yldouright

I've noted T3 turbos come in a variety of trim specs, T3-40, T3-45, T3-50 to name a few. Will any of these flow >600cu.ft./minute keep Air LBM ~45lbs/min. and Fuel LBM ~3.3/min.? That kind of throughput would make 400HP on 5.3L and have practically no lag. Another plus is the ease of fitting a smaller unit. What do you guys think, how much power can we get out of a T3?

JoeNova

With a proper setup, you can get almost no lag out of even a T6. You would be RPM limited with a T3 as compressor/turbine efficiency relation would be out the window by 4000 RPM.

yldouright

@JoeNova
Thanks for chiming in but how can you know the 4,000 rpm number is right for ALL trim varieties of a T3 without knowing the gas throughput numbers? How do you know a proper setup on the right trim T3 can't spin out gas to 6,000 rpm? It's why I asked the question the way I did

Forcefed86

iTrader: (4)

None of the T3 exit volute diameters are large enough to support a 5.3/4.8 flow at reasonable drive pressure ratios. It would be off the compressor map by a ton with any real RPM/load.

You can get more than 400 HP out of a 5.3 with a cam and spring swap...

Good example

http://www.cpgnation.com/the-100-horsepower-upgrade/

JoeNova

Most T3 turbos have a fairly small compressor that can't properly support a V8. Most turbos are at their peak efficiency moving about half their maximum CFM at higher pressure ratios. With a small compressor and a V8, you have high CFM and low pressure, which puts it off of the compressor map. Combining that with a small turbine is a disaster. You end up building exhaust pressure at a greater rate than intake pressure, giving a very high backpressure ratio. Spells disaster for performance. Your only real option is a 62-66mm compressor with the largest T3 you can get. Even then, you're going to be fighting a high backpressure ratio with diminishing boost levels higher in the RPM.

I've tried a single T3, twin T3s, and quad T3s on V8s. Even with twins, keeping power up top is an uphill battle, as boost begins to taper and the backpressure ratio climbs from 1.5:1 up towards 3:1. The easiest way to fight this is with large external gates, but even that has a diminishing return.

If spool is your main goal, you're definitely going about it wrong. With twin T3s, I was seeing boost by 1800 RPM. With a big single BW T4, I was seeing boost by 2600 RPM, and made 900 ft-lbs at 3500 on a 5.3.
With a single T3 GT35, it felt like a diesel. Boost came on at 1600-1800, and it was done by 4 grand. Boost fell from 14 lbs at 3200 RPM to less than 6 lbs at 6000 RPM, even when I cranked the boost controller in to basically cut off air flow to the wastegate diaphragm.

This is a graph for a T4 S363/73 on an LS1. It wouldn't make more than 9 PSI with the gate pinned. Lots of torque, 500 horsepower.
A T3 would be CONSIDERABLY worse, and wouldn't hope to achieved anything like this one did. You would be shifting power down 2000 RPM and losing 100+ horsepower.

1CAMWNDR

iTrader: (21)

You will get heat and backpressure. Not power.

R_trim 93GT

iTrader: (1)

Great job on explaining this one JoeNova. I agree.

ALL ULL C

iTrader: (16)

So then I would have to ask how does AGP get so much wheel hp/tq out of a 6.2L with their base kit which I believe is a 54/57 T3 (.63)? You go to the Camaro5 forum and read the AGP thread there are countless builds that are very mild up to maybe a cam swap in the 6,7, 800whp range. Is it a modified housing as I know they brand it AGP?

I really am curious as I will be building a 6L TT setup and I'll be using BW S254 or S257's with .63 T4 housings. They did try and get me to swap into a T3 housings but I too felt that it may come up short but the results seem to back up their method to madness.

JoeNova

They're using twins, not a single like OP is talking about. A single would be a laughable mistake.
A twin setup I did with T3s made 600 wheel on an LS on a heartbreaker dyno, but the turbos were completely out of steam. Only an upgrade to a .81 A/R T3 housing and a larger compressor would have let me go further.
Twins definitely works. A single won't work very well.

ALL ULL C

iTrader: (16)

Crap, I missed the part he was using a single but read where you did twins and focused on that.

R_trim 93GT

iTrader: (1)

Twin 57/62 T3s with a 0.81 A/R housings will have no issues making 800rw on a 5.7L or 6.0L at around 18psi and will be very responsive. I did this in a C5 corvette with a manual trans and no 2 step. By the 30 foot mark the boost was all there and I can only imagine what the short times would have been with a two-step and/or automatic with a transbrake.

Edited to specify twins. I meant twin T3s in my post but didn't state it. There is no way a single 57mm T3 will make 800rw with a LS V8.

R_trim 93GT

iTrader: (1)

The scaling is different on a T3 vs T4. If you switch from the 0.63 T4 housing and are looking for 800rw, I would choose at least the 0.81 housing with a T3. These parameters are based on using twin T3s.

Edited to clarify twin turbochargers as opposed to a single T3 or T4.

JoeNova

Rear mount?

Rear mount makes T3s more viable. The same exhaust mass with less volume from cooling helps bring the backpressure ratio down.

1CAMWNDR

iTrader: (21)

A single T3, 57/62 made 800 WHEEL hp? I find that hard to believe. TWINs yes. Even a single rear mount T3 57/62 I cannot imagine making 800 wheel hp.......but strange things do happen......

SLOW SEDAN

iTrader: (13)

I've done some AGP kits and they easily make 800+. Also done some others like the APS kit with GT3076 or 3576's and make a good bit with the .82 housing, if you ask you can also get a 1.06 housing as they are same price.

If going T4 I wouldn't get the .63 housing either, at least get the .82's. I ran twin T4's with .88 housings and it worked well.


What kinda busted T3's were those that could barely make 600whp? What boost was out of steam?

JoeNova

Internally gated on a 4.8. Dynojet numbers would've been about 660-670 wheel. This was at 17 PSI.
Twin 5056s with a .63 A/R. Backpressure was through the roof.

R_trim 93GT

iTrader: (1)

It was the Turbo Technology X kit for a C5 corvette. They were in their sweet spot at 18 to 20psi. Much more airmass beyond that and they quickly get unhappy from a backpressure and heat standpoint.

Right on. I meant twins but didn't state it. You are correct, no way a single T3 57/62 is going to make 800rw. Original post edited for clarity.

SLOW SEDAN

iTrader: (13)

Ahh almost hard to find a turbo that small, I think the T3 platform can go a lot further as twins then what those little guys demonstrate. The larger T3 5862 and 6266's have put down fairly impressive power in simple setups and show what they are actually capable of. Granted the OP talking about 400hp out of a 5.3L is pretty laughable here in the FI section, people have damn near done that NA. With a goal of 400hp, pickup some heads and a cam instead of a turbo.

yldouright

I'm glad to see a spirited discussion about this. The placement and ducting of the right T3 along with a good intercooler setup should get me what I need (a long flat 400ft/lbs. torque curve and 400-450hp at the wheel from 9psi and pump gas). I'm not speaking authoritatively but if this is doable, it would be my preference. The application is for a weekend road racer that works as a daily. Noisey cams and loping idles are not desired here so boost is preferred over shafting the motor.

JoeNova

Right. 400 N/A is easy to do on a gen 4 5.3. Pick any 430-440 wheel LS1 combo and copy/paste.

I have quad 5056 T3s on the corvette. On 11 PSI, the power curve looked like it was scaling a cliff when I shut it down (smelled trans fluid badly).
On 17 PSI, it was climbing even harder until I shut it down at 5000 RPM from said trans issue.

That small T3 flange entry isn't much of a restriction with proper twins. And I mean proper, not "I want the fastest spool possible" type turbos.