FieroBob

I am planning to put a 415ci LS2 engine in my 1988 Pontiac Fiero that weighs only 2800lbs.

The car is my daily driver. I want good acceleration, good gas mileage, a smooth idle and good street manners. Max horsepower is not a major concern.
Most of my driving is in the 1,8000-4,500 rpm range. I’m looking for torque.

I also want the car to run on 87 octane gas.

What cam would work best for my application?

Thanks for your time and your input.

Bob R.

1bigcam

iTrader: (9)

for what you want i would just buy a stock ls2, why the 415?? 87 octane i would not do. stock motor dont even like that junk

NoGamesLS1

iTrader: (16)

WTF?! You want to dump 10k into the motor and be cheap on gas? You need to rethink your strategy

81LsElky

umm im confused, cam does not really have an impact on octane, but i may be wrong, i thought it was compression! my .02

ringram

Camshaft valve events along with static compression will determine octane requirements. Well... along with quench, combusion chamber design, swirl etc..

Maybe 9.5:1 static. Not sure on DCR maybe 7?

NoGamesLS1

iTrader: (16)

If you cam has alot of overlap it will bleed of cylinder pressure. Eg a 12.5:1 motor can run pump gas with cam "A" which is a large cam (more overlap)where as it must run race gas with cam "B" since it is smaller and builds more cylinder pressure (less overlap)

King James

iTrader: (13)

Why build a $10k motor only to turn around and skimp at the gas pump to save a couple dollars?

RWC

iTrader: (5)

I get 7.34 DCR for a stock LQ4 with 9.4 SCR. 87 octane usually requires around 10 to 1 or less SCR and 8 or less DCR. The right cam for you depends upon too many unknown factors at this time. I would suggest a quality builder to help spec out the entire engine combo for your specific needs and I think you would be much happier in the long run. If you want to play with cam timing and DCR, check out J-Rod's VE calculator in the Advanced Perf Tech section. Hope this helps.

00slowredz

87 octane

mr2guru

iTrader: (16)

First of all.... why are you looking for that much torque in a 2800lb car? It's just not needed to get it moving as fast as street tires could hook up.

71CamaroLS1

It sounds like, from your description of what you're after, that you'd be very well-served with a mildly modified LS1, LS6, or LS2. All of these will generate enough torque to rock your world in a 2,800 lb car - believe me. If you use the stock ECU, all of them will adapt to 87 octane - though at a somewhat reduced level of performance and fuel economy.

In a car this light, I'd choose a cam that flattens the torque curve a bit, while extending the RPM range - you will have enough terrifying experiences with 60 MPH wheelspin as it is. On a 5.7 or 6.0 motor, something in the range of 220 to 224 degrees intake duration @.050, with a lobe separation of at least 114 degrees, maybe 116, will give you a smooth idle, good torque and responsiveness in your desired RPM range, and still give you excellent high rev power when you're feeling immortal.

If your heart is really set on that 415, bump those cam specs up another 8 to 10 degrees, beef the hell out of your drivetrain, and make sure you experiment with full throttle in an environment with lots of room for error.

For reference, the '67 Camaro in my sig weighs 3400 lbs, and will spin it's rear tires (315s) at 100 MPH in third gear. Exciting as this sounds, in practice it means that the car's potential is mostly wasted on me, due to fear of death and other considerations. If this is really going to be your daily driver, think hard before you turn it into an experiment in extreme physics.

JBsZ06

I'd suggest a worked ls1 which can be had relatively inexpensively..

I would not suggest running 87 octane fuel either..

What transmission are you using?

Sounds like a hell of a ride.

photos?

FieroBob

Thanks to all for the feedback.

Special thanks to: ringram, RWC, 71CamaroLS1, and JBsZ06, for all of your constructive comments and advice. It is greatly appreicated.

71CamaroLS1’s comment about, "an experiment in extreme physics", has given me pause to think. Thank you sir.
While I’m far from being a kid, I still lack any experience with a car who’s engine produced a significant amount of torque.

JBsZ06, I’ll be running the stock Getrag HM-282 transaxle. Reliable sources tell me that it is capable of handling the power and torque of a V-8.

Once again thanks to all for your help.
Additional comments/info/advice would be greatly appreciated.

Bob R.

JL ws-6

iTrader: (50)

I think a 415 CI in a car that small... is probably not a good recipe for your needs. A stock ls2 shortblock with a set of lq9 heads and a cam in the low 220's would be enough to make that little car really fly, and with the reduced compression from the lq9 heads I suspect that 87 octane would be doable, as long as the timing is kept down. It would nowhere near be the optimal way to tune the motor, but for the goals you have a motor like that would probably scare you daily LOL.