Piston massaging
#3147676
05/30/23 07:20 PM
05/30/23 07:20 PM
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Joined: May 2023
Posts: 15 Laredo, Texas
Cudatali
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Laredo, Texas
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Since we know the importance of an efficient head combustion chamber, as I see these pistons I can’t help but notice how much the air is going to bounce around due to the shape of this piston. Anyone ever smooth out the hard turns and sharp edges of this piston? Any idea how much it would affect the compression?
1970 Hemi Cuda 1971 Demon 340 1969 Road Runner 440 6bbl 2018 Demon 2021 Hellcat Durango 2023 Demon 170 soon!
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Re: Piston massaging
[Re: Cudatali]
#3147687
05/30/23 08:02 PM
05/30/23 08:02 PM
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Joined: Feb 2008
Posts: 717 Central TEXAS!!!!
sr4440
super stock
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super stock
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Central TEXAS!!!!
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I am not an expert, but I would be more worried about the pistons being installed with the valve pockets on the wrong side.
Joe
Without Data, you’re just another guy with an opinion.
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Re: Piston massaging
[Re: sr4440]
#3147692
05/30/23 08:26 PM
05/30/23 08:26 PM
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Joined: May 2023
Posts: 15 Laredo, Texas
Cudatali
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I am not an expert, but I would be more worried about the pistons being installed with the valve pockets on the wrong side.
Joe You know I just picked up this car and pulled the engine out to see what was all inside. I hadn’t even noticed that yet. Wow haha thanks for catching that. Lol this is getting more interesting by the minute. Decided to pull the cam out to identify and found the crank had a ridiculous amount of end play. Pulled the engine out and found the crank side journal wiped out along with cam bearings. Obviously I will now have to go through the whole engine. That situation kept me so side tracked I didn’t notice the pistons. Oh well. Thanks again 👍🏼 Still interested on piston smoothing feedback
1970 Hemi Cuda 1971 Demon 340 1969 Road Runner 440 6bbl 2018 Demon 2021 Hellcat Durango 2023 Demon 170 soon!
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Re: Piston massaging
[Re: sr4440]
#3147694
05/30/23 08:44 PM
05/30/23 08:44 PM
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Joined: Jan 2003
Posts: 6,151 Melbourne , Australia
LA360
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In a low compression N/A engine, it's not going to be an issue.
If it was a small chamber head, with a domed piston, I'd be wanting to remove any possible sharp edges and possible pre-ignition points. If it was an engine with several stages of nitrous, I'd be looking at enlarging the compressed area, to slow down the flame front.
A dished piston down the hole, with a factory chamber isn't going to encounter such issues.
Last edited by LA360; 05/30/23 09:20 PM.
Alan Jones
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Re: Piston massaging
[Re: sr4440]
#3147696
05/30/23 08:55 PM
05/30/23 08:55 PM
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Joined: Jan 2005
Posts: 12,424 Kalispell Mt.
HotRodDave
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I am not an expert, but I would be more worried about the pistons being installed with the valve pockets on the wrong side.
Joe Looks like there is 4 valve reliefs so they could be installed either way. I would have put em in the other way but it looks like they were made to go either direction.
I am not causing global warming, I am just trying to hold off a impending Ice Age!
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Re: Piston massaging
[Re: BSB67]
#3147722
05/30/23 11:23 PM
05/30/23 11:23 PM
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Joined: Aug 2019
Posts: 9,621 Super Spudsville
Mr PotatoHead
Half Baked
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Half Baked
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I was just going to post that. Although I have seen TRW replacement forged pistons with two different configs from TRW. Can the OP tell a bit more of the history of that motor or what the car was used for? Those are 2355 pistons, correct? Someone put a “D” dish in them
STOP POTATO HATE!
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Re: Piston massaging
[Re: LA360]
#3147723
05/30/23 11:57 PM
05/30/23 11:57 PM
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Joined: May 2023
Posts: 15 Laredo, Texas
Cudatali
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In a low compression N/A engine, it's not going to be an issue.
If it was a small chamber head, with a domed piston, I'd be wanting to remove any possible sharp edges and possible pre-ignition points. If it was an engine with several stages of nitrous, I'd be looking at enlarging the compressed area, to slow down the flame front.
A dished piston down the hole, with a factory chamber isn't going to encounter such issues. The plan is to install some aluminum heads, get compression between 9.5-10.0. Install a 22X-23Xish cam and a 6bbl setup. With that being said, Would CR close to 10:1 warrant the need for removal of sharp edges? Honestly it’s something I’ve always done even if it’s just the very sharp edges but the face of this piston really surprised me. Terrible design IMO. To answer the question of history of the engine, it is all unknown to me, I bought the car a few months ago and I felt it was overcammed, Removed cam to identify and pick something more to my liking and began to find multiple issues.
1970 Hemi Cuda 1971 Demon 340 1969 Road Runner 440 6bbl 2018 Demon 2021 Hellcat Durango 2023 Demon 170 soon!
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Re: Piston massaging
[Re: Cudatali]
#3147726
05/31/23 12:02 AM
05/31/23 12:02 AM
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Joined: Jan 2003
Posts: 6,151 Melbourne , Australia
LA360
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Do it if it makes you feel better, it's your time.
Is it going to make a noticable difference? No...
If you had 15 or 16:1, then it would be a must
Alan Jones
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Re: Piston massaging
[Re: Cudatali]
#3147728
05/31/23 12:12 AM
05/31/23 12:12 AM
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Joined: Aug 2003
Posts: 43,368 Bend,OR USA
Cab_Burge
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[quote=LA360] The plan is to install some aluminum heads, get compression between 9.5-10.0. Install a 22X-23Xish cam and a 6bbl setup. With that being said, Would CR close to 10:1 . I shoot for between 10.530 to 10.80 to 1 compression ratio on my non ethanol 91/93 octane pump gas BB builds with aluminum heads, that has work very well for me and my customers
Last edited by Cab_Burge; 05/31/23 12:12 AM.
Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
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Re: Piston massaging
[Re: Cab_Burge]
#3147730
05/31/23 01:13 AM
05/31/23 01:13 AM
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Joined: May 2023
Posts: 15 Laredo, Texas
Cudatali
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[quote=LA360] The plan is to install some aluminum heads, get compression between 9.5-10.0. Install a 22X-23Xish cam and a 6bbl setup. With that being said, Would CR close to 10:1 . I shoot for between 10.530 to 10.80 to 1 compression ratio on my non ethanol 91/93 octane pump gas BB builds with aluminum heads, that has work very well for me and my customers Thanks for the advice unfortunately I have no access to non ethanol in my area.
1970 Hemi Cuda 1971 Demon 340 1969 Road Runner 440 6bbl 2018 Demon 2021 Hellcat Durango 2023 Demon 170 soon!
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Re: Piston massaging
[Re: Cudatali]
#3147766
05/31/23 09:09 AM
05/31/23 09:09 AM
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Joined: Jun 2008
Posts: 3,916 usa
lewtot184
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they might work a lot better if they weren't installed upside down,.... . piston/rod assembly as a unit may be in backwards. i'd check for possible bearing/crank damage.
Last edited by lewtot184; 05/31/23 10:12 AM.
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Re: Piston massaging
[Re: mopar dave]
#3147776
05/31/23 10:34 AM
05/31/23 10:34 AM
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Joined: Jan 2003
Posts: 13,417 Marion, South Carolina [><]
an8sec70cuda
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The pistons may actually be installed "correctly". The arrow pointing "front" does appear to be pointing to the front of the engine, if that's the engine stand I see on the right side of the pic. Someone modified those L2355 "six pack" pistons by milling a dish in them...they are normally a 4 valve relief design. I've never seen a dish like that on the "top" side of the piston before, that would ruin any quench you may have had. It's possible whoever machined the pistons put the dish on the wrong side of 4 of them. It really won't hurt anything, just not the normal way of doing it.
CHIP '70 hemicuda, 575" Hemi, 727, Dana 60 '69 road runner, 440-6, 18 spline 4 speed, Dana 60 '71 Demon, 340, low gear 904, 8.75 '73 Chrysler New Yorker, 440, 727, 8.75 '90 Chevy 454SS Silverado, 476" BBC, TH400, 14 bolt '06 GMC 2500HD LBZ Duramax
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Re: Piston massaging
[Re: an8sec70cuda]
#3147780
05/31/23 11:07 AM
05/31/23 11:07 AM
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Joined: May 2023
Posts: 15 Laredo, Texas
Cudatali
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The pistons may actually be installed "correctly". The arrow pointing "front" does appear to be pointing to the front of the engine, if that's the engine stand I see on the right side of the pic. Someone modified those L2355 "six pack" pistons by milling a dish in them...they are normally a 4 valve relief design. I've never seen a dish like that on the "top" side of the piston before, that would ruin any quench you may have had. It's possible whoever machined the pistons put the dish on the wrong side of 4 of them. It really won't hurt anything, just not the normal way of doing it. Thanks for the insight as far as why they may be that way. I agree, the surface shape totally messed with the quench, You are correct the pistons are facing the correct way in the engine. No idea what the thinking was behind this but what began as a quick cam correction is snowballing into a full blown overhaul. I got way too many projects to add to my list LOL oh well, here we go!
1970 Hemi Cuda 1971 Demon 340 1969 Road Runner 440 6bbl 2018 Demon 2021 Hellcat Durango 2023 Demon 170 soon!
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Re: Piston massaging
[Re: Cudatali]
#3147805
05/31/23 12:34 PM
05/31/23 12:34 PM
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Joined: Jan 2003
Posts: 4,771 Moved to N.E. Tennessee
GomangoCuda
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Moved to N.E. Tennessee
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[quote=LA360] The plan is to install some aluminum heads, get compression between 9.5-10.0. Install a 22X-23Xish cam and a 6bbl setup. With that being said, Would CR close to 10:1 . I shoot for between 10.530 to 10.80 to 1 compression ratio on my non ethanol 91/93 octane pump gas BB builds with aluminum heads, that has work very well for me and my customers Thanks for the advice unfortunately I have no access to non ethanol in my area. If there are any boating areas around you check gas stations in that area for non ethanol gas.
In theory, there is no difference between theory and practice. In practice, there is.
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Re: Piston massaging
[Re: Cudatali]
#3147809
05/31/23 12:46 PM
05/31/23 12:46 PM
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Joined: Oct 2005
Posts: 277 Anchorage, Alaska
metallicareload
enthusiast
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enthusiast
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Posts: 277
Anchorage, Alaska
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In a low compression N/A engine, it's not going to be an issue.
If it was a small chamber head, with a domed piston, I'd be wanting to remove any possible sharp edges and possible pre-ignition points. If it was an engine with several stages of nitrous, I'd be looking at enlarging the compressed area, to slow down the flame front.
A dished piston down the hole, with a factory chamber isn't going to encounter such issues. The plan is to install some aluminum heads, get compression between 9.5-10.0. Install a 22X-23Xish cam and a 6bbl setup. With that being said, Would CR close to 10:1 warrant the need for removal of sharp edges? Honestly it’s something I’ve always done even if it’s just the very sharp edges but the face of this piston really surprised me. Terrible design IMO. To answer the question of history of the engine, it is all unknown to me, I bought the car a few months ago and I felt it was overcammed, Removed cam to identify and pick something more to my liking and began to find multiple issues. Depending on the size of the dish, getting a lot of compression might be “difficult”…. Wouldn’t it be “better” if the dish was underneath the spark plug and the quench pad matched up with the chamber?
440, 4-Speed, 3.54 1968, when Dinosaurs ruled the Earth
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Re: Piston massaging
[Re: an8sec70cuda]
#3147815
05/31/23 12:57 PM
05/31/23 12:57 PM
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Joined: Jan 2003
Posts: 14,515 So. Burlington, Vt.
fast68plymouth
I Live Here
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I Live Here
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So. Burlington, Vt.
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The pistons may actually be installed "correctly". The arrow pointing "front" does appear to be pointing to the front of the engine, if that's the engine stand I see on the right side of the pic. Someone modified those L2355 "six pack" pistons by milling a dish in them...they are normally a 4 valve relief design. I've never seen a dish like that on the "top" side of the piston before, that would ruin any quench you may have had. It's possible whoever machined the pistons put the dish on the wrong side of 4 of them. It really won't hurt anything, just not the normal way of doing it. The pistons can be swapped side to side, which will properly orient the dish and quench areas so there could actually be some benefit when swapping to closed chamber heads. The arrow would then be pointing towards the rear........ which some claim is beneficial as well.
68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123 Dealer for Comp Cams/Indy Heads
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