Would you move this cam?

General engine tech -- Drag Racing to Circle Track

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F-BIRD'88
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Re: Would you move this cam?

Post by F-BIRD'88 »

Hate to burst your bubble but you do know that the sae corrected numbers are not the actual power num;ersthe engine did make that day.. Youcangeta higher number by just fudging the correction factor a bit.
Since you will never use the power really what difference does it make
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MadBill
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Re: Would you move this cam?

Post by MadBill »

70GS455 wrote: Fri Mar 26, 2021 7:56 pm... RPM limit is fixed at 6000 due to block structural limitations...
I'm more than a little skeptical about the block limiting safe RPM. How was this number arrived at? Maybe a case could be made for engine RPM peak as a tradeoff with six-figure odometer readouts but I see no direct relationship.
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70GS455
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Re: Would you move this cam?

Post by 70GS455 »

MadBill wrote: Fri Apr 30, 2021 10:07 pm
70GS455 wrote: Fri Mar 26, 2021 7:56 pm... RPM limit is fixed at 6000 due to block structural limitations...
I'm more than a little skeptical about the block limiting safe RPM. How was this number arrived at? Maybe a case could be made for engine RPM peak as a tradeoff with six-figure odometer readouts but I see no direct relationship.
That's a good question. It may be nothing more than folk lore.

From what I recall, there were reports of people cracking blocks at the 625 to 650 hp level and above in racing applications. Then came the advent of the main girdle which bought a little extra margin, I think to 750 hp or so. I've read of racers in the 800 hp plus range and even with the girdle, halo, and block fill were still replacing cracked blocks every season. Then there are those that are just fine.

Then I recall an interview with the original engineer in charge of engine development for Buick back in the late 60s, Dennis Manner He was saying they were seeing broken blocks once an adequate level of hp was exceeded whenever rpms reached 6000 or more. The issue was with main webs cracking near the cam tunnel and he mentioned vibrations as what they suspected was the cause. I dont think he spcified what hp level it was.

So i think the observed failures plus the interview comments were combined to arrive at 600 hp and 6k rpm. I'll pose the question to some ppl more knowledgeable than me and get a better answer.
Scott
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