Just wondering what people have been raising their rev limiter too. Basically i want to go up to 7500rpm, but wondering if just JWT cams and springs/shims would be able to sustain this. The new Rev-up motors go to 7100 stock, just wondering about our 287 motors what they can do with a built bottom end and some cams. Thanks!

-George

 

there are some cars here running up to 8000rpms SMOOTHLY.

 

But, with what type of headwork? Heads can get very expensive, and I would LOVE to rev to 8K but just want to know what is required

 

I'm not too sure about the details...you might wanna PM marluci7. His car makes 700+rwhp and revs to 8000 rpms.

 

you will not be able to go up to 7500rpm frequently with JWT/Nismo springs, so don't even try going 8000rpm... I would say with FI setup, you will need better springs though!

I bent my valves @ 7600rpm with nismo springs (similar to JWT), so I changed the entire valvetrain to Ferrea items with dual springs and the engine now can rev smoothly up to 8000rpm (all you can see on my tacho is all you can go) or even more (but I don't wanna try that out just yet).

Best of luck!

cheers,

richie

 

So how about if i go with Fererra springs,shims,retianers. but leave the stock vavles and use JWT cams. Would this work or would the valve probally bend. Thanks!

Did your vavle bend because it was weak or because of the springs? thanks!

 

I am running the full Ferrea valvetrain w/ 1mm oversize valves, headwork and can rev to over 8K, but I prefer to be a little more conservative and rarely take it over 7K. I do not think the stock valves can handle anything over 7K with boost.

 

My valves bent due to weak valve springs I had in my engine when there was some back fires... but I think t32gzz is right... I was told (by Carl Jr. @ XtremeRaceCars.com) that stock valves are pretty weak... they are 2 piece design instead of Ferrea's 1 piece design valves, so they will break under heavy loads (I think)...

And with FI setup, it is better for you to go for 1mm oversize valves to get better flows... but I reckon if you want to rev it hard to just 7000rpm, you should be safe with just the Ferrea valve springs and Ti retainers... and if you are going beyond that, I think you might want to consider changing valves and the valve guides too since stock valves/guides won't be strong enough for the works according to Carl's Jr. experiences on their drag cars...

cheers,

richie

 

And is it safe with stock bottom to rev to 7.500 or i must change rods?

 

I think you gotta change the rods for 7500rpm for FI!

cheers,

richie