LOW BUCK LS TURBO TEST-BIG SINGLE VS SMALL TWINS

[@bestusernameevahhh5802]

By a show of hands, how many people now have a Disassembled LS in their shop right now because of this guy? We love you Richard. Thanks for kweping hotrodding alive.

[@One_LuvZ]

L59 currently to install on Z32

[@kobygrimes1234]

✋️

[@patrickbecker2481]

Currently have a fully forged 408 waiting to go into my Tahoe 😩

[@clutchboi4038]

Lol I just got a 5.3 I'm putting in a buddies CTSv he got for cheap. Trying to select turbos rn

[@One_LuvZ]

@@clutchboi4038 what's the car gonna be used for and power goals?

[@lucasmullins5100]

Richard Holdener proving that not all heroes wear capes’s and also making me want to spend more money

[@toob247]

@james avery more money not all the money's

[@georgeschnakenberg7808]

All the money's

[@davelowets]

One has to pay, to play..

[@Cultofpersonality09129]

Hero? Get help.

[@allenl9031]

I just read from Freiburger, that Sonny Leonard has passed away. RIP to a race engine legend.

[@8bert9]

I would have never thought that the bigger turbo would bring bigger power in at the same lower RPM. Nice test!

[@davelowets]

@@stevenp3176 What "stock turbos"? A 4.8 LS never came with ANY turbos... 🤔

[@smp3745]

Sir I Thank you. Dude is spilling out real racecar knowledge more than any collage you will ever goto

[@niknasstie]

It took intill 2021 for some bad ass enough to do this test.

[@Its_Jimmy132]

Matt Happel made 1K+ WHP in a SBE gen III 6.0 Colorado in 2017

[@BlindBatG34]

I've got to imagine turbo lag is the only thing keeping the driveline from doing an emergency eject from 700+hp in a 4500lb truck.

[@natemartinez4595]

6000lb truck in my case lol

[@brooks3racing1]

It not the HP it’s the torque. Most guys will pull timing at peak torque to help.

[@davelowets]

I CAN tell you that a 4L60 lasts about 3 weeks behind a setup like this... 😞

[@cooperechols7322]

rip🤧

[@sanfordrhudy774]

I almost pulled the trigger and order a couple GT35's. Richard Holdener, thank you for all of the knowledge that you freely feed us!! YOU DA MAAAAN!

[@MrLightning54]

To me it sounds like whichever kit packages better in your vehicle is the one you should choose if the right size turbo / turbos are available for your power goals. Great video!

[@bradspeed]

100% agree, if there is no space to run the twins a go single.

[@MrLightning54]

@@bradspeed I have a single on my car (2011 5.0 Mustang) and love it.

[@blixxy1320]

@@MrLightning54 I bet she rips

[@drs2000rr]

Awesome video !!! Richard, Running twin gt3582rs, with turbo blankets and header wrap helps the spooling consistency. Being that the twins are less responsive on the 4.8. It Would be great to compare responsiveness in a twin gt35 setup in the 5.3 and 6.0 vs the gt45. These are the things that keep me up at night, Thanks again for all of the shared Knowledge.

[@delagto_5340]

Exactly what I was thinking. As long as the early lag could be minimized it should be fine. The gt45 I would assume will always have the upper hand despite displacement. Although the displacement could aid the spool for the gt35s they are pretty big for a no lag twin set up.

[@drs2000rr]

@@delagto_5340 I’m running them due to space constrictions, they love to be Brake boosted prior to a launch and they love to rev to 7600 rpm. I think more boost and a high revving Ls would show the benefit of twin gt35s.

[@delagto_5340]

@@drs2000rr I’m trying to figure out something for my car and I think that might be the way I’m going to go. The twins can be mounted right next to the bell housing. I’m a cam only car and personally rather have something that can me tamed and wild when wanted to be. Plus I can just turn it up haha 😆

[@drs2000rr]

@@delagto_5340 awesome, make sure you address heat control with heat wrap and aluminum tape over every wire and hose running through the area, and you should be ok, get a good scavenge pump to pull all the oil out of the turbos, and run a low psi warning light incase the pump fails. Happy Boosting

[@delagto_5340]

@@drs2000rr thank you for the tips ! I’ve been searching the forums and reading up everything I need to do. Most of it is exactly what you said. If I take it on i will document it for sure. Thank you!

[@GregoryBirulkin]

This is one of your best comparative KZbin videos. Thank you!

[@JimOrr_OK]

As a long time truck driver I’ve known about putting some heat into the turbo before a hard pull but I never had the reason explained like this. Thank you

[@Drekoushranada]

I'm looking forward to setting up my system. Your videos been beyond educational!

[@patlandymore7035]

An absolutely super test! Really liked the lower rpm comparison showing the twins 150 lb/ft down compared to the singles. I wasn’t expecting that. Thanks for doing what you do Richard!!

[@dee9117]

Dude you are freaking awesome keep up the great work and I’ll absolutely keep watching likeing and sharing

[@bcbloc02]

So now we need this test rerun with tighter ar housings to see what happens. 🤠

[@austindoud273]

It's probably just gonna give you a couple hundred rpm and choke the top

[@LaimisBMW]

@bcbloc02 Or just up the boost and see how the single will perform with that excesive back pressure.

[@littleherms3285]

.63ar is as small as they get in a T3.

[@KreatorOfDeath1985]

I'm thinking more about a single turbo now after watching this. Hmmm

[@BronkStang]

Same dude. Plus cheaper n easier

[@nowayjose596]

It depends a lot on packaging in your individual application i.e. the room to run 1 big downpipe or 2 smaller downpipes, etc.

[@BronkStang]

@@nowayjose596 I’ve got plenty of room but after watching this it’s like dude look at how much more torque he was making under 3500 RPM with one single big turbo

[@KreatorOfDeath1985]

@@nowayjose596 68' chevelles have a LOT of room under the hood. I could put 4 turbos in there hahaha

[@nowayjose596]

@@BronkStang I think if he kept going up in boost you'd see the lower RPM responsiveness of the single and twins start to mirror each other more closely and the twins then starting to make more power at the top end thanks in part to their lower backpressure. That's why he emphasizes the sizing of your turbo(s) for your displacement/boost level/preferred RPM range is more important than if you go single or twin.

[@button-puncher]

Another great video. Thanks! Lag makes sense. Turbine maps only start at 1.25PR, really get going at 1.5PR, and are fully spooled at 2.0PR. One of your setups is at 1.0 and the other is 1.5. GT3582's are good for 1,000HP at 7psi. Like you said, too big for the 4.8L but perfect for a 6.0L. Better match would be Twin GT3082R turbos. They'd be good for 800HP at 7psi and 1,110 at 15psi. Borderline too small would be twin GT3076R turbos. Good for 600HP at 7psi and 875 at 15psi. Those would be great on the street.

[@dbjunior1238]

Now lets see a compound turbo setup compared to the dual turbo setup

[@joetovar46]

Would like to have seen a comparison of the back pressure vs boost for both configurations. Also running each combination to its maximum boost/power would also be a good comparison.

[@nowayjose596]

Agreed. I suspect that as boost continued to increase the lower RPM responsiveness of the single would start to mirror that of the twins and the twins would make a bit more power up top thanks in part to their lower backpressure.

[@littleherms3285]

Ya, I was pretty disappointed he only went to 13psi. Should have at least gone to 18. All of those turbos don't get to their happy place until 16psi. Response is over rated. A good converter can fix A LOT. I had a 2.6L motor with a 70mm on it. Just gotta drive it like a man, it did rev to 8k which helped.

[@heytonyman]

Great lesson in boost threshold. I suppose what a loaded dyno can’t show is the lag difference between single and twins. I suspect the lighter mass twins will come to life faster when stabbed from a 5000rpm roll, and also recover faster after a gear change in a stick car.

[@basscube5]

Great video as usual! I have a set of GT35s (Vs racing style) in a Fox. When the build started I had a garden variety 4.8 with a BTR stg 2 turbo cam and I'd describe the boost response exactly like you found. The power band was ~5000-7500. I currently have a 10:1 5.3 with ported 799s, all else identical and there's wayyy more midrange power now. Pump gas with meth, predominantly street car with a 4l80E for reference.

[@TurbineResearch]

Thanks Richard ! You're the man

[@anthonybillings6554]

This is a great test!!! Specially the extra information you dropped at the end!

[@tonymorris3798]

Twins will make similar power to a big single. The real advantage of twins is "Transient Response" usually called "lag". The ultimate test would be - make sure the exhaust housings are equivalent (same back pressure and similar spool rpm), set the dyno rpm to hold peak-torque-rpm, run the engine at that speed with light throttle, nail the throttle and record the boost response vs time at constant engine speed.

[@richardholdener1727]

that's not how an engine dyno works-that is a chassis dyno

[@azreeal1]

I love to see this with a 1500hp goal. I'd bet the twin setup spools faster than a huge single, but there's only one way to know for sure :)

[@richardholdener1727]

if they are both sized for 1500 hp-then it's a toss up

[@billybadass-ru8st]

you read that wrong...at same boost..11lbs., single is much better! Thanks for all you do. You have best channel out there for engine development.

[@richardholdener1727]

1 is not better than the other-chose for packaging or looks (turbo sizing can make twins and single otherwise identical)

[@tomlenza2768]

Awesome vid. ! Love your channel ! I went to a trade school for automotive technology back around 2005 and learned a lot. it was great but god dam I wish u had been my teacher! Keep up the great work. I look up to u!

[@MD-lm7fj]

Big turbo? Small turbo? Richard why are you making us choose? Let's see some big/small compound setups!

[@jasonrodgers9954]

Richard, thank you for taking the time to make the video! On the gt35 turbos, what kind of increase down low would you have with an all ball bearing better quality gt35?

[@daveb1870]

I've been trying to tell people to wrap all of their exhaust leading up to the turbo(s) with refractory blanket, housing and past the 02 sensors. MAN Turbo AG has some great white papers on this, its all to do with energy, cold metals suck out heat reducing energy, less energy less power. Super insulating, short as possible distances to turbo(s) all equal higher efficiency. Wrap that stuff in refractory blankets, ceramic preferably but make sure you wear proper ppe when handling ceramic. Other substances such as the formable refractory blanket are less of a respirator issue. Once again thanks Richard for great testing!!

[@dennisrobinson8008]

That heat in the exhaust test is similar to the rear mount result. The initial response is better but output over most of the curve is the same.

[@aaronkeller8269]

VS actually had me purchase smaller hot sides as response time was not ideal with a T56 behind a 5.3. Only $100 per turbo so it wasnt that bad of a hit. But once I put the 6.0 in the car, the larger hot sides were needed as they light off ALOT faster. About a 1500rpm difference in peak boost range.

[@keithwilson8624]

So exhaust wrapped exhaust on a turbo setup will improve your spool and performance especially if you’re running aftermarket tubular headers ? Interesting, I enjoy learning little tips and tricks

[@michaelblacktree]

Interesting results. Thanks for sharing! 👍

[@corvetteZ3r]

Ready for your 4.2 atlas test my man!

[@MrBlackbutang]

Yes it does! Back pressure is the key. Why did you run different turbos? True test would have been same turbo’s single vs twin. They would be air flow capabilities

[@richardholdener1727]

your choice is not a single or twin of the same turbo, you would never pick two turbos that size unless your goal was to make twice as much power. Sized properly for the desired goal, single and twin can do the same thing

[@maclogan6872]

One if the more informative tests. Thanks R H

[@jplperformance9073]

Love the tests and the channel

[@besearchingforwisdom6267]

You've gained 100k subs since I started to follow, Congrats dude.

[@richardholdener1727]

thnx-it has been amazing

[@sinistersilverado965]

@@richardholdener1727 you are a hard working guy, you deserve it

[@tptrsn]

Great stuff Richard! I've been running a pair of those "GT35s" trunk mounted on a 4.8, and I can verify that they aren't super responsive, but on the other hand, up over 20psi, they really rip. I'm wondering if up in that low to mid 20s area, maybe they would have more capacity than the 7875? I've usually found that the ability to make power is pretty predictably inverse to the responsiveness of a turbo(s)... But I guess that means that the S475 really wins overall....

[@AdamOpheim]

I run the .63 T3 housing GT35's instead of the .82 tested here. They are very responsive on a cam only (small GM hot cam, TBSS int.) gen 4 5.3. Also really nasty at 20lbs! I don't know anyone that stops at 11lbs on a turbo LS! lol.. I agree this test may have favored the twins if the boost was run up to typical higher levels. We are talking 100hp+ HP difference once setup in a car and taken to a chassis dyno. For reference my twin gt35s made 565/600 on 11 lbs on the chassis dyno. All that heat he was talking about improving response... that REALLY shows on a remote setup too. What size piping to do have feeding them?

[@littleherms3285]

@@AdamOpheim I agree, I also have the .63 turbines and am glad I went with them instead of the .82s. Response is very good with a 3800rpm converter and a baby cam. Made 630whp on only 14psi, 16*, 10.5 AFR and E50. This year, shooting for 800whp on 20psi and E65.

[@tptrsn]

@@AdamOpheim Hey Adam, big fan of your builds!! :) I could probably write a book to respond to this comment, so I'll try to be concise. First of all, I was running 2.25" tubes for each side of the engine, into a 2.5" Y, and the wastegate just after the Y, so at the front end of the 2.5" exhaust running to the back of the car. Then Y-ing out into a pair of 2" diameter feeds up to the T3 flanges in the trunk, and .63 exhaust housings. After watching some of Richard Holdener's videos, it became clear to me that most likely my bad response was just because of my engine making no torque. The supposed to be 5.3 actually turned out to be a 4.8, and I had a Sloppy Stage 3 (Elgin 1841) cam in it, along with a very short runner sheet metal intake to fit under the hood of my E36 I was running it in. I put together a 6.0 with the same cam and intake, and it spooled those turbos like mad. But with the 4.8, the (drift) car eased off the line and ran 10.67 @143, on a 2.1-ish 60ft time, and no boost to speak of for the first chunk of the track. I shifted the 4.8 around 8k+, and up there it ripped real good.

[@AdamOpheim]

@@littleherms3285 those are great numbers and more typical. Folks get a little out of control quoting dyno cell numbers. My setup was non- intercooled , E60, and 8.9:1 or so as well.(241 heads) So the numbers weren't all that stellar. But it hits 20lbs so quickly you'd never know it was a low compression motor. My GT35's really woke up around 17lbs! I think you'll be surprised how much is left in them.

[@AdamOpheim]

@@tptrsn Thanks! Sounds like that combo was just missing a nice converter. I think a 19-2 stator 9.5 from PTC would have woken the bottom end up a TON and allowed a nice front half to go along with that killer back half! Good to see the gt35's doing work! That's a record MPH wise as far as I know? If you're running the cast gt35 wheel anyway. Is the car pretty light? Highest power level I've seen out of the GT35 is around 800whp and they were beyond tapped at 23lbs on an LS1. I haven't seen any trap worth a darn, myself included. only managed 134, but had issues and was booted for no cage. I always thought mine had 140 trap in it at 3000lbs.

[@DoctorMotorcycle]

That's very surprising to me that you had a 1:1 Pressure Ratio on the T3 Flanged GT3582's on 13psi of boost. I suspect you could go even smaller on the turbo's and still keep the PR under well under 2:1. I've always thought it would be cool to do a twin GTX3076 setup (or hell, even GTX2867's) with a small a/r to have a more "factory sized" setup that spools really fast and has the OEM turbo sized punch on a 4.8/5.3 LS.

[@richardholdener1727]

we could use gt3076s at this power level

[@tangstanggt5006]

I would like to have seen both at higher boost levels. Id bet the twin turbo setup would maintain the same boost rate and make more power at the same boost when reaching peak power potential. Lets see some 25+ psi runs.

[@CanadianOnlooker]

The heat issue & turbo response reminds me of learning turbo spool is effected by energy as heat & pressure not just pressure from exhaust flow. EGT & air fuel ratio had a big effect, & because of those the variable cam timing had spool effects. I then looked into WRC anti lag using a gas turbine pre turbo, & a pressure tank to create not only air pressure to the turbo, but burning fuel to create heat/ energy to spool.. Subaru called it the rocket anti lag & its cool af if you Google it

[@richardholdener1727]

I''m familiar

[@Brock_Landers]

Thanks Rich. I'm really depressed tonight, so thanks for posting such an uplifting video buddy. I really appreciate it.

[@nsmturbo5902]

I originally planned on twins but the plumbing takes up a lot of room. I'm gonna go back with a bigger single for ease of installation. I really wanted the cool factor of 2 but the S10 don't got the space.

[@finnroen2334]

Excellent test. Thanks.

[@designsbynoz]

yep.. with a .82 A/R on the two small turbos it did exactly what I expected on a 4.8. I'd like to see what a .68 A/R or even a .58 A/R would have done.

[@AdamOpheim]

Thanks again for the test! Might try the .63 housing GT35's, esp. on a 4.8. (you can buy just the housings pretty cheap) The .82 AR exh housings are on the large side. I run the .63 AR T3 GT3582's with the billet 64mm upgrade ($250 ebay turbos) and the response is like a light switch on a mild gen4 5.3 (gm "hot cam") ... Although like most turbo autos I run a stall that's around 3400 anyway, so maybe I'm not seeing the early RPM issues. Crank that boost up for us and see if the twins shine!

[@tonymorris3798]

Agree. The twins were effectively running a bigger exhaust housing than the single - later spool and lower back-pressure.

[@jackstoepfer1494]

Would do recommend the same .63 on a cam 6.0?

[@AdamOpheim]

@@jackstoepfer1494 depends how you want them to act. Do you want more response down low, or more power and rpm up high?

[@jackstoepfer1494]

@@AdamOpheim I would say low to mid range. It’s for an off road truck. I want to hear the turbines when cruising around.

[@AdamOpheim]

@@jackstoepfer1494 Hearing them is usually a matter of exhaust. Housing size won't change that. Some turbines are just louder than others in general too. Mine weren't that loud and I just had 14" of 3" pipe on them. If you don't plan to push it much past 600-700 range , and want quickest spool possible, the .63's are fine IMO.

[@JPANDLIFE05]

I think the response of the single turbo is much better than the twins because all the 8 cylinders of exhaust gas is being feed into one turbine housing, while the twin turbo set-up splits the exhaust flow into 4 cylinders of exhaust gas flow per turbine housing. This tells me the exhaust pressure and volume from all 8 cylinders into 1 exhaust turbine housing is much higher than the 4 cylinders per turbine housing. This might be the reason for the greater responsiveness on the single turbo setup. This is only my opinion. I've never tested this theory, but this just makes the most sense to me. Now, if you do a compounded twin turbo setup, i think the outcome will surpass the single turbo setup in every aspect!

[@richardholdener1727]

it's turbo sizing

[@MB-ib5ji]

I would so love to see a 1 liter Chevy Sprint turbo big Bang. heck you already have the turbo just take one of those who you got there... and has anyone else wondered if you could rub Richards head if some of that turbo knowledge would rub off?

[@ToddFordingLSX]

Will probably never happen but would be so cool

[@speedbuggy16v]

you sir are a bad influence, but you are correct, "twin turbo" does roll off the tongue nicely, I know in my head that a single will make way more power than I need... But twins oh boy, who does not love a set of twins.

[@time8533]

I would like to see you run twin 7875 on a gen one 406 and see what kind of power it pumps out. 👍

[@FastFoxx82]

Two 7675 🤪 test would be cool too

[@cboy132]

Single with more response. I love it. Where's the remote? Building a 2011Caprice 6.0 with a S480 in the spare tire bucket. Thanks!

[@fryloc359]

In one of the facebook groups I'm in, a guy built a quad turbo vette kart. I'd like to see the dyno chart for that.

[@oliverscorsim]

This was awesome man but hey I really wanted to see just this test butt can you post the back pressure too I wanna see the curves

[@bdog3869]

Richard while you have shown that single vs twins are pretty close. My question is if your looking for a quicker spool, and I know you’ll loose some top end power does it still go that a single vs twins would have the similar results for spooling necessarily while also attempting to keep a somewhat higher HP outcome? Greatly appreciate your input on this.

[@richardholdener1727]

single vs twin is a non issue-turbo sizing vs na power curve dictates spool response

[@SMOKEY-JAYS-DIESEL]

Hey Richard, please do this same test using the same big turbo and one of the little twin turbos Do a compound build that way it gets rid of exhaust back drive pressure I bet the numbers will be a lot better

[@richardholdener1727]

I have compound turbo vids up

[@SMOKEY-JAYS-DIESEL]

@@richardholdener1727 awesome brother. I will check them out

[@bartpang]

I wonder if you changed rpm climb rate on the dyno if it would show a bigger response (Turbo lag) difference.

[@leestevens9214]

Richard, What was the back pressure on the 78/75? you said the back pressure on the 35's was 13.4. But never said what it was on the 78/75.

[@tptrsn]

I think he said what it was in the prior video...? Seems to me like the back pressure was just a little higher than boost in the high RPMs. Like maybe 15-ish..

[@applebitefool]

Id be really curious to see twin GT28s at 13lbs.

[@yotaismygame]

Anyone make gt28s that aren’t internally gated? What about two small BW turbos?

[@martyhildebrand6392]

Would like too see more on a 408 Ford stroker twin turbos

[@SoFLaZ06]

The twins looked like older heavier casted compressor wheels, the single had the billet wheel advantage here

[@SoFLaZ06]

@@hondatech5000 that's a broad claim. there's numerous apples to apples real world comparison where the billet brings in power alot sooner.

[@nemanja162]

@@SoFLaZ06 due to aerodynamics not weight

[@JethroRose]

twins enable you to do things like sequential or compound setups; if you're able to do that it isn't quite that simple. twins are going to be far more plumbing (i.e., it's a packaging and fabrication cost issue).

[@davelowets]

Not too many people use twin turbos in a compound or sequential setup of a gasoline engine. Thats more for diesel stuff

[@44amanaplanacanalpanama44]

I would have used twin 3076r on a 4.8 at those boost levels. Should spool quicker and be capable of nearly 1000hp.

[@VRMN8R]

So which "turbo" cam did you have in this engine??????? Great comparison Richard. Thank you

[@richardholdener1727]

THE WRONG ONE

[@VRMN8R]

Did you take it out of my engine??? Because Im sure its the one I have.

[@outlawstang]

Hey Richard love the videos very informative do you think you could do this for a 4.6 2v with a on3 turbo kit thanks keep it up 🤩🤩🤩

[@jdbas71]

Richard, do you think the response rate difference could also be partly from added heat in the turbo that heats the oil, thus thinning it and lowering the parasitic loss🤔🤔🤔or letting the turbine spin more freely. Would be interesting to see if oil temp has an affect on how fast the turbos spool up.

[@richardholdener1727]

it's not oil temp

[@electrospank]

Whatever happened to the compound turbo idea? I know you started it but I think we missed the final run.

[@robertbenson1966]

Love your videos, i try to make sure that I like them to make your analitics good. Lmk if there is something we fans can do to help. So i road race, sebring, Watkins glen and other tracks, so how long do you think a motor can run at 1000Hp My laps are 1-2 minutes and we run 30 minute sprints. Full throttle is not long because tracks have lots of turns. I just bought a VS turbo and intercooler. I have a 10.5:1 small block chevy, dry sump circle track motor, bowtie block, brodix spch heads, im planning to have 5 pounds boost with a solenoid for 10 pounds on straight away. FYI i bought a VS racing turbo for my car based on your videos. You see guys are spending 50,000$ for 900Hp nascar engines, and i said thats silly, ive seen Richard make power with boost. So my plan is my 475 Hp NA engine will be 600Hp with 5 pounds and 875 at 10pounds. I only run race gas and will keep timing locked at 25 degrees. Your the best and i share your videos on Facebook all the time

[@derekconard8234]

Richard you need to do some twin turbo bbc testing and stuff I know you love ls but give us bbc guys some nice info and testing would love to see some 496-540 with vs racing turbos or borgs

[@richardholdener1727]

I have several twin BBC videos up

[@wayneallen2047]

Awesome. I'm getting ready to do the same now

[@shaneshane1379]

13 pounds.of.back pressure on each head compared to 18 pounds total for both heads raises thought. Pressure is pressure, but in reference to the turbo efficiency, I would have to say the single is more efficient. At 18 pound the single made the same near power level than 2 turbos that took 13 pounds of back pressure each. As far as the engine, lower back pressure is less effort on the engine to feed the boost. Therefore, maybe it won't blow up the first day you get it running.

[@Dodgevair]

If I go the twin route..gonna try a pair of G25-660 .72s I think the twin 3582s might have been a bit of overkill and hence not quite as responsive?

[@fascistpedant758]

I guess it just boils down to the total capacity of whatever turbo combination you are using. I assume the total rating of the twins was greater than the big single. Have you ever tested VGTs or turbos with electric assist for spool-up?

[@paulkleinschmit9871]

I believe that the total capacity was different between the two setups. The single was rated at 1000 hp where one of the twins was rated at 600 hp (1200 hp total)

[@The3chordwonder]

I think I remember before you saying that headers help across the board with turbo, just like NA. Since in this test, the low RPM spool was where most of the difference was, I'm curious if the headers affect how fast it spools up, or if it is kind of a linear boost across all RPMs? I'd be curious to see a headers vs stock manifold test with a turbo (Or pair for that matter).

[@johnhazel5385]

Maybe look at the compressor map. The units might have peak efficiency at different volumes and pressure ratios. If a unit with max effieciency at a pressure ratio of 2 (14.7psi boost) an another has max efficiency at pressure ratio of 1.5 (7.3psi boost) but higher volume the first would work well on low displacement engines and the second would work better on large displacement engines. (both producing the same power.)

[@richardholdener1727]

NO MAPS FOR MOST OF THESE

[@johnhazel5385]

@@richardholdener1727 Are the twins the GT 3582R? www.garrettmotion.com/wp-content/uploads/2018/05/Comp-Map-GT-3582R.jpg I haven't found the map for the single yet.

[@motorosso3349]

Very informative; any ideas, other than cut and try, to determine which turbo is going to have the best response and good power? Are you familiar with "Maximum Boost" by Corky Bell?

[@seanlutzi2911]

Richard, im all in on the single turbo but my question is how do you tap into the lower RPM if your not looking for top end speed. Im looking for towing so what A/R should suffice(.68-.83?) on a 5.3 Silverado Heck i only need 5-7 psi tops.... but want it to hook up earlier in the power band.. say 2800-3400 rpms

[@richardholdener1727]

size the turbo for the desired combination of power and response-a single Gt3582 will be responsive

[@kst8engineer]

@Richard Holdener, now you've got my curiosity up as to how a big/small sequential twin turbo combination would compare in terms of power potential and responsiveness. I'm thinking the flow limitation on the hot side of the small turbo would still limit the power potential.

[@richardholdener1727]

NOT IF YOU SWITCH EXHAUST FLOW OVER TO BIG TURBO

[@kellyheath8547]

I would like to know the weight of the turbos. Light is right! if a s480, or 78/75 can save 10 or 15 pounds over twin 62's then that could be a deciding factor. The other challenge is usually packaging.

[@adamspencer2515]

I understand getting heat into the turbo,it’s actually thermal expansion that makes them work. Compare ceramic coated headers vs non ?

[@andersamby7802]

You did not mention the backpressure on the VS 7875 TURBO😢

[@MrZX1206]

Silly question here, what if you plumbed your exhaust like a compound? All 8 cylinders' exhaust goes into one of the turbos, then into the other turbo making for quick spooling. Next plumb your cold side like a normal twin setup, where each one breathes out into the intercooler, then the engine's intake manifold (not stacked boost). I imagine your back-pressure would be super high, but could you bleed it down with strategically placed waste-gates? You could use your single turbo Y pipe setup, then add the 2nd turbo onto the output of the 1st.

[@rayevans3000]

I'd love to see how two of those 7875s do.

[@richardholdener1727]

I have tests up on singles as well

[@justindube9513]

please do this exact test on a 6.0 liter and then a 408 stroker or any 6.0 liter stroker. I have a gen 4 stock bottom end 5.3 on e85 I'm building for my competition drift car. I have a spare 6.0 liter engine for when the 5.3 lets go. its a twin turbo build with vs racing gen 2 billet 6262 . I'm worried about what the 6.0 might do with those small turbos. don't wanna bend rods down low also wondering what back pressure would be. I built a custom twin set up and don't wanna have to change turbos and fab new pipeing. reason why i ask about a stoker with small turbos on it cause i have a sponsor that might build the 6.0 l wondering what foolish things would happen with a 408 with small turbos. Thanks

[@jefflaney9355]

Second that! Really curious to see the same tests on an LQ4 or Ly6 just to see the low rpm response difference.

[@dbjxxl4822]

Hey man, thanks for all the hard work you do putting out tons of good content! Quick question...for you, how come Dyno pulls don't really ever go below 3,000 RPMs? For example, when you want to build a daily driver, streetable combo especially in a heavier vehicle like a truck, it'd be nice to see what it would do from like 1,500 RPMs up. Is that an issue with how the dyno works, that it can't or they that gutless down low that it doesn't pay to? LOL Just wondering, thanks again for all your hard work.

[@richardholdener1727]

the dyno can load down that low-but how often are you at WOT at 1500 rpm?

[@dbjxxl4822]

@@richardholdener1727 I get what you're saying, I guess that's why they make different RPM stall converters and rear gear ratios lol. Thanks for the reply! Always looking forward to your next test!

[@parkerwayne4323]

Will you please do an 8.1 vortec build

[@richardmorrison6134]

Did you know you can get the GT45s with a .68 exhaust A/R? Would make an interesting test for twins.

[@GearlessChris]

Dang it. I have wanted something with twin turbos since the late 80's. I the other hand, maybe the low response would help with traction on the street.

[@JethroRose]

twins can be set up in many different ways - parallel like this, sequential or compound. the Skyline GTR, FD RX7 (and supra I think) run twins from the factory in sequential setup. More complicated, but the idea is you get the boost response from ONE smaller turbo low down and then the second one has exhaust diverted to it later when the first one is running out of legs. they're inline 6 and rotaries though - v8s sorta lend themselves to twins due to the exhaust layout, but this video proves that a big single can be probably cheaper and easier to fabricate without any major compromises - and in fact is probably easier to size appropriately.

[@00gwclipse]

So what’s your thought on the lack of a multiplication of density present with the twins? Are we looking at two chargers that are struggling to keep up with the efficiency of the single?

[@shaadydog1]

The twins are oversized in potential, they had way more left than the smaller single.

[@Freebaggin]

Excellent work Rick. On the subject, I have a 1974 460 BB Ford in a US LTD, auto 2 door hardtop. Engine possibly rebuilt but I suspect still 8.5 compression ratio, stock heads, Mutha Thumpr CompCam going in soon, Torker II single plane and FiTech Power Adder 1200. I have a GT4708 Garrett turbo to go on. 79.8/108mm compressor, 92.7mm 82-trim GT47 turbine wheel with 1.23 A/R housing. Are you willing tp predict it's response rate? Cheers, Lachlan (Australia).

[@richardholdener1727]

THE COMBO OF THAT CAM AND LOW COMPRESSION WILL REDUCE LOWSPEED TORQUE PRODUCTION-WHICH WILL HURT BOOST RESPONSE

[@Freebaggin]

@@richardholdener1727 OK thanks, we'll see, however when you look at all the Caddy, Buick, motorhome stuff, the turbos you use are not that dissimilar to mine and most of them have comp ratios of the same ilk.

[@davelowets]

I agree fully... Those "Thumper" cams are going in the total opposite direction from a proper "turbo cam". The 107 centerline is too tight for a turbo application. The turbo for a similar stock setup may be close to what you have, but the factory camshafts they would use would be radically different than a Thumper cam.

[@collinvickers1402]

Richard have you considered doing a video on single 7875 vs twin 7875? The 7875 can come in .96 backhousing helping with spool, but very curious on power differences between single or twin of the same turbo if there would be a big difference in power due to less heat, back pressure etc. Also curious if stock(ish) trim 4.8/5.3 could spoil two and see how it comes in on dyno

[@jsmcortina]

Good testing. Could you provide links to exact turbos used ? (Web shops or manufacturers pages please!)

[@ruebenb83]

Yo, Rich! New to building domestic motors. Love the info you put out, wondering if you have any content on which transmissions to use with these high HP motors? Which engine management?

[@ruebenb83]

roller rockers?

[@Grunt300z]

I have a ls3 forged build that is bored to 419. Would the twin gt35 have a better response on my engine due to the larger displacement? I am trying to figure out which turbo setup will be best for my engine. I am wanting to get around 900hp with room to grow. Also what size BOV and wastegates are you running on the twin turbo? Thanks. Your videos are awesome.

[@richardholdener1727]

THOSE WILL WORK-i RUN A 60MM BOV (I THINK) AND A PAI ROF 45MM HYPERGATES

[@Grunt300z]

@@richardholdener1727 this is why you are the best in the business. You help so many people and the answer isn’t always super expensive parts. Plus you respond to us little guys. I’m swapping the ls TT into my 1990 300zx. I’m almost done . You are much appreciated.

[@kencohagen4967]

Ok, what about one small turbo, and one large turbo. One adding all its boost at low rpm, then one that takes over all the way to top rpm? The idea would be to make more low end torque at low rpm to get the car off the line and out of the corner, then at a given rpm power gets extended to red line. Would a valve be needed to shut down exhaust to the small turbo once there’s enough flow to get boost out of the larger turbo, and the opposite on the low end?

[@tomcelica]

Richard I am about to make a video on polishing piston tops or “crowns”. Have you done this type of testing on the dyno? If so, what were your conclusions? Thx buddy!

[@bstgarage7803]

When you run these gen 3 4.8's with the gen 4 rods and forged pistons, are you balancing the bottom end or just going full send?