blown 87

It almost sounds like you are saying that the tension on the slack side has no bearing on the other side.

Once again Ken, I am not trying to be combative, just trying to understand this all.

Which I do not at this point.

How did you chose which tensioner to use?

There are hundreds, if not thousands of part numbers out there for different tensioners.

mark kibort

Well, there you go. kind of a follow on to my question and point, that it doesnt seem like "wrap" is the main factor, its tension. why, in my case, did the passenger side, with more "wrap" jump 3 teeth with much more wrap? It seems to me that the driver side with more "wrap" is on the power side of the tension and has the passenger side cam to always keep tension tight under rapid acceleration. the crank gear has a lot of "wrap", not from the oil pump, but the tensoner that presses the belt around the crank pulley. So,its wrap is on top of the pulley, not toward the oil pump pulley horizontally.

I think what you are saying is that you get better belt wrap with the audi tensioner, and it absorbs some flutter better due to a spring loaded piston movment, whereas the stock tensioner, uses more tension to accomplish the same thing at the cost of pulley wear. However, my pulleys have always looked brand new in all the cars Ive race and driven for over 23 years now. Ive seen some REAL gouged pulleys, but that is probably due to over tension. Maybe the audi tension is easier (no work) vs the porsche tension which needs some skill to set. BUT, if you have the skill, do you need the audi tensioner?

andy-gts

Is it possible to film the tow systems on a dyno with rapid accel and decel . We may be supprised what is found....kinda like what louie did to find the aeration of oil with long hard sweeping turns helping to starve the bearing of oil.
Louie are you out there?

andy

GregBBRD

The actual problem with gear wear is from things being loose. Belts that get good maintainance and are adjusted to 5.0 "belt units" will allow the gears to last virtually forever. When the belt tension goes down...the gears wear very, very quickly. That's why Porsche has that great big "idiot" light come on at 3.7 "belt units".

GregBBRD

I have one of these, for my Ducati's. Not made by Goodyear, but the same thing.

I'll dig it out and see what it tells me.
'
This is the ideal time for me to switch back and forth between stock and your system...to see what the differences are.

PorKen

You'll need to spin the engine with a starter to equalize the belt tension, first.

PorKen

It's still about wrap. You need enough tension to maintain belt engagement.

I would guess your 1-4 gear slip more likely happened after abruptly letting off the gas, after accelerating. The low tension allowed enough belt to stack up under acceleration between the 1-4 gear and the tensioner pulley so that when the pulley went from being driven to driving the belt, the belt walked over the teeth.

If you switched to a PKsn'r, you would likely find that the engine is quieter, and revs more smoothly. Excessive belt tension steals HP.

IcemanG17

interesting that a LACK of belt tension causes the gears to wear...I thought over tension would cause the various belt gears to wear out?

One thing I noticed on the lemons racer that I have never seen before is how much "flap" there is on the belt....when we were adjusting something (can't remember) I would rev up the engine at the TB and could see the drivers side cam gear (5-8?) under quick acceleration-deceleration the belt would "flex" in middle quite a bit.....I would say if the belt position at idle (running) is zero (as in neutral) that the maximum amount of flap is +/- 1 inch peak values.....I don't know if thats enough to skip teeth or anything...but the belt was always set slightly tight on the kempf tool...

blown 87

I thought the belt being loose would make the gears wear faster.

I think that may be the reason that some gears look great after X miles and some are just gone.

PorKen

A used belt can only stretch so far during acceleration. The crank gear pulls the belt tight as it tries to get the cams to turn. The slack side has to be controlled, but not overtight.

At a constant rpm the cams still take force to turn maintaining the tension. (32Vs take more HP to drive the cams, than a 16V, but they make this up with higher volumetric effeciency.)


The one that fit! Which just happened to work well on a 928 engine.

blown 87

The ones I have done did not get quieter, if anything they got louder with a gear type sound.

Mark was your belt loose when it slipped?

PorKen

5.0 (32V, 16V 4.5) units on the Porsche belt tension gauge means little once the engine is turning.

Compare it to 200+ psi compression while turning the engine with the starter. If you have big cams with lots of duration, the dynamic compression will be lower (so you have to have high compression to start with).

The PKsn'r has a more consistent belt tension when the engine is turning than the stock detensioner system. The easiest way to see this is with the flapping. The PKsn'r doesn't flap, and the belt doesn't come off, despite the best efforts of myself, and many others. The stock belt flaps at certain rpm/harmonics, even when set very tight.

blown 87

PorKen

"Which just happened to work well on a 928 engine."


I really don't understand all the wanking on about this improved tensioner system. It works well. It works better than the stock system.

It works well at low rpm, it works well at high rpm. It works well at very cold temps, it works well at very hot temps. It works well on the autobahn at max V, it works well on the dyno at W-O-T.

The whole system is more robust than the stock system. It's overbuilt! It's simpler than the stock system. It's simpler to maintain than the stock system.

What else are you looking for? A 'happy ending'?

IcemanG17

as a possible "answer" to the dilemma at hand....I will kindly volunteer the 928 "estate" Lemons racer as a test mule for the Porkensioner!! 4 races are planned for this season plus a bunch of practice sessions.... We might even venture up north to Porken land for a different POS race car series....

16 hours of racing in a weekend..... x 4 races = 64 hours...add in test days and the engine probably sees 100+ racing hours a year....

:>)