zach914v8

I am in the process of getting my parts together for my v8 914. I have an LM4 5.3 engine.

Here is the plan...

Lm4 stock bottom and pistions.
stock 862 heads send out to TSP for porting and larger valves
asa cam
obx itb intake
180 header made for 351w pantera modded to fit ls engine.
Microsquirt plug and play from efi source

I am hoping this combo could net me 400 to 425hp at the flywheel. Any suggestions? Ideas? I wanted the exotic sound and look of a vintage race car like a gt40.

zach914v8

I guess I should have been a bit more specific. For those that dont know the lm4 is the exact same as an lm7.

Here are my questions for you guru's....

The obx itbs are 52mm each. Are the stock 862 heads reworked with 2" valves on a 5.3 going to flow enough to utilize the itb set up?

The asa cam to me seems like an over all good choice. The car will be running between 3500 and 6500 for extended periods. The car will weight about 2100lbs and have a boxster 6 speed trans. How will this cam act in the low end?

The stock compression is 9:1. In a road car with a bump in compression be worth while? Maybe have the heads milled? new pistions? Or is 9:1 a good place to be?

So does this seem like a sound combo?

DREAMZ28

iTrader: (1)

I'd personally have a cam custom speced, because that cam is designed for a bigger displacement, more race weight, and more compression. Plus if I'm not mistaken it'd be cheaper at $399 vs the $400+ of the asa.


For your goals and your exhaust, you'll probably want a decent amount of overlap, and for that compression a decently early IVC, but I'd let the cam designer decide that. You're not far from your goals, you could just optimize a bit more to make them easier to attain. 400 flywheel isn't too much for any ls based motor with heads/cam really, but you could maximize the amount of torque by playing with compression a bit but mainly having a cam that works with the specs you're at.

garcr4

iTrader: (1)

The ASA cam is an excellent road race cam for the 5.7. It may work well in your application as well but but may require a bit more gear. In the 5.7 LS1 it pulls hard from 3500-6500.

garygnu

do some after market rocker arm bearings ,and use a good push rod .use some after market springs if you use the GM ASA cam.get the cam and push rods last .10-1 would be a good static compression to shoot for .get a good timing chain .

zach914v8

So with the 862 heads, can I safely get to 10:1 by having the heads milled? Or would I need to start looking at pistons? Maybe a combo of 4.8 flat tops and heads work? I would like to try to leave the stock pistons in and get the bump out of the heads if possible.

Also, correct me if I am wrong but, I believe the asa cam requires different length push rods? yes, no?

DREAMZ28

iTrader: (1)

But comp cams pushrod length checker, and check your length before you buy your pushrods.


But valvetrain geometry is what dictates whether you need different length pushrods or not, not the cam itself.

And I don't think you can bump compression a full point just from milling, so you might want to look into the bottom end for that.