garcr4

iTrader: (1)

For the LS Engine guru's:

The SCCA GT-1 rules allow the Gen 3 LS 5.7 with stock 75mm throttle body and manifold. Cam, compression, head porting, exhaust would be open.

What kind of Flywheel HP numbers might be achievable with a 243 head motor?

I know they would be miles from the class leading SB2 Corvettes and canted valve Fords but it would be able to run some 200# lighter.

I have a Grand Am spec tube frame Corvette that could meet SCCA TA rules.

Might do a race or two for fun in 2012.

Thanks for any help

Bosco

garcr4

iTrader: (1)

I should mention the motor is currently stock dimension and compression, stock cam and heads. Has forged rods and pistons and T&D shaft rockers.

Sorta a forged, blueprinted SCCA T-1 motor with custom ecu tuning and headers. None the less runs very strong just as it is, able to beat many regional type GT-1 cars as it sits.

mark21742

With a good tune, ported heads, valve job (if allowed), free flowing exhaust you migraines be looking at a gain of 40-50hp.....as far as cams, can you use anything besides stock specs?

garcr4

iTrader: (1)

any cam and increased compression would be ok

the car already has a good set of custom built long tube 1 3/4" headers which seem to provide excellent low and mid range torque.

mark21742

You said stock intake, can it be ported? That is really going to be your limiting factor as far as making more power. Ti keepers and locks, and a good light behive valve spring should be all you need up top since the stock untamed status to drop off and choke out around 6,400-6,500 rpms, so you wouldn't want to large of a cam.....maybe somewhere around a 228 with low .6xx" lift and a real tight lsa (maybe as tight as a 108 since in guessing idle quality isn't a big concern). Contact someone like Pat G on here and have him spec you a cam that would work perfect for you

mark21742

What about fuel, are you going to be running pump had or race gas? Just for example, I've got a 408 in my 04 GTO running 12.56:1 compression, but with my cam it drops down to 8.25:1 dcr so I can run pump gas safely....in the end is pick the cam first, then get pistons/ mill the heads to get close to the peak dynamic compression you can run on the fuel you need.

PREDATOR-Z

Listen to this guy, and do it all backwards

mark21742

Lol thanks Predator. Your a great cam guy, what would you recomend?

How about compression? I'm not used to being confined by the intake.

mark21742

Oh, lol I guess I could or should have worded that boldest statement different lol yes the hole set is a package, but don't you need your fill can specs first to determine typified end dynamic compression and cranking psi? Please correct me if I'm wrong

trans_am7935

iTrader: (15)

also if you are gonna be running the LS1 @ 3k+ RPM for long periods of time, you should look into a oil cooler (if allowed). some Corvettes came with them stock. not a necessity but will keep oil temp down.

PREDATOR-Z

Well, you certainly take into account the cam while putting your combo together, but cam is pretty much the last thing to choose in order to match the valve events closely to the rest of the setup.
What I'm trying to say is you build your cam around the rest of the combo, not vice versa.

mark21742

Ok, makes sense. I just thought of it as picking the cam with the needed valve events, so you can determine what your dynamic/ cranking psi would be with a given static compression....I just see a lot of people either forgetting/ not knowing enough about how much your valve events play the whole role in getting the true desired compression to get peak performance out of a setup...you see a lot of people saying thongs like "you want to shot for 11:1 max compression for pump gas"...things like that...hell I even had lots of people (and still do) that said my 12.56:1 engine would never run on pump gas lol

The steps I took to get my setup was
1 got my 408 block prepped
2 H beam rods and forged crank to handle just about anything I threw at them
3 ported/milled heads
4 went with an Edelbrock proflo xt intake for my desired rpm range
5selected my cam for the rpm range and heads I had (ended up with a 255/266 .624"/.624" 115lsa)
6 lastly picked my pistons to give me my desired compression

garcr4

iTrader: (1)

I believe you can port the intake, it already has a great bottom end, high end valve springs, push rods and shaft rockers. It is rev limited to 6800, but seems to make power only to about 6500.

With regard to fuel in Grand Am it would be the Sunoco 98, in SCCA I use
110-112. Compression now is stock.

This is a full on tube frame endurance race car with all the coolers etc.
big Brembo calipers, penske shocks etc.

Not much Corvette here except the motor and body. Weighs 2550 without driver.

mark21742

I'm SO jelious lol

PREDATOR-Z

I hear you, some people confuse static with dynamic compression. The latter is the main factor in determining fuel necessary. Quench plays a role as well as well as plug heat range, even gap.

SNLPerformance

iTrader: (15)

Doesn't sound like you have to worry about the compression ratio with the fuel you plan on using and it makes more power throughout the rpm range. So I'd shoot for as much compression as possible without PTV clearance unless your pistons have reliefs. I'd start with running thinner gaskets then milling the heads to reach your desired ratio as milling hurts airflow slightly, but you are hindered somewhat by your intake anyways. The cam doesn't need to be huge if you're only going to turn 6800 and would grind something with good midrange to pull you out of corners quickly

garcr4

iTrader: (1)

If at some point we move away from the Rolex rules, I'm kinda inclined to go with a set of AI top level 243 heads, a good road race cam that pulls hard in the low to mid range, and maybe a slight boost in compression.

The car had very good grip off the corner in the infield section at Daytona, which really isn't known for great grip. We use a road race geared NASCAR type 4 speed, with a 1.87 first gear, this allows us to use first gear in a lot of slow corners. Not real great off pit road or in the paddock though.

nastychevelle

iTrader: (7)

Since it's intake restricted wouldn't a reverse split work well with his setup?