what would be a dream piston for the 'average' build?
- Thread starter earlbrown
- Start date
I'm shooting for under $600 with pins, locks, and rings. That's a little better than $950!
larrym
West Coast Newfy
- Joined
- Jul 17, 2007
I get that part there are many variables that affect the final ratio I just thought they had a higher compression piston available.
Here is the Wiesco part number I had saved for future reference PT120A2 I have a NA 109 I have plans for
I would be just as inclined to support your endeavors when the time comes if it means better parts for our cars. Picked up an oil pump that had been moded to your specs works like a dream.novaderrik
Well-Known Member
- Joined
- May 12, 2004
does it have a reverse dome in it that mirrors the combustion chamber shape with actual quench areas for more efficient combustion?
I get that part there are many variables that affect the final ratio I just thought they had a higher compression piston available.
Here is the Wiesco part number I had saved for future reference PT120A2 I have a NA 109 I have plans for
Those pistons have a 25cc dish. If you 'o decked' the block and ran .027" cometics you would have 9.06:1 with an 8445 head...... But that would put the pistons only 27thou from the head, so that's a no bueno. With .040" total those pistons would run 8.8:1. 9:1 is possible with those but barely. You'd have to remove lots of meat from the block and heads.
I'm looking at using 22cc total dish. That'll give a little over 9:1 with a stock stroke 3.805" at .040" total clearance. As the bore goes up (and stroke) the compression will increase accordingly.
Moving the piston up is the same as decking the block... But you can only get a piston so close to the head. With steel rods, once you get to .040", you really need to be on your toes going any closer than that. Piston rock, or any kind of rod stretch and ruin our day.
If you look at my math from last night, a 25cc slug .040" from a 49cc head is 8.8:1. The only way to get 9:1 with a 25cc piston is to shave at least 3cc out of the heads and set the pistons at .040".
The other downside to running real thin headgaskets, decking hell out of the block, and/or shaving the heads is having to machine the intake manifold (and having to get custom pushrods).
That's one of the cool things about this project I'm working on. With minimal decking and other metal removal it saves you from having to machine the deck, heads, and manifold to raise VE. Plus, if you have a block that's not gouged, it can go straight into the honing machine instead of having to pay to bore it and then honing it to size. (not to mention leaving more meat on the cylinder walls).
The pistons I ordered for my 454 jetboat engine will be here tomorrow and that's how I did it. I stuck the block in a square decking fixture (that I made ) and decked it until the lowest corner came clean and then stopped. Then I honed the worst hole till it was clean and made the other seven match. I knew I wanted my pistons .020" in the hole so I set the CH for that and got the OD at 4.256 so I'd have 4thou on my .010"over block.
If I had to pay for machining and was on a budget, I could have paid to have it honed and measure the existing deck heaight. Then ordered pistons for .020" in the hole/010 over. Saving the bore job money and the decking operation would almost offset the cost of the pistons. Plus this route leaves the deck thicker and the cylinder walls thicker. It's a win win
If you look at my math from last night, a 25cc slug .040" from a 49cc head is 8.8:1. The only way to get 9:1 with a 25cc piston is to shave at least 3cc out of the heads and set the pistons at .040".
The other downside to running real thin headgaskets, decking hell out of the block, and/or shaving the heads is having to machine the intake manifold (and having to get custom pushrods).
That's one of the cool things about this project I'm working on. With minimal decking and other metal removal it saves you from having to machine the deck, heads, and manifold to raise VE. Plus, if you have a block that's not gouged, it can go straight into the honing machine instead of having to pay to bore it and then honing it to size. (not to mention leaving more meat on the cylinder walls).
The pistons I ordered for my 454 jetboat engine will be here tomorrow and that's how I did it. I stuck the block in a square decking fixture (that I made
) and decked it until the lowest corner came clean and then stopped. Then I honed the worst hole till it was clean and made the other seven match. I knew I wanted my pistons .020" in the hole so I set the CH for that and got the OD at 4.256 so I'd have 4thou on my .010"over block.If I had to pay for machining and was on a budget, I could have paid to have it honed and measure the existing deck heaight. Then ordered pistons for .020" in the hole/010 over. Saving the bore job money and the decking operation would almost offset the cost of the pistons. Plus this route leaves the deck thicker and the cylinder walls thicker. It's a win win
Getting warmer. I've been wanting to put my hands on a set of their pistons for a while now. These are the custom units I ordered for my boat. The smallest size they started with was 30 over. I didn't want to bore my personal block so I honed it 10 over and they had no problem changing the OD to 4.260". Since I stopped decking my block as soon as it came clean I set the CH to put me .020" in the hole to match my .020" gaskets and give me as much compression as possible.
They came out of the box looking even better than I hoped. Normally I polish crowns and break any sharp edges by hand. Turns out the finish is awesome and there's no sharp edges that need attention. I couldn't even find any boogers from banging around or a machining error.
The forging looks great, I like how the oil groove looks, the packaging is great. I can't wait to beat the shit out of these pistons.
I think it's time to get with the main engineer and make a Buick print and make these things happen.
They came out of the box looking even better than I hoped. Normally I polish crowns and break any sharp edges by hand. Turns out the finish is awesome and there's no sharp edges that need attention. I couldn't even find any boogers from banging around or a machining error.
The forging looks great, I like how the oil groove looks, the packaging is great. I can't wait to beat the shit out of these pistons.
I think it's time to get with the main engineer and make a Buick print and make these things happen.
TurboTdr3.8
Well-Known Member
- Joined
- Jan 15, 2013
Sweet looking pieces , now we talking !!!!
I was holding back a little until I could put my hands on their work. I was thinking I'd find something I didn't like so I could address it before the print is made. Turns out I couldn't find anything I didn't like. One of the first things I do when I open a box of slugs is to squeeze the ring lands and run my thumb and finger all the way around the ring grooves. There wasn't one booger on any of the ring pack area.
If you look at one of the underside pics you can see they blended the bottom land into the skirt with a ball mill to avoid any stress risers and the oil return holes are already beveled. It's almost like they know what they're doing.
If you look at one of the underside pics you can see they blended the bottom land into the skirt with a ball mill to avoid any stress risers and the oil return holes are already beveled. It's almost like they know what they're doing.
It's not a girl, Earl. Would be awesome to have a choice of decent pistons at a reasonable price.
Well damn. It looks like the market went from nothing to potentially saturated. Mike just posted that FullThrottle has been working with Diamond to make 4.1 slugs for shelf items. I can't believe this hole has existed for all these years and we've both working on this at the exact same time.
I don't know if I can, in good faith, run these guys ragged to make new pistons when their market share would start off at 50% (or less) in a small niche market.
I don't know if I can, in good faith, run these guys ragged to make new pistons when their market share would start off at 50% (or less) in a small niche market.
turboc87gn
Darkside in Detroit
- Joined
- Oct 2, 2008
Yea but some people prefer Je to diamond especially after that bad run of diamond pistons that had collapsing ring lands a few years back I see a lot more people in general with je slugs and wiesco in 3.8 builds
The 4.1 has recently gained popularity for street car builds it seems I think the market share would be more like 75/25 plus price will be a factor
The 4.1 has recently gained popularity for street car builds it seems I think the market share would be more like 75/25 plus price will be a factor
