I need some advice from everyone who cares to share their thoughts. I am trying to get around 400hp with my stock LT1. Should I go with the LT4 conversion kit or should I just redo my LT1 heads and add a cam? I do only have 39,850 miles on this car and it runs great just want more speed like everyone else. Any help would be appreciated.

 

well the LT4's are only rated at 330hp and 350FTlbs of torque, i am currently in the process of ARP 220 cfm head kit with custom grind .660 cam, i was going to go witht he LT4 kit but its not that much faster than a stock LS1 and the new LS2's would smoke em.

 

You aren't going extreme enough with the LT$ to get anywhere near 400 HP. to get 400 (flywheel, about 350 RW) from an LT, I think you will need to stroke it to 383 and add really good heads and cam and headers. That ought to put you near there.

 

Dont kno much about the topic but in a performance mag, either jegs or summit, the ad advertised 425+ with the lt4 conversion kit.

 

Thanks for the responses. I too have looked up the LT4 kit and it does say it will give up to 425hp. I dont know if thats at the crank or rear wheels. I am inclined to believe at the crank. I would do the 383 stroker but my engine only has 39,850 miles on the entire car and if I where to do that it would decrease the value of the car. Any more ideas would be helpful.

 

That 425 will be engine dyno power, under the best conditions with real good heads, long tube headers, low restriction exhaust and intake, no cats, etc., and that 425 is not equivalent to "in the car" flywheel rating. The LT4s from the factory were torquey, 335 HP engines, very good. With a bit of head work and headers, etc. they would do about eqivalent of 365-375 HP: For example, a '96 C4 Corvette (came from the factory with LT4) with ported intake and exhaust ports and the head shaved a bit for higher compression, good LT headers and a 3" dual exhaust and no cats, and a good CAI, will outperform a standard C5 (350 factory HP) but not an 01 ZO6 (385 HP). I would count on that being as good as the LT4 cam will get you. If you go with something a bit more aggressive, which will require more $$ to change out the springs and rockers for heavier duty, you can pick up another 20 HP or so.

 

You can probably do better than the LT4 conversion, by putting on a good set of heads, such as AFR, a good cam with roller rockers, and a good set of headers. Wether you'll get 400 WHP is kinda debetable with either set up. It can be done, but the engine may be a little too radical for street use. Build a small block the NASCAR way and it will put out over 700HP, but you wouldn't want to drive around in traffic with it. You can always make power on the cheap, and keep your engine driveable by using nitrous.

 

You can probably do better than the LT4 conversion, by putting on a good set of heads, such as AFR, a good cam with roller rockers, and a good set of headers. Wether you'll get 400 WHP is kinda debateable with either set up. It can be done, but the engine may be a little too radical for street use. Build a small block the NASCAR way and it will put out over 700HP, but you wouldn't want to drive around in traffic with it. You can always make power on the cheap, and keep your engine driveable by using nitrous.

 

Well thanks again for the input. After reading what you guys posted and talking with a good friend of mine that owns a performance machine shop, I have decided to redo the entire engine. The machine shop is giving me a great deal. I am going with a 383 Stroker Motor, AFR heads with 2.02 valves, LT4 Intake (if I can find one), 58mm throttle body BBK, 30lb injectors, and I can't remember whats going in the bottom half. The owner of the shop told me that it could hold a 450 shot of juice and not hurt the motor at all. He said it would be a little over 500hp with about 545lbs of torque. I will also be changing my stall to a TCI 2400-2800. I will be taking pics of the build up so I can post at a later date. I will also be selling the complete LT1 thats in the car now if someone is interested. It still has only 39,900 miles on it and runs perfect. I just wanted more power.

 

how much do you want for that lt1. and do you guys think my stock 1997 rs auto tranny will be strong enough for this engine?