adjustable cam pulley group buy?

[sambb]

That's it. If he doesn't get these things into his engine pre-kids then he never will. He's got to move on this now.

[sambb]

found another: 1.8T Nockenwellenrad verstellbar BAR-TEK(R) | BAR-TEK(R) Motorsport
ill get a quote

[simon k]

Personally I'm not sure that I would bother with adjusting the cam timing on a single cam pulley/sprocket turbo engine, I've not found it to be good value for money. In general on a twin cam turbo engine we advance the inlet, around 4 degrees is common, and retard the exhaust, around 2 degrees is about the limit before the exhaust valves get too friendly with the pistons. The earlier opening inlet and later closing exhaust gives a faster boost build that is quite worthwhile so we get more power at lower RPM, whilst the max power stays around the same so we end up with a slightly more evenly spread power curve ie; not so peaky.

Accomplishing that with a single cam timing adjustment is of course not possible, so the incremental benefit is much smaller. Commonly similar to adding 0.5 psi of boost. Obviously when everything else is done and we want/need some more then maybe adj cam timing get a mention.

Cheers
Gary

how about an offset key or adjustable gear on the belt end of the cam, and an offset key going the other direction at the chain end to correct it?

IE since the belt is on the exhaust cam, retard that by 2° (which also retards the inlet 2°) so assuming you wanted to advance the inlet 4° you'd put in a 6° offset key

workable?

[sambb]

if its possible it makes sense. I was thinking more along the lines of just doing 3 power runs and logging it with nefmoto to see which gave the best MAF curve. I have no idea how the inlet cam is keyed into its sprocket. The inlet cam has the cam position sensor on it. I don't know how many degrees of freedom its allowed (how far out of the expected window vs the crank signal) it can go before the ECU has a wobbly. Gav did mention that the ECU is always watching with cam timing changes. It could be that beyond a certain threshold you need to set the cams back to zero and just be going for a different grind - nor sure at the moment.

[sambb]

I looked for the BT facebook thread on cam pulleys. I went back a few months but couldn't find it. Based on price and reputation I'd pretty much made up my mind and it turns out my mate with a Clio wants one too. So since Cat Cams do them for both our cars, the Cat Cams one it will be:
CTVW008 adjustable cam wheel details | CAT CAMS performance camshafts

[rgvlee]

Search for "cam pulley" on the group.
Basically was much of muchness. I'd probably go cat anyway.

[simon k]

if its possible it makes sense. I was thinking more along the lines of just doing 3 power runs and logging it with nefmoto to see which gave the best MAF curve. I have no idea how the inlet cam is keyed into its sprocket. The inlet cam has the cam position sensor on it. I don't know how many degrees of freedom its allowed (how far out of the expected window vs the crank signal) it can go before the ECU has a wobbly. Gav did mention that the ECU is always watching with cam timing changes. It could be that beyond a certain threshold you need to set the cams back to zero and just be going for a different grind - nor sure at the moment.

it's irrelevant to the discussion, but the ECU shouldn't care - it's still only 2° of advance on the inlet cam... the adjustable pulley has lots more than that on it...

[sambb]

The ECU does watch though, I think to monitor the VVT. On my other engine I was getting " inlet cam not retarded in time" or something like that errors which was probably the VVT system needing an overhaul. The only way it could know that is by comparing the inlet cams pulse/position (exhaust not monitored) versus the cranks? So if its new zero position is say 2 degrees advanced then it stands to reason that it might not reach retard setpoints in time and maybe generate that same code? Possible but I really don't know

[Sydneykid]

The ECU does watch though, I think to monitor the VVT. On my other engine I was getting " inlet cam not retarded in time" or something like that errors which was probably the VVT system needing an overhaul. The only way it could know that is by comparing the inlet cams pulse/position (exhaust not monitored) versus the cranks? So if its new zero position is say 2 degrees advanced then it stands to reason that it might not reach retard setpoints in time and maybe generate that same code? Possible but I really don't know

It depends on how the ECU interrelates the triggers for the camshaft angles (inlet + exhaust) compared to the crankshaft angle. i'm no VW ECU expert but most tolerate a couple of degrees variation to allow for chain/belt, guide and tensioner wear. Keeping in mind that 1 camshaft degree = 2 crankshaft degrees.

Cheers
Gary

[sambb]

If it was an issue you could theoretically offset key the cam pulse wheel back to the standard position? I assume that the independent cam conversion shown earlier has some way to deal with that.

[simon k]

if it's worth doing, I'm sure it's a case of solving the problem if it arises - looks like the cam sensor is just 4 slots in a pressed steel bucket. It's probably on its own keyway

[sambb]

yeah it us from memory.

[rgvlee]

Anyway price up the cat cams gear and let us know. Ive probably got a timing belt to do at some point and i like wasting my money on things i dont need, this fits the bill perfectly