NASCAR banned OHC motors back in the 60's??
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Originally Posted By: Shannow
Not wrong, the cam was almost at the top of the V and the pushrods nearly horizontal...buick V-6s and destroked SBCs were allowed (IIRC 10lb) extra boost. The Mercedes was made to expressly use the rules/
I was like 9-10 when all of that was going down, but I was really into Indy then. I remember trying to find out as much as I could about it, but in the days before internet, Indy coverage was bad at best.
Not wrong, the cam was almost at the top of the V and the pushrods nearly horizontal...buick V-6s and destroked SBCs were allowed (IIRC 10lb) extra boost. The Mercedes was made to expressly use the rules/
I was like 9-10 when all of that was going down, but I was really into Indy then. I remember trying to find out as much as I could about it, but in the days before internet, Indy coverage was bad at best.
Originally Posted By: bdcardinal
Originally Posted By: A_Harman
Who knows of pushrod engines that can run significantly over 10,000 rpm?
Correct me if I am wrong, but wasn't the Mercedes Ilmor pushrod engine a work around to the rule that allowed higher boost for "stock block" engines in USAC sanctioned races?
Yes, it was designed entirely to take exploit the displacement and boost advantages (47 cubic inches & 10" Hg, IIRC) that Indy allowed pushrod engines in those years. I have a book (Vintage Race Engines by Karl Ludvigsen) that shows its internals. The big trick that they pulled to get the valvetrain to go 10k rpm was using oscillating instead of reciprocating cam followers. And the cam was placed high. And the pushrods were short. And the valves were Titanium. But the rocker arms and pushrods were steel.
Originally Posted By: A_Harman
Who knows of pushrod engines that can run significantly over 10,000 rpm?
Correct me if I am wrong, but wasn't the Mercedes Ilmor pushrod engine a work around to the rule that allowed higher boost for "stock block" engines in USAC sanctioned races?
Yes, it was designed entirely to take exploit the displacement and boost advantages (47 cubic inches & 10" Hg, IIRC) that Indy allowed pushrod engines in those years. I have a book (Vintage Race Engines by Karl Ludvigsen) that shows its internals. The big trick that they pulled to get the valvetrain to go 10k rpm was using oscillating instead of reciprocating cam followers. And the cam was placed high. And the pushrods were short. And the valves were Titanium. But the rocker arms and pushrods were steel.
NASCRASH is a totally lame racing format IMHO…Amazing how many people watch it just hoping for a crash…and NASCAR officials manage the races "artificially" with their silly yellow flags out to bunch up the field…All the better for crashin' when they can get the cars closer together!…TUSCC (formerly ALMS) and WEC World Endurance Challenge racing are the real deal and very interesting in my opinion…NASACR is too dumbed down.
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