acidxrain
20+ Year Contributor
- 32
- 0
- Oct 20, 2002
My friend is upgrading the cams on his evo VIII so he'll be getting rid of the stockers. Would the stock evo cams be a good upgrade for my car (97 gsx)?
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What is the status?
Bottom line is they work.
Im confused. You just listed like 3 things you still needed to do, so how can you conclude "They Work"? Im all for trying new things and making power on a budget but this just seems like a huge pita for minimal gains at best.
This thread was about whether they could be made to work. Yes is the answer.
Not yet, it isn't.
Let us know when (if) they do.
They won't.
Hm. An atheist accused of having God's voice. Odd conundrum. I suspect a vortex of logic.
Now that you've put into the ante, here's the deal: think of yourself as a cam rocker roller. Sit in the roller, just like you're sitting in a roller-coaster car. Stretching out in front of you is the track, and ahead of you is a hill that you'll be going up and over. Oh, and the ride will be very, very fast. Since this isn't a Ducati ride, nor a Mercedes M198 engine, we'll be taking the retaining wheels off the bottoms of the trucks, counting only on gravity (the valve springs) to keep us down on the track.
As we approach the hill, which turns out to be much more steep that it looked like, the rise into the actual climb is tapered some so that our spines aren't speared upward into our brain cases (although most still have enough room in there that damage would be minimal). Kind of like the way a driveway's curb is cut down to near street-level, to save you denting your rims every time you head toward the garage. In the case of DSM valve assemblies, the acceleration ramp is made so that it gives the hydraulic lifter a chance to adjust whatever clearance may be in the valve actuation system, and to keep from slamming the rocker bearings and valve stem tip.
The acceleration away from the ground (cam circle center) keeps increasing as we near the crest of the hill. However, at the summit, we can't be going so fast that we fly off the track (valve float), and the track is carefully designed to keep us just at the edge of flying-off.
As we reach zero gravity, the track starts to fall out from under us again. And again, the profile of the track is arranged so that the wheels never come free of the rails (and the valves and followers don't float). It's not the same shape as the up-side of the ride was, but we're falling very quickly (the valve is closing). But we don't want to drive off the curb and land hard, and we don't want the valves to hammer-out the seats. So there's another nice, smooth ramp to bring us back to ground level (cam circle base). This also is designed so that the fancy suspension under our roller-coaster car (hydraulic lifter) doesn't bounce nor go soft. If the roller-coaster was a hardtail (solid lifters) it would have a different shape from the one we're on. And oh, looky, another hill already. All this crap has to go on just the same, every time, up to seventy times every second. No jostling the riders, no "getting air", no driving up over nor off the edge of the curb. Just nice and smooth, up and down, fully controlled against gravity (valve spring pressure) every last time.
So, what happens if we pick the coaster car up, turn it around and ride the track backward? Oh, we'll still go up and down. The summit will be a bit iffy, because all the careful sculpturing that made sure we'd stay against the rails in the other direction is now tending to bump us clear of the rails at the summit, and the acceleration and deceleration ramps aren't working with this suspension. The lifters are getting pumped-up and bled-down wrong, we're getting air at the peak, and everyone's starting to throw up.

defiant said:Not yet, it isn't.
Let us know when (if) they do.
They won't.