REV Limit of bottom end

[400ZED]

What is the limit of a stock bottom end?
speedway guys in NZ are getting 10 and 11 thousand RPm but that can't be stock.
I have a stock crown bottom end
and am a week off fitting Cams
370 thou lift before clearance
240 @ 50 and some new springs to handle it.
So the question is how hard can this thing rev saftley?
it use to run out of breath over 6000 i am hoping that the cams can breath to 8000- 8500

It is booked in to be tuned next Tuesday do i have to ask him to limit the revs or let it rev till it runs out of puff?

 

[Zuffen]

Let it rev until it runs out of puff or goes BANG.

If it does go BANG we'll all have an idea of how hard not to rev it.

I like to experiment with other peoples engines/money.

 

[chrisman]

there was someone who had a rod let go --i think around 7800-- but look around to make sure.. i don t remeber for sure.. and yes, it easy easier to experiment with other guys engines/money.. it doesnt hurt as much when it breaks..

 

[chrisman]

there was someone who had a rod let go --i think around 7800-- but look around to make sure.. i don t remeber for sure.. and yes, it easy easier to experiment with other guys engines/money.. it doesnt hurt as much when it breaks..

 

[400ZED]

that is a bit harsh after this build i am a little delicate in the pocket.

 

[MaxPower]

Did you end up replacing the bearings or get just getting a replacement short??

 

[400ZED]

i replaced the long motor
i am going to replace bearings and do some work to the broken one which might come up for sale later. if any one is interested in a reco motor

 

[MadPhil]

Yeah I had a rod let go @ around 7800rpm. It was a dead stock standard crown bottom end, and I have only managed to save 2 pistons. All the others were damaged by bits of rod hurtling around the block

 

[Lambo]

Yeah, mad phil i saw an article once in the BMW mag about the loadings in a v12 when the piston reaches the top of the bore and changes direction at TDC it was several hundred tons of force.
Regards
Lambo