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  • Donating Members
  • Member For: 9y 9m 26d
  • Gender: Male
  • Location: NZ

Sigh, Probably should have rephrased that, not the first I have heard of it, but the first I have heard of recommending 5500rpm as a rev limit!!

  • less WHY; more WOT
  • Site Developer
  • Member For: 17y 1m 18d
  • Gender: Male
  • Location: Melbourne

that's just the stock rev-limit and not the worst "safe-zone" to keep to.

  • less WHY; more WOT
  • Site Developer
  • Member For: 17y 1m 18d
  • Gender: Male
  • Location: Melbourne

that's alright, you can make around 1000hp at the crank on a 5,500rpm limit, with the right setup... :P

  • Donating Members
  • Member For: 9y 9m 26d
  • Gender: Male
  • Location: NZ

Na will still be sending it at 8000rpm. Was just interested to hear peoples thoughts. Didn’t buy that billet crank for nothing!

  • less WHY; more WOT
  • Site Developer
  • Member For: 17y 1m 18d
  • Gender: Male
  • Location: Melbourne

well you're going to need strengthened valve guides etc at the top end, heaps of stronger bits for the rotating assembly (bearings, bolts etc) and (and probably more) even then it's risking it, bigtime... get a de-stroked setup if you want it to survive and make stupid power haha

  • Gold Donating Members
  • Member For: 10y 3m 29d
  • Gender: Not Telling

Have a read of this https://www.musclecardiy.com/performance/understanding-piston-speed-in-high-performance-engines/

 

I worked out the maximum safe piston speed for a 4 litre barra ages ago and it was about 5500 rpm iirc.

  • Like 1
  • skids
  • Donating Members
  • Member For: 12y 5m
  • Gender: Not Telling

I say build it strong and tune it properly and that's not a worry.

 

these motors don't like being revved high I do know this but on falcons everything else breaks before the engine :P

  • Like 1
  • Gold Donating Members
  • Member For: 10y 3m 29d
  • Gender: Not Telling

The main reason not to rev it high is the stress on the pistons, gudgeon pins, conrods and rod bolts as it stops to change direction at tdc or bdc. All of this moves a lot faster as it has a long stroke. If you make all of that strong, the stress moves to another part of the motor.

 

It is a fallacy to say that the engine runs out of torque at a set point, as for the most part this is dictated by everything else, ie: cams, turbo, head work etc etc, not the stroke or displacement.

 

You can rev a barra higher than 5500 obviously, but in a stock falcon it ain't necessary. In a 1500hp car with a built motor etc, it is necessary to raise the limit a bit.

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