Engine Speed Limitation in MegaSquirt???

[superart]

Hello,

I am trying to research if the MegaSquirt is the proper ECU for my application. I am looking to control a gsxr-600 engine with a red-line at 16,500 rpm.

I have looked through the manual, FAQ, and forums, but have not been able to find any specs on what the max rpm that metasquirt supports.

The closest that I have found is this link:
http://www.bgsoflex.com/megasquirtspecs.html
It talks about the MS-1, and says that it supports up to 16,000 rpm.

Does anyone know if the MS2 or MS3 can support up to 16,500 rpm? Also if anyone could link me to a project thread where someone is running an engine at or near this speed I would greatly appreciate it.

Thanks.

[Matt Cramer]

It can hit that RPM no problem. There are a few MegaSquirted bike engines out there with similar redlines running MS2. The maximum theoretical RPM limit is around 65,000, but so far nobody's attempted to install a MegaSquirt on an engine that gets anywhere close to this.

[superart]

Thanks for the response.

Do you know off the top of your head what the highest rpm running engine that you have seen or read about? I've looked through the bike forum and the success stories forum, but haven't really been able to find any threads where people have talked about the max engine speeds that they have achieved.

<edit>
here's a good one I just found
viewtopic.php?f=92&t=37177&p=223818&hil ... pm#p223818

[turbo355]

On ms2 we have seen as high as 14500 -15000 on the turbo GSXR 1000's with no problems, 160000 should be no problem for the MS.

[grippo]

When you ask this question you also have to consider the number of teeth in the crank position wheel, if you are running in wheel decode mode. I don't think you can reach anywhere near 16k with a 132 tooth flywheel as your crank wheel. But it should be easily doable with a 36 and maybe a 60 tooth wheel.

The number of cylinders is also a factor, you will never reach it with an 8 cylinder, but then I don't know of many 8 cylinders that can approach this mechanically.

[A McNeill]

What is the source of the limitation? It seems clear from the answers here that it's not simply teeth and rpm but cylinder count too. What is the math on that? I also seem to recall reading somewhere that the tooth count had to be divisible by the number of cylinders (perhaps that only a sequential injection / COP requirement?)

[grippo]

The limit has to do with CPU time. It doesn't have to do much between teeth but it does a lot of calculations every time a cylinder is ready. If too many cylinders, too many teeth and too little time at hi rpm, something will give.

The need for 2 x no_teeth/ no_cyl to be even is that the calculations are done in integer arithmetic and the tooth count would not come out right. That has nothing to do with rpm.