Camshaft specs

[Dr. Diesel]

You mean... like this?





The OBDII ABA cam we mapped out is almost identical to the stock G60 cam. I've yet to delve deeper into specifics, but  the common specs are:
G60 Intake 260 total duration 212 @.050" .400" total lift
ABAOBDII   262 total duration 210 @.050" .416" total lift
G60 exhaust 264 total duration 232 @.050" .400" total lift
ABAOBDII     262 total duration 210 @.050" .417" total lift.

It's a little bit closer to success, but still a major buzzkill, as can be seen below.





I'm actually working with a cam company now to see what can be done. Results very soon.

[truckinwagen]

could you post a graph of a stock cam-vs-piston please?

how much clearance would be needed between valve/piston?

how much would you have to cut valve pockets into the piston tops to clear an ABA cam?

(and thanks for doing all this research for all of us)

do you have any specs from the K-grind gasser cam?
its a mech cam that is supposedly the most conservative cam on the planet.

-Owen

[Dr. Diesel]

I intend to... when I get to it.   Much more pressing matters at the moment.

I don't know what a safe minimum clearance is, or how to come up with an answer beyond dispute.
In the very least, we'd need to know how much growth from heat expansion the internals could possibly undergo, as well as growth from stretch due to dynamic forces. Not to mention how much cank-to-cam phase distortion (i just made that term up to sound smart ) occurs due to  valve spring compression and extension, air charge compression and power stroke (valve train momentum preventing perfectly matched timing to the crank-- same reason for the ratcheting alternator pulley on newer TDI's), and how much timing phase distortion could possibly be experienced from the range of operable timing belt tensions. Then calculate those numbers into a worst-case scenario dimension to reflect the change in piston:valve clearance. I'm sure there's more factors in this equation, but I'm not an engineer.
To be absolutely safe, one would want to maintain minimum clearances as outlined by the OE piston projection/valve face depth/gasket thickness combinations.

As far as cutting valve reliefs in the pistons, I think that'd be somewhat detrimental. The blast ramps already cast into the pistons  are very important to proper combustion, and mucking those up with valve relief pockets could more than offset any gain from ramming a gasser cam in there.
There's a great deal of theory-- and effect, behind those blast ramps. I think there was a topic on here 5-ish years ago discussing it.

I've considered all this for some time now, and have personally come to the conclusion that a custom-made diesel specific performance camshaft is the way to go. I'm well on the way to achieving that at this point. Having said that, if anyone else wanted to try installing a gas cam directly, I'm interested in hearing about it and seeing pics of the results.  

[Runt]

There is a knowledgeable, competent and well respected cam grinder in the lower mainland.  (At least, the last time I talked to them, it was ~3 years ago.)  I was wondering myself what it would take to just bring the little bit near overlap down to provide adequate clearance myself.  I'd have thought (perhaps wrongly) that flycutting the valve recesses 10-20 thou wouldn't be a big deal, but perhaps more thought is needed on my part.  I also haven't got the actual numbers to make the determination of what clearancing would actually be neccesary. Dr. D., BYM has offered the file with the cam data, is there any chance you'd share your file with the piston data?  Any chance you have the same data for a 1.6?  Is this series calculated, or actually measured?  If measured, do you know the piston protrusion from the cylinder it was measured on?  I could easily do a little manip within the sheet to show what sort of clearance would actually be present/required with each cam.  I agree that any change that puts you closer than stock during overlap is probably unwise, although depending on what the factory clearance actually is, I might be tempted to run a TINY bit closer if I thought there would be a significant benefit.  Anyways, with your data, I could easily figure out and show how much tighter each cam would be, and then repost that here.
Before I forget, Thank You to both Dr.D. and BYM for getting and sharing this information in the first place.

[Dr. Diesel]

I'd have thought (perhaps wrongly) that flycutting the valve recesses 10-20 thou wouldn't be a big deal,

If you mean deepening the indentations already on the pistons, they aren't valve recesses, they're blast ramps (our term anyway, maybe not a diesel engineers' term), and fiddling with them will alter, perhaps radically, the way the engine runs.
Otherwise, if you mean to simply cut recesses into the piston, the same thing applies, as it would meddle with the blast ramps.
Someone could try it... Maybe on an old engine, that wouldn't break anyone's heart if it didn't work and was relegated to scrap.
I'd suggest holding off for a bit before pouring time and money into something unnecessary. Performance cams are on the horizon. I too, have hooked up with a good cam grinder. 
When I get a chance, i'll put out the data for those interested.

[truckinwagen]

I have a spare car with a motor in it(mech lifters) that I would not feel bad about experimenting with.

I would be happy to try out some things in the fall, including radical cams and cutting valve pockets in the pistons.

-Owen

[Dr. Diesel]

That's good! Just stick with the scientfic method and do several identical dyno tests before and after and average the results. Change one variable at a time, and document each thoroughly. Without that kind of accuracy, it's speculation. That blastramp profile has a big say in how the engine's power curve looks like. Who knows? Maybe it'll work even better.  
One small issue is hydraulic cams have a much smaller base circle than  solid cams. There isn't an OE solid lifter shim thick enough to achieve correct valve lash. Lash caps on the valves might work.
With the correct valve lash achieved, the gasser hydraulic cam's profile will be significantly less in a solid lifter engine than when measured as a hydraulic cam, remember.
The other unknown at this point is, will hydraulic lifters pump up enough to run a gasser cam in a diesel head. Diesel base circle is bigger than gas too. According to a local valvetrain overhaul shop, there are about 5 different styles of VW hydraulic lifter. Maybe one of the thicker gasser lifters would drop into the diesel head, oil hole hopefully lining up with the bore supply gallery, to take up the extra clearance no problem. Or, maybe not. In any case, the shop said you don't want to run a hydro lifter at either full max extension or full compression. Seems a lot simpler just to make a proper diesel performance cam.

[truckinwagen]

unfortunately there is no dyno that will let a diesel in locally, but accurate 0-60 times could be gathered(I have a lead on a speedo built for a motorcycle that has a built in stopwatch to accurately measure)

as for the lifter thing, I was under the impression that there was only one part number for mk2-3 hydro lifters(gas and diesel)

I have run hydro cams in a mech head before with shims under the buckets(lash caps) with success, so I dont see any reason that would not work. but as you say there is no chance of a mech cam working in a hydro head(as the lifters don't like to be depressed that far) so even if the K-grind was a good fit, it would only work in mech heads.

a performance cam built just for a diesel would be great, but unless the cost can be brought down to what gasser performance cams cost($150-200) I would not be very interested. part of the reason I have been playing around with the idea of a gasser cam, is that they can be had for cheap(especially the stock ones that would be conservative enough to work) and the little bit of fabrication it may take, is what I own a VW for in the first place.

-Owen

[Kudagra]

One thing that wouldnt be bad on an aftermarket came was if we could get the taper like a 16v so we could run adjustable cam sprockets. So just anyone can adjust their timing so far out of specs they can bend valves.

[Dr. Diesel]

Hm. They don't like the diesel smoke? Why not let a diesel in?
I wonder if it's even remotely practical to measure an engine's deflection on it's mounts as a way to indicate torque. Probably not, nvm.
A Gtech or similar would be helpful, for peak HP, at least, as well as 0-60 and Q-mile times.
I haven't investigated the differences in lifters since hearing that from the shop. I do know that G60 lifters are different than diesel, visually, anyway. That isn't to say that they wouldn't happily interchange. Apparently MkIV lifters are different again. Perhaps they meant of all years and engines of VW hydro lifters, there are several different models.

I'll just come out and say it.

I'm on the verge of releasing a drop-in hydraulic performance cam, the price of which I think everyone will find quite agreeable.

More soon.

[theman53]

Hm. They don't like the diesel smoke? Why not let a diesel in?
I wonder if it's even remotely practical to measure an engine's deflection on it's mounts as a way to indicate torque. Probably not, nvm.
A Gtech or similar would be helpful, for peak HP, at least, as well as 0-60 and Q-mile times.
I haven't investigated the differences in lifters since hearing that from the shop. I do know that G60 lifters are different than diesel, visually, anyway. That isn't to say that they wouldn't happily interchange. Apparently MkIV lifters are different again. Perhaps they meant of all years and engines of VW hydro lifters, there are several different models.

I'll just come out an say it.

I'm on the verge of releasing a drop-in hydraulic performance cam, the price of which I think everyone will find quite agreeable.

You meant mechanical right?

More soon.

[Dr. Diesel]

no, i meant hydraulic. Which I suppose means some people (solid lifter people) won't necessarily find the price agreeable or otherwise. 
I hope to have a chance to work on a solid cam grind, but not in the immediate future plans at this time.

[theman53]

Could we solid lifter guys take up the slack with shims or are we just out?

[Dr. Diesel]

hm.
you know what... When I get a chance, I'll set this cam up in a solid lifter engine with the correct clearances and see what kind of a plot it makes. My gut feeling is that the performance improvement won't be worth the cost, but we'll see.
Keep in mind that you'll have to put some sort of a spacer between the valve stem tip and the underside of the mechanical lifter. Either that, or have custom thickness lifter shims made. I'd suggest the former, as proper valve lash caps likely already exist from a valve company like Manley or the like, and having a good job done with the proper materials for lifter shims would likely prove frustrating.

[truckinwagen]

I made lash caps by cutting circles out of appropriate thickness shim stock and putting it under the lifter bucket, worked fine.

this performance cam, are you willing to discuss what it is?
more lift? more duration? etc...?

if the stock cams are really close to the pistons already, what have you changed to make the performance cam, and how much has it been changed?

theoretically how much more air(in %) would it flow? (area under the curve)?

sorry to batter you with questions, but this is a big deal!

-Owen