nitrorocket

iTrader: (12)

I am putting together a tt setup for a 347" ls1 that will have 7.5-8.0:1 compression. This motor will never see race gas. It will be pumpgas only. It will never see over 7000 rpm and will have a stall between 3-4000 rpm. I would will run as much boost as I can with pumpgas, probably 18-24 psi. I will have to see what it will take! Question is, with 2 60-1 turbos, what a/r ratios should I start with? Any other advise would be appreciated. I do not have anything yet, Hell, I still have to build the motor yet, but I have all winter to do that! But have cash in hand and am scoping for the best deals!

Silver02Z28

iTrader: (2)

How much power do you plan to run? Two of those will be enough I'd say!
At 18+ psi you are looking at a pressure ratio of around 2.2. That puts a 60-1 within efficiency at 50lbs/min. So for both you are good to 100lbs/min or 1000hp.
http://www.turbocalculator.com/compr...s/t04-60-1.jpg

I'd say keep the A/Rs around .68 to spool two.

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I would suggest .81's.

-It will spool fine with the right converter

-Less backpressure equals more resistance to detonation

-peak boost will come later making boost spikes and detonation less likely

MY99TAWS6

iTrader: (3)

I can't see why the 60 1 basic can't put out like 30 psi.I have a smaller garret on my talon and it can put out 30psi.Of course you need forged everything and tranny and rear end but it should make huge numbers.And of course you can bolt just about any turbo up easily they aren't that much bigger ,the ball bearing types are the fastest spooling but spool time can be overhyped.With gears and stalls and two steps and all that stuff turbo cars can launch hard as hell and stay in the boost no problem.

I don't think the sts thing is overblown now.In fact if they sell shares in the company I will be buying them and my 99 ls1 will have one soon.Things I don't like are the one tailpipe but muffler shop can fix that and can't use my kenny brown double diamond on one side of car but might be able to mod their piping a bit but if have to sacrifice my subrame for 500 engine or more hp then so be it.

smokinHawk

iTrader: (48)

gosh why does every noob ask why an ls1 "cant push 30psi if the imports can"
airflow my friend, airflow, boost or psi is resitance to flow, blah, blah (im sure you heard this before), the ls1 simply flows more air with less resistance. A certain ls1 formula i know makes about 1400fwhp with about 25psi, now do the math can a turbo or even two that size support enough air volume to produce 1400fwhp

nitrorocket

iTrader: (12)

How did maximum boost become a topic, My question was A/R ratios and any advice from "experienced" twin turbo people with a 347" motors, I have never had motors this little before, so I want to take recomendations from people who have. Also, this is a PUMPGAS only motor and will never see much over 20 psi do to the limits of octane, not the turbo. I surely hope you werent refering to ME as a "noob".

smokinHawk

iTrader: (48)

no this