STop me before crank destruction!

The chamber pressure peak should occur at TDC (assuming the AAU is doing its job), so directly opposite would seem the logical place to put your sensor. However, with rotational energies added in, it's hard to say where it may truly land without some kind of practical testing. I'd be inclined to insert a sacrificial plastic ring or nubs around the crankcase, wind the snot out of it, then see where lies the biggest gap. That would point to where you might want to place your sensor.

On a side note, BeltDriveMan adds credence to your insistance about wet sumping/cold starts, on which I agree with you.

beltdriveman said:

'The camshaft tunnel of the Dominator engine was designed to retain as much oil as possible and the lip was designed to run within 1/8 -3/32 of the flywheel rim to pick up oil from it'.

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Nathan

I hope others are savoring the silly relief side of life with me. Nater Boy Howdy have I thought of sacrificial rub witness blocks, to point of making them of babbit bearing material to let the collisions just slide by flooded by oil storm, ugh, then clac'd the surfaces translation speeds to see it'd ignite the oil layer by pressure detonation then burn Al and steel by the superheated plasma jets of the exploding babbit metal. Main thing though was thought of having to take cases apart to check every 500 rpm after 7000 till chickening out or blowing up.

Flywheel goes mostly up/dn in its deflections but mostly upward arc with pistons at BDC which means unless the bearings or cases fracture, the crank ends are deflecting oppositely, which means its more the centrifugal force of rpm slinging on out of balance flywheel than the added secondary piston jerk inertia. Boosted engines are known tolerate higher rpm d/t their pressure cushioning effect on crank shaft that's similar to lowering its out of balance factor. Sensors should be at bottom or near top of flywheel or may mis lead on the max deflections occurring.

I'd sure like to know what rpm Peel crank deflects 1/8" to have some idea of how much intervals of time I might chance at 1/4" deflection say trying to tear up someone's shaft dynometer. Part of Peel duties while trying to spank big fat tire cycles is not leaking, smoking or leaving qualify parts behind just the surprised pilots. If not then Peel's a failure but sure was fun shooting for the moon.

hobot said:

making them of babbit bearing material to let the collisions just slide by flooded by oil storm, ugh, then clac'd the surfaces translation speeds to see it'd ignite the oil layer by pressure detonation then burn Al and steel by the superheated plasma jets of the exploding babbit metal. Main thing though was thought of having to take cases apart to check every 500 rpm after 7000 till chickening out or blowing up.

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It's for those very reasons that plastic would be "safer" than something metal. I'd try Ultem, which is stable, easily machinable (read, cuts cleanly), and won't create an internal inferno. As for every 500 rpm, shoot, just crank it 'til the valves float. Mine come on around 6500rpm (don't ask me how I know).
If, in fact, the crank is inclined to flex upwardly, build a witness mark block on the bottom of the barrels. People will argue about how to isolate the jug flexure, but at least it wouldn't require a complete teardown to check.

Yep Nater that was plan A, just tap a smallish hole and screw in a nylon or fancy plastic til it stops then turn out by thread count and rev er up to run it back in noting the extra amount that might of been removed. If I live long enough I know final solution to crank flex that'd still fit in cases and also eliminate all piston rock so on top pin needed. Past Peel could run into tire expansion rates so will put stiff foam around tire to measure that, though I expect no fouling or axle flex. Oh yeah I've saved a used pair of plastic toilet lid bolts for this use as gotta wipe away at least one of em.

So if revs kept to 1/8" might live for 1000's of hours, 3/16" a few hundred and at 1/4" might make it to the end of full out sprint to top or around a flat track pinning ears back. Now just need some real numbers to associate.

Only scanned this enough to see if might apply to us so hope someone points out where it might.
http://marinesite.blogspot.com/2013/10/ ... shaft.html

hobot said:

Only scanned this enough to see if might apply to us so hope someone points out where it might.
http://marinesite.blogspot.com/2013/10/ ... shaft.html

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This looks more like a means of cataloging static crank deflection as a means of tracking bearing wear and/or bent cranks. Since it can't be done at speed, there's no way of knowing where in the rotation it might happen. Keep searching; it's bound to be out there somewhere! That or you'll be the one pioneering this.

Nathan

Ugh, if I live long enough I'll fix the crank flex rpm issue and a few more weaknesses at once. Here's the main teaser to begin with.

[video]http://www.youtube.com/watch?v=0H0stoFw3DY[/video]

Nater_Potater said:

The chamber pressure peak should occur at TDC (assuming the AAU is doing its job),
SNIP

beltdriveman said:

'The camshaft tunnel of the Dominator engine was designed to retain as much oil as possible and the lip was designed to run within 1/8 -3/32 of the flywheel rim to pick up oil from it'.

Click to expand...

Nathan

Click to expand...

sorry if this is to picky for some...
1. If you look at a pressure pulse curve of a 4 stroke you will see the pressure pulse is significantly after TDC...not AT tdc.

2. Examination of my unmolested 1950 model 7 engine (and the 51 and 52) and the 1959 88 engine show the flywheel to cam tunnel clearance about double what is claimed. Therefore the reported design concept... IMO... did not make it into production. Also the tunnel/trough in my early production NHT will easily and almost totally drain out at the case half joint and not retain any significant oil.