited octane fuel that won't detonate. In reality we have to deal with possible detonation and that is where quench comes in. Quench both reduces detonation while pushing the charge to concentrate into the spark area and while doing that it adds some valuable turbulence to the mix to speed combustion. Early hemi chambers used that idea and they work well but only for low compression engines. Once you stuff a big ugly dome in a hemi to get the compression up they suck big time.