I have an 82 928 4.5, the camshaft snapped a couple of weeks ago!!! We think this was due the camshaft wheel being loose and thus leaving enough play to snap the shaft. Fingers crossed I should only need to replace the shaft (and cam belt) as my engine is a non-interference engine. I was thinking of replacing both camshafts and boxes with those from a 4.7 or S 928 of the same year, this way I would gain a few extra horses. Has anyone done this or is this not possible?

 

How would you gain more power from just replacing the cams?? You still have a 4.5l motor. Are the cam profiles different between the 4.5 and the 4.7? Unless you are talking Euro stuff that is.

 

Rich,
If your 4.5 has 10:1 compression ratio (Euro, right? Bournemouth?), I'd say the 4.7S cams would be a step in the right direction. It would be interesting to see how the 4.5 setup responds. Without the rest of the Euro S top end or 45mm intake valves, I bet you don't get near the top end HP. But I wonder how it would do up to let's say 5.5k rpm? I wonder what affect the smaller intake runners would have on charge velocity/torque production. I wonder if you would get BETTER low-end torque numbers compared to the Euro S complete setup?

Need to clay the valve piston clearance to ensure that you do not need to provide more valve relief (and I do not mean to preserve the non interference geometry). Must pull the heads to check.

 

Rich,I put the cams from an 84 euro in my 82 along with headers 3" exhaust and k+n filter and rear wheel h.p. went from 165 to 240 on dyno. The 82 has the worst cam profile of all years. You could put the cams in out of a 79 us car and make more h.p. Dennis

 

Rich, from all info I have been exposed to, '78 and '79 engines were the only non-interference units. It will be interesting to hear if your engine is undamaged.

 

Interesting, I have heard of this form of camshaft failure before. I often wondered if my turbocharged 928 could benefit from a different camshaft profile?

The problem is I can not run too much overlap with the turbochargers, because as exhaust back pressure goes up, you get reversion and the heads simply stop flowing.

My understanding is that for turbocharging, you want a mild, minimal overlap cam. Hey, maybe I should get a few of those ****ty 82 camshafts. Jeez, I hope mine don't ever snap, because I think the 81 is an interference engine.

 

After reading your reply's maybe I should have got some earlier cams! I wish I had the luxury of having the car dynode before to see what difference it makes on paper. As I haven’t driven the 928 for a while it’s going to seem fast compared to the VW I’ve been driving on a daily basis.

Anyway as all this wasn’t planned if the car runs o.k and I get some extra power it’s a bonus and I will have had a very lucky escape of what I thought was a dead engine. I’ve got both the 4.7 cams and boxes on the car now and tomorrow I’ll put the new belt and auxiliaries back together then it’s crunch time! Keep you all posted!!

 

from what I have been told the 81 row and 82 row are non interference