Comment:

I have 94 hours on the belt inspect all aspects of the motor when launching kinda like a plane. Turn motor over primary concern is making sure water is flowing into strainer.

Then observe belt tension on everything to see if any chatter or slop. Then close hatch and run it. The belt tension is about .30 off the tensioner on the port side. Not to loose and not too tight is what I was told by you. Observe it with just enough freedom to tighten up when hammering down but not loose enough to cause it to roll over on the top.

Now tell me about detonating issues what does it do...belt wise... I thought the knock sensor jumps in at this point to take away timing to protect motor?

I have had a lot of hours on this belt perhaps I should change it every 55hours.

I need to post a photo of the belt and the light bulb will go off. The belt is intact just all the teeth are gone crazy stuff.

KAP

Be sure to set your belt tension when Motors are hot and or normal running temp. My motors grow a lot and we always had problems until we simply adjusted final tension when motors are warm.

No need to post pic of belt, thats what the rubber belts do when they fail, as there bonded to the inner liner. At 94 hours, your at the end of the belt life, if not passed it.

You can't see belt chatter unless you run all rpm's and driving conditions as many different harmonics come into play during different loads, etc.

The belts need to be pretty tight, I've tried the loose settings and semi tight, don't seem to work, they do some insane things on the dyno. When you set them up tight, they last longer and don't chatter nearly as much.

For wrap, you want to have 180deg of wrap on top, no more. The bottom, port idler is just there to lightly touch the belt, which helps with the chatter/harmonics. The main adjustment is the lower starboard idler, push this until you can't twist the belt more than half a rotation.

Detonation, the same as rev limits, and or any type of misfire causes the engine rpm to stop, or slow down abruptly, the sc, with its inertia, wants to keep rotating, then the belt gets wrapped up and twisted, then when the motor gets back to normal firing, it accelerates while the SC is decelerating, causing a massive "snap" of the belt. Its extremely violent. If you watch drag racing, they'll show slow motion camera's on the belts when the motors detonate, and its unreal how the belt coils up like a snake then snaps, back and forth until it gives. The ECM, depending on the cal, should reduce timing and richen the motor, but this is AFTER the event has occured and depending on ECM processor speed and knock control, it could in fact allow it detonate multiple firings before it catches again.

And earlier I said kevlar, but I meant carbon. The kevlar belts can't be back bent. Carbon and rubber can. Carbon is the best belt but only available in a few sizes. You'll also have to change pulleys to the "GT" tooth pattern. You don't need this, but an upgrade to the "Gold" is a good option, also produces less noise. Its available in 1400,1600,1800,2000,2200,2400 mm sizes.

I think 50 hours is a good number for changing belts, then keep the old for spares.

wow, good info. i had no idea that the belts did that.

We are prob. working the 8mm set-up as hard as anyone.
195t on the bottom and a 43t on top = 452% overdriven! That's almost 30,000 rpm at the blower @ 6500 engine rpm.
Loose is what works best for us. Every engine is different. Stripping all the teeth on a belt isn't crazy, it's just what happens when they fail. I tried running a dual idler with the one on the left side just barely touching the belt to try to "calm it down a bit". We decided the the belt hitting a stoped idler and sliding across it to spool up to speed was inducing too much heat into the belt and did away with them. Going to forced engine oiling in the snouts helped lower the snout/belt temp issues also. We have found alinement of the idlers to be critical. You can make your own spacers but Manhatten Supply has some cool stainless U shaped shims in .010 increments to really dial them in. Idler bearings that are just a LITTLE bit rough will break belts too. It's all a bunch of little things that add up. When they are wrong, we can break 3 or 4 belts a day. When everything is good, 50 hours should be reasonable. BTW find all the pieces of those stripped teeth or your bilge pump will at a really inconvenient time!!! Here is a pic of a guard we have built to protect dry sump belts from collateral damage. Hope this helps, Eric

Whipplecharged:

Fantastic post thanks for the explanation. Your experience in this area is extremely valuable as what you take for common knowledge is news to me and everyone else:). It also builds confidence in the product.

I know 90+ hours is a lot on a belt but figured it would snap before it turned into whopper chopper rubber salad.

It makes perfect sense now. I hit the rev limiter doing the fly bye's kinda hard i.e...bump bump usually it is gradual to the limiter or just before it I back out.

The above is what I do the belt twist is new to me but makes sense.

I think 50 to 60 hours is going to be my service interval as I boat 100+ hours a season. This will allow me to change the belt mid-season and then have a new one until the season ends.

Ok! thanks I feel much better now as I know what to expect. I graduated from a 3.3litre Whipple which is an excellent product to the 8.3 which is whole different animal/monster in making HP.

FYI: I highly recommend/love the 8.3litre Whipple unit it puts out monster HP depending on the set-up from pump gas to race gas. Low profile fits under my hatch and virtually trouble free...knock on wood:lolhit:.
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Boyd:

I think your right on the money about the idler pulleys my port one is a little sloppy and it probably needs a shim. Now the idler bearings do you lube them with anything or are they kept dry. I do not lube them at all is this a mistake. I figured it would all fling out anyway.

Whipplecharged this would be good information to find on your website. Recommended service interval for belt and idler alignment and/or bearing replacement for the idler/tensioners. Any thoughts?

Boyd... I'm headed to the boat here shortly with standard belt in hand and I am really dreading the mess. I'm way ahead of you on the rubber in the bilge somehow it will get past that screen on the pump even if it is just a small little nodule and jam it up.

I'm gonna vacuum the hell out of the engine compartment/bilge.

Thanks again Whipplecharged for the excellent feedback it is much appreciated.

KAP

P.S. The drag racing metaphor of the snake coiling refreshes my recollection I know exactly what your talking about now.

P.P.S. Also Boyd your not the only one overdriving their Whipple to such a degree:drink: good to know I'm not the only one.