samuelblake

I am looking into rebuilding my LT1 into a 355ci twin turbo'ed lt4. I want to do the build in stages. My first stage is the engine without the turbo kit yet. I know I need the compression ratio to be low (around 8.5:1). My 2nd stage will be adding on the turbo system, etc. My question is, will I be able to drive the newly built, low compression LT4 without any turbo's on it while I am between the 1st and 2nd stage or will it tear up my freshly built LT4 to run it without any turbo's at an 8.5:1 compression ratio? If not, ABOUT how much HP will I have running a super low CR like that naturally asperated until I have the $ to add on the turbo's or will it be JUST enough compression to barely start the engine?

5.0THIS

There are motors with a ton less compression than that and they start just fine It's not like the turbo has anything at all to do with the motor starting up. Why do you think it would tear up the motor? As for power, you havent given nearly enough information for someone to make a guess about that. The compression and cam profile would be the biggest differences from a typical NA motor. I honestly have never seen any definitive testing on it, but I've read 10-15hp per point of compression is a good baseline for comparison.

slomarao

are you going to build the setup. No one makes a tt kit. Proturbokits.com makes a single that many people have had good results with. What are your goals? Budget? there are a lot of unanswered questions that need to be taken care of before people can give you 'good' advice. As far as driving the motor setup up for boost without any, it will lack some power because of the 8.5.1 comp. and the cam will not do the best since it should be a turbo grind.

engineermike

I did the same thing a while back. I built a 360 cid (4.040" x 3.50") with AFR 210's, 234/242 cam, 8.4/1 compression, headers, Victor Jr., and Holley 750. In a full-weight 3rd gen, my best time was 11.94 at 114, naturally aspirated. The engine knocked like a diesel (bad bore job), so I never put the blower on it.

km9v

http://www.bankspower.com/twin-turbo-products.cfm

will62085

that wont fit in an fbody...or with the stock lt1 acc. bracket for that matter

km9v

You are correct, mostly:

Twin-TurboFAQs
Please note: At the time of publication, Banks Twin Turbo system
is for installation on a Chevy small-block V8, and is not intended
to be installed on engines such as a 5.7 LT1 or LS1. Some parts
such as the exhaust manifolds and turbos can be used on these
engines, but support parts are not available and certain
components may not fit in the engine compartment.

mongse_1

I think they've been "planning" on releasing that kit for the past 5 years. I have yet to see one on a car or in production, other than the one they have on their site (which I saw @ PRI last year).