MMW Dyno Repository. Lots of interesting info!

[328iJunkie]

S50 equipped car down on power as well?

Yes. Only did ~230whp tuned with 3.5" MAF/24lb/headers/etc

[Butters Stoch]

Good work

[hobbit382]

Yes, did a before and after on an M52 and then did a tune on an S50 Car equipped with them. They Didnt make any power (acutally lost power) though the owners of RR insist this was an isolated issue.

any thoughts on why it would lose power with more lift and duration?

[328iJunkie]

Doesnt technically have more lift or duration depending on how you look at it. Its a regrind. They 'create' lift and a new profile by removing from the base circle. My theory is the lifters are not taking up the slack they assume they are.

[hobbit382]

Doesnt technically have more lift or duration depending on how you look at it. Its a regrind. They 'create' lift and a new profile by removing from the base circle. My theory is the lifters are not taking up the slack they assume they are.

correct. The lifters have only about a mm extra to extend (unless you pull them apart and remove the locking ring) but I doubt they grind them more than a mm. Did these cars make any ticking noises indicating the lifters weren't taking up the gap as designed? Or maybe they do take up the gap but "squish" down more easily negating the extra duration?

[328iJunkie]

No new noises that i was aware of. Im not going to get into RR cam specs as they hold that close to the chest and wouldnt be kosher. I again never conclusively determined the cause. Pulled them and put S52s back in. Power jumped back up and ideal vanos shutoff point dropped back down.

[dohcdoh]

Hmm, interesting about those cams.

[328iJunkie]

:P

[hide1]

I do appreciate rereading this thread from time to time. it makes me feel pretty good about the power my m3 is putting down untuned, better than most s52's posted and based on what you have acheived, I'm counting on a few extra hp once we get the timing and fuel corrected for altitude. We were as low as high 10's in some places. However, you should know, maybe you misstated it or misunderstood how the cams are made, the riots add zero lift to the original lobe, only duration. If you put a micrometer to them you would know this and if you spoke with the owner/ designer he would have stated this emphatically.

[328iJunkie]

I do appreciate rereading this thread from time to time. it makes me feel pretty good about the power my m3 is putting down untuned, better than most s52's posted and based on what you have acheived, I'm counting on a few extra hp once we get the timing and fuel corrected for altitude. We were as low as high 10's in some places. However, you should know, maybe you misstated it or misunderstood how the cams are made, the riots add zero lift to the original lobe, only duration. If you put a micrometer to them you would know this and if you spoke with the owner/ designer he would have stated this emphatically.

I know they don't add material but do *try to add lift by removing from the base circle. Thanks for the kind words

[pizzaman09]

This is an incredibly interesting thread. It took some research but I finally found the elusive back to back comparison of an M50 vs. M52 manifold swap with no other mods.