LOW $ LS TURBO TEST-CHEAP EBAY GT45 VS THE FAST FIVE

GIANT LOW BUCK LS TURBO TEST! GT45 VS 62, T76, 7875, 7582, S475! HOW WELL DOES THE CHEAP GT45 TURBO YOU BUY FROM EBAY, AMAZON AND OTHERS SOURCES REALLY WORK? I COMPARED THE LITTLE GT45 TO FIVE DIFFERENT TURBOS, A PTE 62 MM, A T76 FROM CXRACING, A 7875 GEN 2 FROM VS RACING, A 7582 FROM FORCED PERFORMANCE AND AN S475 (T6) FROM SUMMIT RACING. ALL TESTED ON A CAMMED 4.8L. FULL BOOST AND BACK PRESSURE RESULTS ALONG WITH HP & TQ.

[@davy1458]

Richard holdner......i don't know what I'd do without you.....you make the time I spend in the bathroom on my toilet so much more entertaining and informative. ....

[@user-ub5nq1yq4i]

All the best plans were made on the Porcelain Throne

[@bennyfactr6122]

What makes the gt45 so good is the 1.05a/r is not so large as to make smallish displacement v8s(the most common) laggy while still flowing enough to make power at relatively low boost. It hits the sweet spot for the majority of hobbyists.

[@BDauto86]

Based on your testing/data, I grabbed a 5.3 with gen4 rods/lifters, installed a mild stage2 cam and ported 706 heads with a GT45. It's a pretty cheap combination that makes alot of power in a street car.

[@evanwelch3235]

hey there i hope you see this. how's that combo working out for you? is it reliable? how much boost are you running? thanks

[@BDauto86]

@@evanwelch3235 yea I've changed a few things but that's a solid setup. The eBay gt45 is hard to beat for the price but the 7875 is a better option for 4.8/5.3. You can safely and reliably run 5-13 psi on either turbo with a good tune. Some guys take engine apart gap the rings and reseal, some just run them. A cammed 4.8/5.3 with either turbo at 5-10psi can make 450-550hp and capable of well over 600 depending on combination.

[@tylershimek6167]

This is almost my exact set up, still need to snag the lifters but I can’t wait to see what she can do!

[@BDauto86]

@@tylershimek6167 make sure to get a good set of lifters from BTR, Johnsons, Morels or Summit. Delphi/oem LS7

[@theshark2804]

@@BDauto86 I had to gap my rings since the cylinders had rust in them. New rings with a ss2 and springs. I’m hoping to break 600

[@joshmajors5963]

THANKS FOR ALL YOUR TESTING!!!!

[@Wickhaven1]

Richard you are directly responsible for me taking my just 5 year restored 78 TA, from 180 hp to 800 hp. Started watching in March 2020 and promptly turboed my Pontiac. By May it was done correctly and with plenty of runs on it, pretty solid. Using the factory y pipe and a 78mm turbo. Ring gap and e85 👍 Why dont everyone do this?

[@richardholdener1727]

send pics

[@bradleynelson5915]

Pictures or it didn't happen. 😅

[@burqueninja5056]

Richard is a legend, he knows his shit!

[@chadstout270]

Thanks for all of your testing. Im building a drag week project with my dad and my sons and your videos have converted my dad from "it needs a big block" to "turbo LS is the way to go"!

[@richardholdener1727]

turbo big blocks also work well

[@dirtcheapmedia3390]

@@richardholdener1727I’m working on one of these myself 500 Cadillac 92/103mm turbo

[@Friendsofdonr]

is it bad practice to get notified Richard uploaded a new video, and hit like before you hit play? You know it's gonna be good

[@richardholdener1727]

THAT IS PERFECT

[@Friendsofdonr]

@@richardholdener1727 I do what I can. A like here and there and a watch every chance i get. Thanks for putting up with me on FB messenger! Keep the content coming. I appreciate the data

[@gothicpagan.666]

Lots of people can't be wrong. Well at least two of us 😂

[@Swaps-n-Stuff-WhistleGang]

I'm guilty

[@sanger440]

Richard has always said the gt45 was a decent turbo to 700-800 hp max builds. I believe this test more than confirms this. That VS 7875 seems to be the logical next step up over 800 hp turbo with its low back pressure At 700 ish hp in this test. Great work.

[@garagecedric]

A tip is to measure the compressor outlet temp, if you compare them at the same boost you will get a good number on the compressor efficiency differences.

[@exploranator]

or the turbine inlet temperature.

[@streetwarriorracing]

This man doing the most for us. Cheers!

[@RENEGADEX800]

Great video. I'm learning more every video I watch!

[@0zmosis2001]

On the first run on the gt45 for every 2psi of boost you added you pretty much got 15hp, just thought that was pretty cool how accurate it was for every time you added boost at least for the gt45

[@Adrianzx]

Compressor efficiency and back pressure made the difference. I guess something could be said for journal bearings and turbine clearances to housings as well

[@ryanaxberg9263]

cool test richard, these are the tests that I enjoy the most. I know its hard and doesn't seem to work that great doing a air to air intercooler test on the dyno because of the lack of airflow, but I was wondering if you could do a test sometime of a higher horsepower combo of like 1000 horse and test out different air to air intercoolers if you put a really strong fan infront of them. Like a smaller dimension 3 inch core to a big 4 inch core or even something bigger and test pressure drop and temperature drop across it. thanks for everything you do

[@jetjox2000]

I agree, perhaps a eBay core vs Garrett vs Spearco and Griffin etc.. Bar vs Tube and Fin

[@richeager7066]

Been boosting daily since 1985 (Buick T Type) and owned just about every turbo performance model since. 87 GN, 89 944 Turbo, 91 Syclone, 93 Mitsu GSX, 94 RX7, 97 SupraTT, 04 Evo 8 RS, 05 C6 Vette rear mounted 80mm GTS. and the most important lesson I learned was always use a tighter stall convertor than everyone else and keep tranny temps low, have a small wet single nozzle nitrous setup on a hobbs switch. i usually ran a 50 to 90 hp jet and set the hobbs to cut off nitrous at 5-7 psi. i always kept the system on in case someone wanted to try me i was always a wide open throttle away from full boost. and in case i needed more i also had a scramble button on my shifter that would give me max boost and disengage the hobbs switch for as long as i held that button for. always having the next size up turbo, a tight convertor, and my spool up kit use to smoke everyone and kept repair costs down. those big loose stall convertors tear up transmissions and driveline parts and buildup too much heat., holding the brakes and gas to build boost off the line is suicide.

[@Florida_as_Fuck]

Got dang Rich, you've owned some "bucket list" cars.

[@chipcurrey653]

None of those vehicles came with everyone's best indestructible friend the 4l80E

[@hogheadv2]

Careful exhaust system design will be needed to keep back pressure to a minimum. So often overlooked.

[@javierrflores]

I was just thinking this .

[@JohnnyAnderson1]

I feel pretty good about getting a Gt45 now, lol and I needed this motivation to get to work finishing it....

[@madmod]

I just love the value for the money that these cxracing turbos offer.

[@JohnnyAnderson1]

@@madmod yea so much better than the eBay GT45 lol

[@madmod]

@@JohnnyAnderson1 they have a good quality gt45 that is probably comparable to the dna turbo.

[@davidreed6070]

A pair of gt45s on a 6 liter should be fun, that is what we're going to do thank you for the great work. I'm looking for back pressure to boost pressure for a pair on a 6 liter so I can have Ashley cut a cam

[@Sweak22v1]

Love the low buck videos.

[@GurjB]

Great video Richard, keep em coming!

[@dennisroberts2857]

Great video on on differences between all outputs from each turbo. I'm going try one of gt-45 on 350 chevy vortec.

[@randallmason9687]

In the next video would You please overlay just the top power runs from each turbo? Thank You for all of the testing and great info!

[@hydrocarbon8272]

This is a GREAT vid for many reasons. It shows a "small" compressor can still be fine for an LS and how a large turbine can massively affect response. I think the best part is running all at 11psi & measuring drive pressure. That effectively shows doubling backpressure on a turbo engine shows a loss of 15%. Knowing there's a fairly linear power increase til the compressor is done, that means the tiny 65mm turbine would make the same HP as the 88mm with an extra 4-6psi of boost. In other words, there's no need for an oversized turbo unless you can't increase boost pressure (tune-OS limit, MAP sensor, etc)...or blow out exhaust gaskets from backpressure. For future reference I'm adding the turbo sizes vs HP at 11psi: 76-65 605 HP 62-69 636 HP 69-77 658 HP 78-75 679 HP 75-82 672 HP 75-88 706 HP

[@richardholdener1727]

I doubt you see 100 hp at the same boost level if the turbo will support that power level to begin with

[@dalethomas9307]

That 75/82 on a 6.0 is a ton of fun on the street.

[@lindsaydempsey5683]

Another great video Richard thank you, a brilliant head to head comparison. A clarification on sizing when you say 62 mm Comp and 69 mm Turbine, I presume that 62 mm Comp means that the inducer size (inlet dia of the compressor wheel) is 62 mm and 69 mm Turbine means 69 mm dia of the turbine exducer (the smaller dia of the turbine wheel where the exhaust gases leave the wheel). Yes?

[@gregkeen4907]

Nice work Richard!!

[@doaburnout1205]

Well you talked me into getting the gt45 I'll be buying them tonight!!!!

[@fiskshopworx1541]

Thank you. It looks to be the gt45 and T76 would be idea for street. The other "bigger" turbos more for race.

[@lc2kid]

Turbine A/R housing size is a big part of back psi. Efficiency of compressor wheel is a big part of boost power

[@ryanjohnson6636]

Awesome video man very informative keep it up

[@MrTDM09]

I’m actually on the market for a turbo. Good to know these results

[@lucysmith4242]

Rich thanks for the videos!

[@jaimeoops]

Nice video! Thanks Richard.

[@erikmarkus2239]

New subscriber here! I run this same exact CX racing turbo at 11psi on an 8.2:1 Pontiac 400 with bowl blended 4X heads. I’ve wondered how effective it would be to do some deeper testing, as I’m sure hot side back pressure is off the charts. Home garage built and tuned, the thing rips for the price!! I do not know how much power it actually makes though.

[@johnnylsx3384]

I’d love to see a test where the same turbos but with different upgraded features are tested. For example, journal vs ball bearing or maybe different compressor wheel designs/upgrades.

[@aXBlackDeathXa]

I imagine there's a multitude of reasons for less power at same boost. But it boils down to efficiency whether that's in the turbine design, bearings, general tolerances, etc.

[@mopar2ya165]

I think it would be interesting to use identical as possible turbine housings as possible. Back pressure is so important. Ive run a little t3/t4 50 trim .63 hot side, compressor flow was about 43 lb/min. Car trapped 122mph. Swapped to a holset pro40 about 71 lb/min with .55 hot side. Car trapped 117ish. Backpressure was 2.5:1 and settled to 2.2:1 at 25psi intake pressure. When you cant get the combustion gasses out, you mix it with incomming air resulting in garbage combustion. There is a lot of power on the hot side.

[@fascistpedant758]

At the higher back pressure, the T76 requires ~35 HP more than the Summit turbo to pump the exhaust gasses. The higher back pressure also reduces scavenging by ~35% reducing mass air flow by ~8%. That's my best guess. I wish we could get mass air flow readings, it would help explain a lot sometimes.

[@kerryb2689]

You can probably roughly gauge MAF based on power output.

[@chipcurrey653]

He isn't using a MAF

[@ze_german2921]

This was an awesome comparison

[@thatoneguy454c]

I have a set of DNA tubular unequal length headers and they work great. Put some ebay titanium heat wrap on them and an ebay turbo blanket. It drastically cut my spool time and I have had no issues with them.

[@cheeseburgerbeefcake]

The GT45 price point would be interesting to factor in here too; gains per $ of turbocharger I suspect it gains quite a lot of points vs the other units ($160 vs $450-600?), it also appears to have really good power delivery for daily use rather than just for peak performance, a number of the units had stronger curves than the T45, and the T6 would be fine for race/exhibition purposes but annoying every day.

[@pgf202]

High back pressure is choking the motor. The psi might be the same but the cfm of air flow is different. Boost pressure is a measure of air flow restriction. A turbo is a closed loop system that is controlled by pressure. When back pressure drops there is less restriction on the intake side, without pressure control we would actually see boost pressure drop. With a supercharger you actually see the pressure drop when anything is done to make the engine breath better, because the supercharger has nothing to increase airflow to maintain a pressure setpoint.

[@Ramb1t0]

Bro your the best no competition seriously!

[@richardholdener1727]

Appreciate that

[@button-puncher]

In the future, I'd like to see a non-preheated test for each turbo. That tells us if it's going to be a laggy turd on the street. Just at one common boost level to show the weakness between all of them. It'd also show if the cheap turbos are using heavy or poorly designed wheels or bad bearings that prevent it from spooling. Thanks again for all of your awesome work.

[@richardholdener1727]

your turbo is pre heated when you drive

[@button-puncher]

@@richardholdener1727 Ohhh, OK. Thanks Richard. I was under the impression that you'd have to do a brake stand, rev to 4k for 10 seconds to get everything red hot to achieve the same results. So I'm guessing that it's just another side effect of the dyno cell wind tunnel. In a typical engine bay, things would be nice and warm. Thanks again for the replay and for all that you do!

[@kolejohnson73]

Do you know what exhaust housing is on your dna gt45? I see several, would a larger housing, like a 105 or 115, that are shown now, drop back pressure if this one is the std 70ish sized ones that have been around for years?

[@MariosEvoCy]

The channel definitely deserves more subscribers, and I hope it gets it as it bares quality content. As far as the difference between the gt45 and the other turbos, with the exception of the 62mm one which it is significantly smaller than the rest and thus it made the least amount of peak power, I will say that in general the turbine wheel size and aero is a determining factor of power as it controls backpressure, then its aero comes into place, then the exhaust housing cm2 area and a/r, then these are in relation to the compressor size , aerodynamic design, and its blade surface vs hub area aspect. All these characteristics are interrelated. If for instance the gt45 had a billet wheel of the same size as the cast one, at 69mm inducer that is, with more efficient aerodynamic design, less hub area thus more blade surface area, it would make at least 20 additional hp to the 691hp it made at 13psi.

[@kamrenwood1894]

Marios EvoCy good point. But also keep in mind that a/r makes a significant difference in power output as well. Look at how the 76/78 .96 ar turbo in this video made a decent amount less power than the 69/78 1.05 ar gt45 turbo, the gt45 had less back pressure as well. Even though the 76/78 has a 7mm bigger comp inducer and the same size turbine exducer, it's still limited by the .96ar housing. I saw a test done on a Honda motor, where everything was kept the same with the tune, turbo, and engine. The only thing they changed was the ar from .82 to 1.0 I believe, and it picked up over 50hp and tq if I remember correctly. That coupled with what I just saw in this video, taught me what a huge difference ar makes. Even if it's just .10 of a difference.

[@MariosEvoCy]

@@kamrenwood1894 I've already mentioned turbine housing cm2 area and a/r, you need to re-read my comment. The determining factor is the turbine wheel, as it is the one controlling the backpressure characteristics, the a/r plays a less significant role in power output. Besides if a cm2 area and a/r of a turbine housing is enough for the volumetric efficiency and exhaust gas mass/volume of a setup, then adding more cm2 area and going to a bigger a/r will not add more power and it will only make the setup less responsive. It will only add power if the existing cm2 area, a/r, one uses is insufficient. It is far better to have a big turbine wheel in a smaller exhaust housing , than a small turbine wheel in a huge turbine housing.

[@kamrenwood1894]

@@MariosEvoCy ok, then why did the 69/78 1.05 a/r gt45 turbo make more than the 76/78 .96 a/r turbo? Please explain.... by your logic this makes no sense, it shouldn’t be possible.

[@MariosEvoCy]

@@kamrenwood1894 Just because you do not understand, or have not certain knowledge on physics, does not make what I typed impossible or redundant. I will do explain things some more. You need to re-read my comments. The above result proves exactly what I said. The 69/77 gt45 1.05 a/r made more power because the characteristics of both its wheels are more efficient than the ones on the 76/78. The gt45 turbo on the 96 a/r housing ,would still beat the T76. If you compare for instance the compressor wheels of the two turbos, you will see that the hub area of the 76mm turbo has more mass than the one on the 69mm gt45 turbo. So the overall inducer measurement might me at 76mm but the actual blade surface area has not much difference than the 69mm one, plus it also seems that the aero on the gt45 compressor wheel is of a bit more efficient design. The same goes for the two turbine wheels, the 1mm overall difference in the exducer could be lost in the hub area, plus the gt45 turbine might have a bigger inducer than the T76 one or a better aerodynamic design. I also said in my previous posts, if the cm2 area and a/r is insufficient on a certain setup it will rob power from it, but going on a larger cm2 area and a/r will not necessarily mean more power, and most of the times it does not if the turbine housing already in use has been chosen correctly and it is the right size for the capabilities of the CHRA and wheels of the turbocharger always in relation to the setup it will be bolted on to. So it is not just a mere factor that allows a turbo to reach its maximum output, and the turbine wheel plays the most important role on the efficiency of the hot side. Two wheels of the same overall size but with different aero and blade surface, one being more efficient than the other, do not flow the same CFM. A wheel with a not so efficient aero and large hub area, will not flow more than a relatively smaller in overall size wheel with more efficient aero and less hub area. It is the blade surface that counts. You can also clearly see what I am saying here if you compare the little PTE 62/68 on an 81 a/r turbine housing, which at 11 psi it made 636hp vs the T76 which only made 605hp. So having a not so effective turbine wheel even if it is the right overall size, which will not flow as it should and trying to gain back some of that lost efficiency through an oversized turbine housing it is by no means the correct practice. It is far better to have the same large wheel or even larger with the right hub area, blade surface and most efficient aerodynamic design in the smallest turbine housing suitable for your turbo and application. I hope my post helps you understand and get some more insight on things.

[@kamrenwood1894]

@@MariosEvoCy I get what your saying, but larger or more efficient turbine wheels are not the biggest factors in letting exhaust gasses escape quicker. That’s what the a/r and turbine housing efficiency is for. The turbine blades are nothing but a restriction in the exhaust. A more efficient turbine wheel will just help spool rate. A bigger turbine wheel especially in relation to the compressor wheel, just creates more leverage over the comp. so you can keep boost up at a higher rpm. But if the exhaust can’t escape fast enough, back pressure will cause your to lose power by interrupting the engines scavenging effect. IMO the ar and the efficiency of the turbine housing would be the biggest factors in preventing this, whether or not you are using a properly sized turbo for the application. Unless you have zero back pressure, allowing more gasses to escape will always net more power. The efficiency of the turbine blades would come last imo. I just don’t see a need to get all in depth using physics and such when we’re dealing with something so simple. There is no need to over complicate things. Exhaust needs to get out, and air needs to get in for an engine to work efficiently. Let’s just agree to disagree, I’m not going to sit here and argue this for a week.

[@mikemarshall1394]

Boost pressure is one thing, volume/air density is the determining factor.

[@mavsformulaful]

Awesome, great vid again. I was just about to email you and mention I was thinking about the vs7875, do you think any other inexpensive turbo was better for my 11 to 1 383ci (280/212cfm & 235/242 112lsa) w/ 1000+hp goals. I was hoping Summit would do a s480, but maybe i should look at it too. What are the VS and Summit max hp again? I cant remember where you mentioned that info..

[@Turbokrankenwagon]

This confirms my stance. I always tell people to go bigger on turbo. Smaller turbos make less power and more heat at the same boost levels. So when people say every turbo will make the same power at the same boost given the hp parameters of each turbo is wrong. Always go as big as you can afford in my book. But that’s just me.

[@madmod]

The turbo that comes into power sooner will be better on the street. That big turbo is perfect for drag racing where your leaving on a trans-break or 2step and your not worried about spool time.

[@Turbokrankenwagon]

@@madmod yeah maybe. I’m used to big turbo small displacement stuff. So turbo lag on street I don’t find to be an issue. If I had the luxury of a 4.8 v8 that made 300ftlbs at 3k rpm I’d be going to the big boy. Partial throttle driving who cares about spool time...

[@madmod]

@@Turbokrankenwagon i feel you haha. I have a 4.6 2v and its getting a roots blower lol. Turbo is looking to be awfully affordable these days though. I figure id see even less back-pressure than a 4.8/5.3 truck motor so i could probably have better luck with one of the smaller exhaust sides and not compromise in power or boost response on the street.

[@Turbokrankenwagon]

@@madmod cool man, let’er eat!

[@otm646]

@@madmod the casual observer doesn't notice that he doesn't start these pulls until 3,000 RPM. For most street motors that's 50% of the RPM range if not more. Smaller really makes a difference from 1500-3000. You get off the line in first gear, shift to second and go WOT. That's the street side of the performance equation he rarely ever looks at because of dyno limitations.

[@ericflower9855]

Still not bad for the gt45 $140 "or so" 69mm ...really good budget turbo ..wonder how many made there start in the ls world with this turbo...long gone but still a soft spot for it..

[@tomcelica1030]

The fast 5! ROFL! Classic! ❤️

[@bobreichel]

I've got problems with my 2016 f150 3.5L ecoboost tubors. I see replacement turbos on ebay. Just wondering if there worth getting? I not looking for adding power just to be able to use my truck in normal operations.

[@Scarlet_1971_cuda]

Need to put up the final bests of each turbo with full curve. I'm not a peek HP guy. I like to know where the power is on a graph. Then based on application I could figure out what is best for that application.

[@SMOKEY-JAYS-DIESEL]

You should purchase one of these and try it out Aftermarket GT42 GTX42 Turbo Charger Billet Wheel T4 Inlet 6 Bolt Outlet it would be awesome to see the dino numbers I run the same turbo on a 2015 custom built Tahoe and it runs awesome I would love to see the numbers versus these other turbos

[@reedhanson5945]

The power difference at the same intake manifold pressure (but higher exhaust manifold pressure) is from the higher in-cylinder PdV pumping work caused by the turbine housing being too small, restricting flow and increasing pressure. If you had a cylinder pressure sensor it would be very clear that the negative PdV work during the EVO period is much bigger when you have higher back pressure. When the exhaust valve is open, the higher back pressure acts against the piston, creating more negative work that is robbed from the crankshaft, producing less shaft horse power. With turbine sizing you need to find the sweet spot between too much lag and too much BP.

[@kylemilligan752]

Sounds good on paper, but you have completely ignored the inert residual exhaust in the chamber because of backpressure. You have also ignored the heat buildup in the chamber and valves, when the pressure differential does not allow cooling from fresh air and fuel on valve overlap.

[@reedhanson5945]

Yes, the exh residual does go up slightly with more back pressure, but its on the order of a few %. This will raise the temperature at the start of the cycle,and reduce the VE thereby reducing power slightly. Similarly, the higher engine dP will reduce scavenging, reducing power too. However, I think these losses are small compared to the higher PMEP caused by the high back pressure. With proper instrumentation this can all be measured and proven. If the airflow rate (which it should be if the boost is the same ), spark timing, etc are the same then you should have the same IMEP. If you had a cyl pressure sensor, you could measure the IMEP and PMEP. Assuming the the same IMEP between the different turbos, then the only other loss is the PMEP. Which is caused by the high back pressure. The moral of the story is that cylinder pressure senors tell you everything. I dont really know how these guys do engine testing with out them.

[@exploranator]

Simple answer, which you already know, Richard! More power on same boost pressure means the turbo is more efficient, producing less backpressure to produce the same boost. I wonder if the exhaust temperatures were higher on turbos with the same boost levels that produced less output power. That is pretty universal, yes?

[@boost1728]

I’ve watched the video a dozen times but I can’t find a graph of all of the turbos horsepower and torque compared to each other- am I missing it? Was hoping to see a graph like you showed for backpressure, but for output. Maybe in a different video? Would love to see how they all stack up.. hard to compare them when we can’t see how they all do at 5psi, 10psi, 15psi etc overlayed with each other.

[@niklasj4680]

Awesome as usual, but can you please also test a Holset HX 55 turbo. Nobody ever do an comperison with a Holset turbo. Thanks again for a great video.

[@travisabrahamson5092]

Also a pair of holset hy35w using the internal wastegates 👍👍👍

[@timweb1510]

Keep em coming

[@khg8519]

Hi richard - my experience with china turbos is good but the compressor house is not shim'd is if you tighten the comp house up it will pinch the wheel - you can see it if you start the motor then slowly tighten the wheel it will stop spinning - also the turbos are only supported by one of the bushes this it how they are ment to be allows for the rotating mass to move against gravity the turbo does move around spin a bike wheel between your hands and turn around while holding it

[@richardholdener1727]

I don't have that problem with any of the turbos-the wheels all spin

[@madmod]

The s475 would be great for the drag racer that leaves on a 2step or trans-break and isnt worried about spool time on the street.

[@capcloud]

This is gold.

[@lexomotorsports]

Right on

[@kolejohnson73]

Emusa shows a gt45 with billet wheel and a 1.15ar exhaust. I would love to see that compared. Interesting to see what those small changes actually do in performance. In the diesel world all the "batmo" wheels and the like are sold as world changing, I'm interested to see the difference on the dyno. That newer version of the gt45 might be a better match for 5.3 and 6.0.

[@timothybayliss6680]

Batmowheel is good but they are really heavy for billet wheels and ungodly expensive. There are some Chinese billet wheels that weigh 80% of what a batmo does and will flow 95% or more what they do. They were great when they came out but compared to the gtx Garrett or sxe warner they are kinda meh.

[@flux_core_fx]

Does anyone know the specs on the 62mm? Is it a T3? 6266? I have one with a t4 housing in thinking about running on a 5.3 for autocross. Thanks

[@timboro3433]

Very good stuff

[@autorulette6578]

What kind of inyectors do you put in it? I have the same proyect my third gen camaro 5.3

[@mk-jm5tv]

do you gap the rings on all these stock bottom end test motors?

[@Paulster2]

I don't know why the power being down on the higher back pressure would be surprising to you, Richard. If there is more exhaust back pressure at a given PSI boost, it takes more energy to push the exhaust out of the system, which means you'll have less power output at the crank. Compare headers to a stock exhaust in the same way. We put the headers on an engine to free up back pressure, which allows us to produce more power/torque. This is the same thing. When there's less back pressure, the engine doesn't have to work as hard to push the exhaust out of the system, which means there's more power to do work at the crankshaft. Less exhaust back pressure = more crankshaft power.

[@richardholdener1727]

HEADERS DO NOT MAKE POWER BY FREEING UP BACK PRESSURE-SCAVENGING IS VERY DIFFERENT

[@Paulster2]

@@richardholdener1727 - I wasn't trying to compare the action, but rather the consequence of putting headers on an engine ... although, what is scavenging? It's the process of moving exhaust more efficiently out of the system. This means the engine has less mass to move, which means it frees up power. With a turbo, if the hot side is more efficient and does not create as much of a blockage for the exhaust to get out, the engine doesn't have to work as hard to push against the back pressure. Less back pressure = less work = moar powa.

[@kamrenwood1894]

Paulster2 Richard knows what he's talking about. But scavenging is where enough exhaust gases are able to exit through the exhaust, that a low pressure zone is created (or a vacuum), that vacuum in turn draws more air in through the intake valve as it's opening (more air and fuel = more power). Excessive back pressure will disrupt this effect, therefore not allowing the same amount of AF charge to enter the combustion chamber at 1 given time. Obviously this will have a negative impact on power production, hence why the increase in back pressure hurt power the power output. But that has nothing to do with the engine having to "work harder", or use "more energy", it's just able to breath better with less back pressure. I'm sure Richard already knows this, as he is much more seasoned than I am, I'm just really getting my feet wet with all of this stuff. He's been doing test like this since before I was born I'm sure lol.

[@kerryb2689]

Pumping action of the backpressure is not the only consideration. If there's more backpressure than boost, you still have that much extra exhaust gas remaining in the cylinder preventing fresh (burnable) air from getting in. Some of it will actually flow back into the intake manifold during valve overlap.

[@kamrenwood1894]

@@kerryb2689 thank you for reiterating what I just said. Nothing wrong with redundancy!

[@18ssgti]

please apologize for my english im a frenchy... bigger the turbo his, bigger the power will be. for sure the exhaust pressure will play alot on that. people think that there is an easy calculation about 1 bar (14.7 psi) and oem hp. add 1 bar to make double hp. Yes it does that most of the time when using middle turbo size. We reach on a honda motor that makes 178 whp fully built motor at 0 psi. (waste gate open). with a 72 mm at 5 pounds we did 374 whp (on race fuel for sure). I done runs a diesel turbo on a street setup, it was a gt3576klvn (variable turbo). The hybdrid thing that you should try its to find a 120mm with a vnt systeme. you would see big hp at low psi and an amazing low back presure because of vnt systeme at any rpm. With that kind of big turbo you ll find out missing fuel fast from small injectors. i loe your video and your tip by the way im not bashing here. just telling if you canget a real big turbo you ll freak out on hp gain on low psi. by the way if you get a vnt and you cant run the electric vnt motor, there is some mechanical actuator that can work or just finding the right spot for spooling and not having too mutch back pressure at full rpm. vnt turbo can be really big and it doesent matter the engine size because of the vnt. Please try that and show to the entire world

[@richardholdener1727]

the size of the turbo does not change the calculation unless it is too small

[@18ssgti]

so why we reach 374 whp at 5 psi? you said you would like a magic hybrid match between gt45 and another turbo. get an variable real big turbo you ll see my friends (over 120mm). no offense richard

[@brandonpylant9349]

Would it be possible for you to start adding in average hp/tq.

[@markrich3271]

I told you this Richard last year , that different turbos made different powers at the same psi . You argued with me how I was wrong.

[@richardholdener1727]

If both turbos can support the same power level at the same boost with the same back pressure-same power

[@supercharged6771]

What we need guy's is a electronic back flow regulator valve, once the turbo is spun up why need more pressure

[@Bbbbad724]

Richard, do you think that this as a single, the S475 on my 390 at 13 lbs would be between 800-900 and be happy? I have the thick truck block and crossbolt mains on 2 and 4 and I plan on a block fill up to the core plugs. Do you think that would be better for the FE with that boost curve? I am kind of thinking of a T4 hot side at 13. Or would I be better off with a pair of GT45s and 13? NA power will be at 500 hp/ 500 ft lbs with twin45s intercoolers and E85, and a Roller cam from Bullet 245@.050 and.600 lift on a 110. 3800-4000 lb car.

[@richardholdener1727]

I think I would get the inexpensive s475 T6 from Summit on a 390 at 900 hp

[@robertdraffen3902]

Would love to see u run some test with the vs s475 t4 83 that's about the best of both worlds

[@MixalisChaniotikos]

Richard when you mentioned the turbine size in mm, are you referring to the turbine exducer (outlet) or turbine inducer (inlet)?

[@timothybayliss6680]

Almost all turbo companies list turbine exducer. Precision does, turbonetics does, vs racing does. I can't think of one that uses turbine inducer.

[@turbosupra2jzdragracingtob249]

I would like to see this same/similar tests on 5.3 and 6.0

[@benjaminwingchun9665]

Did you bang the K24 yet? I noticed you labeled the turbo here but couldn't find the video

[@carltonacey3298]

Do a big bang test on a built 4.8,5.3,6.0,and 6.2.😁 Stock block limit.

[@tech1fab]

Maybe you could do tests on waste gates. I'm new to your show so mabe you have.

[@AdamOpheim]

Believe the CX racing 76 is a p-trim 65mm wheel. Which is why it did poorly. The t4 S475 is a 75mm exh wheel (same size as vs 78/75) T6 s475 is an 87mm. You measure the exducer (small side) when sizing exh. wheels on turbos. Borg lists the big side of the wheel. Not accurate to compare major exh. wheel size on some turbos and the minor exh. Wheel size on others. Thanks for the test! My moneys always on the T6!

[@richardholdener1727]

T76 MEASURED 3 INCHES

[@AdamOpheim]

@@richardholdener1727 the exhaust wheel? Cx doesnt make a 76mm compressor with a 76mm exh wheel im aware of? They have a q or p trim exh. wheel 68mm or 65mm. Unit on the vid didnt look like a q to me and even the bigger .96 t76 cx units we used as twins had a 65mm exh wheel. Even tho it was labeled as a "q-trim"If u have a 76 exh wheel, u have a unicorn. Show me where to buy those! Both listed as .65 wheels. www.cxracing.com/turbocharger/turbocharger-t4-turbo/TRB-T76-Q96-R www.cxracing.com/TRB-T76-P68-N

[@Joe-it1pn]

Ur the goat

[@tomconner5067]

Remember, less backpressure at peak boost = lower temperatures and the flexibility to advance the ignition timing at peak boost levels at a minimal risk engine damage from fuel air detonation on throttle body and common rail port fuel injected systems, Direct Gasoline or Indirect Gasoline Injected (Diggi's and Iggi's) the dynamics are pre engineered to operate under higher cylinder pressures and engine temperatures without the complications of pre ignition, DIG GDI DGI, which ever order, Indirect injection uses a separate chamber to initiate the ignition, acting like a magnum primer in a large caliber firearm, to optimize the application and transformation of the dynamic properties in the contained explosion into a more efficient, effective, and complete concentration of the released energy into a concentrated point of applied physical force, very high boost can be transformed into higher engine efficiency power and force output.

[@suicidal_racing]

Gt42 is close to what u want 1.05 t4 76/75.. but the ebay billet tc7875 is $75 cheaper on ebay being $280 which is 78/75 .96 t4. You should talk about blade count also on the exh wheel an how more will spool faster but also choke faster..you can get into blade angle also an wheel weights.

[@evil_me]

I would love to see what my turbo would do on a ls, it's a bw S500 94/110 and it likes to move some air lol

[@tech1fab]

Great test! What I struggle with is a decent waste gate can cost just as much as a turbo. The generic GT45 cost less than a good waste gate. If you can't control the turbo properly what is the point?

[@texasstreettunes1310]

Vsracing 44mm v2 is what i used with my gt45 no issues here. Got it for around $99 on summit.

[@olof103eriksson]

Building a 6 liter twin 56mm turbo (Kinugawa TF06-18KX) for drifting I run into this reasoning all the time. I want back pressure (at top, from turbo sizing, signs of high gas velocity). Back pressure (turbo sizing for spool up) is what will help me get my 800 horses instantly when I need them after I had to correct for the driver error of the leading driver. I also want those 800 hp straight away after I have been braking into a corner and need to rip the tire loose again, once loose the power needed will be reduced by 20-30%, so a 1000hp engine with a 500hp building boost up to 1000 is not as fast as a 800hp engine that has 800hp when I throttle on, it will have 500hp when I need 800, and 1000hp when I need 600.

[@ChurchAutoTest]

You never want back pressure. You want high exhaust energy, which usually mean high exhaust velocity (since exhaust mass is relatively constant for a given power level/fuel combo). Back pressure hurts boost response, but a smaller housing/wheel will give you better exhaust velocity at lower rpm in exchange for increased back pressure at high rpm. The trick is finding ways to increase exhaust energy before boost onset (as well as reducing turbo rotating mass/friction) without increasing back pressure. That's where all the newer aerodynamic solutions on the latest turbos really help.

[@TwoLotus2]

@@ChurchAutoTest True, but I think Mr. Olof meant that he is willing to trade ultimate HP for good throttle response for his track car. Entirely reasonable IMO.

[@ChurchAutoTest]

@@TwoLotus2 yes could be a language issue

[@olof103eriksson]

​@@ChurchAutoTest I have put a couple of brackets in there, you are correct in what you are saying and it is a language barrier. If we were choosing between two turbos of the same tech level (like a g25-660 and a g30-770) the one that shows more back pressure on top will probably be faster in my application if it can make the power I need. Ball bearing also makes a significant difference in mid corner even though they do not show any large gains in a dyno As an example, this year we had one car at the track making 550hp with very little back pressure and one car making 460 with 1:1.05 ratio. The car with 550hp did not have full boost before first corner which was in 3rd gear, the 460hp car had full boost in first gear. The leap was enormous down the starting straight. Note that this is cars not built for dragracing and not having tires that would stick in a drag racing start, the cars dont have sequentials with ignition cut either which would help in this case

[@jetjox2000]

Wondering if the’re any Richard Holdner quick formulas for sizing the exhaust side for a 1 to 1 back pressure at peak RPM based on displacement/ Rpm/ Boost pressure?

[@richardholdener1727]

NEED TO ADD NA POWER THERE TOO

[@PreacherDan]

I want to see what you can do with a Ford 3.7 cyclone v6 with a turbo.

[@laned8418]

Great video! Richard, I have a question unrelated to this topic. If im dis assembling a Junkyard LS to determine the condition of it, is it ok to put in new main bearings while i'm in there without any machine work? If the crank looks good, is it ok to just throw a set of bearings in without machining? Or has the crank slightly worn to the shape of the old bearing? Thank you.

[@richardholdener1727]

IT WILL WORK-BUT I LIKE TO CHECK CLEARANCES WITH NEW BEARINGS

[@laned8418]

@@richardholdener1727 Thanks for the reply! Whats your preferred method? Plastigauge or ?....

[@timothybayliss6680]

@@laned8418 plastigauge is usually within half a thousands of a micrometer. It's quick and works surprisingly well. I watched a video of one builder comparing his micrometer to plastigauge and none of the main bearings were more than 0.0005 different.

[@otm646]

19:13 you're really going to confuse guys with this one. We need to be talking in terms of mass air flow not boost. From an instructional standpoint explaining the A to B airflow difference is substantially more useful than looking at horsepower at a given boost level because there are so many factors going into pumping efficiency.

[@richardholdener1727]

99% of people talk boost-not mass flow

[@SchofieldBrothersRacing]

How would the VS Racing 7875 with the .96 AR work out on a 4.8? The 1.25AR and 4" downpipe is going to be hard to package in my chassis. I think I could get a 3" in there tho.

[@richardholdener1727]

it will work

[@DannyWalls-xf3dh]

thank you for the prompt reply what size injector for about 700 hp ? this is going in a 2007 Solstice Gxp with 6L80 trans.

[@richardholdener1727]

80 POUNDS

[@dudewutuptube]

Maybe @turbolabamerica could help with that t76 gt45 hybrid you mentioned at 18:45?

[@AsaSpadeSS]

Out of curiosity, how reliable are these cheaper turbos? I mean I always figured they'd make decent power of course but how many pulls are you getting out of these ebay/cx racing etc turbos before they start wiping out bearings? Or are they all using the same internals as the bigger names, just less efficient wheels and housings 🤔.

[@richardholdener1727]

I have run these for 10 years

[@lucysmith4242]

Reversion and residual pressure after evc probably kills the power on turbos with more restrictive turbines and exhaust

[@richardholdener1727]

WRONG CAM THEN, RIGHT?

[@michaelangelo8001]

@@richardholdener1727 Wrong turbo.

[@68turbopowered]

Do you have a link to THIS specific GT45 Turbo? there are like 10k different versions on Ebay

[@bananafc5705]

get wither dna or maxpeedingrodsp

[@LEGOCAMARO]

That summit turbo is looking more and more like the right turbo for me

[@dilsher12]

Can't go wrong with the S475 , built like a tank . I run a t4 S475 without a blow off valve and it hauls ass .

[@LEGOCAMARO]

@@dilsher12 Definitely not a bad choice! But I actually wanted the lag for my ls4 5.3 going into a hhr and want it to drive like small engine big turbo car.

[@jkK-lw9lu]

Did you log turbine rpm? I’m curious if you go big on the hot side to lower back pressure, your turbo efficiency eventually would drop due to overspeed

[@richardholdener1727]

no