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454 Max RPM?

DavidB

DavidB

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Stock 454 in desert racing. What's the max RPM you'd run it in short bursts and long term?

Couple young guys I know (they drive hard) are racing and blew off the crank pulley and are throwing belts. I've got a feeling they're running the 454 too hard and fast. I think a 454's power band is lower than a race smallblock, and I think they're running it like a small block. 5.13 gears with 35s and a TH400.

Input?

Thanks.
 
I don't know specifics, but you are correct about the power band. Small blocks love revving, big blocks don't. 35's with 5.13's will get the rpm's up there pretty quick too. If dropping int a small block isn't an option I would suggest regearing. 4.10's are good with 35's for the trail. But for desert racing 3.73 would be better. The engine has enough power to push the rig around just fine.
 
I wouldn't run a stock 454 much over 3,000 RPM for any length of time. Short bursts to 4,800 RPM will be ok. Gear your truck to keep the motor in the 3k range for your speed and you should be able to keep it together.
Just a side note, with the relatively high gears you'll be using make sure you run a couple of efficient trans coolers to keep that trans from cooking itself. Run a gauge and don't be suprised if you have to put fans on the coolers to keep it under 220 degrees.
 
My big block has hit 3,500 once or twice when I was @ WOT but it pulls best at rpm's much lower than that... I'm on 32's and 4.10's with a 4l80.
 
I wouldn't be afraid to spin a stock one to 5500 with a different cam and big ovals. I spin my 427 to 7500 but has a few better parts in it.
 
Mine has bounced off the 6k chip a couple times, and on this most recent rebuild I made it a little more RPM friendly. Now I just gotta make the damn thing run. Butyeh, 5.13 and 35s is wayyyyy too high to be spinning a relatively stock 454
 
a stock 454 with that high of a gear will get you great power on the lower rpms but if you wanna race it id suggest to go with a wider gear ratio.

"RACE, BREAK, FIX, REPEAT..."
 
You have to remember that they are racing, not cruising down the interstate. On and off the throttle constantly ,wide open throttle accelerations, etc... trying to go as quick as possible. A stock 454 in good shape should have no problems in regards to durability hitting up around 5k rpm. You said the issue was with the belts and pulleys, which doesn't seem like it has anything to do with the engine internals, and thus revving the engine too much.

Even with 5.13's and "only" 35's you should be able to go way faster then what I'm guessing the chassis/suspension of the truck can take (I'm guessing nothing too wild if it has a stock engine) while desert racing.
 
6.2Blazer said:
You have to remember that they are racing, not cruising down the interstate. On and off the throttle constantly ,wide open throttle accelerations, etc... trying to go as quick as possible. A stock 454 in good shape should have no problems in regards to durability hitting up around 5k rpm. You said the issue was with the belts and pulleys, which doesn't seem like it has anything to do with the engine internals, and thus revving the engine too much.

Even with 5.13's and "only" 35's you should be able to go way faster then what I'm guessing the chassis/suspension of the truck can take (I'm guessing nothing too wild if it has a stock engine) while desert racing.
Click to expand...

Actually, it's an '80s Ford with Giant equal length beams and 4 link rear, coilovers. It'll just about go as fast as you want out there.

My concern was breaking the center out of the crank pulley. A lot of accel/decel would stress it. And the faster an engine spins, the more centrifugal force the belts get, and the more they whip. I think they figured out the PS pump was crooked though.

I had the truck at my shop and revved not too hard in N trying to diagnose a decel backfire and it hit 6 grand easy, so I got to wondering how high they were running it racing, and how high it should be run.

Thanks for all your input guys.
 
stock 454? 5500. END OF STORY. there is no reason to rev any higher. big block = big parts = lots of mass. buy a tach with a memory and data log how high it will rev. when it pops, check the memory on the tach. then set the memory 200 rpm less for the next motor.
 
dick_landy said:
stock 454? 5500. END OF STORY. there is no reason to rev any higher. big block = big parts = lots of mass. buy a tach with a memory and data log how high it will rev. when it pops, check the memory on the tach. then set the memory 200 rpm less for the next motor.
Click to expand...

:haha:
 
At 5,500 rpm, even with 5.13 gears and only 35's, thats well over 100 mph.
 
Yeah, but they're spending more time in second, not cruising along in third. Someone put it well when they said desert racing is ditch to ditch or corner to corner drag racing. They spend a lot of time accelerating full throttle in the 40-70 mph range, a lot of on/off throttle. In second, if you're breaking the tires loose all the time and winding it out, the 454 is gonna be screamin'. I need to get some seat time and see how they're running it. He siad he thinks it has 4-something gears, and runs 3-5000 RPM, so that's better than I thought.
 
If you're going to run that motor that hard make sure it has a good set of valve springs. Big block valve trains are extremely heavy and real easy to get into valve float, new springs and rockers are relatively cheap insurance. Also the oil pan needs to have at least a 6 quart capacity with good baffling, last thing you want to do is run the pan dry at 5,000 RPM. If you'll at least do that the motor will have half a chance of making it 500 miles, if you don't make sure you keep a bucket in the bed to pick up all the parts that are going to end up on the ground.
 
Had an Olds 455 with 35" tires, thm 400 and 3:73. 140mph on the dry lakes made the Trophy trucks work to pass it. Short bursts of 6,000 sustained 5400,maybe thats why it kept wiping out the main bearings???
 
My stock 454 from a 75 Monte Carlo is pretty much screaming at 4500 rpms. I have taken it up over 5k plenty but that is it. I have replaced the valve springs on it twice which has helped it stay strong. Its a torque monster, not a high-revver. I dont have a tach on my 93 TBI 454 but it has a whipple twinscrew supercharger so I don't need to wind it up either.
 
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