oakley6575

iTrader: (5)

With that LSA, I bet it idles so nice. Do you have any vids of your car?

oakley6575

iTrader: (5)

So I've been doing some research and looking at compressor maps on different turbos. Basically I've been trying to find a turbo that is at it's highest efficiency when pushing 10lbs of boost and making 650-750 hp.

What I have been seeing is that I will have to run a pretty huge turbo to be efficient at 10psi.. Somewhere around an 88mm turbo. What are your guys thoughts?

HRHohio

Here's one (Pre-Turbo): 2002 Camaro Convertible (Bad Z28) - Midnight Mayhem September 16, 2011 - YouTube

Here's one against Hawaiian Built (He hooked, I didn't, I got a lot of other excuses too...lol) (Pre-Turbo) (Drivers view): BADZ28 vs. Isley's Truck Midnight Mayhem September 16, 2011 (2nd Run, Isley Wins) - YouTube


Here's one after the turbo, but with a huge boost leak. IAT Sensor had been blown out of elbow and sitting behind radiator, big hole in elbow. My assumption is that it pulled some timing and I never got into boost. So I ran a 13.1 (bad track prep) on the LS9 Cam only. (That's my story and I'm sticking too it.)
Ran a 12.89 a few minutes earlier @~2-3 psi...
02 Camaro SS vs 02 Camaro with rear mount Turbo - YouTube


Car has some sort of electrical issue right now. I took it back to Cali to have the builder figure out. Rough idle when cold, stalls, etc. Stumped...for now. Maybe stuck injector, maybe bad computer, ground wire, who knows... uggh. I miss my car.

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HRHohio

Have you gone forged yet? (Forged Pistons / Rods?)



Here are a few links.

First one says, "It has a 65mm turbine. That makes the measurements pretty much identical to a TC76 (76mm incuder, 102mm exducer compressor) with a F1-65mm turbine wheel. "
Source: on3 turbo - Page 6 - LS1TECH posted by Killernoodle

This matches up with their ebay ad for the ball bearing one, I think. (See link far below).

With that info... read link 2:

MP T76 vs TC76 F1-wheel vs S400 which direction?
It's going on a 6.0 LS3 Head car.

You can get the On3 T76 Journal Bearing for about $349 Shipped.
eBay - New & used electronics, cars, apparel, collectibles, sporting goods & more at low prices

You can get the On3 T76 Ball Bearing (i did this) for $717 shipped.
On3 Performance 76mm Ceramic Ball Bearing Turbocharger | eBay
It has the bigger compressor exducer (64.5mm)

Can't seem to find any maps out there for these though. But I think you'll be able to meet your goal of 650-750 with a T76, but not at 10psi. 12-13 psi maybe. With a good cam, you may only get to 600 @10psi. But it would be good to have some other opinions chime in.

Good luck. Happy reading!

oakley6575

iTrader: (5)

The only reason I'm limiting myself to 10psi is because of the high compression and weather conditions.

Yes this 408 is fully forged and built with callies crank/rods and wiseco pistons. I guess if I want to do this turbo deal, I need to change the pistons.

HRHohio

Gotcha. I agree, at 11.4:1 I'm not sure how high you can safely go. Dropping it down to 10.5 or 10:1 would obviously allow you to push it more. Methanol/Water will really help up the anti-knock too. I think it might be cheaper to port your heads than replace the pistons. Plus may be more beneficial (better flow).

It's really going to come down to the tuning. You can have it pull timing too if your temp gets too high (IAT). My tuner told me that's what he did because he wanted to give me a safe tune in this desert heat.

We should get together sometime when I get my car back (soon I hope).

oakley6575

iTrader: (5)

By porting the heads, I would be down to 10.5:1 but I don't think that will be low enough to run 12 psi. Or would it with the meth kit?

I'm going to port the heads whether I change pistons or not. It all comes down to how much boost 10.5 compression with meth can handle safely.

oakley6575

iTrader: (5)

And I have hptuners so tuning isn't a big deal. It's one of my favorite things to do.

HRHohio

I'm not for certain, but I think if you're forged, you should be safe up to 15 psi or so...especially with methanol. I'm stock bottom and I see 10 psi.

If you go too low, you're going to have a dog off the line. Tricky balance.

BuffJoeyD

iTrader: (2)

To catch up a bit, underhood temps absolutely affect IAT- everything starts soaking heat up and the air in the motor and in all the cold air tubing is going to bring the temps up.

Front mount is always the way to go. Rear mount isn't bad- so don't read it that way at all. Rear mount the piping under the car is going to act like a partial intercooler as well, but others would argue that you have more charged air compressed and being heated.

If you are talkin strictly boost # I would say keep it around 7psi, and keep your motor compression up. Most people don't think like I do ( so again just keep doing your own research ) but I like a motor than can pull its own weight. With your truck I would bet that the 408 works great, and is fun to drive now. The drop in base compression is going to ( simply put ) decrease the power output that you spent the money to have built into that motor. ( Maybe Im of the wrong mindset ) To me, you drop compression when you are to cheap to build a motor / the turbo you want to use is going to make more boost than your current motor can reasonably run/ or are looking to build something that is high end wide open power.

I think LS style turbo builds are for people that love their current power but want more power wide open. ( when you are simply talking about a driver type car ) Far too often people make so many "turbo build" changes and then are unhappy with the "low end " power of the car after, and it spends a lot of time in boost.

Small turbo, quick spool, low boost. end of long post