Hello everyone,

I've been "lurking" on the forums for quite a while, and got sucked into the FI section. I've been debating on building a nasty N/A motor, or an even nastier turbo motor. My last car was turboed, so I have some experience with FI.

First let me give a list of goals I would like to achieve with a built ls1(8:6:1 pistons, h-beam rods, cam, springs, intake):

-at least 600whp
-Turbo spool around 2k
-Power to redline
-Capabiltiy of 800whp
-It will be a street car
-make people cry when they take rides in my car

It seems on here, with a mildly stock ls1 (stock cubes, intake, cam, ported stock heads), going the single turbo route, a t76 with an exhaust a/r of .96 is just what the doctor ordered. Many people seem to be pleased with the response and potential this size turbo offers. The more I read though, it seems this turbo spools between 2500-3000. Please correct me if I'm wrong. The thing is, I would love to be able to start making boost as quick as possible, which brings me to my next problem. Twin turbos. It seems the most resonable twin turbo setup is twin 61-67mm turbo, but I cant find any info for a good a/r for the exhaust side for my goals.

Lets say I was to get two PT61's, I would definitely get a t4 tangential (from what I read this is the way to go for LS1's). Now the choices of turbine a/r are .58 or .68. Now here come the questions:

-First and foremost, which a/r for the dual PT61's would be most appropriate for my goals?
-Between the two setups, would it even be reasonable for me to go twins?
-If it is more reasonable to go single, should I go with the PT76, T4 tangential, with the .81 a/r or .96 a/r

If I'm completely out of the park with these two choices, please point me in the right direction. Thanks for you time and any help in advance.

 

Anyone?

 

it might be hard to make 800whp from a turbo that is spools at 2000rpm. A TC unit will spool very quick and definatly get you past 600whp. A 76gts(pt7675) will spool a little slower but will get you to 800whp.

 

yea I see what you're saying. Do the twins spool much quicker than a single then? People on here say they see 10psi at 3k with their pt76. How much quicker could twins spool for the same amount of power as a pt76?

 

i have even seen some make good power with twin t3 turbos... i think i have seen something in the 800 ranges a few month back...

 

Thats really impressive. From what I've been reading, the majority of people have been saying to stay away from the t3 twins because of the extreme backpressure

 

Im not sure, I have'nt done much research on twins.. 10psi at 3k is not bad at all.

 

You can make 800whp, and you can get spool at 2000rpm, but I really doubt you'll get both. Twins don't spool that much differently than a single. They just package differently, which can be handy depending on what car they are going into.

 

Pt76gts and a spool valve might let you achieve your goals.

 

Or twins with spool valves...

 

i was gonna say just run single t4 with a spool valve. try it without the spool valve first, if you want boost to come on quicker then order the valve