Camshafts

[racer_x]

Anybody know for sure if the 1.5/1.6 NA solid or hydraulic cams are any different than the turbo cams?

Quoting from the SAE white paper,

The intake valve has a maximum valve lift of 8 mm. Intake opening is at 5 degrees aTDC and intake closing at 14 degrees aBDC where both timings are rated at 1 mm of camlift. The maximum valve lift of the exhaust valve is 9mm, with opening and closing at 27 degrees bBDC and ~ degrees bTDC respectively. Intake valve clearance is 0.2 to 0.3 mm, and exhaust valve clearance is 0.4 to 0.5 mm. All these geometrical dimensions are identical with that of the 4-cylinder naturally aspirated Diesel engine.

(my emphasis added.)

The whole white paper is on Roger Brown's site at http://www.4crawler.com/Diesel/SAE/vwtdsae.shtml. If you are interested in these engines, it got lots of info.

[caddy]

solid and hydrolic are different but same for na and turbo ( in europe!)

[JimK]

I know that Piers at Piers Diesel Res. takes a stock camshaft and regrinds the camshaft for the cummins in the Dodge diesel trucks and the results is faster spool up, reduced egts, a little better mileage. They also offer new and billet camshafts. I would suspect that he could also do that to a vw camshaft.  good luck JimK

[malone]

I know that Piers at Piers Diesel Res. takes a stock camshaft and regrinds the camshaft for the cummins in the Dodge diesel trucks and the results is faster spool up, reduced egts, a little better mileage. They also offer new and billet camshafts. I would suspect that he could also do that to a vw camshaft.  good luck JimK

If I recall correctly, Piers take cams to Colt Cams for the regrind. That's where I got my VW TDI cam done and my TD cam might be sent there as well.

[TDIMeister]

How does it work?

[VWRacer]

Most interesting info and a great discussion...thanks!

Mike, I missed your "naysayer" post on the other thread, but I don't understand why you think cams can't help the performance of a diesel, or is that not what you meant?

On the old forum there is a thread where a guy from the UK talks about fitting a solid lifter (83-84 JH?) GTI cam to his 1.6TD. He was so impressed with the increased performance that he had Piper Cams grind him a custom version that is even better. Looking at the table on the link I am guessing that there is little or no overlap with a solid GTI cam, but with its greater duration and (maybe) lift it can flow more air at higher RPMs. I can't access that forum from work, but will try to find it later if someone doesn't beat me to it.  :mrgreen:

Sorry, I'm not believing it. I tried a J cam (solid lifter from a JH engine) in my diesel head once. Valves hit pistons when I turned the crank by hand. Unless this guy machined something for more clearance, there's no way he actually ran the engine with a 049J cam installed.

IIRC, The J cam (vw part number 049 109 101J) has about 7 degrees with both valves closed. The diesel cam has around 11 degees with both valves closed. The J cam has 0.369" of lift (both intake and exhaust), and the diesel has 0.315" of lift on the intake valves and 0.354" of lift on the exhaust valves. Intake valve clearance is the big limiting factor. On the diesel with the stock cam, the valves come within 0.2mm to 0.3mm (0.008"-0.012") of the piston.

You might be able to grind the diesel intake opening profile and exhaust closing profile onto the J cam and get something that works and delivers better performance than the stock diesel cam. You might also be able to cut some valve relief into the pistons for valve clearance, but again, you would have to be careful not to remove any moer than necessary for valve clearance, and that might lower compression more than you want (see chart above).

The J cam does have enough duration to run optimum volumetric efficiency somewhere around 4500-5000 RPM's. For duration, it's just about right for the diesel engines. The problem is valve to piston clearance with that cam installed.

Sorry I took so long to reply, but I've been on the road racing with Champcar's Totyota-Atlantics.

Rest assured that I don't 'believe' it either. I am passing along the info-lead as part of a conversation. As noted by QuickTD, Simon clearanced the pistons (and head) to make it work. FWIW, Simon is very credible in UK TD performance circles, so if something I wrote about him seems unlikely, the fault is probably mine...

Edit: I was going to add that I have both "G" grind and a Callaway "C" turbo grind cams. Might be fun to play with those on a high revver!

[JimK]

I know that Piers at Piers Diesel Res. takes a stock camshaft and regrinds the camshaft for the cummins in the Dodge diesel trucks and the results is faster spool up, reduced egts, a little better mileage. They also offer new and billet camshafts. I would suspect that he could also do that to a vw camshaft.  good luck JimK

If I recall correctly, Piers take cams to Colt Cams for the regrind. That's where I got my VW TDI cam done and my TD cam might be sent there as well.

Small world, I had heard that also, Mark, Piers, Bob and the rest of the guys there are very smart guys, good luck JimK

[steve]

I didn't see any comment regarding the need for a vaccume pump on the diesel.  I thought I'd add the reason has nothing to do with the cam.  It's because gas cars have a throttle (butterfly valve) and the diesel has no flow restriction like that to make vaccume.

[gigaz2]

Anybody know for sure if the 1.5/1.6 NA solid or hydraulic cams are any different than the turbo cams?

Quoting from the SAE white paper,

The intake valve has a maximum valve lift of 8 mm. Intake opening is at 5 degrees aTDC and intake closing at 14 degrees aBDC where both timings are rated at 1 mm of camlift. The maximum valve lift of the exhaust valve is 9mm, with opening and closing at 27 degrees bBDC and ~ degrees bTDC respectively. Intake valve clearance is 0.2 to 0.3 mm, and exhaust valve clearance is 0.4 to 0.5 mm. All these geometrical dimensions are identical with that of the 4-cylinder naturally aspirated Diesel engine.

(my emphasis added.)

The whole white paper is on Roger Brown's site at http://www.4crawler.com/Diesel/SAE/vwtdsae.shtml. If you are interested in these engines, it got lots of info.

remember that in the SAE paper they are still using mechanical lifters.
so, NA and TD are the same as long as they are mechanical.

I still haven't seen the 1.6 hydraulic cam's specs anywhere

[TDIMeister]

I've analysed cam timings of some OEM 8V gasser cams and have found them to be very close to what several aftermarket vendors have been offering as performance upgrade cams.  I have also run engine simulations and found gains running these cams over the OE Diesel units (simulations were done with TDI as baseline, but it applies mostly the same for IDI).

While not plug-and-play, you could install cams with P/Ns 026 101 109A (from A2 GX/HT), 026 101 109G (from A2 RD/PF), 048 101 109D (from A3 ABA), 050 101 109A (all A4 2.0 8V).  These are all hydraulic cams.  You may need to increase the piston-valve clearance by machining the valve pockets a bit deeper.  Best to try fitting the cam in the head, remove all the valves except for one cylinder, place Plastigages on the piston with the remaining valves underneath each valve, bolt everything back together, turn the engine by hand, check the Plastigages and deepen the pockets as necessary.  You will likely also need to machine the lifter bosses because the lobes will hit them otherwise.

Edit: if nothing else, each of the abovementioned cams give a big bump in lift.  The least of them gives 10mm lift (.393") up to 10.6mm (.417").

[TDIMeister]

Each of the above gasser cams closes the intake valves 16-18 degrees later than the AAZ cam.  This will drop the dynamic compression ratio by about 1 full point compared to the AAZ cam.  Cold start will likely suffer, but this can be dealt with pretty easily by tricking the glow plug to come on at a higher temperature threshold.

The ABA cam has close to the same overlap timings as the AAZ cam so there should not be any need for valve-piston clearancing (but may still need lifter boss clearancing).

[gigaz2]

I was able to get a 048 101 109D and it doesn't seem to need any more clearance on my hydraulic head, wait, going to the shed to take pictures

TDImeister: do you have the hydraulic 1.6 cam specs?

[gigaz2]

hydraulic 048D cam on hydraulic 1.6TD head
exhaust:

intake:



stock 068L grind intake:


PS: just realized that when talking about clearance in the lifter bosses everybody refers to the TDI heads, so I might get lucky on this one

[TDIMeister]

Keep us posted when you get the 048D cam installed and running!!! Is this going into a 1.6TD?  A long runner intake manifold and some head work would complement the cam very nicely! Sorry, I don't have any 1.6(T)D hydraulic specs.

[gigaz2]

I have a usable hydraulic 1.6 head for that build, planning a 1.9TD head with Renault prechambers, but that won't be in the near future.

the only thing that is keeping me from using that cam is the pulley, a hybrid adjustable on has to be built from the gasser and the diesel ones.

Its a shame we don't know the hyd 1.6 cam specs, I can measure it, but that isn't as precise as having VW telling what it is (or should be)