82 Euro SC rebuild dyno results
 

This is a reprint from my "82 Euro SC rebuild" thread.

Here are the dyno results. Keep in mind, the D class (big port USA SC motor) I have been using while I rebuilt mine made 193rwhp on the same dyno. A top flight Euro SC motor built by a race shop makes 215rwhp with 36 degrees and race gas.

My original stock motor with 113K miles and pre-74 heat exchangers made:
181rwhp
170 torque

Today the new motor (with about one hour of running time on it) with racing headers made:
163rwhp
176 torque

Here is the plot. The black line that starts on top of "STPPwr" is today's run, and the red line that starts just after it is the old motor. You can see that both the horsepower and torque start out higher than the old motor (black lines), but at around 5400 the new motor peaks, whereas the old one continues increasing until about 6000. It starts right up every time and idles smoothly without any throttle input. Before the rebuild I had to keep my foot on the gas to prevent it from dying when I started it.

The book says the cam timing spec is 0.9 to 1.1 so I set it to 1.0, although I just found a thread here that says it should be 1.4-1.7. Also, the chains seem louder than they used to, or rather, I don't recall being able to hear chain noise before, but I hear it now. I'm starting to think I lost my cam timing when I installed the tensioners.

The ignition timing is set at 31. It was in the low 90s today and the dyno of my old motor was in October 2009 so it was probably in the 70s. I confirmed that I am getting full throttle by having my wife press the accelerator to the floor while I watched the linkage and the linkage can't travel any further.



http://forums.pelicanparts.com/uploa...1311793071.jpg

ninesixfour,

If I am reading this correctly lines are a bit hard to follow, the original run started off on the way too lean side and then settled down to about 13 to one A/F and held that through the meat of the pull. Your second pull started of a lot richer, made more power than the previous run, and then around 4700 RPM started to go even richer richer than the previous pull and started to lose power. It looks like the motor does not like a 12.5 A/F.

I am guessing an ECU chip was added to make power or other changes were made. If a chip was used it likely added ignition timing too, it is possible it added too much for the fuel you are using.

The bottom line here the motor needed a bit more fuel below 4700 and did not want any more above that point. The A/F changes should not account for the hard roll over you see on the second pull so I think timing may have come into play above 5000 as well.

Just read where this is a new motor with fresh rings, if you had lots of plow by on the dyno I could see ring seal but I doubt it will change all that much, the rings and cylinders are pretty good out of the box.