Dyno results

[emcon5]

Ben: real RSRs had much hotter cams, higher compression, larger ports, MFI, among other things. Apples and oranges. (unfortunately)

Bobby: Dyno was on a Dynojet

Charlie: the cam timing was center of the range for a 964.

Wil: All true, even different dynos with unknown configurations we can still compare the shape of the torque curve, and the RPM of it's peak.

Tom

[Bill Verburg]

When looking at dyno data you might want to keep the information here in mind.

[rdane]

From a Dynojet? Man I would have lost that bet
How much time on the engine? Is it broken in and the rings sealed up?

With the same mods (20/21 web cam) in original USA 3.0 liter form, I was 182 at the rear wheels...215 crank. Nice torque bump. I do like how your torque comes up to 150 early on at 2500 rpm where the 3.0 holds off to 3500. But I would have hoped for a higher number and longer duration.

I would have expected more for the money involved.

My 3.4 will be in shortly. I'll post the results asap.

But here is the original 3.0 last fall.
'79 CIS SC with SSIs, a 2/2 Danke and a 20/21 web cam

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For easy comparison

[camgrinder]

DynoSpot racing has a 268 Dynojet. It has a heavier set of rollers than a 248 dynojet does.
We did a back to back test within days on DSR's dyno and a local 248 and saw a 8 hp loss on the 268 vs the 248. Almost a 3% loss on this particular car. I believe the numbers on the 268 over the 248dyno.

[aigel]

Advancing / retarding the cams should not make any significant difference on the flat six, especially with the mild 964 cams.

George

[emcon5]

Thanks for the input guys.

I really think what is happening is the smaller intake ports and runners are making the incoming air move faster, for extra torque down low, which is exactly why the factroy made them smaller in 1980. Consider that a factory 3.2 had 192 lb. ft. at the crank, and my engine (if you believe the numbers) has ~186 at the tires, that certainly worked to bump up the low-end torque.

As the RPMs climb, the small runners start restricting total airflow, making the torque drop off earlier, and with it peak HP. I Honestly think I have a 240HP engine, with a 200HP induction system on it.

With my stock CIS, this is probably not a bad thing. I bet that nice flat AFR line wouldn't be as flat if it could pump more air. It would probably go lean up top.

All in all, I am pretty damn happy with how it turned out. If I ever move somewhere without smog testing, I would get the heads done and go to Webers, or some sort of EFI.

Tom

Edit: spelling

[rdane]

'83 SC, mods '73 OEM exhaust, Triad 2in and 2 out muffler and a Webcma20/21 grind. Engine was recently rebuilt to factory spec and is now well broken in.
173hp (F#173hp) and 174# of torque. This is a good comparison for the early and late SC heads and the later 9.5 compression pistons.

I was talking with Peter at Andial yesterday. He mentioned the early 98 RSR pistons are known for low compression. I would think that the problem more than the heads. I would be interested if you came to any other conclusions or had done another dyno since the first.