hacker-pschorr

This is the example I'm always talking about. The theory that a stronger belt might buy you some time if there is a failure in the system.

No matter which pump you use, or what rollers you buy, there's always a chance one of them will stop rotating and take out the belt. A stronger belt, might give you enough time to shut down the engine before the belt snaps, like what happened here.

I am NOT advocating this belt is an excuse to avoid the regularly maintenance interval, just an added level of security.

https://rennlist.com/forums/944-turb...for-951-a.html

Christopher Zach

Not so much a stronger belt, but one that can ride over a jammed impeller in the water pump. Interesting.

worf928

They’ll *all* slip over a seized roller or pump pulley. They will *all* melt to the seized roller and/or pulley once the engine stops. *None* will stay in one piece if you attempt to start a 928 where the belt has melted to the rollers.

Please find me a ‘rubber’ 928 timing belt. There are no rubber timing 928 belts. They are all fibre reinforced. Yes, in 1980 it wasn’t Kevlar it was something else.

I am *NOT* advocating against the ‘racing’ belt. I’m not advocating using 30-year old belts.

But, these threads always have some baloney in them: people will form an erroneous assumption and use it as a means of justification.

928NOOBIE

Concerns from me would be will the belt stretch like the Conti belt, providing some additional relief on pulley/water pump bearings? My understanding is the Conti belt is widely recommended for that reason?

worf928

I don't recall ever running across this theory before.

The Conti belt is widely *derided* for that reason.

hacker-pschorr

Who said anything about re-starting the engine? Did you even read the quote I posted? Why on earth would anyone knowingly start an engine with a seized component in the belt system?

All's I'm saying is a stronger, better reinforced belt might (notice I said might...) buy a few precious seconds when sh*t goes wrong saving your engine. What is so difficult to comprehend about that?

After helping Twin Turbo Todd setup his engine with the very stiff valve springs, and seeing just how much stretch the stock belt needed before his cams started to spin, versus the racing belt which needed none. It was clear how much stronger that belt is.

Frankly I see zero reason not to use it with all 928 applications, or at least those with interference motors.

I have zero affiliation with this belt, as you I see erroneous comments made about it and thought this example was interesting enough to share.

dzaprev

My son purchased a 944 and the one of the pulley seized and didn't break the belt. He pulled over and belt stayed in tact. He was 17 and called and said its started to screech and I said pull over now. So they do hold up for a bit.

worf928

This one?

Of course I did and it is to this quote that I responded.

That quote is the product of fallacious reasoning.

It is certainly true that a *rubber* belt would have snapped. It's also true that a belt made of cobwebs would have snapped. Neither case has anything to do with a 928 timing belt because 928 timing belts were never made from cobwebs or (non-reinforced) rubber.

An OE(M) belt would have - and they have - survived in situations where the water pump pulley was seized long enough for a shut-down without snapping. Thus the "100% snapped" isn't even true for a normal Gates 928 timing belt.

This quote further reinforces the erroneous belief that 928 timing belts 'just snap' because of <insert demonstrably false premise here>.

Thus, my issue is that promoting the 928 racing belt because a 928 non-racing belt is guaranteed to snap on a seized water pump pulley is baloney argument.

And the point there was that no belt of any composition rubber, Kevlar-reinforced, or cobwebs, would have survived and thus still not a valid reason to use the racing belt.

And again, I don't dispute that a better belt might be good. What I will not swallow is reasoning based upon a demonstrably false argument.

Note further that I do understand that it wasn't your quote. But, it is nonetheless baloney and, again, reinforces an erroneous belief.

This is a different animal.

I know you don't get a royalty from the racing belt. The use of the word "promote" in this post is from the dictionary:

If the reasons people used for promoting the racing belt were along the lines of:
- less stretch, less dynamic cam timing variance (already proven more-or-less)
- reinforced teeth less likely to be shed in high-spring-pressure applications (any evidence of that??)

then we would have things to discuss, kick-around, test, etc.

Furthermore, *I* use the racing belt for 'upgraded' 928 engines. So, I'm not a "denier" either.

V2Rocket

you may find this an interesting read.
stock belts likely nylon/poly/FG cord reinforcement.

https://www.linearmotiontips.com/whe...-applications/

worf928

Excellent! Thank you for that. There are some very discussion-worthy tidbits in that article.

Jim Devine

These are NOT timing belts, so a little off topic. but Gates also makes serpentine (rib) belts made of the same material (per call to Gates)- order using the full ko---- number, can order from napa etc. looks to be useful to drive the alt without slippage/ streching

Size chart- note the # of ribs etc- https://assets.gates.com/content/dam/gates/home/resources/resource-library/application-specs/428-3291-rpm-belt-dimension-list-newbrand.p

http://www.gatesracing.com - click on serpentine belts

928NOOBIE

My understanding is the belt is widely recommended for that reason. Greg and Ken both recommend/use the Conti belt for that reason, if I have understood their comments correctly

ptuomov

I think the racing belt is the way to go with stiffer valve springs and higher acceleration cams.

The required slack side tension depends on the pull side tension. For this reason, I'd also want to either run Porkensioner or slightly higher tension with the stock detensioner if the springs and cams aren't stock.

I'm not sure that the originally quoted post proves anything, but it's nice to hear that someone had only a near miss.

NoVector

SeanR

Hardly, none of us recommend that belt. Who would want a rubber band running critical components.