lilmiller74

Like the title says im looking at some possible directions to go next with my car and some help and guidance would be much appreciated.

My car is h/c and sprayed ls2 vette, Im looking to just add forged pistons and rods and all new bearings and stay stock cubic inch.

What would be a good compression ratio to go with? I was thinking i want to get as close to 12.0-1 unless there is a more optomal cr. I will be running the car on e85 so the compression wont be an issue.

I am running stock l92 heads that I plan on porting and milling and I am going to be looking for a new cam as well. The car will also still be sprayed and I will most likely be hitting it with a 200-250 shot.

What do you guys think think I should do cam wise? Im looking to make 500 wheel on motor and if there are any ideas on how more power could be made with this fairly simple set up your info would be appreciated. It is going to be mainly a street car so I dont want anything to radical but im not scared of losing some driveability.

Fastdriver1992

iTrader: (1)

Personally i would rather see u send out your 243 heads to get ported/milled. You will get alot more velocity with those heads where the l92's may be too large especially on only a 4.00" bore. With e85 people run as much as 15:1 SCR. Plus from what i have read the ls3/l92 heads don't like a 4.00" bore. They are more effective on a 4.030"+ bore. Just my .02

lilmiller74

So you would ditch the l92 head that i already have and go back with 243 heads?

1badeagle

iTrader: (9)

The L92 are proven to make power on a 4.0" bore just fine. They do pick up a good bit more power when they are unshrouded though.


Honestly Casey, When you have the motor out, bore it for a 4.030". Get the valves unshrouded. Find a set of pistons with a small dome to make up for the valve releifs for the L92 valves. Mill the Heads to get the compression up close to 13:1. Have Rick Crawford port them and reshape the valves and get a good 5 or 7 angle valve job. Ditch teh stock valves for a set of ls3 hollow valves. Get Pat G to spec you a custom cam so you can wind it out to 7500 Rpm and let her rip.

This should let you run with IMSTOCK2

Sales@Tick

iTrader: (3)

This is something that drives me nuts every time I read it. Square port heads have low velocity because they are sooooo big, right? NO!

Air speed in the intake runner is all about how much CFM you can move through a given orifice at a given amount of lift.

I agree about the valve shrouding though as with a 4.00" bore the intake valve is jammed up against the cylinder wall bad between .150"-.350"/.400" valve lift. On a 4.0" bore I'd like to see a maximum of a 2.05" intake valve.

I also agree with the compression ratio as I have several customers running 13:1-14:1 on E85 in street cars.

I run 12:1 with customers on 93 pump gas in 80% of the forged N/A builds I help spec for people that come to me for that service. I wouldn't even run E85 N/A unless my CR was 12.5:1 or higher.

lilmiller74

Thanks for the info that's exactly what I'm looking for. I wasn't sure how high I should go with the cr but with that info I will definatly go higher than 12.1.

lilmiller74

I also might just have it bored out to an ls3 cubic inch then as well.

yonerhottlt1

iTrader: (21)

Your not gonna have much room to bore out that aluminum block. Maybe .005-.010 which will only get you an extra 1-2 cubic inches but that's about it. Someone correct me if I'm wrong...

Sales@Tick

iTrader: (3)

Yoner is correct.

1badeagle

iTrader: (9)

He should be able to go to 4.030 bore correct?

Fastdriver1992

iTrader: (1)

Would u say that a stock l92 heads would make the same or more power on 4.000" bore then a set of CNC ported 243's? Also i suggested 243's because of the 64cc chamber and would help bump up the compression ratio. milling a set of L92's enough to get a 13:1SCR+ would cut down flow numbers wouldnt it?

I'm just curious because i've seen many 383ci+ builds using trickflow/AFR 225/235cc cylinder heads, and if i'm not mistaken the l92's are 260cc runner. Just my way of thinking if a 225/235cc runner is big enough to support 383ci then wouldnt a 260cc runner just be overkill for a 364?

Sales@Tick

iTrader: (3)

If I could personally choose a cylinder head for a 4.0" bore motor it would be a 220-230cc runner every time with no larger than a 2.055" intake valve or a 2.06" intake valve like PRC uses on their As Cast 225cc heads.

We actually just used those PRC as cast 225cc heads with our V.2 Polluter camshaft to make 506rwhp/443rwtq on a stock bottom end 6.0 GTO.

low2001gmc

iTrader: (148)

that is impressive martin and good info to know. im not near 500rwhp but i gotta say i love my lq9 with me ported ls3 heads, lunati 232-238 cam, ls2 portworks ported l92 intake and tsp 1 7/8s....on a budget....

lilmiller74

what did your setup make?

yonerhottlt1

iTrader: (21)

Negative...he would need to sleeve it or use an iron block 6.0.