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Re: Speed Pro forged aluminium pistons - Any good? [Re: vinnyd76] #2433374
01/12/18 01:58 PM
01/12/18 01:58 PM
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Porter67 Offline
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Its been shown over the years and ive seen it first hand if you take out the shortened compression height of the stroker pistons that factors in them being really light a oem CH performance piston vs a old trw produces a very minimal difference in performance and if good machine work is done and some common sense is used they are not too hard on parts either.

I myself will use all the old trw-s at $300 a set for street builds vs the now $800 diamonds that were $500 just a few years ago for the same piston.

Look how the stock 340-s ran and reved and look at there oem piston weight.


Re: Speed Pro forged aluminium pistons - Any good? [Re: DaytonaTurbo] #2433378
01/12/18 02:04 PM
01/12/18 02:04 PM
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There is no question that the Speed Pro and old TRW forged pistons are solid and reliable. They are stable and will take a lot of abuse. Literally millions of them have been put into service through the years. At one time they were the only forged pistons that were readily available for many engines. My gripe with them is mainly in two areas, weight and recently, cost.

The 318 piston/pin in the picture weighs 767 grams, according to the scale. Stock weight of a 318 piston is 591 grams. Stock weight of the pin is something like 170 grams. So the piston is a stock replacement weight.

Mopar pistons and connecting rods were nothing if they weren't heavy. The 720 gram 340 piston is my prime example. That's without pin. Another example is the LA's 645 connecting rod. At 758 grams, it is fat. Even the early 318 skinny rods were 726 grams. It isn't hard to buy a new rod at least 100 grams lighter. If you look you can shave off 150 grams per rod.

In Mark's Mechanical Engineering Handbook in the Automobile section I first ran across the concept that at a certain gear ratio it takes as much power to accelerate the engine rotating parts plus rotating parts of the drivetrain as it takes to accelerate the entire mass of the vehicle.

This puts a new light on rotating mass.

R.

Last edited by dogdays; 01/12/18 02:09 PM.
Re: Speed Pro forged aluminium pistons - Any good? [Re: vinnyd76] #2433391
01/12/18 02:31 PM
01/12/18 02:31 PM
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fredericksburg,va
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They are already in there guys,
if the price is right, buy the thing, nothing wrong with them.
If starting new, that's a different thing.

Re: Speed Pro forged aluminium pistons - Any good? [Re: vinnyd76] #2433397
01/12/18 02:42 PM
01/12/18 02:42 PM
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fredericksburg,va
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cudaman1969 Offline
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Mark's Mechanical Engineering Handbook in the Automobile section I first ran across the concept that at a certain gear ratio it takes as much power to accelerate the engine rotating parts plus rotating parts of the drivetrain as it takes to accelerate the entire mass of the vehicle.

The reason people run in light weight shoes instead of work boots. The reason Greek Olympians competed in the nude. (Filled up the stands too)
I could go on.

Re: Speed Pro forged aluminium pistons - Any good? [Re: vinnyd76] #2433507
01/12/18 05:25 PM
01/12/18 05:25 PM
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Manitoba, Canada
DaytonaTurbo Offline
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I guess the beef I have with that idea is a 440 with heavy forged TRW's will, in neutral, rev up from idle to 6000rpm in a fraction of a second. Astronomically faster than it will ever accelerate the car. If that's the case would lightweight internals make a difference on ET at the track? I don't have any practical experience to say yes or no but I would sure be interested if anyone knows of an article where someone built an engine with heavy pistons, ran it at the track then swapped in identical but lightweight guts and ran it again.

I'm sure there is a rate of vehicle acceleration that would be equivalent in terms of energy consumed to that required to accelerate the internals but that rate could be something imperceptible.

Re: Speed Pro forged aluminium pistons - Any good? [Re: 340Cuda] #2433533
01/12/18 06:19 PM
01/12/18 06:19 PM
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Shopping @ HoBo Fright
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Originally Posted By 340Cuda
I think those are the same as what used to be called TRW. If so, used them a lot in the distant past. No problems at all other than they were heavy and we often had to cut the valve reliefs deeper for roller cams.

Bill

I used a set of TRW they were heavy and thick. But strong I had them milled to have a 340 zero deck with closed chamber heads


[img]https://i234.photobucket.com/albums/ee87/fast340six/sig%20pics/2840886-340SIX-1.jpg[/img]
VP of the MPM in New Orleans
73 Dart Sport 340/ 70 challenger vert. That may still get built, If I live long enough
Re: Speed Pro forged aluminium pistons - Any good? [Re: vinnyd76] #2434467
01/14/18 03:53 PM
01/14/18 03:53 PM
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Not mine, heavy but a good deal at 250 shipped if on a budget and I think this number is a ihra? approved 340 piston.

https://www.ebay.com/itm/Set-of-8-Pistons-for-340-Chrysler-Engine-2332P-040/273013813461?hash=item3f90e430d5:g:BVoAAOSwXOhaUO4q&vxp=mtr

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