I have recently swapped and lq4 bottom end into my car. I am now looking at boosting it. I am looking into a rear mount and was wondering what i should do with the heads and a good cam. I am planning on using the factory 317 heads and having work done to them but what all should i have done and to what extent. EX: if i shave them how much? And what cam should i use.... lift, duration, and LSA. And what kind of boost can the stock bottom end of a LQ4 hold.


And i am bulding this as if it were a DAILY DRIVER so nothing to extreme

 

I don't think you'll benefit much by having the heads reworked if you're going to boost a stock internal lq4. By milling them you'll slightly increase the CR (ie wrong direction most turbo builds go), but either way it shouldn't affect your power levels much. If it were me I'd save that money for arp rods & good springs for that cam. Find you a cam that doesn't have much overlap. 220/220, 224/224, 114-115 LSA are popular stock cube FI cams. How much power can a LQ4 handle? Tough question to answer cause every motor isn't the same. I've heard of guys blowing rings at 8 psi (roughly low 500's rwhp through m6), but there are also a few guys going pushing over 600rwhp on them with no problems. I think there is a sticky about stock internal builds...

 

Yeah he will benifit from work done to 317's.It will not only raise hp.power to boost ratio...

You will also benifit from lower cylinder iat's & boost on the given proper setup.

 

true, he'd end up needing to run less boost to achieve the same hp as if the heads were untouched, but it's known a higher CR fi engine will likely detonate before a lower CR engine. ex. if a higher CR engine detonated when it reached 10psi, then it's less likely the lower CR will detonate when at 10psi, therefore can possibly reach 12psi before detonation. however, there will likely be a 0.5 point lower compression, so guesstimating around 2-3% less HP at the same boost level with the untouched heads. it almost cancels each other out. But as you mentioned I do agree with you that lower IAT's is possible with less boost.

OP, what fuel do you plan on running? I'm assuming pump gas. As every person will say, you can only benefit from an intercooler and/or meth. Goal is low IATs & 10-12ish AFR and you'll be alright.

 

My advice, put rods and pistons in the bottom end because boost is addicting.

I've heard 550 w/m6 and 500-550 w/a4, it all really depends on the tune.

 

good advice ^ tune is key. I was doing some searching and came across a guy that was pushing 16+ psi on a stock LQ9, though it is a time bomb, it blew everyone's minds it was still holding up. crazy stuff.

 

On my last car I ran 11psi for a year with meth and 642 rwhp. Car did great!

 

i do plan on running pump gas just like i stated above that i will be bulding this like it is a DD!!! The car has never seen less then 93 octane since i have owned it any way. An intercooler is a must in my books and i am still kinda iffy on the meth. I was using the shaving of the heads as an ex. i geuss using porting or a 3, 5, or radius valve job as an ex would have been a better idea. And i am planing on putting stiffer springs. this is my first turbo set up on an ls so what are good cams to run on a turbo set up.

 

If your budget allows you to go with a set of forged rods and pistons do so, and it wouldnt hurt to get the heads o-ringed either. Camaroandreas did 1170+hp on a engine dyno with a stock 6.0l block, crank, and 853 heads at 20-30psi using pyramid rings.