LQ4 build...cam,heads, general Q's
 

Getting ready to start the build up of my 2005 LQ4. Gonna try to get what info i can give out to help clear up my goals.

Engine is 2005 lq4 6.0. bone stock, 317 heads, 150k miles on it.

Car it will go in is a TBD GM big body wagon. Looking at anything from a 60-70's Chevelle wagon (the one i WANT), the more realistic 80-90's Caprice wagon. All in all, about a 4000lb car. Plan is to go auto, simply due to the cost of going Manual with a decent trans, a 4l80 is cheap.

Goals, It is will a driver. Might take it to the strip just to see what it will do, but mainly just want a fun weekend car to take on family road trips and be a fun car to drive. Of course i want ti to be somewhat fast with plenty of power to play with, but reliability and driveability are priority over just sheer power.

want to keep the power in a more usable range. a car that makes peak power at 6800 RPM is no good for me.


My thoughts:

High compression. swap the lq4 pistions for some flat tops. The big question with this is heads. Swap for 706/862 heads for smaller chamber. for my uses, i don't think the smaller runners and valve will impact my overall power all that much. flat tops, and the 61cc chambers on stock .051 gaskets i think should be me in the 11:1 range. Or mill the stock 317's .030, netting about a 66cc chamber from my googling and about a 10.5:1 CR. but with better flowing heads?

Cam. again. more low end, usable power is the goal. I have been reading up on cam stuff but still not all sinking in. from what i can gather, for the low -mid power i want, the cam needs a lower duration. No idea here. most cams i see are all higher duration. not sure on lift. really pretty clueless on the cams. i'll continue my reading, but would rather a "pro" chime in than me take my best guess.

otherwise. Standard stuff like headers. using either the stock truck intake or a TBSS intake most likely.

any info is appreciated. Thanks

looked at those, but i can have my 317's milled .030 for only $120 at the local Engine machine shop. Looks like 243/799 are going for about $500 around here and the 317's flow nearly the same. smart money is to just have them milled a touch. Might keep the Dish pistons, but 05 "should" have floating wrist pins, so pretty easy swap on the pistons vs heating the rods to remove. Not for sure doing that, but definitely looking into it.

I'll look into the howards cam. I was suggested by another person to look at Vinci cams, they seem to have a few that focus more in the RPM range i want than your typical BTR or TSP cams do,

I plan on springs, retainers,and pushrods as well as the oil pump, valve seals and such. I plan on taking a bit of time to put it all together and doing it right the first time. Doing any general maintenance i can while it is apart.

Thanks for the input!

That is what I did, Stock LQ4 bottom but refreshed, 799 heads and a WS6 store ASA high lift cam. I have it built but have not installed it yet. North Carolina is on pause for a hot a$$ summer.

After seeing Richard Holdners LS head test last week, thinking most likely going with 706/862 heads and leaving the stock dished slugs in the engine and a slightly thinner head gasket. For my RPM level, the 706 heads made more down low than 243's and loss up top was minimal.

according to my math, stock pistons, about 7cm/3 dish, a 61.5 cm/3 chamber and using a .041 head gasket to replace the .051 stock unit should net me nearly 11:1 comp, pretty much the same as an LS2. seems to be a pretty simple way to boost power and compression and stay pump gas safe. 1.5 point comp increase for pretty much the cost of gaskets. i'll take it.

Now, Cam selection? was suggested the Vinci Butt kicker but it seems decidedly small, but i don;t know much when it comes to decoding a cam's specs.

Thats almost the Exact same setup that im looking to run (except a t56 and 4.10 gears in a 2ns gen trans am) Do you have any videos of it running? Trying to decide on a 750 or 850 DP What RPM do you shift at?
Also What MPH where you running?
Sorry for all the questions..

Youre trying to do a whole lot that really isnt that necessary.
This is what i did on my personal truck and would recommend to others often.
Find some 243/799s. Yes you can mill your 317s but then you are stuck with a thinner deck. You can find em for around $450 or so still not bad.
Use a gm stock head gasket.
Poor fuel quality is going to be your enemy so dont chase some high cr number. leave it in the high 9s low 10s.

There are many cams to choose from, all of which will depend on your gears and stall converter.
As mentioned before, our High Lift ASA cam is a good choice but only if you have at least 3.42 if not 3.73 for that and a 2800+ stall. Youll be over the 400hp range there very likely with that setup.

Why not go higher CR? i'm not after anything in the questionable range IMO, i mean a stock LQ9 is 10.5, LS2 is 10.9:. i see no reason not to chase the high 10's. legitimately looking for an answer here as to why? Yes, fuel quality is not certain, but 91 should be more than safe with 11:1 CR. It going to be NA and stay NA. No plans to ever go boosted on with this engine so the higher the CR, the more power i can squeeze from it easily. If you have a reason to stay lower CR, then i am willing to listen.

Gears will likely be very dependent on the final car and transmission. Most likely going to be a 4l80e though with a proper converter in the 2600-2800 range to keep it mild mannered on the street. Gear, very TBD. won't be too low, can't imagine any lower than 3.73 to keep highway RPM's in check, but being it is a car the tires will be smaller than a truck so 3.23's, even as high as 3.08's would not be out of the question.

EDIT: Not trying to push my point, if there is a legit reason to do it one way vs the other i am good with going that route. but if the reason is " everyone does it this way", i need something better than that. also, i will add what knowledge i do have comes from building ATV engines, and 11:1 is never an issue with a water cooled small engine, air cooled is a different animal altogether.

Because ive personally tried it. There is a reason gm has lower cr in heavier vehicles. Its not just for smog/emissions.
Running that much cr you will run into issues youll be chasing for a while.
Also, double check your LQ9 compression ratio specs.

great. Might try to keep it around 10.5:1 then. and yes on lq9 comp, 10.1:1, can't trust the google machine all the time.

.035 quench minimum. cant guess on ptd youll have to measure, but its really a waste of time and $100+ bucks extra for gaskets on your build.
Fuel quality and seasonal blends effect all fuels.

check Cometic for the head gasket thickness you need .I would use the heads you have .before you mill the heads ,figure the dynamic compression ratio with the cam of your choice .a good torque cam will raise the cylinder pressure some .

i'll get the engine all torn down and measure PTD

and yes, in theory my cam choice should give a boost in dynamic CR, but Cam has yet to be spec'd out. the High lift ASA cam from ws6 store looks appealing though.

heads will either be milled or swapped. 9.4:1 even with more dynamic is still too low of a CR. If it were going in a truck and i was towing with it all the time, then yes. but in a car i expect some performance out of, static CR stands to be raise at least somewhat. just not as extreme as i was originally shooting for.

THANKS! Ill stop highjacking this thread now Sounds great

https://ls1tech.com/forums/parts-cla...eads-sale.html

I dont know if there still forsale or not but you could ask him. Those would put you a little less than 10.5:1

LQ4 stock bottom end leave the dish pistons

61cc truck heads

Stock head gaskets

=10.7x:1 (or use 64 cc 799/243 heads for 10.2x-10.30)

Cam Motion drop in truck cam with $70 LS6 valve springs

Tons of fun from idle to 6k or so RPM, cheap, easy. Even be ok with stock stall.

SCR and DCR will be high so it will be snappy and efficient, will require 91/93 octane, whatever you have there.

As for using low compression in heavy vehicles I agree, but OP stated it would be 4000 pounds, Camaro's, CTS, Chevy SS, GTO, etc all were very close to that weight..