QCK57

Hi all,
i have a technical question that some more knowlegable LS gura maybe able to answer.

I have a LS1 346 with heaps of other mode-
LS1 ported heads 2.08/1.6 260cc 64cc
228/235 .610 117LSA
plus all the other go fast goodies.

However now buying a short motor. Looking at 408/415 cubes LQ9.

Will my GT3076R twin turbos push 20PSI through the motor till redline
7,000RPM?

Or should i be heading towards smaller cube's???????????

Also do you think the cam will cope with extra cubes?

cheers
Paul

Armageddon

iTrader: (41)

The cam should work decently ok.

The turbo question... I don't understand why people are so hung up on psi numbers. There are so, so many other things to take into consideration. The volume of air the two GT30s are going to flow is massive compared to some single turbos people are making big power with. The questions you should be asking are:
Will my turbos meet my power goals without overspinning?
Will my powerband be awful because my turbos are taking too long to spool?

You should never design a motor around a turbo...

That being said. You should do research on the combo you're looking to put together and figure out what a realistic power goal is.

Professor_speed

iTrader: (8)

I would expect peak power at around 5500 rpm with the turbos. 2 gt3076r are about the same as one tc76. That being said what is your power goal? at 20 psi on 346 those turbos should be about maxed. I would not expect to make much more horsepower with the larger engine but it will make the power at a lower rpm, a lot of torque, with an instant spool. I think your cam would work well with those turbos.

QCK57

Thanks for te\he advice.

looking at 700rwhp as my end target.

Proffessor that was my question will the turbos flow enough air to feed the 408/415 to redline/7000RPM.

What is the simplest way to calculate this.

Also what twin turbos sizes; that people know of in the 408+ cubes that work together and make power through the whole rev range.

cheers

stevieturbo

Agreed. An ability to hold 20psi to xxxx rpm can often mean sweet fa

And cam choice in any given engine capacity will have more effect on rpm's available than turbo choice.

If all you want is 700hp, then a pair of GT30's would be more than capable.

TurboAv

iTrader: (6)

The www.forcedinductions.com website has a lot of good info along with air consumption calculations to figure out how much you engine will need at a given RPM.

Professor_speed

iTrader: (8)

for 700 hp and 400+ cubes i don't think you will need 20 psi. (probably around half that) at a lower pressure ratio they should go to 7000rpm. you will be right at the end of the compressor map and they will be blowing hot air. those turbos will be at peak efficacy (coolest air coming out) at about 5000rpm

The best way to figure it out would be to look at a compressor map. and do the math. garret's website has maps for that turbo and instructions on how to do the math. (turbo tech 103)

cam and turbo choice will affect the engines ability to breath. even a small cam like yours with big turbos will breathe. if the turbos are too small no cam in the world will allow it to breathe. A big cam and smallish turbo will fall on its face. (ask me how i know this )

The way i see it is the cam must work with in the confines of what the turbo is capable of. Cam selection should be based on how the turbos will interact with the displacement of the engine. figure out what rpm your engine will be operating in based on desired power and what the turbo(s) is capable of providing. choose a cam that will work with that power band. (This a simplified way that I spec a cam) take if for what its worth.

All that being said i would run what you have with the bigger engine. I'm willing to bet the gt3076r 408 will be a blast to drive. for you goals the parts you have should do it.

smokinHawk

iTrader: (48)

I would believe that gt30's would be to small and choke the engine
gt35's would be a better choice.
You'd probably run out of steam by6000 rmp with the 30's

98Z28CobraKiller

iTrader: (17)

That's an entirely incorrect statement.

chuntington101

hmmmm GT35rs. Do you know if Garrett is coming out with the GTX comp. blade for the 35??? I here these new 11blade wheels are supposed to be rather sepcial.....

ScorpionT

GT35R or Precision 6262 would be great. The GTX compressor is definitely nice, the new blade design is quiet and makes nice power. Ive heard Garrett wont have the new compressor for the 35R for another 8+ months, I hope its not true!

chuntington101

Yeah im hearing some good thing about the 6262s. The EVO guys seem to love them.

8months!!!! thats cr*p! do you know what turbos the GTX is avalaible for now???

Cheers

Chris.

DrTurbo

iTrader: (3)

Be patient on the GTX wheels. Alot of new stuff coming.....