HOW TO: PICK THE RIGHT TURBO!

[@95Sn95]

I love your real world mentality vs channels that just mess around with big dollar equipment that's unaccessible to most of us vs several junkyard based engines and repurposed or budget add ons, I absolutely love the other guy builds, please do even more! I watch all your content keep up the great work!

[@zadokmotorfreight2423]

agree 100%!

[@DBSSTEELER]

I love it when you talk combinations. So many people don’t understand how important getting the right parts that work together is.

[@ProjectCarTV]

Good stuff as usual. I got rid of my 4.2L Trailblazer btw.

[@lukestrasser]

This was a great test! I was surprised a little bit by how high the back pressure was on the S480. Really killer test Richard.

[@r.h.5052]

I've recently found your channel and find it educational to say the least. Dispels the myths. This is from an old school 67 year old gear head with his first LS. ( SS truck LQ9)

[@richjames85]

Your the best engine guy on here so simple to understand best explanations iv heard I'll be sending a lot of people here who think 1000hp turbo will give them 1000hp at the wheels on a stock engine

[@StabyMcStabsFace]

Run hard, it absolutely can. If it's an efficient motor, it can make well above the turbos rating.

[@brooks3racing1]

I’ve been waiting for this vid. Thanks Richard! Pls keep up the great work. 👍

[@richardholdener1727]

Thanks, will do!

[@dr_tate]

@@richardholdener1727 thank you for all your work.. I'll come help with the wrenching when your in So-Cal ... I'd like to see the same turbo with 3 different hot sides.. see how it would effect the curve.. which one would be better for the street with the backpressure that's not too crazy

[@crw3673]

This turbo comparison, reminds me of cams. Smaller cam, more responsive down low. Not as powerful. Large cam, fall off down low, more power up top!

[@GnarshredProductions]

you are correct. Smaller turbo makes boost at lower rpm and better for torque but runs out of breath up top in the higher rpm's, bigger turbo doesn't light off until higher rpm's but when it does come on pulls like a freight train up top. An engine with a smaller cam would probably be better with a smaller turbo and bigger cam should have bigger turbo. It's all a balancing act where you have to choose components based on what sort of rpm range you want the engine to make the power at.

[@joelstevensz06]

@@GnarshredProductions I think that is the opposite of what Richard holdener was talking about in his b-tec video

[@randalljames1]

But I want something for nothing!! :) is funny how much guys scrutinize parts like this when it makes so little difference for most...

[@edwinavila8023]

Good info honestly never put that much thought to the hot side. Thank you!

[@GermanShepherdsofOKC]

Couldn't have said it better myself, no fairy dust marketing! Flow is what it is, if it flows it goes doesn't have to be magic.

[@PupcreekStudio]

Excellent video. Your explanations of boost vs HP vs displacement were very enlightening.

[@bosshoggett]

What would have been really interesting was advancing the cam in the larger turbo to see if you could recover the low end torque to match the smaller turbo at what cost to peak horsepower.

[@mikef-gi2dg]

There is that combination thing again.....power desired, intended usage, money available. I have never built a 600 hp engine, there is no way I would try turbo, without a dyno, can't afford to just blow it up......good demonstration.

[@mikef-gi2dg]

thats 1000+ hp turbo...

[@jamesshaw89]

Love your videos, I'm trying to pick a turbo now and find the right balance and you are helping a ton!

[@MegaRomans01]

Super informative presentation, thx for for your work. Also no the way you did it with the bleed valve illustrated the differences in turbos better and the back pressure chart was cool

[@mikenoyes3460]

Why not just bolt different hot side housings (AR) to the same turbo? That would really make your point.

[@bill2178]

Yes size the compressor for power and turbine ar for efficiency

[@boosted2813]

@@bill2178 finely some one gets it.

[@richardholdener1727]

we can do an AR test

[@richardharris492]

I think he means changing hot side wheel more so than AR size

[@mikenoyes3460]

@@richardharris492 Not really. Same wheel just different AR housing. The Housing AR size is a big driver on back pressure. A housing swap is quick and relatively cheap compared to a wheel (cartridge) change so is something that someone might consider doing. I think it would be a great test to perform.

[@lloydholt6511]

As always you have a way of simplifying a problem so a dummy like me can understand it. Kind of like eating the elephant, one bite at a time.

[@stevesolo16]

One issue that should be looked at is whether or not it is worth spending the extra money on dual ceramic ball bearings or does the traditional film layer/journal style better suits your needs? Not everyone needs pricey ball style bearings. Most people don't even know how to run them correctly. They flood the bearings with the wrong type of motor oil, which will hinder the balls from spinning in the races. Ball bearings actually need very little "race" oil. A fine mist is what high-quality bearings are designed to work with. They need just enough to keep them cool and from making metal to metal contact with their surroundings. Many times film layers/journals are superior to balls if it is going to have a super high shaft speed(small turbos) and only a hydro-dynamic layer can cope or the engine is going to get street use. Research before dropping $2500 bucks on a turbo when a $900 dollar unit might meet all your goals and even last longer, in some cases. There are some really good companies here, in the U.S. who make their own niche' turbos. There are some really smart guys here in America ready to help you with one phone call. Try getting genius-level answers when calling an overseas manufacturer. If you are watching Mr. Holdener's videos, take notes. His experience is invaluable.

[@jamieknight9636]

Great work Richard love what you do. thx for helping the fellow man as you do. as mentioned above back to back rear housing change would be interesting with spool rpm being a consideration. something else that might be interesting for the viewers is b2b different design turbine impeller of the same diameter. thx again

[@Wolf462]

Hey man, new sub here. I’ve only seen about three of your videos so far but damn SUCH GREAT STUFF!!! So awesome to get real world data and see comparisons that average joe’s actually build! I know it’s different strokes for different folks and the high end stuff is cool to watch on KZbin but some of us are junkyard dogs trying to make power as cheap as possible hahah I’ll be watching all your stuff now. Thanks for what you do brother.

[@richardholdener1727]

welcome, check out the junkyard stuff-plenty of videos on cheap stuff

[@patlandymore7035]

Great test! At some future point it will be really interesting to see a back to back comparison of different exhaust housings on the same turbo. Suspect it will be a bit like the LSA cam test.

[@randallslocum5252]

Ok we need more people here for the 4.7L Dodge test!!! So here with me!!! But definitely need to know about the turbos and how do you size them so awesome video

[@richardholdener1727]

I think you might be the only one

[@BillyP-49Chevy]

Richard Holderner, I love how people insult you then they say, " I'd love to see blah blah blah" You can't win Rich. Thanks for videos.

[@JaMarvelousjmar]

on the extreme side of things I'm still waiting to see you feed a SC with a turbo, maybe even twin snails into a slug. Keep up the good work, cheers

[@maxwelltollefson9947]

You should take a look at Banks power. Gale has done many of these “super turbo” combinations. Granted it’s on diesel but most of it ports over.

[@richardholdener1727]

that is happening

[@marcocasillas5023]

Great video on lots of information so I can get the right turbo for my tow truck

[@kd6tas]

I'd like to hear/see more about back pressure. You mention a point where you start to worry about back pressure. Explain that. When is back pressure a problem and how does that problem manifest itself? In videos I hear it mentioned but never explained.

[@ahoneyman]

Double the air and double the fuel gives you double your original bang. Big hotside impellers need a lot of wind to get started spinning. Before they start really spinning it's basically just in the way. Size your turbo to be on boost at the rpms you see most often.

[@foxairandheatinc8345]

Nice videos. Keep up all the great work. The reason one turbo makes more hp per psi on the same setup is because of where it is on the compressor efficiency map. As it becomes less efficient, it starts generating more heat and less airflow, thus reduced power. And it depends on the application. There is always a limit to how much octane, boost and timing you can get into a motor. Lowering the compression will allow you to run more boost and timing without detonation. If you exceed the turbo's efficiency map it can no longer produce enough air to keep up with the boost required. Thus is falls off.

[@richardholdener1727]

the amount of power a turbo supplies is a function of the na power much more than the map position

[@foxairandheatinc8345]

@@richardholdener1727 I would rather drop the compression and run higher boost and make more horsepower than run a high compression na motor that makes great power off boost with limited boost due to getting into detonation

[@daverr8163]

Great test . It was interesting to see the results of both turbos at the same boost setting.

[@Jeff88coupe]

A neat test would be to see what power each of these turbos would make on the same test motor maxed out. Put 25-30# spring in the wastegate and let them eat on race gas. That will really show the difference in the hotsides and back pressures.

[@russellbroadwell]

It would be cool to see this ran again changing both hot sides larger hot side on 475, and smaller on 480.

[@markhuffstetler1315]

That was great information Richard especially on the 6 LT. Still like to see more on the 455 Buick with cam, intake, heads and compression, thanks again Richard.

[@billwhitfield7437]

Spot on information.. huge help to my future build

[@darrenditmar2991]

Another great video exactly what I was looking for thanks

[@kirbycleland2288]

I've been watching alot of your videos and I absolutely love them! I'm learning alot! I live in South Dakota and I want to build a sbc or ls twin turbo with a blow through style fuel injection from Holley for my 4x4 squarebody chevy pickup. I want this to be daily driven year around summer and winter. Is this a bad idea or I guess any do's, dont's, or advice on the extreme cold in winter for doing a twin turbo blow through fuel injection build? Also I would love to see you do a beginners guide to tuning a boosted engine for both fuel injection and carbureted engines to get a beginner like myself on the right path and not make instant junk.

[@rubenquezadajr.5322]

Thanks for your input.. Very helpful for a beginner

[@Rusty63ss]

Great info! Thank you for sharing. I can see that you are a shoot out kind of guy. How about another cam shootout? 5.3L LS with these three Elgin cams, vs a GM LQ4, E-1838-P, E-1839-P, and E-1840-P. Now I know this is difficult to do on the dyno, but would like to see the difference down low as well as up top. Thanks again for providing great information for all of us.

[@revtec4267]

oH WHERE oH WHERE IS THE VS racing turbo with the Elgin -1840P cam ? Richard please 😁 great video anyway

[@Harbinger428]

We are the Borg ~ love the Star Trek TNG reference

[@richardholdener1727]

welcome to the collective

[@VTLIFE-so4dc]

@@richardholdener1727 I have been assimilated. And I love it.

[@waynebollentin989]

I read this test a few years ago in Hot Rod. Already know the outcome on this for sure lol..

[@TheJdizzle02]

Thank you Mr. Holdener.

[@huddleberryfin]

Great test! AR trst would be great too. One that I’ve really been dying to see some results from are a twin scroll turbo on a properly divided twin scroll manifold (perhaps easier on a 6?). Lots of info about this 10 years ago, and now you don’t hear too much, yet all the OEMs use them? Great job keeping us entertained while stuck at home.

[@R0yL33]

For those running older motors and only looking for say 50% power improvement ie. 7-8 lbs of boost, I find that pressure ratio (1.5) well below the most efficient boost level of every compressor map out there.

[@RecklessBlueF100]

Hey Richard, been enjoying your videos for a while now. As soon as i saw this title an idea poped into my head for the junkyard guys. Would you consider getting a bunch of popular junkyard turbos together an testing then out? Hx35w, twins maybe? duramax turbos? Semi turbo (lol exhaust) im sure theres more but itd be sweet if it sparked an idea to test out some low buck junk again!

[@michaelblacktree]

I like this idea. Also, I'd like to see how turbos from diesel engines work on gasoline engines.

[@duncandmcgrath6290]

That’s an comparison I’d like to see , a junkyard turbo shootout.! I’ve got a home brew setup: Its a 5 ton deck carrier with HX35 huffing a blow through on 427 tall deck . 10 psi is where I’ve capped with big a increase in usable power .

[@richardholdener1727]

those are hard to find sometimes

[@davidciesielski8251]

Thank you very much..... I kinda knew most of this before, but now I can see it in my mind. This was a big help............................thanks

[@victorwesterlin82]

Thanks for the information. I’m thinking about going to a turbocharger.

[@dilsher12]

Richard like I said in my previous comment a big engine does not produce more 'back pressure' compared to a small engine at same HP level , yes the boost to back pressure will way more on the bigger motor but the actual back pressure should be close . Can actually prove my theory if you go look at your VSracing turbo vs Borg, @ 6500 rpm the 4.8 produces about 20 psi of back pressure and makes 800 hp . In this video same turbo on the 6.0 its produces about 875hp @6500rpm and about 22-23 psi of back pressure. Yes the boost to back pressure ratio is way off on the bigger motor but it proved my point that back pressure( exhaust gas volume) is a function of HP not displacement.

[@John1Brady]

Good test and data. That said, it would have been so easy to also do a matched boost run for more data. A more complex effort but also interesting would be a matched backpressure test.

[@GIGABACHI]

Richard Holdener: Patron Saint of the Holy Snail and purveyor of Boosted Facts.

[@Cheap0]

Good stuff man great info as always I kno how to work on cars but dont kno everything you got real fill in the big gaps I have especially on turbo stuff

[@azreeal1]

I do love these tests. However, I do wish the comparisons were more apples to apples. In this case I would have liked to see an electronic boost control used because I think the top end difference would have been a lot less drastic. Just my opinion.

[@Saddendude]

More backpressure also equals more heat. More hot exhaust gas left in cyl. Less cold charge air filling the cyl

[@thehappytexan]

I assume a 2:1 drive psi to boost psi ratio always equates to more responsiveness, but at what point do reach diminishing returns? A 1:1 ratio is probably more ideal, but is also more lazy down low? I’ve heard so many horror stories about toasting exhaust valves from excessive drive pressure, and how you have to have inconel valves. What’s your opinion on ideal drive pressure at max boost while also having response for a street car?

[@corystansbury]

So I'm not Richard, but did a lot of work in Turbo Vipers and a very well known, record-holding 911 turbo. In my viewpoint, traditional turbos (I'll until recently) would drive like an OE application with max target EBR of 2 (and tuning needs to watch EGTs), had a good mix of power and streetability around 1.3-1.5, and became very racecar at 0.8-1. These days, I feel like a very power-capable turbo can be made to make power everywhere without needing to go to 2... More like 1.5-1.7. A perfectly streetable turbo is now in the 1.1-1.3 range, and race applications are well under 1. Some of what we see here is the issue with manifolding 8 cylinders into one turbo. You just can't use the exhaust energy that efficiently versus a well designed twin system. Puts you very much in my "traditional" category.

[@Hatcher426]

@@corystansbury this is why I would love a test like this with the same turbo s475 but with a nice turbo header hot side and see the backpreasure comparison. I want 700 wheel and still be a fun street car with a head cam fuel system 5.3 or 5.7 this looks like the setup with an ar change or headers on the hot side.

[@richardholdener1727]

back pressure is only 1 part of the response equation-and something you look at after you have done everything you can to improve na power production

[@TurboRanger351]

Did you mention the exhaust AR size for both turbo? If you did I just missed it. Great video as always.

[@Meineke-pm7eq]

Would have liked to see a 4.8 and a 6.0 and then two turbos. 1 a s475 with a 1.32 AR and the other a s475 with a .96 or 1.0 AR. That way you see what the hot side change is vs engine size.

[@bigblock406ta]

My gess is if you ran them at the same boost level the one with the least back pressure would make more power but only buy 5 or so hp.

[@stephanM5]

Thanks Richard, what do you think about the variable vane turbos that Porsche is using in their cars that give great response in the lower rpm and fantastic power in the upper rpm range. Great video keep em coming.

[@timoneal9654]

Very helpful--as always. Thanks.

[@Rick90lx]

If you run a similar test again, you should put a 1.58 exhaust housing on the S480 and record the difference in back pressure.

[@ozysniper]

Hi from Australia Richard, I love your vids. I have a 2014 Jeep SRT 6.4l SBE with 25k miles, I am working on a rear mount turbo system and am going single turbo. trying to pick the best hot side size for response for a peek power of around 750 crank HP, around 8 PSI (street use). I was looking at CS racing 7875 or pulsar turbo G42 1450 Which is a perfect clone of Garrets g42 1450 turbo. any advise on hot side wheel size would be much appreciated. Keep these vids coming! I have learnt so much from you. you simplify things so well. you have given me the confidence to do my own set up. Love your enthusiasm.... Glen Z.

[@richardholdener1727]

I KNOW THE GEN 2 VS RACING 7875 WORKS WELL

[@mastercricket7626]

what would be the difference if say u took the 480 hot side and put it on the 475 and see what that would do for responsiveness? so like the difference between a top end drag car or a street car that stays mid range n stop n go so responsiveness would be top priority then ..... im upgrading from a journal bearing to a dual ceramic ball bearing turbo for response n hopefully better power as i kept hot side at .63 and upped compressor from a 57 i think i was to a 60 so i should see more response and more boost going on bearing response differences .... love your vids bro super informative ... peace n love fam keep it rad stay safe and build on bro l8z

[@krakhedd]

I want to see what happens when you use a turbo w/ the 75's compressor specs and the 80's turbine specs

[@bluejay693]

Awesome video! Got a video idea. Could you do a test on a centrifugal blower where you pulley way down to try and bring on boost harder and just use a watsegate to vent any extra boost up top? I always wondered if that would work. Would probably run into belt slip early but I'm not sure

[@richardholdener1727]

it does work

[@kwik440]

Hey Richard, thanks again for taking your time to make these aWESOME videos ! I tried the ebay turbos on a 355, make 1335, with a blow through carb(CSU) but after 30+ dyno pulls,the seal let go,(smokey as heck) but they made big power, have you had good luck with these turbos lasting /

[@djracing5231]

Running a 1.2 A/R on the S475 would be a useful comparison for impact on backpressure and response v power

[@hydrocarbon82]

Would have liked to see a small turbo like a S366 too - not all guys race a huge turbo on full kill mode. I've seen plenty of cases where a smaller turbo beat a larger turbo car from the better response.

[@timothybayliss6680]

For the billet wheel, ball bearing, twin scroll testing, an engine dyno might not be the best way to test it. A brake dyno will make the results almost irrelevant. The only way it would be worth doing is if you could load the engine at an rpm lower than the boost threshold and have the the rpm/s at something wild like 1200 or 2k. I doubt the engine dyno you have can hold a v8 that low, it would be like 1500rpm, or have the rpm escalating that fast. You might be able to do it with a really small engine to cut the torque at load in and a really big turbo. If you had something like a b16 and loaded it at 2500 and ran it out to 8500 it gives you a huge sweep and you can test boost response if you can have the rpm/s fast enough... The thing is as soon as the boost comes in and pounds the torque out, the dyno will slam the door to keep the engine acceleration consistent and make the torque spike worse, not better. You almost need to test this with an inertial dyno, the brake fusses with turbos.

[@DodgyBrothersEngineering]

Or do it on the road with a data logger. You can always extrapolate HP from numbers.

[@michaelangelo8001]

@@DodgyBrothersEngineering Some people are building test sleds, just for that purpose.

[@boosthit811]

This is why I would always choose to use twins on V engines. Back pressure is too high and the crossover point is so early in rpm range.

[@jayshaw7217]

Love the content. I have a question can you make 1000hp on 91 octane fuel only? You said you mixed 91 and higher octane mix. Is it even possible to run double atmospheres with 91octane only safely. Thanks keep up the great info and content

[@richardholdener1727]

I HAVEN'T

[@yotaismygame]

How did you know!? I’m shopping turbos right now...while at work 😎

[@MixalisChaniotikos]

Richard, Looking at your graphs, at around 5,800-5,900 both turbos are producing the same boost, with the larger turbo making ~20-30hp more. Is this a result of the lower back pressure of the larger turbo, and does the larger compressor wheel have any part to play? If it’s purely a function of the back pressure, is there some sort of formula that you can apply to work out how much Torque you would need to sacrifice to drive the differential back pressure over boost pressure? Thanks!

[@richardholdener1727]

I don't have that formula

[@bdugle1]

This is another super informative video. Thanks! I wonder though, when a different size engine (like 4.8 vs 6.0, like you were using as examples) makes the same power, isn’t the hot side flow the same? Lbs/min airflow in would have to equal lbs/min out, seems like. The little engine would take longer to get there, but the resulting flow should be the same-or not? Would pinning the waste gates closed with CO2 affect the way the boost comes in? Is there a solution using variable A/R, like a diesel turbo? Is there a way to get the back pressure curve you showed on the BBC with twin eBay turbos on the little LS? Inquiring minds...

[@lordhumungous7908]

I thought pound for pound flow was a good measure when looking for junk yard diesel turbos to use on a gas engine. I figured that my gas engine will run half the boost and double the rpm of the diesel so it all works out. But it turns out that it's not about matching mass flow but matching volume flow. So a 7.5L gas engine that turns to 5000rpm will need a turbo from a 15L diesel that turns to 2500rpm.

[@idriwzrd]

Have you ever done a comparison of different hot-sides on the same turbo on the same motor? Great videos, very informative!

[@johnwargo2590]

I'd like to see you compare a late 80's Ford 2.3 liter turbo engine (aka Mustang SVO) to the current 2.3 Ecoboost engine. 1st stock, then ported head, bigger (roller) cam, then finally with bigger turbo. With video please. Sounds good to me. BTW, I'm sure we've crossed paths while I was at Travis back in the day.

[@jamesonmurphrey8583]

This man is all about maff. I like da maff.

[@alj2264]

Is it possible to run a quick spool valve that chases boost pressure for example { 8 LB of boost @ 12 LB of back psi } { 16 LB of boost @ 24 LB of back psi } { 28 LB of boost @ 28 LB of back psi } This would be achieved by using a quick spool valves on a twin scroll housing With an actuator spring psi of 29.4 PSI { atmospheric psi 14.7 x 2 = 29.4 } To avoid choke flow

[@bcbloc02]

Drive double boost seems really bad. Curious if you went to twin 75's how would the power compare? Also what if you went a way bigger AR? Could you make the same power with half the boost if you got the back pressure more close to 1-1?

[@Vallo995]

when a test about oil pump and how much hp we can have when we "decompress" the block, how many hp can give oil pump sistem or exhaust sistem? also a question, if i boost an na engine, i should increase the oil pressure or i leave the same? when an oli pump upgrade have sense?

[@davidisbell2150]

What turbo would you recommend to provide 6 pounds boost on a 454 peanut port engine with an RV cam in my tow rig?

[@richardrohr5106]

Please do a vid with compound induction. With turbos and with turbo and super charger. Thank you

[@richardholdener1727]

THOSE VIDEOS ARE ALREADY UP ON THE CHANNEL-TURBO/TURBO AND TURBO/BLOWER

[@blaineallison6561]

I thoroughly enjoy your channel. You address all the crazy thoughts I have during the day while wrenching. Have you tried building a compound turbo setup for an LS? I'm an LS guy but run compounds on my cummins. It always seems to be in the powerband while towing. Just a thought and it would be cool to see a setup that holds 14 psi of boost from 3500 rpms. Keep up the great work.

[@Dodgevair]

I'm thinking of using a G42-1450 on a GM 525HP crate engine. 12psi from down low is the goal. Would love to get Richards take on this.

[@jasonb1750]

​@@Dodgevair I was thinking the same turbo on a 408 stroker

[@calvinevans8305]

Good info I would like 475 with a little more ar for 7 to 9 hundred HP street car.

[@OCofthe3]

Richard, there is major missing point here. Its not just the back pressure thats causing the power difference for a given boost level. At the boost level you are running and the RPM range, the S475 is running into choke toward redline. The s480, on the other hand, is just more effecient at these pressures and flow rates. It would have been nice to see the intake air temp with these different setups. Towards your redline, the S480, according to some of the boost maps for similar turbos, could be as much as 20% more efficent than the s475. So, the s475 is cooking off horsepower. What would have been neat to see is the s480 with a smaller A/R or turbine. I'm wondering if it had a smaller one, it would have outperformanced the s475 accross the board.

[@niknasstie]

What about comparing twin turbo set up to beat both down load and up top?

[@rotaryturbo88]

What size wheel and housing were used on each? You just said “smaller vs larger” but never specified actual sizes

[@robhudson6133]

Hi Richard great video do you think there is much to be said for regulating back pressure post turbo cheers

[@richardholdener1727]

big exhaust after the turbo-check out the turbo exhaust video

[@thetriode]

The stat missing I'd have liked to have seen would have been outlet temperature. The back pressure stuff is far less frequently measured and interesting. What is your opinion of the 2:1 backpressure rule of thumb?

[@yotasavage]

Great video!

[@matthewallison3600]

I wish you would put the turbo specs!

[@BrockJaden]

Isn't that where looking at the compressor maps come into play? Figuring out the efficiency of the turbos at the power levels you're looking for. Now, obviously the compressor map isn't going to help you choose a hotside, but it's definitely needed when selecting what turbo to use for your power goals. I'm in the process of selecting a turbo for a twin charging application on a 4.6 2v modular and it's looking like I'm going to need an s488 for the power levels I'm wanting at the boost levels I'll be looking for. It will be feeding through an intercooled m122 supercharger. Most people when twincharging make the mistake of not selecting a big enough primary to support their goals at the boost level that the primary will be running at and then they get frustrated when they can't make the top end power they were expecting. Maybe you could do a twincharging test to showcase how choosing the primary is so important in a twincharging compound boost setup.

[@richardholdener1727]

the map is looking at a small thing--the general turbo size and max capacity is the big thing you look at first

[@joeknowski675]

You always talk about the right ring gap. What is the right ring gap for turbo or how do you find that out? I have a 5.3 ls engine wanting to run 600-800hp. 0.020- 0.025 is what I've come up with. Any help would be greatly appreciated

[@richardholdener1727]

I run .007 per 1 inch of bore size

[@joeknowski675]

@@richardholdener1727 thanks for the quick response. I love your videos. Hope you and your family have a happy Thanksgiving

[@johnnyg9507]

Cool Video! Great Info!

[@russelljackson7034]

Right on

[@ttzfer]

I'd like to see this same test done with twin turbo setups. And please explain to people that boost doesn't add between the two.

[@lrmmorgan]

If you changed your boost control, say to Dominator with co2,could you raise your lower rpm boost? Then maybe lower the pressure at higher rpm, so it doesn't built too much?

[@zadokmotorfreight2423]

Excellent videos!!

[@chocosmith2243]

Can you add the turbo ar specs to the description?

[@jmm98ls1]

A test I've always been curious about on a turbo motor is what happens to a given combination and it's power/boost curves as camshaft overlap is increased or decreased? I expect the boosted curves would mirror NA curves like most of your tests show, but what happens to the hot side choke point? If you've got a turbo that's oversized on the hot side for a given power level, can you make it more responsive with more cam overlap?

[@richardholdener1727]

if the overlap adds na power-then yes-it will be more responsive

[@joelstevensz06]

Thanks richard! This was exsactly what i asked for, but it leaves me with 1 question- I believe you said that the S475 would have to much back pressure for the 6.0 and the S480 MIGHT be the better choice. Would the S475 be the right choice for me on the 2500 6.0 LY6 if its my tow vehicle or if im going to do a rear mount turbo and looking at MAX 650-700 HP/TQ? AND Does that change back pressure or response with A rear mount stock muffler location? Sorry if you've covered this. Love these videos learning alot!

[@chipcurrey653]

Why would you ever want to do a rear mount unless you absolutely had to?

[@richardholdener1727]

use the S475 for that application

[@joelstevensz06]

@@richardholdener1727 your the man thankyou for responding! Greatly appreciated it and all you do

[@joelstevensz06]

@@chipcurrey653 its not right for every application just like everything else, but there ARE alot of benefits the 2 main ones being UNDER THE HOOD TEMPERATURE AND WIRING, The 2nd would be the stealth of it.

[@chipcurrey653]

@@joelstevensz06 I tuned an 05 GTO with a rear mounted 7875. It did not get into boost ( i would call "getting into boost 5 psi or more) until 4500 rpm. I advised the owner to move it to the front using the hooker manifolds. The same exact combination with the same turbo now "gets into boost" at 2500 rpm. 2000 rpm sooner. I cannot see that set of tradeoffs ever being worth it. If you pop the hood on any modern diesel, or the trunk on any 911 turbo you will see the factory engineers designed the shortest log manifolds possible.

[@dilsher12]

I don't think a bigger motor would produce any more exhaust back pressure than a smaller engine at 1000 hp . Probably be pretty close but what is going to be skewed is the back pressure to intake pressure ratio.

[@richardholdener1727]

back pressure will 100% be higher on the bigger motor

[@dilsher12]

@@richardholdener1727 Well that would make for a good video, same turbo, same hp level ( not boost ) and different displacement say 4.8 vs 6.0 and see if the back pressure is much higher on the bigger motor . I might be wrong but I think it would be a difference of 1-2 psi .

[@dilsher12]

@@richardholdener1727 Can actually prove my theory if you go look at your VSracing turbo vs Borg, @ 6500 rpm the 4.8 produces about 20 psi of back pressure and makes 800 hp . In this video same turbo on the 6.0 its produces about 875hp @6500rpm and about 22-23 psi of back pressure. Yes the boost to back pressure ratio is way off on the bigger motor but its proves my point that back pressure( exhaust gas volume) is a function of HP not displacement.