I have a lq4 engine that I want to increase the compression levels with. I am thinking about getting a pair of 799 heads. I don't mind using 93 octane gas, what compression should I go for and how do I reach it? I am not goin to use a turbo or supercharge it or anything like that.

 

243/799 heads will help raise the cr and give you some more power/torque and crisper throttle response on the lq4.You can also have the heads milled to give you more cr increase and also use thinner head gaskets.Do you have plans for doing cam swap or headers in the future?

Stock lq4 is 9.5:1 mostly and switching to stock 243/799 heads if i remember correctly will bring you to about 10.2:1 maybe a little more but can still run lower octane fuel.Milling the heads can get you to 11:1 and then you really should run 93 octane and up and you will have a substantial increase all around.You do need a retune after a head swap to make it optimal. Search the forums..lots of info on lq4s with this combo making good power on a budget.

 

Thanks, how much needs to be milled to get into 11 compression, or will a thinner gasket do the trick? I plan on doing cam.... And all that other fun stuff in the future, but I'm on a tight budget and I figured the heads were a good way to start. So far I have

Ls1 intake
Z06 exhaust manifolds

Other than that I was going to keep it stock for now. Using the 799 head, can I use the same push rods on the lq4?

The only other thing I would love to do is make the idle a little
More choppy than stock. Would shaving the heads make the rockers lift a little more? Enough to make a sound difference? Or is there a really cheap cam I can use the stock springs and stuff til I get enough money for a proper set?

 

if you want 11:1 compression you need to mill the head and use a thinner head gasket and at that point..you will need to measure pushrod length.The stock pushrods will be too long most likely.I milled my heads .030 and stayed with stock thickness gasket and was able to use 7.4 hardened pushrods with my 228r cam.

Shaving the head doesnt affect the rockers, but it does affect your piston to valve clearance and depending multiple variables like cam duration/lift,pushrod length can be shorter or longer than stock..or flycutting the pistons is also needed.But lets keep it simple for now.if you have future plans for doing cam swap,then mill your heads during that time so you can take the proper steps to set the motor up with the right parts.Talk to vendors about the cam and what they suggest for yous goals of the car and thell them your setup and what would be safe to get the compression you want,the power you want with what you got.they will set you straight.

Many great vendors frequent these forums,Tsp was great with helping me pick out parts,Ive seen Martin from Tick always helping guys on here and his new line of cams are something to look for..and he is also very knowledgeable.Eps has great rep too..the list goes on in my book.For now..do lots of reading and decide what your end goal is..to every detail you can think of.You need to think of reasonable goals to make a proper running driving car.Dont just chase a dyno number.Street/strip car..daily driver/cruiser...is driveability a concern,auto or manual car..rear gearing,rough guestimate of power you would like etc. Answers those and call up some vendors.You will realise the details and lil things..eat a budget up in a blink!Supporting mods come with a price for horsepower.

 

Thanks for the advice. I really want to keep it simple for now and just get away with what I can for cheap. I am planning to do mods later on (2-3 years from now) but would like to make it enjoyable til than. Do you know if I can get away with just 799 heads and a thin head gasket without pushrods or piston interference? And do you know about what compressions that would be?