LowDeck451
Well-Known Member
On one of his videos from a day or two ago he’s in a wrecking yard trying to find a 360 Magnum to test performance mods on and try the piston reversal idea. Should be fun!
Richard Holdener to test the Piston Reversal theory
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Posted it a little while ago in a reply here;
UTG engine build "callout"
I’m looking forward to this myself. I like the non Chevy videos.
UTG engine build "callout"
I’m looking forward to this myself. I like the non Chevy videos.
I want to see just how he does it and what the results are. Oughtta be interestin.
Next question, do the Magnums have offsets?
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LowDeck451
Well-Known Member
My question is, are the performance aftermarket piston pins offset differently from a production piston to take advantage of this ‘power gain’? I honestly don’t know but I bet they would do it if there’s a gain to be had.
Supposedly, yes....but the argument rages on about any power advantage. I've heard of it, read it and seen people do it for so long, you kinda have to wonder if it's not true.
pishta
I know I'm right....
"...In one of the 'Direct Connection' engine seminars years ago, legendary Chrysler engineer Tom Hoover said ..... that reversing the piston creates a bit more torque but also creates more cylinder wall wear..." Tom Hoover...who is he? 
LowDeck451
Well-Known Member
Yeah, I read it in the Mopar Performance book years ago and have no reason to doubt it, but I’m on the fence about now lol. IIRC, Uncle Tony said the power gain won’t show on a dyno test, but would in a car, and Richard says if it’s true, it WILL show up on a dyno because that’s what a dyno is for. Kinda makes sense lol.
I absolutely agree with Richard. It doesn't take a genius to understand if it shows up in the CAR, it would certainly show up on the dyno.
OEM is offset
Aftermarket is centered
Topless69
Well-Known Member
I agree with this also. I believe you would see gains/losses on a Dyno before you would notice it in a car.
Dartswinger70
Well-Known Member
Well, it looks like someone is going to finally put this one to bed...i suppose if there is an inkling of gain Uncle Tony is off the hook...
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replicaracer43
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chryslerfat
Well-Known Member
Waiting myself to see if legend holds true
I ran a 1971 demon with 340 that had pistons turned around so notches were at the rear...ran super strong but had a ping sound because pistons were coming up and hitting barely....gobs of power and incinerated tires @ 35mph with 727/3000/ man valve body and 3.55's
my68barracuda
Well-Known Member
Why would that be, UT just regurgitates what he hears. As mentioned above other folks have said reversing off set pistons will show a slight power increase for years, this is not new information. Anyone the understands what the ‘ thrust side’ of a cylinder is will understand why. For the guy searching for a junkyard engine to run a test. A well worn bore and piston will not show much change, why? Because the piston and bore are worn and there will be excess piston clearance regardless of how the piston is installed. A meaningful test would require pistons-rings-bores well within new factory specifications.Well, it looks like someone is going to finally put this one to bed...i suppose if there is an inkling of gain Uncle Tony is off the hook...
Exactly. So reversing aftermarket (performance) pistons won't make a bit of difference.
As for reversing factory pistons, which are offset to reduce piston slap when cold, that is a trick that's been in the Mopar Performance Engine Manual since I was a young man. Uncle Tony didn't come up with the idea on his own. Reversing the factory piston reduces friction some (probably small) amount. How much performance is gained, don't know, but any kind of performance build is gonna replace the factory pistons anyway, so why worry about it unless you're on a super tight shoestring budget?
You have to remember this was from the 70's- 80's, back then you had the D.C. Bible or someone that's done it. No forum rumor mill stuff back then. Iirc Hamburger or mancini told me flipping the pistons was like 7 hp, we flipped them all the time,was it worth it? I don't know, no dyno, circle track stuff so no track times or anything, you just did it with stock pistons. Also, custom pistons were like $600, I don't remember what trw forged were but they also were pricey for a guy that didn't probably have $1000 in the whole car. Will be cool to see what Richard comes up with!
Dartswinger70
Well-Known Member
Only thing I have to say is, junkyard engines are already loose so it would still be a waste of time flipping pistons in one.
replicaracer43
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And I'll say it AGAIN.......what kind of "performance" engine build uses cast pistons .050 in the hole and a cam so small you dont need valve reliefs?
pishta
I know I'm right....
I get that guys pop ups on my browser all the time. Someone post the link if i miss it. Nicks garage should also do it, I tend to believe his stuff more than most as he has nothing to gain, just showing the data. He still dynos a lot of stock build motors only for the sake of finding out if the specs are correct in the manuals. Usually they are very close but it seems most Mopars exceed the printed values.
He did a customers 351C (added a 4bbl carb and intake only) and I was surprised how low it really was, right inline with the printed data ~ 280-300 HP? Yeah I know there were many flavors of the 351c.... 2bbls and all.. 72 lower-po 340 with a cast iron intake and early 2.02 heads... 370/383 ft-lbs. Stock cam and small tube headers.
He did a customers 351C (added a 4bbl carb and intake only) and I was surprised how low it really was, right inline with the printed data ~ 280-300 HP? Yeah I know there were many flavors of the 351c.... 2bbls and all.. 72 lower-po 340 with a cast iron intake and early 2.02 heads... 370/383 ft-lbs. Stock cam and small tube headers.
True..... But!!!....
What kind of “Class” in racing would require stock pistons? Ether today or yesteryear?
As mentioned above.... the super right on budget would seem these kinds of tips and tricks.
In my head, if I had to run a stock piston & bore size, then the cams I’m looking at are low lift.... stock-super stock class type cams I think. Long duration and stock lobe lift.
True for the “LA” engine, not so much for a Magnum engine, mileage dependent maybe? IDK!
All in all, a good used core is going to be a Magnum IMO and I think you could build quite a runner with the base long block.
Dartswinger70
Well-Known Member
Well you know there will be a feller who goes to a local garage and asks the mechanic to "flip my pistons". The mechanic will say "why" the feller will say " " I want flipped pistons are you going to do it or wha...?"...
TT5.9mag
Two atmospheres are better than one
For what it’s worth my junkyard magnum when torn down showed very little measurable bore wear or taper at 91,300 verified miles. Rod bearings showed a little scuffing, main and cam bearings looked brand new. Measured factory ring gap on all 8 top rings and all were 020-024.
Notches At the rear..??
Oh, I thought you were talking ‘valve’ notches.
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