Z01#316

Just had my L98 stroked to 383, stock 113 heads heavily ported, LPE 219 cam, forged pistons, Scat crank. There isn't a local rear wheel dyno where I live and no one locally has facilities to dyno an FI car. My engine builder dyno'd my engine using a Holley carb and edelbrock single plane manifold. Peak CHP was 402.6 at 4600 and peak torque was 482.5 at 4100. Engine builder advised I should see more hp with my Superram above 4600. Carb BSFC numbers were rich above 4800rpm. Does an engine with a carb dyno the same as an engine with FI? Worse or better?TIA Tom

skid

Most comparisons I have seen are pretty close with the carb usually edging out the FI for torque and near identical readings for HP. Carb's work best at WOT vs part throttle.

2manyfuncars

Low speed and mid-range are typically much better with the superram and FI. You have the longer runners and better fuel distribution at lower speeds. At extreme top end usually the shorter runners of a single plane/carb set-up will make a bit more hp if you are comparing to a superram. The SR's work great on the street and road racing - I have one myself.

Good luck

glen242

What's CHP?

Z01#316

crank horsepower.

427Hotrod

Man that's a weird tq curve. Peaked Hp at 4600 rpm with a carb and a single plane? And peaked TQ at 4100 rpm??

Definitely strong TQ numbers, that's what the 219 cam is good at, but that sure looks like a tight rpm spread. I usually like to see 1500 rpm spread to get a real good pulling ride.

But I know lots of killer superram cars go awful fast with low rpms and short shifting, I just wouldn't expect to see that with ported heads and a single plane.


JIM

SWCDuke

You can't make a blanket statment. It depends on plenum size, runner diameter, length, and flow efficiency, and the relative restriction of the carb versus EFI throttle body.

That said the L-98 TPI system was matched with valve timing to provide a very strong mid range torque peak, but at the expense of top end power, so, for example, a single plane manifold with a big carb will make more top end power, but with much less low end and peak midrange torque.

A typical 180 degree manifold and a modest sized carb will generate a torque curve more similar to the TPI system, but will probably make more top end power, with less peak torque. The long TPI manifold runners help create that high midrange torque, but they choke the top end.

It's all in the details.

Duke

Z01#316

Actually on a graph it was pretty even, both torque and hp. My engine builder advised the carb was getting rich above 4800, causing my torque and hp numbers to decrease. I was hoping to recreate what Lingenfelter did with his 383 and ported 113 heads : 440hp/480 lbs torque. His hp peaked at 5250rpm, his torque at 4500rpm. My torque curve is very similar; however the hp #'s are way off. The only difference I did was use 1.5 rr instead of the 1.6 that Lingenfelter used. Would that cause the difference? My builder advised the superram FI should keep my air/fuel ratios leaner above 4800rpm, thus allowing me more hp in that range. BTW my tune is by Ed Wright. Engine is still being installed, so I don't have any driving inputs yet.

cv67

Excellent torque #!