*7M Crank RPM Limit*

[IJ.]

Update!

Turns out the bottom end isn't an issue with either crank!

I broke a valve spring

8000 sustained isn't the best idea!

 

[JustAnotherVictim]

Good to know but I don't think most of us will hit that high.

 

[jdub]

Update!

Turns out the bottom end isn't an issue with either crank!

I broke a valve spring

8000 sustained isn't the best idea!

What kind of springs you using Ian? Still Ferrera + retainers?

 

[IJ.]

JaV: Try harder

JD: Yep!

Looks like some of the inners were a bit tight in the outers and due to expansion it caused the outer to be nicked by a bucket....

 

[jdub]

JaV: Try harder

JD: Yep!

Looks like some of the inners were a bit tight in the outers and due to expansion it caused the outer to be nicked by a bucket....

Wow...that's the 1st time I've heard of a Ferrera spring failure :3d_frown:

 

[Jaguar_5]

If It'll break, leave it to IJ to find the weak point!

 

[IJ.]

Same here

Looking at the BC singles!

@ 8000 the springs get red hot so I guess the many many times it went there took a toll!

 

[JustAnotherVictim]

Looks like you have a lead foot problem. :icon_razz

 

[IJ.]

JaV: but but but..... I installed another return spring to make it harder to nail it !

 

[JustAnotherVictim]

Keep taking it to the limit.

 

[jdub]

Hmmm...8K rpm huh. Maybe you should back it down to 7800 IJ

 

[IJ.]

Think I'll be dropping the limit on this build!

 

[SublimeSupra]

I dont want to hear that take it to the limit!8.5k do it!You seem to be the pioneer around here as far as pushin it.

 

[drbowser3]

I know of a BUILT 7M revving out to around 8500rpm

 

[SublimeSupra]

Dang really is it around us.Cause i notice your name you post on TR alot.I dont post there much my name is addicted2boost.

 

[IJ.]

Mine will easily go to 8500 when fresh just NOT for sustained periods like I've been running it....

Even then I'd be wanting to swap out valve springs every 2000>3000 KM's as a safety measure.

All well and good flashing a motor to 8+K holding it there is another matter entirely!

 

[NashMan]

holding any 7m or 6m crank for perdoes of time will kill one mostly the head thou as in vavle train ect

 

[IJ.]

Ryan: So far no real failures in the bottom end revving it this hard but yes the valvetrain is suffering and it's been built with the best of everything!

 

[drbowser3]

Isn't it usually the valve train that limits redline???

 

[IJ.]

Not always, many times you'll wipe a bearing or suffer some mechanical damage during sustained high RPM running.

Having said that I've never heard of a Ferrera spring breaking before.......
(I'm sure it happens it's just not a common thing)