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Ok, now we are starting to sound like a Gates Racing Belt commercial, which is where this was heading anyway, nothing new to learn just the same ole thing well documented, "Contis" are bad, Gates are best".
Twin Turbo Todd experienced significant belt stretch on his motor with a standard Gates belt. Over 10 degrees of crank rotation before the cams started to move.
Zero with the Gates racing belt: https://rennlist.com/forums/928-foru...vs-racing.html
Todd & Carl have talked quite a bit over the years sharing information on builds. I'd find it odd somehow this information never made it from Todd to Carl.
I don't think it's out of line for people to ponder why an all out race engine wouldn't use the absolutely best timing belt possible. I think your tin foil hat is on a bit tight DR
I don't think it's out of line for people to ponder why an all out race engine wouldn't use the absolutely best timing belt possible. I think your tin foil hat is on a bit tight DR
In a paint thread, OK I have seen it all before. Maybe you need to tighten yours just a bit. LOL!!
All the best,
Dave
__________________
David Roberts
2010 Jaguar XKR Coupe - 510HP Stock - Liquid Silver Metallic
928 Owners Club Co-Founder
Rennlist 928 Forum Main Sponsor www.928gt.com
In a paint thread, OK I have seen it all before. Maybe you need to tighten yours just a bit. LOL!!
It's also a thread about Carl's race car. I've seen many posts in other 928 areas (mostly FB) discussing this broken belt. Lot of people curious and concerned.
I got to get into the shop so I will be away from my keyboard for a while.
I just wanted to say... that if you are focused on the belt alone, you are focused on the wrong thing.
I strongly believe the harmonic wave sent backwards during engine decel from the Left cam sprocket to the water pump was the major cause of the belt failure. I will be making an idler for the smooth side of the belt in that span, and I'll post about it when done.
Maybe this is more an issue when running without timing belt covers like I do? Would the timing belt covers prevented this? I do not think so, but I also do not KNOW.
I'll make the idler, and I'll make it available for other racers. Like DR said, "racing improves the breed!"
It's also a thread about Carl's race car. I've seen many posts in other 928 areas (mostly FB) discussing this broken belt. Lot of people curious and concerned.
Funny, back in the beginning of PorscheFans and Rennlist I used to get weekly calls from John D. to help diffuse a negative 928 thread, he tasked me with that for years. I usually tried with humor to good success to realign the threads. Guess I am not so good at that anymore, especially with you lately, not sure what's up with "that"... or I guess times have changed...or ???
Carry on my friend,
Dave
Carl, my apologies for my part in this created distraction.
This the concept for the additional belt idler. It doesn't have to touch the belt much, only .010" is all, so no worries that it will change belt tension. But it prevents the harmonic wave from snapping the belt like a kid snapping a wet beach towel.
Note that such guides are already on the 928: under the crank sprocket to prevent the wave from jumping a tooth, and the one between the belt to the right of the water pump.
08-02-2018, 11:11 AM
