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Home > Paul S trials and testing > Another Rolling Road Log

alpa

520 Posts
Member #: 2093
Post Whore

Grenoble, France

In my case the rev limiter comes so quickly in 2nd that it takes me some time to notice that RPM does not increase and the shift light is on.
I'm not using the same pulse for both cylinders, I'm firing every revolution, the inner's pulse is way before the intake, the outer's is just before or during the intake (it's dynamically positioned).

Did you do anything to improve the boost build-up at say 4000 rpm ? Mine is a bit slow to come, in 2nd gear the full boost is reached above 5000RPM. I'm going to play with retard/richness to see how to improve that.
It's a quite common problem on engines with big turbos, every engine needs different solutions.

Edited by alpa on 7th Jun, 2010.

std 998 A+, g295, MD266, RHF4, 109hp @0.8bar/5400rpm


Paul S

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8563 Posts
Member #: 573
Formerly Axel

Podland


On 7th Jun, 2010 alpa said:
Did you do anything to improve the boost build-up at say 4000 rpm ? Mine is a bit slow to come, in 2nd gear the full boost is reached above 5000RPM. I'm going to play with retard/richness to see how to improve that.
It's a quite common problem on engines with big turbos, every engine needs different solutions.


No, however I have recently noticed that although the rolling road log shows full boost at 4000rpm, that is in top gear and the turbo has time to spool up.

In reality, on the road in lower gears, full boost does not come until around 4500rpm as turbo takes its time.

I would be very interested if you find a way to reduce the spool time by playing with the fueling and timing.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."


alpa

520 Posts
Member #: 2093
Post Whore

Grenoble, France

Last night I tried to improve spool time. Did not work. Lean, rich, ignition retard: no significant improvement.
I'm going to try a "soft" ALS strategy: miss ignition of a cylinder from time to time to make mixture burn by itself in the exhaust manifold. This is used today as a launch control strategy and is not supposed to destroy the turbine neither exhaust valves.

std 998 A+, g295, MD266, RHF4, 109hp @0.8bar/5400rpm

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