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Mpi Rev Limit ?


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#1 Odds

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Posted 06 July 2020 - 08:47 PM

Hi All,

Still getting to know our 2000 MPI and beginning to drive it a little more enthusiastically :)

My question is whether it should/would have a factory rev limiter ?

I’m currently revving it out to about 4K between changes, but wondering how much further it would go ? I’m not sure what the stock power band looks like, so not sure how much more it would have to give at higher revs.

What’s your experience ?

Thanks

#2 Ethel

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Posted 06 July 2020 - 09:39 PM

Half as much again. Unlikely you'll be able to persuade it to self harm.

 

Other than mechanically by missing a gear etc.



#3 Curley

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Posted 06 July 2020 - 11:12 PM

Hi welcome to the forum

 

4K sounds a little short shifting to me, I run a soft cut at 6200K because my cam does not produce any extra power after that. Assuming you car is relatively stock I'd think peak power to be somewhere around 5500-6000rpm to have all but dropping off entirely after 6500.



#4 bluedragon

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Posted 07 July 2020 - 01:55 AM

A stock MPi Mini is listed by the factory as generating peak power @5500 rpm. I doubt it will rev much higher than this because for the MPi, the limitation on higher revs is from the twin injector shared port system.

 

Because of the cylinders sharing intake ports, there's only a limited amount of time for the fuel injector to squirt fuel into one cylinder before the other cylinder starts to draw fuel for itself - i.e. "charge robbing." This time window gets shorter and shorter as revs rise, making it harder to get enough fuel to support higher revs.

 

That's one reason the MPi motors put out very nice torque in the low and midrange, but run out of steam at the top end. It's also why it's hard to hot rod an MPi for big HP numbers - tricky to get the fuel required to support more revs (how most built motors post big numbers.)

 

 

Dave



#5 Wazzah

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Posted 07 July 2020 - 03:28 AM

MPI 6150 rpm.

SPI 6850 rpm






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