barnfire

Hey guys,
New to the forum, but have been researching a lot of build threads, specs, etc. and have a few questions specific to a motor I just bought locally and beginning to build
What I have:
LQ4 Block
K1 Tech 4.0" forged crank
K1 Tech 6.125" Rods
Wiseco 4.030" Pistons -3cc dome
Untouched 317 heads
Cam:
"custom grind" duration @ .050" 238 intake/245 exhaust, @ .006" 291/303, Lobe lift 0.3120"/0.3160, Valve lift - 1.7 ratio .530"/.537" 112 LSA

My main question is about these cam specs. They don't seem to match many of the popular cams listed in the build threads, on any of the popular cam manufacturers websites, and the closest I've found are considered "low-lift" cams but have much less duration than this cam.

Now, what this motor is planned for: going in a 1989 Camaro (will get a 6-speed) that will be mainly street-driven with occasional autocross and road course. Probably will never see a drag strip. My goal is 500whp. Want a really aggressive idle. Looking to get the motor running, in the car asap, with the ability to upgrade heads/intake/etc down the road. Will I be able to do this with this combo? What about heads...port the 317? go LS3 CNC? AFR/TFS? Really at the very beginning of this build and looking for input. Thanks in advance!

handyandy496

iTrader: (9)

With that cam your going to need some compression. Figure out how much compression you will need per your cam specs and fuel your going to use. You have a low compression head. You might want to sell that unless your going fi. If not a set of ls6/ls2 heads would be best. Why is your lift so low? Is there a reason? Even with 1.8 rockers its low. even with 1.85's its only .577 lift. Should be 600 to 620.

Darth_V8r

iTrader: (4)

I'll try to provide you some insight. Kind of a neat looking build, IMO.

Cam -- Assuming there is a "+3" missing off the LSA onthat cam spec, that's almost the exact same cam I took my old 346 to 539 HP on. 237/245-112.5+2, but it was a solid roller, so it was more like 232/240 with the lash. Bottom line -- I like that cam spec. Now, there is a fair amount of overlap in that cam. It will have strong midrange, but at lower speeds, light throttle, there will be a PITA factor to deal with. I would strongly suggest taking the lift into the .625 range and run PSI1511 springs and titanium hardware with them.

Compression -- The build as it sits right now is at 11.3:1 compression. I would run a thinner head gasket at 0.041", which will get you to 11.6 static and 8.5 dynamic compression, which will do great. That's assuming a 73cc combustion chamber, FWIW.

Heads -- AFR are my favorite castings. Usually the price tag turns people off, but if money's not the concern, get the AFR 260's. I would personally take the LS3 heads over the 317 heads on a 408 every time. That would take your compression up to 12:1, in which case, you'd want to run that cam either a bit retarded, say on a 111 centerline or run octane booster or see below for alternate spec. But the LS3 heads will be a great budget upgrade over the 317's AND the LS3 heads have far better intake options, such as fast midlength that are not available on the cathedral platform.

IF IF IF IF...... you were to run the AFR 260 heads or LS3 heads at 12:1 compression, I'd slightly tweak the cam spec myself to 239/249-113+3. Run a light clutch to regain your throttle response, and you'll be quite happy with that engine.

Good luck with your build, whatever you decide

barnfire

So a little back story, I purchased this motor project from a guy locally who lost interest in the project. So as is sits I have a bare block, brand new unassembled rotating assembly, stripped heads, etc. got excited about the deal, bought it, then realized the cam specs were unusual (according to the very little I know). So essentially, I'm at a very good point where I can change the cam, heads, etc. going forward. Appreciate the reply and agree with going into the 0.600" lift range.

Great information Darth_V8r, I really appreciate it. Looking at the cam spec sheet, it only specifies 112 LSA. No +3 mentioned anywhere on it. the low-speed, light throttle pains sounds like a real PITA for street driven car. What it sounds like to me (in order to stay within my budget) that it may be best to go with LS3 heads, a new spec on the cam, and invest in a FAST intake setup. Even if I could swing the AFR's, I'd still be looking for a higher lift cam.
The cam you're suggesting (239/249-113+3) should be spec'd with .600-.620 lift correct? Will that give me the mid-range i'm looking for but slightly better day-to-day drivability?

KW Baraka

iTrader: (7)

This cam will have about 18* of overlap. This is on the edge as far as drivability goes. Had this much overlap in my SS with an A6. With a good tune, it's manageable.

Still, coming in with something between 10* and 14* will go a long way towards making the engine 'act right'. ;-)

Midrange torque shouldn't be an issue with compression at about 11.5:1.....and I'd be surprised if you came in at less than 500 to the wheels.....REAL surprised.

Best of luck!

KW

Darth_V8r

iTrader: (4)

All true! What I listed below should hit closer to 550. But yeah that 239/249 will be a little tricky to drive. If you are concerned about DD, then do a 232/242-114+2. That will give you about the same EVO and IVC but will get overlap down to nine degrees and be far more streetable. Would still easily clear 500 hp