Increasing the factory 6800rpm Rev Limit
03-12-2008, 02:45 PM
#31
Racer
Join Date: Dec 2003
Posts: 497
Likes: 0
Received 0 Likes
on
0 Posts
It seems to standard practice these days for serious racing engines (or so I read) to design the valve spring so it is quite close to coil bind under normal conditions. This makes sense if you are designing a valve spring to be as low mass as possible.
It is strange to me that the stock valve springs in air cooled engines are nowhere near coil bind under normal conditions.
6800 rpm has been mentioned a few times in this thread. I caution that the stock rpm limiter is closer to 6600, and I think that sustained use at 6800 rpm risks a retainer failure.
It is strange to me that the stock valve springs in air cooled engines are nowhere near coil bind under normal conditions.
6800 rpm has been mentioned a few times in this thread. I caution that the stock rpm limiter is closer to 6600, and I think that sustained use at 6800 rpm risks a retainer failure.
03-12-2008, 02:50 PM
#32
Rennlist Member
A little OT, I think there should be more of a buffer between maximum allowed engine RPMs and the RPMs at which an engine begins to fail. So if the max RPM of an engine is actually 7200 that causes it to fail, I would not want to see 6800 at the rev limiter. I would want to see more like 6000. It all boils down to how close to the knife edge you want to be, and IMO, reliability is #1.
03-12-2008, 04:35 PM
#33
Racer
I've bought the 3,8 conversion FVD from a other rennlister, compression 11.4.1. Thinking of getting other cams (nine had some nice one), rockers,valve springs,
03-12-2008, 06:22 PM
#35
Nordschleife Master
Thread Starter
Jason, thanks for the correction, I was going by the tach face since I don't have an accurate method to check the RPM limit. The calculations based on camshaft profile and spring pressure at factory installed height is 6800rpm, so they did give a some room for advanced RPM.
