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Years ago I knew a guy that worked at a successful race engine shop that mainly did 4 cylinder engines. They weren't keen on grinding cranks 1st undersize, and usually advised a new crank budget permitting. OK these stroker engines aren't revving to 8k + and probably only spend seconds over 6k, but grinding that much off and then the force required to cold straighten isn't as good as an option as an original 3.0 crank IMO.
There is a shop in Redding California that rebuilds harmonic dampeners. I believe the cost is around $250. It's pricey but so is everything else on a built 951. IMO it's worth it. http://damperdoctor.com/index.php?ro...mation/contact
If you get a new motor in by June, after I've been sitting on my next-gen motor parts for way too long, I might actually be shamed into action...
If all parts come in as expected it will be done
Originally Posted by 951and944S
Out of curiosity, do you run a non spring damped clutch disc..?
And solid engine mounts..?
On track, short of natural backlash in CVs and transmission gearing, only the length of the long input between the clutch spline and the transmission input shaft coupler absorb torsional forces through the drivetrain when you remove the spring center from the disc and the isolator (rubber mounts) that both absorb torsional forces when you hop the rear tires on an errant or missed rev matched downshift with high grip tires.
BTW - re your video, it's hard to do with traffic, but in a car with your power, after out lap, try making some laps in 5th gear only...., never downshift.
This will teach you momentum faster than anything else.T
Spec hybrid clutch, does have springs, LR semi Solid mounts. This is definitely not a torsional failure.
Thanks for the input on my driving. I will give that a try. I have improved quite a bit since any posted videos
Originally Posted by V2Rocket
looking at the metal grain patterns in that photo that looks like a crack->snap caused by crank whip rather than torsional stress.
probably could've used a revised (heavier?) harmonic damper along with the larger radiuses as mentioned.
if it were torsional failure...easiest to picture a splined driveshaft twisted from mega torque input, the metal twists on itself as if it were a a towel being wringed out, if smaller scale.
I think this is just simply a load failure. I do not believe the harmonic balancer played any major role.
Originally Posted by Voith
That has to be the luckiest outcome for failure of this proportion. Hope you make it even better this time.
God helped me on this one
Originally Posted by Humboldtgrin
There is a shop in Redding California that rebuilds harmonic dampeners. I believe the cost is around $250. It's pricey but so is everything else on a built 951. IMO it's worth it. http://damperdoctor.com/index.php?ro...mation/contact
Another consideration - When you take the crank out to maximum stroke, you really cannot optimize the fillet radius. The more I look at the 94.7mm stroke, the more I think it is better to back off a bit. This pics shows what could have been if there was enough material. Rebuild will be 92 mm stroke with optimized fillets and nitriding.
2? years ago i was gauging interest for having custom billet cranks made, i think Molnar was OK with 94mm (will double check), something around $1500/pc with 5 pc minimum.
i think he wanted a larger rod pin though.
surely the necessary fillets could be built-in at that point.
Reusing my block, had to overbore the sleeves 0.010" out to 4.040". Quite a bit of wear in the bores, on the order of 0.003" to 0.004". The rod ratio on the 95 mm stroke is 1.58 and it is a factor in terms of wear. Something to consider as you go higher in stroke. Got about 10K miles and a lot of track events. Rebuild is coming along, just need my 92 mm crank and then it can go back together. Hopefully have the crank in 3 weeks.
I doubt many if any besides Emanuel and I would be interested but I will have a quote in a few days from Marine Crankshaft on a full Billet Hybrid Stroker crank at 94mm. Their work is phenomenal even by my standards.
I doubt many if any besides Emanuel and I would be interested but I will have a quote in a few days from Marine Crankshaft on a full Billet Hybrid Stroker crank at 94mm. Their work is phenomenal even by my standards.
Originally Posted by V2Rocket
2? years ago i was gauging interest for having custom billet cranks made, i think Molnar was OK with 94mm (will double check), something around $1500/pc with 5 pc minimum.
i think he wanted a larger rod pin though.
surely the necessary fillets could be built-in at that point.
04-06-2018, 05:55 AM
