Hey Guys,

I'm wondering what the highest RPM anyone here has run on a stock bottom end?? Any issues running that RPM and how long have you been running it that high for?


I'm building a new motor this year, valve train will be all aftermarket and balance shafts will be deleted, so no worries there.


I'm more worried about the kinds of piston speeds these motors are seeing at say 7500rpm or higher, with my new set-up I might need to rev this thing to 7800rpm.....and that puts my pistons speed quite high.


I would love some feedback to put my mind at ease, I would hate to pop the bottom end and junk my $1600 head.


Thanks guys!

 

Limitation is in the valvetrain. Many people have done 7500 with stock longblock just fine. Valve float gets risky any higher. Most everyone does 7200 all day every day on stock engine. I did for a few years and rode it hard often.

I've never heard of a single person overspinning the bottom end.

GM build book I believe details their drag engines spinning 9k+ RPMs.

PCM has a hard limit of 8192 RPMs I believe, but you gotta open HPT and check a file because I forget the exact. I think ZZP and others have done 9500ish with a standalone...

If you got rid of the balance shafts and did the springs you should be golden.

 

GM's drag motors use a 2.0 bottom end tho, the rod ratio is much better than the 2.4's. Stock for stock the rods on a 2.4 are much longer than a 2.0, so the piston speeds on a 2.0 at the same RPM are much lower than a 2.4 at the same RPM, to not mention the rod angle is much better. I'm worried with the increase cylinder side wall loading coupled with the piston speed something is gonna give... ie. a ring land.

Was this ZZP motor that they rev'd to 9500rpm a 2.4 bottom end?

 

The 2.0 they stroked to 2.4 I think. In the redline. I could be wrong though.

 

Your refering to the ZZP motor?

I wonder if they kept the same rod length tho and just got custom pistons with the wrist pins moved down....hmmm.

 

Yeah. The one in tims ion. I have no idea about rod length or none of that mess so I can't be of anymore help. Lol

 

I didn't see which section this was posted in and you didn't mention the engine, so I didn't see the 2.4

You are wise to question what you did, however I don't have much info on it.

ZZP's stroker as was stated would be a good source of info. I'd PM, email, or call ZZP and ask them for some info. They did the testing and should be able to give you a little info. It was Tim's Ion that has the stroker in it. May need to inquire about some of their products.

Good luck!

 

Anyone else?