~JOSHUA

iTrader: (92)

I'm picking up my 100% complete brand new stg 3 Incon kit from a member here who's decided to move on to other things.

I just made 421/385 cam only with my Lunati 236/236 .581 .581 112+2 on a 108 intake centerline.

There's a local guy (Cablebandit) who's maxed out a stage 1 kit and he says that the 112 LSA will bleed off the peak cylinder pressure and I can run more ignition timing at the same psi and not worry about getting bad gas.

I'm only planning 550 rwhp until I upgrade the bottom end, and he says that I can get well over 700rwhp on that cam. The turbo wastegates don't care what cam is in the car.

I only drive about 3k miles per year, any opinions?

cablebandit

iTrader: (37)

if you dont want to keep the cam, i will trade you my 215/215 114
The 112 will bleed a little midrange cylinder pressure which is very helpful for running pump gas on a stock motor. A smaller cam would probably help it spool a little quicker.

~JOSHUA

iTrader: (92)

I really don't want to swap the cam, it'll save that much work on the Incon install. I'll change it if somebody says "hell no that's a bad choice!"

Do you think I really should do the swap or really is this cam a keeper for the next couple years until I go into the bottome end?

Thanks again. ~Joshua

engineermike

Overlap does not bleed off cylinder pressure. Cylinder pressure is bled off at the beginning of the intake stroke when the piston is rising and the intake valve is hanging open (up to 50 deg ABDC). In effect, wider LSA's bleed off more cylinder pressure than narrow.

Excess overlap will bleed exhaust pressure into the intake port.

If you make very effort to keep the exhaust pressure down, the cam will work great. When I say "down", I mean <1.5x boost.

I've run 20 psi boost with 48 psi backpressure and 2 deg overlap and it worked reasonably well, but much better when I dropped the backpressure to 34 psi. You have 12 deg overlap, so yours will be more sensitive to backpressure.

I believe Speed, Inc. just made almost 1000 rwhp through an auto using a cam that was 236/242-112, so it CAN work well when mated to the right turbo and exhaust system.

Also, keep in mind that just about all turbo GN's use aftermarket cams ground on a 112 LSA, while the stocker is on a 106 (no kidding).

~JOSHUA

iTrader: (92)

Wow, that's an eye opener. I knew the aftermarket GN grinds run 110-112LSA on average.

The Incon kit comes with all exhaust components to bolt right up to my factory SLP DD (Firehawk) cat-back. This set-up will not have cats. I was planning to run that exhaust which is decent as far as cat-backs go. I'm worried that my 6 psi won't work well with this cam, that's why I posted the question.

I'd really like to keep this cam because it sounds great and the effort saved on the swap is also a plus if it can stay.

Thanks for all the advice. ~Joshua

p.s.- How much back pressure do you think the SLP DD and stage 3 turbo piping will have? You mentioned you got your back pressure to drop, but I don't know what exhaust set-up you had. Thanks. ~Joshua

engineermike

Low boost means low backpressure. With only 6 psi, the backpressure should be under 10 so the cam will work well. Expect the same rpm range as current and to exceed 550 rwhp at 6 psi even with a conservative tune (assuming a 6-speed).

I'm not sure what all the spec's are on the downpipes and SLP exhaust. I can tell you, though, that a 3.5" Aerochamber was WAY restrictive on my combination. I have a 3.5" Magnaflow on order. It's generally accepted that you need a straight-through perforated core muffler, which will give you the least amount of backpressure possible.

~JOSHUA

iTrader: (92)

You have no idea how pleased I am to read that part.

under pressure

iTrader: (13)

I think you have little to lose by running the cam. How quickly you spool is also dependent on other factors. Your biggest battle will be keepng the horsepower down to the safe levels you need for now. It should sound beautiful.