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Discussion Starter · #1 ·
Is there a way to tell what an engine's max RPM's would be. I was just thinking about this today, and got curious as to what mine would be.
 

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dictated by cam and valvetrain. 99% of pushrod fords are in the area of 6500 and less, beyond that we can get extravegant and build a cleveland to turn 9000
 

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Rev it 'til it blows and then rebuild it and try 100 rpm less the next time. If it stays together you're there. If it blows then rebuild and try 100 rpm less, etc..

J/K
Many, Many things come into play that can't be answered by your question.
How about a detailed list of what you've done to the engine and electrical first?
 

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Stock (and especially old) valvesprings leave more than a little to be desired - most won't buzz to 6000 without floating on the stock lo-po engines. The bottom end could handle 6000 probably without a problem (but you wont make power above it) but exactly as woody said, the number one limiting factor for RPM is valvetrain and cam specs.

Second is rod bolt strength, third is rod strength, fourth, piston strength, fifth, crank strength, sixth, block strength, in order of decreasing importance. (or in order of which limits will typically be reached first.)

<font size=-1>[ This Message was edited by: thekingofazle on 6/21/06 12:48am ]</font>
 

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Discussion Starter · #7 ·
I was just curious as mine has never seen over 4500. I am running stock bottom 289 with Windsor Jr. heads, scorpion roller rocker arms, hardened pushrods with guide plates, and a DUI Ignition system. I can't see that I would ever go to 6500 rpms but was just wondering what the approximate limit would be.
Thanks all!!!!!
 

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I think the limit is up to your boot!
 

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I bet you're cutting those heads short at 4500RPM. They're pretty big (180cc's)

Stock 289s are pretty tough, I'd say 55-5800 should be a good shift point... if you have any cam in it.
 

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Discussion Starter · #10 ·
No real cam, just a edelbrock performer. Strictly a street car so I have never really wound it up. Kinda afraid to try after all the work I put into it!!
Thanks for the replies!
 

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I had a '82 El Camino once that would not, I repeat, WOULD NOT exceed 4000 RPM in neutral with the pedal through the floor. 229" Chevy V6, I think it had 50 HP and 45 lb-ft of torque, but it did get decent mileage. I got smoked by a Geo Metro once from a stoplight. No kidding! It was SO bad that the turbo 350 transmission would stay in low gear if you floored it. After about 5 minutes of waiting for it to get to 4200 RPM (which it never did...), I'd have to let off the gas to make it shift to 2nd. It wouldn't run 70 mph on the freeway either, well, it would if the wind was just right. The El Camino's cruise control worked great. HOld it to the floor and it'd run 67 mph all day long. That lack of power is exactly why I rolled it...trying to make it do something that it wouldn't and not paying attention to what was going on. I drove it nearly a year after I rolled it...had a wrecker flip it back over, pried the door open and drove it home...and continued to drive it. Later on I sold it to my neighbor who actually used it for parts to build an identical truck...only his had a GN turbo V6 that flat FLEW. It was to this day one of the fastest GM vehicles I've ever ridden in....probably close to 600 HP, 28 psi boost on race fuel, and it sounded great (for a V6).

Anyway...back to the question...all engines are definetly different. I've been on motorcycle 4 cylinder engines that will rev to 20,000 (both of them had the limiters "removed" by means of a programmer), most stock 600cc class bikes now are limited at 16,000 with the exception of the Yamaha...which limits at 17,500. It's all in the valvetrain, head flow, and bottom end stability. Those jap bike engines...are hilariously TINY on the bottom ends. VERY small journals, light cranks, teensy rods that you wouldn't think would hold together at 4000, 6mm bolts rather than larger ones that would be stronger....but it's all in the name of weight, or lack of it. Most are also using titanium for valves now too, including the Yamaha 1000cc bikes...each cyl has 5 of them. 20 in all. Cams are hollow and each one is probably less than a pound in weight. And the head....OMG, of all of the hand port jobs I've seen on V8 heads, I have never, I repeat NEVER seen port work like the ones on a japanese high-revving 4 stroke. They are SOOO smooth flowing, tapered JUST right, and they work. Some of the 450cc single cylinder heads are flowing as much as a complete V8 small block head...and are making around 60 HP now out of one tiny displacement cylinder.
 

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On 2006-06-20 13:40, psivory wrote:
I was just curious as mine has never seen over 4500. I am running stock bottom 289 with Windsor Jr. heads, scorpion roller rocker arms, hardened pushrods with guide plates, and a DUI Ignition system. I can't see that I would ever go to 6500 rpms but was just wondering what the approximate limit would be.
Thanks all!!!!!
Stock rod bolts will fail and cause alot of damage. Maybe even a piston failure. you might wanna keep it down around 5000 till the bottom end gets built. Get the stock crank polished and prepped, install arp 2000 rod bolt and a good mini dome piston and then your limit will be the cam and valve train..
 
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