Well how do you do it?

 

He's talking about changing the camshaft timing by redrilling the locating notch in the spocket. The thing to keep in mind here, is that you may gain 10hp at high rpm, but you will decrease the available torque in the low range (ie. taking off from stop light) to the point where driving around town becomes cumbersome. This is really only a good thing to do if your building a race engine, with race clutch (because you'll wear yours out faster by slipping it to get the car to move) and a custom cam and valvetrain. Then you would install an adjustable cam gear to dial it in.
This cam adjustment is viable, don't get me wrong, but makes it difficult to drive in the "normal" rpm range. I did this on my 318, and changed it back after a few month because the gain at the top was not worth the HUGE sacrifice down low. For a track car, this would be a good idea, but use an adjustable gear so you know excactly what your changing.
--Dan

 

Thank you Dan for the "voice of reason"

 

OHH! this all makes sense now ^__^

would this be the same as the adjustable aftermarket cam sprockets available for other cars?

 

I feel like I have lost no power at any rpm range, in fact, the DSC is still kicking in to stop wheel spin at take off- and this is with a cvt! I have found the right index for the stock cam, told you exactly how to duplicate my great result(500 miles after) in an effort to help the others who own under powered Minis, but without having to buy the difference in price of an S model to get good performance out of it. If you refuse to believe you can have your cake and eat it too, fine. I will continue to enjoy my continually faster Mini, while you nay sayers spend money. I'm just trying to help. Think about it- what would I gain by posting bad and erroneous tips and tricks? I still consider you folks "Mini driving friends", since no 2 people are alike, their opinions will differ. I don't know all there is to know about the '02-'06 Minis, but I will continue to learn and offer advice, though I may be shot down by vendors and "experts". My car will be fast, but without a vendor sticker one. -Jeffy.

 

I don't have a horse in this particular race, however I have used modified cam timing once or twice in the past to 'tune' a power band. And my experience was the same as Dan's. If I may paraphrase, by changing the cam timing you can move the power band up or down a bit at the expense of power production elsewhere.

In Jeffy's case, he's got a CVT. Makes a big difference over a manual transmission. The theoritical point of a CVT is to keep the engine in the most effective rpm range for the immediate task at hand. So if you're accellerating from a stop, the tranny will allow the engine to run up to somewhere near the peak of the torque curve and the car will launch. With a manual tranny, you'll either burn up the clutch or the tires trying to do that. A manual tranny needs to have a wider torque curve than a CVT can get away with.

So in the future, who knows? We might all end up with some sort of advanced CVT device hooked up to engines with peaky power curves like old 2 stroke dirt bikes. Single speed engines with accelleration rates and speed dialled in via the transmission.

Or big, two cylinder diesels with earth-mover torque running at three figure rpms with twenty-speed trannies.

 

Does anyone know how much one of these gears are, I would be willing to test this out on my car but I would like it be reverseable.

 

I was thinking the same thing.. I know HKS makes one for a 1.5 SOHC crx. its around 120. I imagine it would be close

 

Spunky has an interesting point. I haven't noticed my rpm's changed from before, but I'll start watching for it, and report the findings. That is about one adaptive computer, isn't it? One time I inadvertently left a vacuum hose off, and started the car. It surged at idle for a couple of minutes while I didn't find the disconnected hose, but the computer compensated and the idle stabilized! The next day I had another look and found the hose off, reconnected it, and the computer re-adapted while I stood there. I don't want anyone to experience any power lag over my mod and recommendation, so I'll keep an eye on my tach the next couple of days. I'm impressed with Spunky's observation. -Jeffy.

 

Looks like they've had one in the UK for a while - though I think it's for the S.
http://www.gtt.uk.com/parts2.asp



GTT ADJUSTABLE VERNIER CAM SPROCKET

 

Threads merged so all the content is in one place. The newer title will stay with the thread since that was apparently why the latest thread was created.

 

I have been observing the tachometer for evidence that my cvt transmission is compensating for a lack of low rpm power due to retarding the cam timing to increase high rpm performance. It seems that I have happened upon the right cam timing for the engine/car combination, no compromise in performance of any kind. I feel that the car drives as before the mod with the only exception being a boost in power at high rpms, which aids in passing. The car is happy and so am I. I only wish I could tell you in degrees how much to retard the cam, but someone with a degreed cam sprocket could duplicate the position by comparing a modified as described stock sprocket with the degreed one. It's all good. It's up to you if you will do it with yours. Have fun, reguardless. -Jeffy.

 

GOOD thread everyone!!