Dyno Run - RX3 on a DynoJet

[rtking]

Originally Posted by Weldangrind

There certainly is evidence to support that max power is found between 12:1 and 13:1. If I had access to tuning software, I'd certainly add a little more fuel to see what happens. What is the opinion of the dyno operator?

While I think you're right, for legal/emissions reasons, the dyno operator suggested that I enjoy the RX3 as is, and if I were seeking more power, perhaps a bigger bike would be an option.

I can understand his response... the California Air Resources Board and EPA are really cracking down on shops, and this shop has former employees from some of the big aftermarket exhaust / tuning companies. They did say that any sort of tuning would require that the bike be off-road only and towed in and leave on a trailer.

That being said, there's nothing wrong with the power the RX3 puts out. It hauls my heft around to 83.x mph (GPS speed) on a flat and level highway, and does fine at a 75 mph cruise. I think there's some power to to be hand by richening the mixture to the 12.5-13.0:1 range. But it won't be inexpensive to come by.

As an old hot-rodder, I too am always curious about what other efficiencies can be gained to free up power. It looks like Zongshen did a fine job and, short of degreeing and reprofiling the cam and adjusting ignition and fuel (all expensive routes to take), Zongshen did a fine job of maximizing the power output of the RX3. As a close friend (and fellow Ford enthusiast) stated, this is the equivalent of 440 rear wheel horsepower from a 5.0 V8 normally aspirated engine. Very impressive power output for the displacement.

[CSaddict]

Power is generally all in the timing.

[NzBrakelathes]

The 300 kit changes the engine to a much torqueir motor and less to no need to rev the shits out of it.

[sqwert]

As I've posted elsewhere, and these dyno graphs confirm, according to my rump dyno the 300 kit drops peak horsepower to about 8000, peak torque to about 7000. Still almost the same horsepower at 9000 as stock, but power dives right after 10,000, right before the valves float, where the 250 was still pulling another 500rpm or so before the valves float.

SpudRider, you are so right about how well Zong has the Delphi set up for the RX3. Using a slight up hill to control driveline slop, I can slow idle under load, 1500rpm, in 6th, crank the throttle WFO, and the Delphi does such a good job with the air/fuel ratio not a beat is missed, 80mph top. I've never had any vehicle with such command of the mixture.

All I've done to make the Delphi perform this well is nothing. Zong set it up perfect for the 250, Delphi set itself up perfect for the 300. Took a few miles each time, more than adapting to a different valve setting or motor oil, but those improve, too.

Rolled over 10,000 miles yesterday. Still running the original spark plug. Never missed a beat. When is a change due?

[ChopperCharles]

I'd love to see the AF ratio for the 300 kit. I'll bet it's leaning out a lot and there is power to be had.

Charles.