bluoval6
07-20-2017, 11:53 PM
So I've been thinking about playing with my cam timing for a few months now. There was a thread a while back on this trying to figure out what the optimal settings are, but there didn't seem to be any conclusion. I had to do a VC gasket anyway, so I got brave and tweaked my intake cam a bit. Figured I'd post results in case anyone else wants to try this. For reference, this is a 98 M44.
What I did
After accessing the cams, I first made a reference mark on the back of the sprocket and the cam hub, so I knew where I was starting. Loosened the bolts and moved the cam to full travel in both directions. Made marks at the end of travel. My original mark was dead center between the outer marks, which indicates to me that my car never did have the intake cam tweak for rough idle I've read about. I made 2 more marks midway between end of travel and the original mark. I've read that the sprocket gives +/- 4 degrees of adjustment. If that's true, then I now had marks every 2 degrees. I decided to advance the cam to my first 2 degree mark.
Results
First minute: It fired right up and settled into a definite lope, like I had just put a street/strip cam in it. After 20 seconds or so, it smoothed out (possibly DME had to relearn a bit). I revved it a few times and immediately noticed a bit more intake noise (airbox is modified similar to the "fogged" idea).
Road test: I let it warm up a bit and went for a drive. My first impression was that it seemed peppier in the midrange. Intake noise is definitely more pronounced (probably won't notice it if your airbox is stock). First time through the gears seemed ok. After getting out of traffic, I was able to explore the power delivery at different RPM (manual trans makes that easy). Torque below 2k seems to have suffered a bit, but not unmanageably so, especially with a manual. 2-3k seems about the same and above 3k feels stronger. I haven't had a chance to wind it out yet, so not sure what 5k plus feels like yet, but I expect to feel gains similar to the midrange.
I'm not expecting 20hp out of this, but if I can get 5, it'll be worth the little bit of extra time. When I have a chance to get it out on the interstate, I'll report back.
What I did
After accessing the cams, I first made a reference mark on the back of the sprocket and the cam hub, so I knew where I was starting. Loosened the bolts and moved the cam to full travel in both directions. Made marks at the end of travel. My original mark was dead center between the outer marks, which indicates to me that my car never did have the intake cam tweak for rough idle I've read about. I made 2 more marks midway between end of travel and the original mark. I've read that the sprocket gives +/- 4 degrees of adjustment. If that's true, then I now had marks every 2 degrees. I decided to advance the cam to my first 2 degree mark.
Results
First minute: It fired right up and settled into a definite lope, like I had just put a street/strip cam in it. After 20 seconds or so, it smoothed out (possibly DME had to relearn a bit). I revved it a few times and immediately noticed a bit more intake noise (airbox is modified similar to the "fogged" idea).
Road test: I let it warm up a bit and went for a drive. My first impression was that it seemed peppier in the midrange. Intake noise is definitely more pronounced (probably won't notice it if your airbox is stock). First time through the gears seemed ok. After getting out of traffic, I was able to explore the power delivery at different RPM (manual trans makes that easy). Torque below 2k seems to have suffered a bit, but not unmanageably so, especially with a manual. 2-3k seems about the same and above 3k feels stronger. I haven't had a chance to wind it out yet, so not sure what 5k plus feels like yet, but I expect to feel gains similar to the midrange.
I'm not expecting 20hp out of this, but if I can get 5, it'll be worth the little bit of extra time. When I have a chance to get it out on the interstate, I'll report back.