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Valve Overlap Specification Methods

Old 04-29-2018, 12:18 PM
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Default Valve Overlap Specification Methods

Hi ALL, I would like to state the Valve Overlap Amount Specification I use for quality engine performance.

I invite other methods to be shared, to help LS-1 tech Members.

I often fit a camshaft of 180/188 .525" on a 102 C/L
This engine operates at WOT for 25K hours.

MY Overlap specification is based on time spent at PTO vs WOT under the Mode of engine operation.

THUS at PTO there is a LOW overlap requirement. (low port air density)

The fact that runner lengths MUST also match is a major consideration.
The Exhaust Pressure (E-MAP) is a great concern for correct spectfication.


Other Thoughts ?

Lance
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Old 04-29-2018, 12:51 PM
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Originally Posted by Pantera EFI View Post
I often fit a camshaft of 180/188 .525" on a 102 C/L
This engine operates at WOT for 25K hours.
Hi Lance! First, just to clarify, PTO = Part Throttle Opening ?

What is an engine operated as above used for? Stationary industrial comes to mind. 25K hrs is a LOOONG time! lol
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Old 04-29-2018, 01:16 PM
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Originally Posted by G Atsma
Hi Lance! First, just to clarify, PTO = Part Throttle Opening ?

What is an engine operated as above used for? Stationary industrial comes to mind. 25K hrs is a LOOONG time! lol
We have large forklifts get there at the mill. They're 40k lb lift capacity at 4' away from mast and run non stop. Approx 7800 hours per year. We had one that the hour meter stopped at 14,981 and has been stuck on that number since 2011. That's our "little" one. It only has 33k loft capacity at 2'. It's much more maneuverable.

A cam like lance proposes makes a lot of sense in this application. These motors never exceed 2500 rpm or 20 mph.
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Old 04-29-2018, 04:28 PM
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I was thinking large stationary engines, but totally see it in a forklift! Long hours accelerating and decelerating, revving to lift, a super-mild cam would sure do it!
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Old 04-30-2018, 10:08 AM
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Default 1 Million Mile Engine

Hi ALL, yes this is a 1 million mile [email protected] MPH average.

True, the application is for CPS in Paris, Texas.
A Natural Gas pump, engine running on NG.
The engine is maintained, oil changes/filter changes WITHOUT ever being stopped !
This type of engine is fitted with my IGN-8 and ignition coils.
This engine's MAX RPM is 1800.

The Oil Pump is the first item to wear out.

To ALL, a good guess though the Overlap question requirement was not addressed ?

Lance
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