[JohnMH]

A stock 999R has a certain map in its ECU which sets the fuel delivery parameters.

Now remove the stock pistons and add a pair or pistal high compression ones.

All other variables held equal, will the engine want a richer map? I have a DP ECU for a 57mm system, then was given a Dynojet map to try for my specific bike (pistal hc pistons, gasflowed heads, corsa air runners, 57mm Akro prototype race exhaust) while I wait for a Nemesis ECU. To my utter amazement the sheet of numbers were almost all negative (ie leaner than the DP ECU seetings). Does this make sense?

The bike still does not run as fast as I thought it would (I can run neck and neck straight line with a stock 09 GSXR 1000 and I outweight the Suzuki pilot by 20 lbs).

Next question, I have read that high comp engines want a cooler spark plug. I run the stock NGK race plugs without the bridge to the electrode. I cannot "feel" any detonation from having too hot a plug, but I am not sure I would until it was too late.

Anyone have any guidance on plug heat range for a high comp testastretta engine?

 

[Bella749]

I cannot vouch for the map you received; I have not had good experience with pre-built maps. The HC pistons would not require more fuel, but may require less ignition advance to prevent detonation. What kind of fuel are you running... leaded race gas? You would likely be good.

I'm not sure of the fuel quality in UAE, but in Iraq, they call it "benzene" for some reason, which suggest the gasoline has a higher benzene composition. Benzene has a high octane component which may help your situation.

 

[Mojogoat]

Try a lower grade gas, if it doesn't ping, your timing is not set to optimum, you may even gain HP/TQ with the lower octane with your current ign setup. Colder plugs are used to prevent det where there is a problem. I built a HD motor where the compression and cam put it right on the edge of detonation. The output of the motor was quite high but very sensitive the quality of fuel, air temp and even elevation.

 

[JohnMH]

Fuel is the one thing which seem pretty good here. I have another bike (888/955 corsa) which was built for C12 race gas. I tried her on pump "super" here which is 98+ octane and she ran pretty well. I have not had any detonation here on any bike, although the effects of the fuel on the inside of your fuel tank and rubber bits is another issue. Interesting idea about running regular, I may try that. I raced an RZ350 once (22 years ago!) which liked regular gas even with a milled head.

So no change in air fuel ratio with higher compression. Ignition advance may be affected. Makes sense.

What is the seat of the pants effect of higher comp pistons in a Ducati? I have never had a stock 999R. The bike seems to have an extremely strong midrange lunge (it easily runs away from an 09 GSXR 1000 in midrange), but seems to run out of breath as it approaches 11,000 rpm. Gearing is short, but 6th gear is still pretty fast (I would have expected more top end, but that is comparing it with my last race bike, a revvy 749R).

I think a custom map is the only real solution.

 

[Mojogoat]

Sounds like your map is for the lower octane most of us have to live with. Higher compression gives you a pretty consistant power & Tq increase everywhere in your power curve including MPG. I'll bet a lower octane will give you more power. Lean mixture equates to more power in different parts of your power band. The treshold is a fine line between max power and melted pistons. More fuel is a way to cool and lession detonation but not the correct way. Custom dyno map with your local fuel and near your location will give you the max power for your setup. The person mapping has an effect depending on how conservative and the amount or risk he senses you want to take with your motor on taking it to the edge; closest to detonation, where the max power is.

 

[rz33v4]

I went to 10.5:1 CR on my 944SS and was disappointed with low-end performance. The two things which really helped were 1), adding more fuel on the PCII between 2-4000 RPMs and 2), replacing the spark plugs with one heat range colder (Denso Iridium).

 

[DukeDesmo]

My 916 has a raised compression ratio and gasflowed head. I had the powercommander mapped on the dyno and there are more 'negatives' than 'positives' in the map (although most of the positives are larger than the negs) but surely this is all dependent on the ECU (which is probably over-rich anyway) and setup during TPS/throttle balance/airbleed procedures etc.

Anyway from what I have seen (and heard from tuners) any map that wasn't specifically mapped to your bike is never going to be right. I started with a zero map onto the Ducati open pipe eprom but got a 7hp gain by custom mapping.