Really depends on what you want...Do you want an LS1?

Both cars can be made really fast, with my new heads and cam combo im hoping for 400RWHP in an extremely streetable setup.

LS1s are also alittle more expensive to mod, but the mods yeild greater results.

For example if you put $2000 into the engine of an LS1 and an LT1, you would put more goodies on the LT1, but end up making around the same power. Roughly.

 

I've had LT1s, an LS1, an LS6, and now an LT4. Out of all of them, the LT4 is my favorite engine. It has more low end grunt (torque) than the LS1/LS6, and will make the same HP as an LS1 but will pull a higher rpm (and remember, mine is a factory LT4, which doesn't have the hotcam). Also, as someone already stated, the LT4 benefited from some of the things they learned on the LS1, and was actually a precursor to some of the LS6 technology (hollow/sodium filled valves, higher compression ratio). Here's a great site for full details on the LT4:
http://www.grandsportregistry.com/lt1vslt4.htm
Finally, to get all the benefits of the LT4 is more than just the heads, the pistons are different, the balancer is different, the crank while the same part # as an LT1 crank is specially machined, and there are still other differences.

Anyway, after having said all that, I would not recommend you upgrade to the LT4 "kit". As I already mentioned, a true LT4 is more than the kit, and while you see most of the benefits from the kit, it's really not cost effective. You can make much more power from ported LT1 heads (or get some LT4 heads and get them ported if you really want), and a custom/aftermarket camshaft.

 

Why would you not recommend a lt4 conversion for $2200?The lt4 conversion kit will make 425+ hp.big jump from the stock rated 330/340 lt4.

 

425+ hp is "potential", not how much you're gonna see with that. All that is in that kit is factory LT4 parts plus a hotcam. So 330 hp + hotcam = 350 hp? There are other routes to go that would offer more power for less money. 2200 will get you Lloyd's heads plus CC306 plus longubes plus springs + retainers. Throw in some drag radials, sfcs... drool...

 

No the lt4 has given proven 425+ hp after mods to your vehicles engine management systems.lt1 edit.Its ADVERTISED TO GIVE YOU 425 PLUS.

 

Not to doubt you ,but I thought it was called the comp cams 305 cam?

 

it's been in development since ATLEAST 1994, in the corvette museum(sp?) in bowling green, kentucky, there's a wrecked C5 style corvette on display. i guess it was one of their "crash test" cars. and you can see under the hood and it's an LS1, or atleast has an LS1 intake.

and the thingie next to it, that talks about it, is dated 1994.

 

Don't believe everything you read in Summit. It takes many other mods to get that advertised "425+" hp they claim. CAI, good headers, full exhaust, programming, among other boltons to get there. Theres nothing wrong with that kit in my book but there are cheaper ways to make more power than the LT4 conversion kit.

 

Yes, the LT4 conversion kit can make 425HP, but that is flywheel HP first off. Second, you'll also need all the bolt-ons including long tube headers, and dyno tuning to make that. So when all is said and done, you will have spent well over the $2200 advertised price, and will end up with 350-360RWHP (on an M6 car). Not bad certainly, but you can make more than that with other cam choices and fully ported heads. As a matter of fact, you can make more with just another cam choice and unported LT4 heads. There is another LT4 Firehawk owner that with just a CC306 and long tubes that made 350+RWHP on a Mustang dyno, and Mustang dyno numbers are significantly lower than a dynojet.

 

Potential. That package is just all LT1 to LT4 stuff with the addition of the hotcam. You won't see a 100 hp improvement with the addition of a cam like that and some tuning. I would say 360-370? You can get to 425 hp with that stuff, but it's gonna take more mullah in bolt-ons to get there- the stock manifolds and exhaust would definitely have to go.