Safe RPM for 383 - Team Camaro Tech
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post #1 of 13 (permalink) Old Feb 7th, 01, 08:21 AM Thread Starter
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What is a safe upper RPM limit for a 383 with 4 bolt mains, Scat crank, and stock 5.7 rods?

Thanks,

Ray
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post #2 of 13 (permalink) Old Feb 7th, 01, 08:24 AM
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6k

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post #3 of 13 (permalink) Old Feb 7th, 01, 09:20 AM
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When I dyno'ed mine it hit the top torque at 4700 and top HP at 5200, was 408 lbs and 362 HP no sense in trying to squeeze more that those rpms
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post #4 of 13 (permalink) Old Feb 7th, 01, 10:48 AM Thread Starter
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Yes, but those rpm figures would depend on what cam, intake, heads, etc. you were using. I want to know what a safe upper rpm is for the bottom end so I will know what rpm to target the cam at.

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post #5 of 13 (permalink) Old Feb 7th, 01, 11:11 AM
 
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you need to tell us what type rods and crank you are using etc,forged, cast, 5140,4340,then we might be able to tell you a rpm.
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post #6 of 13 (permalink) Old Feb 7th, 01, 12:53 PM Thread Starter
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Scat crank, stock GM 5.7 rods, KB Silvolite pistons. The Scat crank should be familiar to many here. (That's all I know about the rods.)

I had the shortblock built in 97, but have been using a TPI which has a low RPM capability. I have recently changed to a TPIS MiniRamII intake which can support a much higher rpm. I need to know what a safe rpm is so I can use as much of the rpm as possible that the new intake supports. I need this info to decide on a new cam and so I don't break anything reving to high.
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post #7 of 13 (permalink) Old Feb 7th, 01, 01:05 PM
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I have stock GM rods in my stroker along with a scat crank. The builder that put my engine together said the rods were the limiting factor in the lower end and he felt it should live @ 6500 but 6000 was a more reasonable number.

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post #8 of 13 (permalink) Old Feb 7th, 01, 03:22 PM
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I would have to agree, the 383 is not much for rod to stroke ratio but the chevi is a strong rod so it should live very wellat 6,000 and even higher for short bursts(6300)

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post #9 of 13 (permalink) Old Feb 7th, 01, 03:23 PM
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dam, I meant "CHEVY"!
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post #10 of 13 (permalink) Old Feb 7th, 01, 04:02 PM
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That little icon with the pencil at the top of your post will let you edit it!
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post #11 of 13 (permalink) Old Feb 7th, 01, 05:02 PM
 
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What you are searching for is very easy: It's called MAXIMUM AVERAGE PISTON SPEED. For using stock smallblock chevy parts you should keep your maximum average piston speed at 4000 feet per minute (FPM). The formula for doing this is simple: (CRANK STROKE x RPM)/6. That will give you your maximum average piston speed. Then to determine the ENGINE RPM at a maximum average piston speed of 4000 FPM is: 24,000/ STROKE. So the maximum RELIABLE rpm for a 383 with stock parts is 6382 rpm. For a 350 it's 6897 rpm. For a 327 it's 7385 rpm. For a 302 it's 8000 rpm. A 283 is also 8000 rpm. Look at these numbers and think. You will see they are very close to what everyone for years have turned these engines with no problems. Hope this answers your question.
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post #12 of 13 (permalink) Old Feb 8th, 01, 03:51 AM Thread Starter
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Thanks everyone.

This helps alot.




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Ray

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post #13 of 13 (permalink) Old Feb 8th, 01, 08:33 AM
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see i was right first!

[This message has been edited by Chris Edwards (edited 02-08-2001).]
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