"hate this piston design"
#3206039
01/18/24 09:11 PM
01/18/24 09:11 PM
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Joined: Sep 2018
Posts: 170 West Palm Beach, Florida
Craig J
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Last week I was going to sell the crank, rods, pistons, fresh machined 0.030 over RB block to make a 493, and a local buyer informed me that his mopar consultant 'hates' this piston design.
I am a curious why these won't work in an 87 octane street car RB stroker application. Sorry the pics are sideways... technology has defeated me on fixing that...
Thanks Craig
Last edited by Craig J; 01/18/24 09:21 PM.
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Re: "hate this piston design"
[Re: Craig J]
#3206044
01/18/24 09:52 PM
01/18/24 09:52 PM
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Joined: Oct 2005
Posts: 273 Anchorage, Alaska
metallicareload
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Anchorage, Alaska
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I have heard an engine builder say they don't like dished pistons they didn't elaborate why. With a quench pad, I don't see why they would be much worse than flattops?
440, 4-Speed, 3.54 1968, when Dinosaurs ruled the Earth
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Re: "hate this piston design"
[Re: jwb123]
#3206046
01/18/24 10:11 PM
01/18/24 10:11 PM
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Joined: Sep 2018
Posts: 170 West Palm Beach, Florida
Craig J
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For a low compression street engine what is wrong with them? What kind of pistons are they Cast, Forged, or Hypereutectic? Lot of guys don't like Hypereutectic type pistons, but for a street engine not an issue, most stock engines now have hypereutectic style pistons, many old part number cast pistons have been replaced with hypereutectic style pistons. Just have to set a couple clearances different. Heck, I have used them with good success in mild drag engines. next question is what kind of chamber? If it is a 906 style open chamber, I would not like them either, no quench, if using a closed chamber head then again what is wrong with them? Pistons are forged 2618.
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Re: "hate this piston design"
[Re: AndyF]
#3206068
01/18/24 11:52 PM
01/18/24 11:52 PM
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Joined: Oct 2005
Posts: 273 Anchorage, Alaska
metallicareload
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If they were designed for open chambers there would be some kind of pop up dome right? These look like every other Big Block stroker piston which have a quench pad on the intake side, and a dish everywhere else. I would think a quench area around the spark plug would be beneficial, but what do I know, I'm a filthy street guy.
440, 4-Speed, 3.54 1968, when Dinosaurs ruled the Earth
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Re: "hate this piston design"
[Re: Craig J]
#3206089
01/19/24 03:35 AM
01/19/24 03:35 AM
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Joined: Aug 2003
Posts: 43,311 Bend,OR USA
Cab_Burge
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Last edited by Cab_Burge; 01/19/24 03:36 AM.
Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
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Re: "hate this piston design"
[Re: Craig J]
#3206187
01/19/24 01:26 PM
01/19/24 01:26 PM
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Joined: Dec 2006
Posts: 2,122 Byron, NY
W.I.N. Racing
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My guess is they don't like the grooves and trough cut in the OD. The grooves (as noticed in the pic) seem to be carbon collectors. Also noticed in the pic it looks as if there is a sharp edge at the face/OD interface
Last edited by W.I.N. Racing; 01/19/24 01:28 PM.
'01 P1500, Blown/Inj BAE,/Veney ,Bruno/CS2,Dana 60 '01 Dodge 3500 S Cummins Auto, Fresh air kit, 4" Exhaust, '05 Dodge Magnum R/T - Too Much to list '60 Willys CJ5 '01 International LPX - Project,DT466, Allison '64 Plymouth Valiant, Inj 528 Hemi, 2spd
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Re: "hate this piston design"
[Re: Craig J]
#3206197
01/19/24 01:44 PM
01/19/24 01:44 PM
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Joined: Jan 2003
Posts: 14,514 So. Burlington, Vt.
fast68plymouth
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Fundamentally, I like reverse dome/reverse step-dish type pistons…….. but I’m not loving the ring grooving on that particular set.
It wouldn’t keep me from using them though.
Icon shows the top ring land to be .350” from the top. Is that how far down those are?
68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123 Dealer for Comp Cams/Indy Heads
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Re: "hate this piston design"
[Re: AndyF]
#3206277
01/19/24 05:25 PM
01/19/24 05:25 PM
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Joined: Jan 2003
Posts: 14,514 So. Burlington, Vt.
fast68plymouth
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There is def something “not good” going on at the top edge.
Last edited by fast68plymouth; 01/19/24 05:26 PM.
68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123 Dealer for Comp Cams/Indy Heads
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Re: "hate this piston design"
[Re: slantzilla]
#3206298
01/19/24 06:18 PM
01/19/24 06:18 PM
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Joined: Jan 2003
Posts: 14,514 So. Burlington, Vt.
fast68plymouth
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What is the purpose of those grooves? Contact Reduction Grooves These grooves are machined into the top ring land above the top ring to minimize contact drag when the piston rocks over upon reversal. They add minimal volume to the crevice volume, and they also help resist detonation by disrupting flame travel into the crevice volume where pressure spikes might unseat the ring.
68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123 Dealer for Comp Cams/Indy Heads
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Re: "hate this piston design"
[Re: AndyF]
#3206386
01/19/24 11:28 PM
01/19/24 11:28 PM
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Joined: Sep 2018
Posts: 170 West Palm Beach, Florida
Craig J
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The grooves are a good idea, but it looks like the top groove was too high. Maybe a design error, maybe a machining error. I don't really know without seeing them. Sometimes pictures don't show everything. I believe the pistons I have are just an older version of this one from 440source. This discussion now has me a bit curious....I am certainly not a professional engine builder, and have never had an engine assembled in my garage on a dyno. Due to covid parts shortages I have a not very good combination in my car: 440 +0.032 (yes...32 over) with very old style L2295F30 TRW pistons, LY rods, 75 cc Performer RPM heads, a Hughes "real 6 pack" cam, performer 440 intake (fits under a flat e body hood) and iron hp manifolds. It has sky high cranking compression, but I think it would probably be safe on an engine dyno up to 6000 rpm with 112 octane fuel and conservative timing. If I can find a dyno around West Palm that would put up with my nonsense it would be amusing to make 3 pulls with this not so great ~12.1:1 440, then go home and put the same heads, intake, carb, exhaust manifolds, and cam onto this ~9.8:1 CR 493 with the 'hate' pistons and run it again on the same dyno to compare the results... does ~10% increase in displacement overcome ~20% lower static static compression ratio?
Last edited by Craig J; 01/19/24 11:37 PM.
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Re: "hate this piston design"
[Re: Craig J]
#3206409
01/20/24 01:38 AM
01/20/24 01:38 AM
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Joined: Jan 2003
Posts: 20,217 Park Forest, IL
slantzilla
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Park Forest, IL
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What is the purpose of those grooves? I have heard them referred to as anti-detonation grooves however, I do not know if that’s correct Thank you.
"Everybody funny, now you funny too."
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Re: "hate this piston design"
[Re: fast68plymouth]
#3206410
01/20/24 01:39 AM
01/20/24 01:39 AM
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Joined: Jan 2003
Posts: 20,217 Park Forest, IL
slantzilla
Too Many Posts
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Park Forest, IL
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What is the purpose of those grooves? Contact Reduction Grooves These grooves are machined into the top ring land above the top ring to minimize contact drag when the piston rocks over upon reversal. They add minimal volume to the crevice volume, and they also help resist detonation by disrupting flame travel into the crevice volume where pressure spikes might unseat the ring. Thank you too.
"Everybody funny, now you funny too."
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Re: "hate this piston design"
[Re: Craig J]
#3206444
01/20/24 10:00 AM
01/20/24 10:00 AM
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Joined: May 2005
Posts: 2,010 Apollo, PA.
B1MAXX
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The grooves are a good idea, but it looks like the top groove was too high. Maybe a design error, maybe a machining error. I don't really know without seeing them. Sometimes pictures don't show everything. I believe the pistons I have are just an older version of this one from 440source. This discussion now has me a bit curious....I am certainly not a professional engine builder, and have never had an engine assembled in my garage on a dyno. Due to covid parts shortages I have a not very good combination in my car: 440 +0.032 (yes...32 over) with very old style L2295F30 TRW pistons, LY rods, 75 cc Performer RPM heads, a Hughes "real 6 pack" cam, performer 440 intake (fits under a flat e body hood) and iron hp manifolds. It has sky high cranking compression, but I think it would probably be safe on an engine dyno up to 6000 rpm with 112 octane fuel and conservative timing. If I can find a dyno around West Palm that would put up with my nonsense it would be amusing to make 3 pulls with this not so great ~12.1:1 440, then go home and put the same heads, intake, carb, exhaust manifolds, and cam onto this ~9.8:1 CR 493 with the 'hate' pistons and run it again on the same dyno to compare the results... does ~10% increase in displacement overcome ~20% lower static static compression ratio? Cranking compression would probably still be up there with the same cam I bet.
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Re: "hate this piston design"
[Re: B1MAXX]
#3206730
01/21/24 04:21 AM
01/21/24 04:21 AM
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Joined: Sep 2014
Posts: 4,457 Washington
madscientist
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I called Icon about these pistons several years ago. For use with open chamber heads you can run the pad proud of the deck. On closed chamber heads you run them to zero deck.
They reduced the outer band as a way to increase piston volume while keeping the dish reasonably shallow.
That’s all it is.
Just because you think it won't make it true. Horsepower is KING. To dispute this is stupid. C. Alston
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