1QwickLT1

iTrader: (1)

Hey guys, is there any difference in building a 383 lt4 vs a 383 lt1?? I wanted to get a lt4 block, but couldn't find one. Also, what are the advantages of a lt4 383 stroker over a lt1 stroker?? TIA

Dave

ZL1SS

iTrader: (4)

Well just about the only difference I can think of are the heads. LT4 heads flow more than LT1 but if you are doing a 383 you have to be doing a P&P job as well so It really doesn't matter. Just go with the LT1 block and be done with it.

TitanZ

iTrader: (4)

LT4 is a 4bolt main block

1QwickLT1

iTrader: (1)

I knew that, but i wasn't sure if it would be better to stroke a lt4, or a lt1, or if it even mattered. But i guess not lol. Thanks for the input guys

TD's z

well a lt4 block has a 4 bolt main

thanks to yours truly we now have a lt1 intake port that flows around 290 at .600 with a 2.02 valve wich is comparable to a good set of lt4 heads there also cheaper than lt4 heads and great for a stroker

a good machine shop could fix you up with 4 bolt mains on a lt1 but you shouldn't need it if your going NA and keeping it at a reasonable rpm

93turboLT1

Well let me try to help with your decision with my own experience. My buddy and I have debated this same topic before, and theres no right or wrong answer its just when you do pick your route, spending your time and researching every area to ensure you are going to net the result you wanted. See I have a 383 LT1 right now in my 93 Z28, a comp 503 cam and a stock LT1 heads ported. (a disappiontment) Now the LT4 route is going to be more expensive and there no way around that. You will have to buy all new, (except your block) if you want the LT4 head and intake design. Now unless your goin for every last ounce of juice, the LT1 head will suit your need perfectly...I've heard the LT4 head is only good for about 40hp more at there maximum port. But if you scimp on your heads regaurdless your going to be disappointed and WILL NOT achive the gains you think you will even with a huge cam. A great set of heads will make a smaller cam perform much greater then a big cam with a cheap set of heads. (not to mention the needless wear on your Valvetrain, lack of driveablity, and gas mileage.) Going back to my disappiontment, I have a fully forged 383, but the heads are only stock ported with stock valve size. My cam is mild, but I can obvouisly tell that these heads are holding me back. I'm prolly in the low 13's with street tires, and low 12's with tires and 3.73 gears. The LT1 is plenty capable of 400rwhp and everyday driviblity, and I don't want to see you do the same thing I did....Just make sure you get a nice set of heads, (either one), and I cam with durations over 230 degrees, and your garrenteed 400rwhp, and you'll be very glad you did it.

Camaroholic

iTrader: (1)

I don't think there was *any* difference between a 4-bolt LT1 and a LT4 *block*. I know there were some rotating assembly differences (knife edged crank, filleted journals, etc), but those don't matter with a 383. The top end is where most of the difference was anyhow.

If you have a 2-bolt block, just splay it and be done with it. It'll be stronger anyway.

If you have a 4-bolt block (I have one ), use it.

OneMeanZ

iTrader: (2)

1QwickLT1

iTrader: (1)

Thanks for the replys guys. So should i get a set of LT4 Heads + intake to go along with my 383?? I was gonna get like a cc306 cam + 1.6 rr. My dad will do the porting and whatnot, so that is no biggie, and im sure he will try and squeeze every ounce of juice out of it for me thanks again

Dave

Vendetta

For heads definitely go AFR if you've got the money. Their setup is the same as the GM LT4 heads (raised runner). Check out their website =========>

1QwickLT1

iTrader: (1)

What is so different in the AFR heads than p+p any other stock head?? I have always wondered whats so special about them? How does a company produce so much more power than a good p+p?? Thanks

Dave

TSAEB

iTrader: (5)

afr heads can also ported right...if so how much more air flow is there with p/p heads than lt4 head p/p

SAPPER

iTrader: (10)

If you want a good set of heads that flow, see Total engine airflow------->
Bryan makes any head flow better than AFR or anyone else out there.
LT1 w/ exg $1500, but well worth it.
I have seen all the other companies p&p heads and Bryan's will give you a woody, they are sweet and I'm gonna get my LS1 heads from him too.
Read his bio and you'll know why

SS MPSTR

iTrader: (1)

I debated this very topic myself at one point, and made my decision. I started putting together the LT4 package on my LT1 a few years ago, and finally stepped up and sent my LT4 heads to Advanced Induction. The port job turned out beautifully, and I have a custom cam matched to my headflow and goals/expectations of the car. I too have seen great peak numbers out of large valved LT1's, but it is the area under the curve I care about for my street engine. My LT4's are well over 290 CFM @ 0.600", but make what are considered good peak flow numbers for LT1 heads at much lower lifts. What was mentioned earlier about heads is true - don't skimp there.
As far as bottom end is concerned, it all depends if you want to spray it or make hellacious numbers over 6500RPM. I plan to spray mine (200) and spin it to 7k RPM +, which necessitated a forged Scat assembly, H-beam rods, and JE pistons in my mind. I like the extra insurance even though it cost me a few more bucks. I stepped up and did the four-bolt main conversion as well as a few other tricks I've learned along the way. It pays to read and follow along with the folks on other boards who are making ungodly power (i.e. Mindgame and others).
My engine is currently being assembled and I'll post up numbers when available if anyone is interested.