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Old 04-02-2024, 04:30 PM
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Default Cylinder Offset Changes Everything

This video does a great job of explaining what happens as a result of offset.

https://www.youtube.com/watch?v=gwtZkHoVMso

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Old 04-02-2024, 07:16 PM
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Very interesting.

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Old 04-02-2024, 09:26 PM
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Wonder how hard balancing wood be?

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Old 04-02-2024, 10:42 PM
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I racked my brain on the optimal CYL angle away from the crank CL. Seem there could be advantage to the cyl pointing toward the rod throw to improve TQ-Arm eff.

But it gets complicated. There is a pony in the poke.

I don't recall balance being a complication. TQ-arm eff IMPROVEMENT across the meaningful CYL PSI makes all the diff. I recall TDC and the cam durations, LSA are effected.

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Old 04-03-2024, 12:01 AM
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Haven't all Pontiac V8 engines since 1955 had about 1/16" cylinder offset?

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Old 04-03-2024, 12:30 AM
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Inline would be easy to offset, but a V
configuration complicates things. Even
our 194 is offset 45°.

OHC6, or Iron Duke?

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Old 04-03-2024, 12:30 AM
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Quote:
Originally Posted by Jack Gifford View Post
Haven't all Pontiac V8 engines since 1955 had about 1/16" cylinder offset?
This video was talking about a noticeable crank offset

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Old 04-03-2024, 01:01 AM
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Just so you know, Suzuki does not offset its cranks. Honda has a 4.5mm offset. KTM and Husqvarna use 5mm of offset. Kawasaki has 8.5mm of offset, and the Yamaha YZ450F offset is 12mm.

https://motocrossactionmag.com/ask-t...-crank-offset/

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Old 04-03-2024, 03:40 AM
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I've watched a ton of that guy's stuff over the last couple of years. He explains things very well.

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Old 04-05-2024, 08:14 AM
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Stan, have you analyzed TQ-Arm eff vs CYL offset from the Mains CL? That would be an eye opener to optimize vs Stroke & Rod length.

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Old 04-05-2024, 10:35 AM
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Mark,
I have some calculations in my software that I coded sometime ago, but am not sure just how accurate they are.

If you still have my software. You can play around with them on the Comp Gauge screen and let me know what you think.

Stan

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Old 04-05-2024, 11:04 AM
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The only offset I recall analyzing in labs at GMI was wrist pin offset. This was done to reduce cylinder wall wear more than anything. The cylinder bores were always on the main bearing centerline of the crankshaft though.

One interesting finding during development of the 301 was confirmation that the combustion forces on the main bearing cap were always higher than the balancing load needed to offset rotational forces. That justified removing the crankshaft counterweights on that engine in an effort for better fuel economy.

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Old 04-07-2024, 08:19 PM
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Default Interesting Video- More questions

Great video, are Pontiacs offset? Also, Pontiacs are known to have more torque than other makes with same displacement, is this due to a smaller piston and larger stroke?

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Old 04-07-2024, 09:22 PM
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@Stan, i still have your CARFOR SW, but have not run it in awhile (8years?), due to lack of relevant projects. I want to look at that Comp Gauge screen and trysome parameters,,if i only had the time. This Summer is going to be BUSY with work.

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Old 04-08-2024, 08:23 AM
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X72GPX it’s due to first off the longer strokes that Pontiacs have then other brands on there street production motors.

For example a 455 Buick has a 3.90” stroke as compared to the Pontiac 455 stroke of 4.210”.

Secondly pontiacs rod center to center is a long 6.625” which favors low speed power.

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Old 04-09-2024, 09:16 AM
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PMDs TQ; yea, long STROKE with Long Rods, then add tall rectangular ports (not round) with a decent Squish chamber+slug Flats sending the mix toward the Spark+ kernel.

And a smokin great Intake, even the 2-bbls.

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Old 04-15-2024, 09:47 AM
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Didnt flathead fords have a ton of crank offset? like .250"?

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Old 04-15-2024, 11:42 AM
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Excellent video.

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