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rotating assembly

Post  460pulling on Sat Dec 08, 2012 12:04 pm

I have a couple of questions on what i need to plan for. I have a a460 block thats bored 4.5, older a460 heads/intake. I am building a pulling engine for a 2wd puller. The rules changed and its any displacement. I am looking to spin it 7500rpms. My question is what crank/rods/pistons should i go with i would like to have 14+ c/r. Will a scat forged crank/hbeams with arp 2000/and domed pistons with 1/16 ring pack spin 7000-7500 max of 7800. in a 540+ ci engine and live. Where can i learn about piston speed and such? Or what are safe limits? And i also want to make my power at 72-7300 so i can run up to 75-7600 and when the sled get on me and it drops back to where its got the grunt to keep on getting it. What stroke rod ratio is best for torque?

Thanks Jesse


Last edited by 460pulling on Sat Dec 08, 2012 1:20 pm; edited 1 time in total

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Re: rotating assembly

Post  dfree383 on Sat Dec 08, 2012 12:12 pm

For something like 8500 rpm I'd be looking a higher end parts, like Oliver steel or BME aluminum rods, Bryant or Crower cranks, ect.

Not the the scat stuff is bad or anything it just the details that make the difference IMO.
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rotating assembly

Post  460pulling on Sat Dec 08, 2012 1:12 pm

I hit the wrong number. Im going for 7000-7500. Max of 7800rpms.

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Re: rotating assembly

Post  rmcomprandy on Sat Dec 08, 2012 8:18 pm

It won't matter what kind of parts you put in that engine ... it will never get to your RPM target without a cylinder head to be able to feed that many cubic inches in that engine at that RPM level.

What heads do you intend to use...?

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Re: rotating assembly

Post  460pulling on Sat Dec 08, 2012 8:50 pm

I will have motorsport a460 heads. Flow 452int 319exhaust.

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Re: rotating assembly

Post  rmcomprandy on Sun Dec 09, 2012 1:56 pm

Average piston speed is about 94 feet per second with a 4.500" stroke at 7,500 RPM.
In my opinion: Much to high for a 1/16" ring pack to remain sealing with an unpressurized engine.
Using a 4.300" stroke will get that average just under 90 feet per second to maybe give those rings a chance at sealing if they are back-cut to remove some ring weight; (with matching ring groove depth), and there is some type of gas porting to help them...

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Re: rotating assembly

Post  460pulling on Sun Dec 09, 2012 2:31 pm

What ring thickness would i want to use.

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Re: rotating assembly

Post  rmcomprandy on Sun Dec 09, 2012 2:58 pm

460pulling wrote:What ring thickness would i want to use.

.8mm top
.043" second
3mm oil

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Re: rotating assembly

Post  460pulling on Sun Dec 09, 2012 3:28 pm

What crank and rods are people running? And aluminum or steel rods?

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Re: rotating assembly

Post  schmitty on Sun Dec 09, 2012 10:01 pm

460pulling wrote:What crank and rods are people running? And aluminum or steel rods?

There are about as many combinations of these as there are members. Laughing The good quality forged cranks are capable of handling what you are after, as well as a good set of forged rods. Cool The crank prep is about as paramount as anything, and Adney Brown at Performance Crankshaft is about as good as you will get. Sonny Bryant has some really nice stuff too, as well as Crower. As far as rod brand, the Oliver stuff is darn hard to beat.
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Re: rotating assembly

Post  460pulling on Mon Dec 10, 2012 9:47 pm

Now well i took my a460 block and its bored 4.39. I know i should run atleast a 4.44 bore to avoid shrouding since the a460 heads i am getting have 2.35 intake and 1.88 exhaust valves. I can run any displacement.
for a pulling truck which crank would be best? 4.14, 4.3, 4.5

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Re: rotating assembly

Post  rmcomprandy on Tue Dec 11, 2012 12:06 pm

460pulling wrote:Now well i took my a460 block and its bored 4.39. I know i should run atleast a 4.44 bore to avoid shrouding since the a460 heads i am getting have 2.35 intake and 1.88 exhaust valves. I can run any displacement.
for a pulling truck which crank would be best? 4.14, 4.3, 4.5

Do the math ... it is all about power to the driving wheels.

This depends upon a lot more than stroke.
The induction, engine power output and RPM along with multiplying the gear ratio used in the differential for all the different engine combination RPM levels will determine what is best for you.

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Re: rotating assembly

Post  460pulling on Tue Dec 11, 2012 3:58 pm

Ok i see what your saying.

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