UTG engine build "callout"

[replicaracer43]

Ok, what we have here is a typical run of the mill 318, although this is a magnum variety, a 94 casting I believe. This engine is here in order to grow in to a 390 inch mill, but that's another story. With the stock crank, and std bearings in place, the piston is "in the hole" .052 as installed from the factory, notch to the front.... Flipping the piston around, it measures .053 in the hole, with the notch to the rear. So a grand total of .001 difference, and then consider your running probably. 0025-.0030 rod bearing clearance, I'd say its basically "net zero" I did confirm the piston has wrist pin offset, although I didn't measure the amount, the .060 @RustyRatRod spoke of is pretty close.

 

[RustyRatRod]

Ok, what we have here is a typical run of the mill 318, although this is a magnum variety, a 94 casting I believe. This engine is here in order to grow in to a 390 inch mill, but that's another story. With the stock crank, and std bearings in place, the piston is "in the hole" .052 as installed from the factory, notch to the front.... Flipping the piston around, it measures .053 in the hole, with the notch to the rear. So a grand total of .001 difference, and then consider your running probably. 0025-.0030 rod bearing clearance, I'd say its basically "net zero" I did confirm the piston has wrist pin offset, although I didn't measure the amount, the .060 @RustyRatRod spoke of is pretty close.

View attachment 1715739056

View attachment 1715739057

Oh ok. You measured the whole ball of wax. The whole enchilada. The whole shootin match. I really couldn't get an "accurate" measurement, because the jaws of my dial caliper aren't really lone enough and couldn't get the the center of the skirt. But you measured the sho nuff deck clearance. I knew it wouldn't be much. Nuff said.

 

[replicaracer43]

But looking at my pictures, it looks like .048 and and .053, in which case its .005 difference, +or- your rod bearing clearance. Damn it's been a long day

 

[replicaracer43]

And thinking it over more, I need to re measure it tomorrow with the engine on a stand, and the piston level, that block sitting on its side is introducing some variation that's probably skewing the numbers

 

[RustyRatRod]

And thinking it over more, I need to re measure it tomorrow with the engine on a stand, and the piston level, that block sitting on its side is introducing some variation that's probably skewing the numbers

Either way though, it's splittin hairs. It ain't addin nuthin for compression.

 

[replicaracer43]

Either way though, it's splittin hairs. It ain't addin nuthin for compression.

I agree, I mean, if the pin is offset WHATEVER amount from the center, then swapping it is just moving the offset to the other side, (same amount off of true center) I would expect the measurement to be the SAME, and I probably frigged up with my last minute setup there.

 

[rumblefish360]

Steve has to worry about how his action impact Motor Trend which, in my opinion, why he didn't call out Tony by name.

You did hear him say Former Automotive Journalist, which is Tony.

I heard it. Couldn’t miss it.

 

[Dartswinger70]

the one feller said his valuves hit the Pistons on his 340. Someone else replied." Pistons weren't in backwards ?" I almost replied " he wasn't watching UTG was he" but I dint...I didnt..

 

[318willrun]

And thinking it over more, I need to re measure it tomorrow with the engine on a stand, and the piston level, that block sitting on its side is introducing some variation that's probably skewing the numbers

Either way though, it's splittin hairs. It ain't addin nuthin for compression.

But compression isn't the advantage they are looking for, is it??? I thought it was to have a better angle on pushing the crank down on the power stroke ???? That was my understanding of the old trick from DC... I could be wrong.

 

[replicaracer43]

But compression isn't the advantage they are looking for, is it??? I thought it was to have a better angle on pushing the crank down on the power stroke ???? That was my understanding of the old trick from DC... I could be wrong.

It's been mentioned in this thread numerous times that it's to help compression, but it surely doesn't. And the angle the rod pushes on the crank changes throughout the stroke, so I doubt that amounts to anything either

 

[RustyRatRod]

But compression isn't the advantage they are looking for, is it??? I thought it was to have a better angle on pushing the crank down on the power stroke ???? That was my understanding of the old trick from DC... I could be wrong.

No, right. Someone was quoting one of the other guys who said that it also somehow "magically" raised the piston in the bore. You're absolutely correct though, just the flip itself is "supposed" to reduce some friction and free up a little power. That's what I've heard from TONS of people through the years. I have some old dirt track friends who have SWORN by it for years......and they were coincidentally some of the best racers out there.

 

[318willrun]

It's been mentioned in this thread numerous times that it's to help compression, but it surely doesn't. And the angle the rod pushes on the crank changes throughout the stroke, so I doubt that amounts to anything either

yeah, really it would have to be put to rest by a dyno test. Somebody, somewhere, that has a dyno will get a million of views on youtube for doing this experiment!!! Calling Nick's Garage..... LOL

 

[RustyRatRod]

yeah, really it would have to be put to rest by a dyno test. Somebody, somewhere, that has a dyno will get a ton of views on youtube for doing this experiment!!! Calling Nick's Garage..... LOL

I just cannot see anyone paying dyno time to see what flipped CAST pistons will do. You'd have to have two otherwise identical engines, OR tear the same one down and flip the pistons and dyno it both ways. What a headache to find out a 3HP difference......OR that it looses power OR remains the same. Totally not worth it.

 

[yellow rose]

It's been mentioned in this thread numerous times that it's to help compression, but it surely doesn't. And the angle the rod pushes on the crank changes throughout the stroke, so I doubt that amounts to anything either

If the .060 offset was the equivalent of a .060 longer rod, you’d be damned hard pressed to find a single horsepower by flipping it around. Going from a 5.700 to a 6.000 or even a 6.125 rod needs more than just a rod change to find any real power. It’s not just change one magic thing and you start knocking down records, winning all the trophies and kissing the girls.

Just flipping the piston would be way outside of measurable error on any dyno.

 

[RustyRatRod]

If the .060 offset was the equivalent of a .060 longer rod, you’d be damned hard pressed to find a single horsepower by flipping it around. Going from a 5.700 to a 6.000 or even a 6.125 rod needs more than just a rod change to find any real power. It’s not just change one magic thing and you start knocking down records, winning all the trophies and kissing the girls.

Just flipping the piston would be way outside of measurable error on any dyno.

S'what I'm thinkin too.

 

[318willrun]

If the .060 offset was the equivalent of a .060 longer rod, you’d be damned hard pressed to find a single horsepower by flipping it around. Going from a 5.700 to a 6.000 or even a 6.125 rod needs more than just a rod change to find any real power. It’s not just change one magic thing and you start knocking down records, winning all the trophies and kissing the girls.

Just flipping the piston would be way outside of measurable error on any dyno.

well then, the argument shall continue for the ages until electric 1 seater Honda's fill every driveway. Until then we'll have 3 type of "I"'s. I have, I have not, I don't know !

 

[replicaracer43]

Not to mention ANY "real" performance engine build includes increased compression, and a bigger camshaft that will normally require valve reliefs, preventing flipping them, and i doubt any good performance piston has the pin offset anyway. so it's a pretty low effort build that "could" even benefit from this idea. Like, it sounds good in theory, but in the real world it's a waste of time.

 

[replicaracer43]

And I'd bet the rings in the "magnum" 318s would make more power difference than anything else in a dingle berry hone rebuild, especially since the bores are normally pretty nice on those compared to a carbureted 318 from the 70s

 

[318willrun]

And I'd bet the rings in the "magnum" 318s would make more power difference than anything else in a dingle berry hone rebuild, especially since the bores are normally pretty nice on those compared to a carbureted 318 from the 70s

Maybe magnum pistons in a LA would be the real "clicker" ??

 

[rumblefish360]

I like that idea......

 

[Topless69]

I just cannot see anyone paying dyno time to see what flipped CAST pistons will do. You'd have to have two otherwise identical engines, OR tear the same one down and flip the pistons and dyno it both ways. What a headache to find out a 3HP difference......OR that it looses power OR remains the same. Totally not worth it.

EXCEPT maybe for the clicks...

 

[RustyRatRod]

Maybe magnum pistons in a LA would be the real "clicker" ??

As long as you make up the difference for the compression loss. Remember, the Magnum has a shorter deck height and the Magnum pistons a shorter compression distance. It's not a ton, but there is a difference.

 

[rumblefish360]

And unbelievably, as we speak of this piston flipping test, Rich H is searching the junkyard for a 5.9 to go on a Dyno.
Click this..... Thank you Rich!

 

[replicaracer43]

After a good nights sleep, I leveled up the block "sorta" and remeasured, and again, being a little more precise, its basically "net zero" as far as any compression increase.

 

[Dartswinger70]

Wasnt flipping pistons done in order to reduce drag or friction? Uncle Toney says a lose engine is a happy engine...