fmyth

iTrader: (1)

Last year I bought a sand rail with a Turnkey Lq9 engine in it. Turnkey advertised it as their 450hp package. It's a stock Lq9 short block with a GM Hot Cam, stock 862 heads and a LS1 intake and throttle body. It's in a sub 2,000lb car with a manual trans. It runs great, has awesome torque but runs out of steam at 6k rpms. I have the engine out to refresh the trans and would like to make some mods with the goal of increasing power in the upper RPMS.

I've read every thread on here I can find about LQ9 combos and have come to the conclusion that the 862 heads and LS1 intake/TB are likely holding it back in the upper RPMS. I have also read that I'll be limited by PTV clearance due to the stock flat top pistons. This is a low mile/hour engine and I want to keep the short block stock for this season (Halloween to Easter).

I am considering swapping the heads for a stock set of 243's and installing a Dorman LS2 intake and 92mm TB and keeping the hot cam. I believe this would lower my compression from an estimated 11.4 to 1 to 11 to 1. I think I can do it all for 2k.

What kind of gains should I expect?

Any other mods I could make that would get me another 40-50 hp and pull to 6,500 rpms for a 2k budget?

G Atsma

For heads, find some 799's as they are identical to 243's, and came in all 5.3 truck engines since about 2007 until 2014 or 15.

Crf450r420

iTrader: (1)

What is the end goal and what are you okay loosing? If you are going to stroke it to a 408 later you might want to just get LS3 heads now. Then you can probably leave your cam for now. The stock LS3 intake is cheap on Amazon and it is one of the best factory ones made. If you don't go big heads and use more cam then you'll loose more low end and street type manners, which I wouldn't think you'd care much about.

fmyth

iTrader: (1)

I have done a little research on the LS3 head/intake swap but am concerned about PTV clearance with the LQ9 and GM Hot Cam.

Tuskyz28

You don't really have to start watching your PTV clearance to around 233-235 intake duration camshafts.....

NAVYBLUE210

What about +12-16 exhaust splits with <112* LSAs + ADV?

To broad of a statement with other variables.

Tuskyz28

Cam duration (lift plays less of a part) and piston-to-valve (P-V) clearance are inversely related. Each successive step up in duration decreases PTV.

Crf450r420

iTrader: (1)

The intake is okay to about 230 degree duration on and stock LS3 with flat top pistons. Which GM Hot cam is it? Most of them were huge 117 LSA.

fmyth

iTrader: (1)

The PO tells its this one:

LS Hot Cam
Duration @ .050" Lift( Deg): Intake: 219 / Exhaust: 228
Maximum Lift (in) W/ 1.7 Rocker: Intake: .525 / Exhaust: .525
Lobe Centerline ( deg): 112

I have no documentation on it so will need to check PTV clearance if I go with the LS3 heads.

Crf450r420

iTrader: (1)

No cam is perfect, so it's best to check when getting close. I'm pretty sure you will find it over the .080" needed to be safe.

With stock heads and gaskets.

KW Baraka

iTrader: (7)

There's only been two "GM Hot cams".

One for the Gen-II small block (LT1/4) and one for the LS.

Both have 112* LSA's.

Jus' sayin'.....

KW

Tuskyz28

Basically sane thing I said in my first post.

Crf450r420

iTrader: (1)

The only GM Hot cam I ever used was a .550/.550 lift on a 117 LSA and that one wasn't really large enough for any of our builds, just used it when people insisted on a smaller cam that would idle very well.

Tuskyz28, I guess I'm not crazy.

KW Baraka

iTrader: (7)

..........

KW

G Atsma

NO such thing as GM Hot Cam with .550 lift OR 117 LSA

Crf450r420

iTrader: (1)

I have catalog here full of fresh BS just for you. 2012 GM Performance Catalog. I was wrong it's not 117LSA, it's 117.5LSA.

G Atsma

That's an LS6 cam, NOT a Hot Cam. Read the print!

Crf450r420

iTrader: (1)

You got me I don't know the cams that I never use and I call the 10 cams GM offers hot cams, not the first time I've had my own name for things and it's not the last. They don't do anything for me as only one or two of them are close to a hot level cam and none of them really fit our needs.

KW Baraka

iTrader: (7)

Trivia note....both the LTx Hot Cam and the LSx Hot Cam have the same duration, same lift and same lobe separation angles.

Don't know why GM Performance Parts did that....but most Hot Cam users in the LT and LS world seem to be happy enough with the results.

Of course.....for 'hard core' power......the hot cams fall just a bit short.

KW

G Atsma

They're happy because since it's called a Hot Cam, they bought the BS, put it in, loved the lope, and gained power. The fact that they're clueless as to what they could have had that would have done WAAAY better, is immaterial. GM made it, so it had to be good! lol