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18:1 Standard size pistons

Twisted Steel Performance

Twisted Steel Performance

Anything worth doing is worth overdoing.
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Pauline, SC
I'm almost ready to make a CNC run on pistons, they will be cc'ed for a true 18:1 ratio with valve pockets. I have 2 new crate P400 motors to build that will have the pistons machined and will have 4-5 + sets of NOS standard bore sets here to machine.

Question for the forum is would their be any interest in these in standard size bore, or would you prefer oversize sets. I have a supplier for NOS standard bore.

The NOS standard bore sets will be machined for valve clearance & 18:1 and have a 3 side coating and the pins coated for a complete set of 8.

So standard or oversize is the question....

I see a lot of people prefer to save cost and freshen up a standard bore block, would their be interest in low compression coated pistons in standard size ?
 
I might need a set of standard size. What is your estimated price ? Also I wouldn't need valve reliefs.
 
The CNC program is being written to include the valve reliefs but could be omitted, the reliefs aren't going to take much away as they will only be around .050" deep, and they will only be seen on the edges. My thinking is if someone uses a timing chain or carbon build up over time this would prevent the possibility of a valve strike.. and not having them wouldn't change the cost any..

piston mod.jpg
 
That looks similar to others I've seen. I've always wondered how that change in the swirl bowls affects things. I've always thought about shortening the rods but have heard that the flat area not in the swirl area was detrimental. Anyone actually know anything about it or are they just assuming.
 
I think it needs the "quench" area around the outside of the piston. These are the Kennedy design, and I do have his permission to copy it.. I believe this design removes most of the "piston rock" in the cylinder making for a quieter motor by the piston not rocking as much by distributing the flame & pressure around more of the piston top..

As far as I know no one has proven or disproved the design..

I have consulted diesel engine builders about the design and the valve reliefs and all tho they are not IDI builders they have the same thinking I stated above so I'm not changing it any other than ccing to get a confirmed ratio...

If someone has a better design bring it, I'm open to other thoughts..
 
I would like to have this same thread on the other forums for more input but they won't allow it... their vendor cost is way out of my wallet LOL....

@Will L. you know one of the forums ...
 
Couple more questions. So would it be possible to easily change the compression ratio? I'm concerned about going too low and making it hard to start in my cold climate. Also will they have the steel support for the ring land?
 
Yes they do have the steel upper & lower support in the lands..

And yes The ratio could be changed with ease. I'm considering 18.5:1 anyways, that would benefit better starting as well as plenty of room for more boost while keeping the cylinder psi lower.

At this time I'm only planing to run 4 sets other than the 3 P400 sets for customers. If I get enough interest I will run more stock style sets.

I don't have a finale cost yet, the more sets I run per batch the cheaper they get, that is why I'm gauging interest... A savings some might think about would be no coatings, I wouldn't recommend it but would offer what ever a person wanted as best as I could.

One more thing, these do not have rings so those would be sourced elsewhere, or I could supply them also as needed...
 
Haha, I was already excited wanting to say something there for the folks there. No one else they have deals with it so afaik not stepping on toes of any vendor.

Back on my hummer this evening- WOHOO! Is it bad to kinda hope for a piston skirt scratch or two? Haha

So only the marine optimizer had 18:1.. what was the normal hmmwv/ truck optimizer blocks again?
 
Back to your original question on standard vs oversized obviously the best choice would be standard but.... As our supply of used blocks ages oversized might be a consideration.
 
These are a month or so out at this time, it will be a limited run of 10 set right now. Those that would like to get on the list should go to my web site and fill out the contact form so I can keep track of who was in line, once I know the final cost I will publish it and go from their. Those on the list can always opt out at any time.

Note these are offered on several different sites and interest is higher than expected.

https://twistedsteelperformance.com/contact-us
 
I currently have an engine block at the machine shop that has to go out to .040" on all cylinders. I would be interested in a set of these pistons in oversize of .040" if you could do them.
 
I could do them but at this time I don't have that oversize... If you can find a set in the next few weeks I could machine them in the same run as the standard ones and not cost you as much as running one set.. You can drop ship here if you find a set...
 
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