Since the LT4 heads flow 240 CFM which is much higher than the Stock LT1's (212CFM) or even ported LT1's (sometimes 237CFM), I'd like to bolt one on along with the intake manifold.

Problem is the intake manifold has larger runners which I think will hurt bottom end torque. Is this true?

Moreover, the original LT4 came with a 10:8:1 compression ratio which is more than the LT1 (10:4:1) and it also came with larger fuel injectors.

My question is should I still go on with the swap? Can it be done succesfully without having to swap the injectors. And last of all, will I get the 40 HP I'm looking for? Thank you.

 

post in lt1 tech

 

Moving to LT1 Tech......

 

There is absolutely no problems doing this swap, just bolts right on, BTW my LT1 ported heads flow 287cfm @.600 lift on the intake, which is quite a bit higher than any stock LT4 head I wouldn't go LT4 unless I got the heads dirt cheap & than port them before doing the swap, the compression increase comes from the heads themselves.

 

Shouldn't be a problem at all, should bolt right on since they both use the same block.

Stock LT1 intake runners are 170cc, LT4s are 195cc with slightly raised runners compared to the LT1 (about 2.5mm higher). Depending on how far you want to go, I'd plunker down the extra cash and get a set of AFRs (eithr 195s or 210s) which will go a good deal farther than the stock castings.

Loss of bottom end shouldn't be a concern. I've never heard the LT4 owners complain.

 

Funny you should mention the part about us not complaining. It took me a while to get used to the LT4 coming from an L98(modded to the tune of 350rwtrq). I wont say the LT4 is a dog down low, just different than what I was used to but it does have less low end than even a mildly modded LT1. Part of the difference in compression ratio is the pistons too. The LT4 has smaller valve reliefs which bump the CR a bit. I've got a dyno chart of my stock LT4 vs my modded L98 and its intresting to compare the two when overlapped on the same sheet. I'll see if I can dig it out sometime.
You should be fine swapping the LT4 stuff over but the others are right, unless you are getting a screaming deal on em, it may be cheaper to port your stockers AND make more HP.

 

Ok thanks.

 

go with the ported stockers unless you are getting the LT4s at a good price.

 

What kind of heads would be recommended for the Hotcam??

 

only go lt4 if thier a good pri 1ce and this place sells them at $630
http://www.sdpc2000.com/search.asp?s...=lt4&doQuery=1

 

FWIW, my 97 LT4 SS came with 24lb injectors, and it also made 300+rwtq from 1800rpm's, peaking at 325rwtq.

But, like other have said, you will get better performance by spending the money on porting your LT1 heads/intake.