Fuel

[jtopiso_imp]

Why not email and ask them what octane they recommend?

I can say- at least whatever was done to my ECU def had ign timing changed in some way.

Can't speak to whether than means advanced in some areas- or 'restrictions' removed- which would mean advanced compared to where it was.

My dyno results on the Guhl ECU keeping in mind that I had already controlled / added fuel and still did- netted 3 wheel hp, and I figure that is all ign timing as everything else was unchanged.

Keep in mind just adding fuel (richer a/f) by itself cools the combustion chamber and can lessen the chance of detonation.

Very well may still be tame enough to run regular gas, but why risk it over a few bucks a tank.

Here in Colorado, regular grade E-10 gasoline is 85 octane, not 87. My CB ran great on 85 even at 14.000’+ elevation. Zero pinging, zero noticeable power loss, zero issues, and gas mileage in the mid-60’s.

Knocking depends on how much power you actually pull. Knocking isn't ever an issue if all you pull is 30 HP at 2500 rpms. The Honda guidelines do have to take into account that somebody may run her at high rpms all/many a times.
The impact of elevation (or atmospheric pressure), this is compensated for by the injection system.

None of that is true. 'Power' itself is irrelevant to pre-igntion / detonation.

HOW that power is made is a contributor- but the power value itself is not.

Meaning- higher compression ratio? More octane needed.

The VERY important variable is load, and time.

A high compression engine driven correctly can be fine- and give that exact same engine / fuel / vehicle to someone 'taking it easy' can damage it.

When you mention 'Honda has to take into account high RPM'- well, they certainly do- but not for pinging issues.

High RPM concerns are much more inertial mass, valve spring, rod bearing, oiling issues...and noise.

You see detonation problems at lower RPM & high load- as in your example- 2,500 RPM up a grade but in a high gear - more throttle, bogging around is MUCH worse than flying through higher RPM quickly- even if 8-9k.

In the 90's I used to have to park in a commuter lot at a train stop- and the road out of it was long, steep, and slow speed limit. The amount of cars driving up that hill always crawling slow both in car speed and too low engine RPM- sounding like cans of marbles used to drive me crazy.

All they had to do was downshift, let the rpm climb a bit, let the gearing do the work, which means they would have backed off the throttle- less load, and stopped the pinging.

None of that is true. 'Power' itself is irrelevant to pre-igntion / detonation.
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I don't wonna get into a useless argument, but I worked aircraft engines for years, on an engine test bed, with direct measurements of all parameters. The picture I painted is a simplified version for our m/c, but to say none of this is true is a bit stark ... unless supported by facts.You would have to tell us a bit about where you learned your lessons, and how ???

None of that is true. 'Power' itself is irrelevant to pre-igntion / detonation.
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I don't wonna get into a useless argument, but I worked aircraft engines for years, on an engine test bed, with direct measurements of all parameters. The picture I painted is a simplified version for our m/c, but to say none of this is true is a bit stark ... unless supported by facts.You would have to tell us a bit about where you learned your lessons, and how ???
The thing is that power output, engine load and engine speed are related. So you can see a correlation between self-detonation and power output, but the cause will be the excessive engine load. If you got the same power at different engine speed (e.g. shorter gear), it wouldn't self detonate. So it's not just power...