PPI Typhoon

iTrader: (1)

Ok, I've done some searching and my situation is a bit different due to length of piping, so I'm sorry if this question is repetitive, but figured I'd lean on some others for advice. This is actually the 3rd iteration of this whole setup as I have changed the transaxle and intake, which drastically changed my whole setup.

Here is my setup:

Factory Five GTM
LSX-376 B15
Twin 6266's, mounted towards the rear. V-Band inlet/outlet 0.82 a/r.
Twin 46mm wastegates
I HAD Kooks headers in there, but the new Lamborghini transaxle interferes with them, so went back to LS3 manifolds.


Picture for reference to placement of turbos in relation to engine.


The LS3 manifolds have a 2.5" outlet. The V-band inlet on the turbine housings are 2.25". Should I reduce it to 2.25 right at the exhaust manifold? This would make it easier for routing as space is already tight to work around the shift cables, axles, etc. Or should I run it 2.5" and reduce it to 2.25" at the turbo? Is that going to make any difference?

My goals are 1kwhp at least once on the dyno, then dialed down to 600'ish for the street. I just want to make sure I'm not causing a handicap by picking the wrong size. Not to mention it has been ridiculously expensive having to do this whole thing 3 times over. I'd like this to be the last time.

Thanks for any advice anyone can provide.

Forcefed86

iTrader: (4)

2.25" is more than enough diameter, reduce it right out of the manifold.

2.125" or even 2" would be plenty if it's easier to work with IMO.

Using 2" out of each manifold on my 370. One to each side of a 1.24 T4 scroll. My back pressure is less than the 2.5" setup I merger pre turbo last year.

Slick setup!

stevieturbo

The actual opening in the LS3 manifolds is probably a lot smaller than 2.5"

I opted for 2" ID Sch10 tubing when I adapted my truck manifolds.

When the hole inside the turbine housing is barely much over 1.5", going larger just seemed pointless when I wanted good spool and power ability.

And if your turbine housings are V-bands...that suggests they are based around T3 housings, even at 0.82A/R it's probably a pretty small hole in there.
The LS3 manifold or 2" ID pipework will certainly not be a limiting factor compared to the small turbine housings.

Mine are 64mm BW units with T4 flange and 0.88

chuntington101

Cool build! What do you plan on doing for intercooling?

Shearer

Such a prime opportunity to make a kick *** set of headers. I could have fun in there!

Reduce it down to 2.125" right at the manifold. Any good fab shop should be able to take the 2.125" tube and swedge it to fit the flange opening on the OE manifold, or whomevers manifold flange you buy. Since the turbos are solid mounted I would run typical 16ga tubing with a flex section in them up to the turbos. Mount the wategates in the back close to the turbos.

PPI Typhoon

iTrader: (1)

Yes, they are the newer Precision V-band housings based on the T3, so they're a 2.25" inlet, 3" outlet.

The CNC flanges I got off of the C6 exhaust manifolds are 2.5. I think I will eventually drop off the car to my local fabricator once it's running to see if he can fit me a set of headers, but for now I'm running the manifolds. This has been a year long project already.

I was told by a few people that if I went with the T4 setup, my top end would benefit, however I'd loose the low end spool, but being a 2400 lb car, the T3 should be plenty for my goals. Hell, the stock LS1 that was in there before was more than enough.

PPI Typhoon

iTrader: (1)

This is what I originally had planned for the intercooling.



However, after going to SEMA last year, I stopped by the Lingenfelter booth and saw their intercooled intake:




It's a 2 piece unit that houses an pretty beefy water/air intercooler core inside:





So that intake frees up a lot of space in the engine bay while also moving the intercooler cores from sitting right over the hot pipes. It took 3 months to get it, but I liked that option better in the long run. I liked the look of the twin intercoolers, but after speaking with the engineers at Lingenfelter, they assured me that their intake would easily support my 1khp goal as they had it running over 1200hp in their shop with no issues.

PPI Typhoon

iTrader: (1)

I opted for the 2.5" reduced to 2.25" at the manifold, then 2.25 all the way back. I've not really seen 2.125" piping, at least not in my sources.

As for the headers, I had a really nice set of Kooks, which you can see here:



The problem is that the Lamborghini transaxle is significantly bigger than the Porsche unit, which caused the headers to exit basically resting up against the passenger side of the trans.




I'm making everything with V-bands so once I make the transition to custom headers, I just have to replace a small section of pipe and not change the setup completely.

vettewreck

iTrader: (1)

We're gonna need more full pics of this GTM. Thats all I'm saying

PPI Typhoon

iTrader: (1)

If you mean in general, here are a few before all the mods:










Playing with the idea of a wing:

stevieturbo

That's a pretty damn cool looking machine.

JoeNova

Awesome looking car. I think you may have went a little overboard on your engine combo, but everyone chooses a different path.

I've had my eye on the GTMs for a few years now. Also the RCR SLC. The biggest problem being the transmissions. I've added up the cost and I can get the GTM kit for $25,000 and a donor C5 for $3500 (wrecked) with engine. I figure odds and ends and since I do all of my own work, I can have one together for $35000.

Then I see that transmissions will range from $4000 (for a pretty much busted Porsche G50) to $24000. No thanks. I've had 800+ HP cars that cost me a lot less than that transmission. I must say that I envy you for what you've done here haha.

rotary1307cc

iTrader: (5)

Wow bet that is fun, looks great too

IronBlocked

That's the most beautiful-rare car i've seen

PPI Typhoon

iTrader: (1)

I bought the car built, and it had the G50 in it. It now has the transaxle out of a Lamborghini Gallardo. That conversion has run me just shy of $20k. Yes that's expensive, but considering the power I plan to make, the G50 would not hold up.

The power will be completely overboard, but that's kind of the theme I'm going for with the car. I have about as much into the GTM as I spent on my stock Nissan GTR. Considering the outcome, it's a relatively good deal.

I do plan on getting an SL-C next. Fran at RCR has been taunting me about buying one since he's the source of the adaptation parts for the Lamborghini transaxle. I told him I'll be doing an SL-C as soon as I have more garage space.

oscs

iTrader: (19)

Over board? In a car like this I feel like he should have went bigger.

JoeNova

I would have went shorter stroke, smaller displacement, less overkill on the intake/intercooler setup and probably still made the same numbers. These GTMs typically only weigh 2500 lbs and the transmissions are ridiculously expensive no matter which route you take, so I would be trying to keep low-end grunt down to make it a little more manageable and less likely to take out an input shaft.

A destroked 6.0 with those same turbos would have been a little better suited IMHO. Everytime I've mashed the pedal down in a 2500 lbs car with a big block, things get out of hand quickly. Replace that with a high revving small block, and its far easier to keep in a straight line.


Then again, this could still be the Envy talking.

oscs

iTrader: (19)

Your opinion I suppose. I know what big power and little weight feel like. If this where my car it would be no less than 1600 WHP

rkreigh

stainless works makes a nice set of upswept headers that might fit nicely

I would like to try and use the new 8 spd vette tranny and convert it to a transaxle with a custom shaft and bell housing to mount the lsx engine right to it

in a car that light, I doubt you'd break it very soon and that is a beefy tranny for future upgrades

for the kind of numbers the transaxles cost, I'd sure like to try

I would like to first build a RPM 4l65 or 4l80 and use that to see if this can be engineered to work

pm me if interested

Ryanbgb22

OT but did you ever see the mustard yellow ls7 GTM in your area? My uncle owned that car and was in the Phx/Scottsdale area and mentioned seeing a couple others around there. These cars are awesome, definitely a project I want to do someday.