ALH Camshaft re-grinding ??

I know there are aftermarket Cams available (Colt, etc.) for our TDIs. However, has anyone had an ALH or any other TDI cam, re-ground? If so, where, who and were you satisfied with the results (performance)?

I know with some cams there's not enough metal left to make much difference with a re-grind! So, it may be that these cams cannot be re-ground.

To be straight-up, I have no clue what the lift, duration, overlap, etc., might be on the ALH Cam. I guess that info is in the Bentley... just need to look.

Thoughts, comments...

In a nut shell, as long as the cam is in fair shape, it can be reground to make MAX lift. This is done by reducing the base circle. The lifters are hydraulic, that means that the lifter makes up the difference effectively making the cam lobe longer than it was before.

Some builders have machined out the base of where the lifters sit to gain more depth on the valve and in doing so you can use more shim to even get more. You’re getting into very specific head work here and I would not do this myself. Leave this type of head work to a Pro.
You can get undercut valves, port and polish, gasket match the ports, put larger valves in, set the seat back a hair, more lift, cam profile, 2x helper springs, titanium spring retainers, etc.

The head on a TDI is like a graphics card on a gaming PC. It should be the one item of the engine that costs the most for one part. This is where you spend big F***ing bucks to get the most you can. More air means more fuel

Colt cam is contracted here in the states and has put a ban on the sale on another cam manufacture. You’re pretty much limited to Kerma for colt brand. I am not 100% sure on the details on this issue but I remember reading about it passing by. Don’t take my word on the availability but that’s what I remember and I’m too lazy to go find out again.

I am by no means well versed in cams but....I thought reground cams, because of the base circle being reduced, creats a faster/steeper incline thus causing increased wear....or something like that.

For a relativly low cost savings I would stick with new whether oem or aftermarket.

I'm sure Franko6 would have something to say on this topic.

Um no., yes in principle I would make it have a shorter radius but who cares and it would not make beans worth of more wear. We rev to up to 4500 and on performance cars usually like 6K. Some Hondas I think have a smaller cam and rev up to 8K. Heck F1 cams must be really small because the 12 tiny piston engines rev up to 12K or higher. Point here is that a reduced base would not change the wear. We are talking like 0.040" on the cam lobe. In most cases, a regrind does not take down any more than you need to on the end of the cam lobe but just enough to make it new again or more duration. The base is what changes the lift.

Big base circle or small the tip has to be bigger by x amount to get x lift. I can't see that making a difference. The lifters might not have enough internal travel to make up for the reduced base.

For a stage 2 colt cam, yes there is plenty to work with. this is how it works. For anything else you need a custom made cam or a New cam with a profile grind. you would be surprised how much the lifters cam make up. You can reduce the base by more than the lifters can handle by using a shim on top of the spring retainer and valve.
Colt 2 cam is not so much about the lift as the regrind restores it back and then adds a tiny bit, but what it does do is increase the duration the valve is open.

Mongler98, yep, I'm aware of where the metal has to come off to increase lift. And, that's what I am looking for......... maybe another 0.010 or slightly below whatever maximum might be. I'd rather leave the duration alone.

I called the local machine shop in my area. They've been doing automotive/truck crankshafts, head work, performance cams, etc., for years... seems the shop may be in the third generation of the family. Anyway, they do not have the charts/guide plates (whatever the term is) for any overhead cam. Bottom line, they only do cam re-grinds for V-8 engines.

So, I sent out a request to two shops that I found on-line. One ask me to fill out their on-line form which ask questions that I cannot answer. I've not heard back from the other source.

Well, with the reduced sulfur fuel and EGR delete, the Intake system should stay clean and as smooth as the polish. An improved Intake, polished ports and a cam with a little more lift should wake-up a sleepy engine, especially with a few other mods (injectors, 11mm IP, VNT 17 Turbo, specific tune, etc.).

Word of advice Andy, when it comes to this stuff for head work on a TDI, go to one of the trusted builders here for the work. Unless your guy does this stuff to TDI's don’t bother.
A port is more than just making it smooth. When putting out higher EGT's you want the smoothest exhaust port possible. Almost mirror like, at least to a 320 grit polish. The reason for this is that high spots get hotter faster and cool faster; this can lead to cracking or burn out issues. A pit from casting is not a huge deal but not ideal. The reason for gasket matching the intake and the head is so there is NO turbulence. Make sure you do equal amounts. You’re not trying to make more volume in the ports but rather smoother, no cast parks, and a perfect transition for no turbulence to form. A TDI head is very difficult to port more volume in without a CNC or mad skills and LOTS of time and volumetric measuring. The head has a swirled pattern on it and if you disrupt that part its bad news blues. You can’t just deck a head and block. Evidently you must measure the block from the main journals, and the head the same way from the cam journals if you’re going to be putting big power down. This was one of my few mistakes I made years ago when I did my head job. Point is, don’t take it to any shop. Have it go to the right builder and pay up for the machine work. A port and polish you can do yourself.

Mongler98, advice well taken. My thread involves two future projects, one TDI engine and one Gasser engine.

The "turbulence" thingy is something many people are not familiar with and have no clue of the potential catastrophic dangers when cleaning Intake Manifolds.

The photos below are of a head that had the Intake removed and cleaned. But, the mechanic(s) never bothered to clean the Intake Ports in the head...



Below, results at 70 mph when a slab or two of the crud flaked off. Look at the valves to the right........ they are in trouble too.

Have you done tune and nozzles already?

The best bang for the buck is a tune . A cam change is the last thing any one should be doing.
* Tune
*down pipe upgrade
*turbo upgrade
*intake upgrade
*injector upgrade
Now you need to upgrade rods to run high Boost

CNGVW, How much difference does a larger downpipe really make? I would think the larger downpipe would only make a noticeable difference after a turbo upgrade. What am I missing ?

As the only shop racing a TDI in roadracing in the USA Chump/Lemon a 2.5 is all you need ( No Cat )


I have installed a lot of www.IDPARTS.com down pipe on stock engines my customers say they feel more pep. So yes a down pipe upgrade ( No Cat ) will let it breath better!!

AndyBees said:

I know there are aftermarket Cams available (Colt, etc.) for our TDIs. However, has anyone had an ALH or any other TDI cam, re-ground? If so, where, who and were you satisfied with the results (performance)?

I know with some cams there's not enough metal left to make much difference with a re-grind! So, it may be that these cams cannot be re-ground.

To be straight-up, I have no clue what the lift, duration, overlap, etc., might be on the ALH Cam. I guess that info is in the Bentley... just need to look.

Thoughts, comments...

Click to expand...

To get an answer, try private message to oilhammer, franko6, paramedick. It may be a good approach or not.