Carbureted LSX forum - LQ4 Build

I've just recently Acquired an Lq4 that was pulled due to bad Cam bearings, I'm looking to have a nice street motor, hoping for around 500hp. I've been hearing alot about the LS3 heads, on the stock LQ4 bottom end making some decent numbers, with a matching cam. I'd like to stay carb'd to keep the nostalgic feel to the project as well. What Head/intake/Cam combo's can you guys reccomend me on a decent LQ4 build? It's going to be an N/A motor, probably about a 2800-3000 stall, and pump gas. Some people say to Get the L92 heads, instead of the LS3's, and some say visa versa, waht have you guys tried, and had the most luck with?

Also, if it's any help, I'm not trying to spend tons of money on this thing, but I want to do it right at the same time. I'm a newb with the LSx based motors, so please bear with me as I'm just doing what I can to educate myself.

thanks again.

Are you looking for max power or just something that will go from stun to kill at the stab of the throttle? LS3/L92 heads are a more expensive head that is simply not needed if you are not looking to make the absolute maximum power for racing. The cathedral port heads do great for the street. I run the factory 317 heads that came on the 6.0 in my camaro. I will tell you this, on the street, not too many out there can say they have not seen my tail lights when i used to run on those late nights at the designated meets.

If max power is the gal, then i assure you would not be looking for such a small converter. So stick with a set of 316s or go with the tighter chamber for more compression and use a set of 799 or 243 heads, they are cheaper than LS3/L92 and bump up compression...even easy to find.

Then you get to make a cam choice, that is a small converter, so anything that is in the mid 220s with a 110 or so LSA would work well. It would be a torque monster and still pull to 6500.

Im kinda biased to the ls3 heads on my lq4, but I didnt run the engine with the 317 heads so I cant say how they are. But I was scared of a sluggish feeling down low in the RPMs but I dont feel any hint of it down low. What is it with these cam bearings? Mine were out when I bought my "good used engine". Glad I decided to tear it down before I just threw parts at it.

Had one pull a cam bearing out with the stock cam before.

I'm honestly not looking for the most power possible, but I'd like to have a good amount. I don't plan on taking it to the track more than once or twice, maybe just to dial it in once it's in a car. I've been reading more and more about ported 243 heads.

This engine had lost oil pressure, so they had just yanked the motor, and supposedly it needs new cam bearings... regardless, i'm still going to take it apart and have the machine shop look at it to veirfy.

The converter may need to be larger if you want moderate power.

I also agree about might need more converter.

These engines LOVE compression and you just don't with the LQ4 pistons. To give you an example. A friend of mine has a 00' Camaro that had LS1, it had a cam and a set of 243's on it. It was a six speed and it made 407 HP to the tires (he had all supporting mods of course)

He spun a main in the LS1, He picked up a LQ4 and put his cam, heads, intake etc on the LQ4. When he went to have it tuned it only makes 351 HP to the wheels now. He has more cubic inches now, but a lot less compression.

IMO, I would get a set of PRC stage 2.5 5.3 heads with a 62cc chamber. This will get you to approx 10.3 compression with a stock gasket instead of the 9.4 like the LQ4 is now with the 317's. These heads are $1234 though, but well worth it if the budge allows. Add cam, and have fun.

You'll get TONS of opinions just like I just gave mine. Good luck

Fried cam bearings seems pretty common :(

362923

Shaving the stockers is more cost effective for getting the compression up and the LS3's will need shaved too.
I went the LS3 head route (shortblock at machine shop)
Stall a bit small....but should work fine on a mostly street car....depending on cam.

I also agree about might need more converter.

These engines LOVE compression and you just don't with the LQ4 pistons. To give you an example. A friend of mine has a 00' Camaro that had LS1, it had a cam and a set of 243's on it. It was a six speed and it made 407 HP to the tires (he had all supporting mods of course)

He spun a main in the LS1, He picked up a LQ4 and put his cam, heads, intake etc on the LQ4. When he went to have it tuned it only makes 351 HP to the wheels now. He has more cubic inches now, but a lot less compression.



Sounds like

1) the LQ4 without a cam should make 351 RWHP

Or

2) The tuner sucked.

You think my LQ4 is making less than 400 to the ground with the 317s? Not a chance in hell. The LQ4 with stock head has served me so well it has only seen a couple tail lights. My LQ4 in my 2001 Silverado made 292 tot he ground with just a tune through the 4L80 trans and a 14 bolt rear. A 4L60 or 6 speed and a 10 bolt, not to mention a set of headers and intake im sure your buddy had, 350 RWHP all day without cam.

just sayin.

Sounds like

1) the LQ4 without a cam should make 351 RWHP

Or

2) The tuner sucked.

You think my LQ4 is making less than 400 to the ground with the 317s? Not a chance in hell. The LQ4 with stock head has served me so well it has only seen a couple tail lights. My LQ4 in my 2001 Silverado made 292 tot he ground with just a tune through the 4L80 trans and a 14 bolt rear. A 4L60 or 6 speed and a 10 bolt, not to mention a set of headers and intake im sure your buddy had, 350 RWHP all day without cam.

just sayin.

I'm not saying anyone's car is making anything. Just gave an example of what he ran into.

IMO, a dyno is a tuning tool and the #'s really don't mean a whole hell of a lot.

Example # 2. My buddy has a 99' Vette bolt on car with headers and exhaust. His car was tuned years ago and made 331 HP and 360 TQ. He had to change the PCM cause it crapped out, so He needed to have it tuned again. This time the car made 325 HP and 330 TQ. He was all upset and said I guess it was a different dyno and tuner. BUT, he's TOO caught up in the #'s. The car now has a 3000 stall where when it was tuned last time it had a stock converter. It's not gonna make as much TQ through a stall. Guess what, the #'s are lower, but the car picked up 2/10ths and 2 MPH over the last tune.

Also, IMO the only #'s that matter are Trap speed most importantly and then ET. I'm not sure if the OP meant he wanted around 500 HP to the tires or flywheel. But, I think most here would be in agreement that if it's to the tires, you're NOT gonna get there with a 9.4:1 motor with stock heads on it unless you spray the hell out of it.

Yeah, I was just ballparking with that Stall, I may even go the route of a 3500 stall... All I know is that I'd like a nice streetable engine, with a rough idle, that makes a good 450+ Hp. I dont' really plan on taking it to the track, or ever bringing it over 6K unless it's on the dyno. The ported 243's may be the route I should go.

So, it's been verified, my 6.0 does have the 317 heads on it. I personally want more compression, so I'm looking at still at a set of built 243 heads, and a nasty cam. I'm also, now leaning back towards fuel injection for ease of use, and driveability. Is Texas Speed about the best place to go to? I'm sorry for the newb-ish questions. I honestly don't know much about the combos available in these, and I'm doing my best to gain as much knowledge as possible.

I'm hoping to keep the stock crank,rods,pistons etc... And go with all top end accessories, to make some nice Horsepower, and of course, the rough sounding, nasty idle, which will obviously come from my cam, supported by my heads I choose. You say the stock 6.0 pistons with 243's won't make much over 10.0:1?

(mods feel free to move this if neccessary. since it's not specific to carburation)

Also, FWIW, if I do find a set of 243's, what's the way to determine if they're ls2 or Ls6 heads?

You will usually be as to tell if they have the yellow or blue springs, that would be ZO6 I think. Doesn't matter though, the springs are useless with a real cam. There are so many combinations out that you need to find one and mock it. EFI or not. Many combos out there that will let you know what works. Milled 243 heads will be over 10:1, so do not worry.

Well...my 9.4:1 LQ4 with L92 heads and only a cam and valve springs made 551hp at the crank in the carcraft build. Hows that for low compression?