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750hp
No it wasn't modified in any way, just unable to get the same pattern on all the ring gear teeth while setting it up. Grin and bare it and hope for the best. Rick |
If I had to hazard a guess it would be the wristpin area of the piston. As the RPM's escalate on these engines (close to 10k for pushrod motor) they continually lighten the recipricating weight of components and by doing so reach an area with unknown results, regardless of dyno time. Pistons by nature are the first thing to look at as they travel up & down (duh!) inside and stop and reverse direction at the top & bottom of the stroke. Their weight or lack of it it directly transfered to the rod. Allowing for quicker acceleration because of less weight. But as they are removing material to reduce wieght, strength is compromised at some point. These guys are closing in on 850 Hp and 9600 rpm in non restrictor plate trim.
This is real punishment, and pounding for hours at a time. Thats my story and I'm sticking to it! Rick |
All I can say(knock on wood) is that I have thrashed for over 2 years a cup style, RDI rebuilt 358ci (660hp)motor. I adjust the solid roller lifters and thats it. I was banging the rev limiter at willow (8200 rpm) a few weeks ago on most laps. No car except for greg lapoint(sc347) has stayed with me on a straight. Wanta be racers like me don't usually break these motors. You can get plenty of power out of any motor to make a cobra fast. If you want to thrash it and have it last, there is no better way than a cup style motor. Scott
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Roush blamed himself for the pistons saying he tuned for mileage. He also said they were going to run more piston to wall clearance and enrichen the mixture. I read this stuff on Roush's website so who knows if the public gets the real story.
I suspect the pistons got too hot and tightened up in the bores. A few years back everyone went to direct feed pin oiling to help with the piston pin problems. Speaking of light weight, has anyone seen a piston-guided rod set up? Scott |
scottj:
Piston guided rod???? Explain........... Rick |
The piston pin boss is machined to accept the width of the rod and a pair of spacers giving .005/.007 side clearance. This centers the rod on the crank and allows the width of the big end to be reduced by .080 per side, resulting in lighter rods. Less rod weight equals a lighter crank to achieve balance. Net result is an overall lighter assembly.
Scott |
And so the development of the old pushrod motors continues.... :) 800+ Sprint cars, ???hp Nascar. 1000+hp carb'd small block drag motors. Where will it end ????
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I, for one, hope it never ends. There is no such thing as too much horsepower!
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Amen ! ;)
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