Other Ways To Implement A Rev Limiter?

[hendrixgr]

Hi.
I think i found a fault that will damage a Hayabusa turbo engine (gen1 with extra plenum injectors) when it hits the rev limiter.
This fault appears because the way my extra 4 plenum injector controller (AIC1) works.
If i am right while the stock ECU uses sequential injection (each injector is fired when the intake valve is opened)
the AIC will only batch fire which means that when ecu # 1 injector fires (or whatever number of injector you connected the AIC1 trigger input to) it triggers the AIC1 and all 4 AIC1 driven plenum injectors fire, something acceptable if you don't hit the rev limiter.
If you have the stock ecu rev limiter activate after #1 injector fires then all 4 cylinders will get a reduced dosage of fuel
which waits inside the throttle bodies coming from the plenum injectors.
Of course this quantity of fuel is usually only 50-70% of the needed fuel which leads to a very lean condition.
I don't know if just one round of lean cylinder firing is enough to destroy the head gasket and damage the engine so if it isn't then there is no problem and my questions need not to be answered.
Now my questions to the experts:

1) If i have the rpm limiter set at say 11000 rpm can i reflash the ECU in order to retard timing just before the rpm limiter, say 10800 and use this retarded timing as a help to the rpm limiter?

2)Is there any way to cut ignition also when the rpm limiter hits?

Chris

 

[Boosted Cycle Perf]

Why not make the rev limiter the same on the secondaries as the main ecu?

 

[hendrixgr]

Hi.
You are right but unfortunately the secondary controller (AIC1) does not have a rpm limiter
built in afaik, it is relying in the main ecu cutting the #1 injector drive signal in order to cut fuel.
I am starting to save money for a stand alone ECU.
Chris

 

[POWERHOUSE]

Chris, go into your ecu and put your rev limit up to 12K. Try not to go there! Your power drops before that anyway, and you don't win races by rolling into the rev limiter all the time. Ideally, you want a hard cut, but if you have no options with your secondary controller, just raise the limit higher than you will ever go. You can retard timing through the ecu if you want, maybe you should put some kind of shift light on the bike . . .

 

[hendrixgr]

Chris, go into your ecu and put your rev limit up to 12K. Try not to go there! Your power drops before that anyway, and you don't win races by rolling into the rev limiter all the time. Ideally, you want a hard cut, but if you have no options with your secondary controller, just raise the limit higher than you will ever go. You can retard timing through the ecu if you want, maybe you should put some kind of shift light on the bike . . .

I like the idea of retarded timing in conjuction with elevated rpm limit (for now...)
How low in degrees can i go after say 11000 rpm?
I was thinking something in the neighbourhood of 27 or lower degrees.

 

[BIG CC RACING]

Why not make the rev limiter the same on the secondaries as the main ecu?

That's more difficult than you think. Stock clocks run inaccurate rpm & even the slightest imbalance can cause a burn down & even without it I would not wanna have 20psi banging on a rev limiter for a minute of abuse. Hendrixgr is technically correct on thinking of an ignition kill.

 

[hendrixgr]

That's more difficult than you think. Stock clocks run inaccurate rpm & even the slightest imbalance can cause a burn down & even without it I would not wanna have 20psi banging on a rev limiter for a minute of abuse. Hendrixgr is technically correct on thinking of an ignition kill.

Hi.
I understand exactly what you mean and i agree 100% but for now and for street use only will timing retard help?
I can construct an ignition kill my self pretty easily with a cpu and some mosfets, something that it will be ready in a week or so but i will also start saving money for a stand alone ECU that can control 8 injectors and work closed loop.
Btw i understand the difficulty of synchronizing the stock ECU fuel cut rpm threshold and any external unit and that an imbalance will cause one limiter to activate before the other destroying the engine.
Thats why i am starting to think that a stand alone ECU is the way to go (your opinion really counts)
Chris

 

[BIG CC RACING]

I have not seen a standalone to run as smooth on the street as a good piggy back set up. Ignition kill is the way to go.

 

[hendrixgr]

I have not seen a standalone to run as smooth on the street as a good piggy back set up. Ignition kill is the way to go.

Now that is a good piece of information THANK YOU very much.
Chris