dwfronk

I have a lq4 in my car. I put a set of stock 862 heads on my car jut to get the compression up a little. I've been thinking of taking my 317 and having them shaved some and putting them on my car since they flow better. Would it be worth shaving them some and putting them on my car and how should I shave them. I don't want to go too far and mess up the flow.

TA63

iTrader: (5)

Is the LQ4 cammed? you could cut the 317's .025 and use the comectic .040 head gaskets to get to about 10-1.

chrisfrost

iTrader: (8)

Hello , how are You today ? Actually if You do have a cam , and maximize the flow intake and exhaust , You can have more power from lower compression , especially if You have dished pistons . With cam and maximized flow , with the lower compression (static) ratio , the area of the cylinder and combustion chamber is larger than those areas with higher compression (static) ratio . You're static ratio maybe less , but because of the cam and flow into and out of the heads You're dynamic compression will be quite high . It is not uncommon for a set up like this to have 250lbs. of cylinder pressure or compression .The main thing to try to make happen is the quench area . The best quench measurement is between .035" - .045" from top of piston to the bottom of the flat part of the cylinder head with the piston at TDC. And with a little bit less ratio and a good quench area the engine will make more power due to the fact that You won't experience pre-ignition or pinging as much allowing the computer to run at a more advanced ign timing . What is directly responsible for this is less heat which is another advantage . Good luck

bww3588

iTrader: (49)

Stock for stock...assuming a stock lq4 with 862's...you probably lost a small amount of power switching to 862's. Even tho you probably gained some power with the increased comp ratio, you probably lost more with the smaller runners and smaller valves of the 862's.