Toxcheap

I started my last reply stating I have different opinions, that's all. Mine are based on actually experiences. Have you run an adjustable cam sprocket on a 10 valve, on a cone track and 1/4 mile? And what am I to be careful about, changing the cam timing? It's common knowledge if you change the cam timing on a single overhead cam set up, timing of the intake and exhaust both change no kidding they're connected. I don't think you read my reply correctly. I thought I was clear: changes to the cam timing move your slope up and down the rpm range, but do not add or subtract power. I think your confused with changing intake to exhaust durations. Where retarding the exhaust cam fattens up the torque band. This is the reason our asymmetrical 268/260 kicks ***.

As for mechanical lifters causing knock anomalies it's well documented as well, that's why VW Motorsport and Audi cam out with a special bushing that mounts between the block and mic, filtering out the noise of the lifters.

Not saying your wrong about anything, just saying my opinions and experiences are different.

HTH
TOX

Adam Mowafy

Could you guys tell me what the stock cams lift is? I am not going to change my cam just yet. No sense in putting it in now since winter is almost here. But in the spring time when I am satisfied with the k24 and 1.8, I probably will want to take the next step into a hotter cam. I have heard so many opinions as to how the 272 affects the cars overall performance. I think SJM told me once to go with 258i/260e? cant remember if thats right or not? I do not want to lose low end tourque. top speed means **** to me becuse of where I live and also because of how many points I have I am looking for better acceleration. so if there is a cam that would provide good power across the rpm band without sacrificing low end tourque than please state your opinions. Now remembert I said opinions which means you guys dont have to agree ok

Thanks for the great insight as for timing adjusting and cams (both of you).

Adam.

shortyq

Toxcheap:
Cam timing on a SOHC does affect power, you are changing compression ratio. If you want to test this, try a static compression ck with cam stock, advanced and retarded. Again, this is a VE issue, a retarded stock cam will blow thru more than one set at the stock -0-. Lowering the compression ratio on a retarded cam actually increases the power cuz you've lowered the effective compression ratio at high rpm's which means you can add more boost without detonation. The downside to doing this is a loss of actual power in the torque band (lower rpm) where the late opening of the exhaust valve is detrimental.

If you can vary the opening of I and E valve according to rpm, you get the best of both worlds. On a symetrical or asymetrical single cam, you get one OR the other. However, change the intake tract, you can actually tune out the loss of low end.

I've run cams advanced and retarded for over ten years. What you find is that audi builds really nice cams and centers them pretty well to reduce power tradeoffs. A better, or even a dual resonance intake manifold however, could reduce these tradeoffs further.

Moving cams around centerline is pretty common practice. It *DOES* change power. It can also extend peaks and mellow peaks while doing so. Changing the RPM of these peaks is better left to the IM.

YOMV

HTH

Scott Justusson

Toxcheap

Adam we had techtonics regrind a solid lifter 5000/UrQ cam to their hydraulic corrado profile (268/260) and it is awesome. Good idle, good mid power and most importantly finally pulls really hard to reline. Move peak from 5900 to 6400, on a mildly tuned corrado it dyno'ed 12hp!
Hope this helps Oh, almost forgot the most important part it only cost $150.00 (you supply the cam)

Good Luck
TOX

Toxcheap

I spoke of the cam info above. But wanted you to know Techtonics has been building VW motors since the sixties. Had an engine dyno and flow bench back then too!

Here's an example: Collin's 8 valve rabbit with standard C.I.S. no turbo, supercharger or NOS ran a best time of 12.80@107.5 in 1991!!!!!!!

Here's a link to their history page check it out.

Later
TOX<ul><li><a href="https://www.techtonicstuning.com/history.html">https://www.techtonicstuning.com/history.html</a</li></ul>

Adam Mowafy

I will look into that. Once spring comes I'm sure I will be having them work on my cam. Thanks for taking the time to answer all my questions. I know that I have a lot of questions but I guess I just have a huge thirst for knowledge.

Thanks again.

Adam.

Adam Mowafy

DO you know what the specs are on the stock cam?

Toxcheap

How bad do you need them? They're in my bently at my garage down the street

Adam Mowafy

I was just curious dont worry about it. But thanks

shortyq

Ok, I haven't seen that dyno chart Toxcheap. Not sure if you got 12hp in the corrado or the 5ktq... Regardless, this discussion centerlines (pun intended) around playing with a given cam advancing and retarding it. Whatever gains you got on a regrind, I suspect is from changing the overlap and ramp. However, the known physical properties of resonance tuned intakes, esp with sohc is their propensity to make cam timing adjustments steal torque to get HP, and vice versa. A properly designed intake manifold can have massive effects on this physical property of sohcs.

Thanks

Scott Justusson