The usage here is kind of wide so I'll give you kind of a ballpark. Combustion chamber should be 53.8, bore 86, stroke 97, deck height 219.5, piston to deck height should be flush (its a h22/f23). I'm more worried about flame travel more than anything because it may or may not be centrifugal supercharged with an intercooler. I think a flat top will yield 10.78:1 compression which is a bit much going the forced induction route but not impossible, stock is 8.8:1 with a -14cc reverse dome and that's not very much for n/a, but I hear it makes good power. So if a flat top piston does not have better combustion then I'm going the reverse dome route, what exactly idk maybe 9.5:1ish. I know that's a lot of numbers and bull crap, I'm a technical guy and I'm in the middle of planning, so all I need you to say is flat top or dome if you have anything else to say throw it at me.

 

You know people are at like 11.0-12.x and are pushing mad lbs of boost nowadays. 10.7 aint really much man. If you have a good tuner, you cam even go a bit higher..

 

Oh yeah I know, but I don't really want to but I don't want to do that with the only block mods being h beam rods and forged pistons and it being a street car that I will drive most days, not my only car, but closest thing to a dd. I don't want to exceed 550hp and that's just my limit in reality I don't want to go anywhere near that. If I was running a supercharger I'd probably only run a few pounds of boost, it doesn't take much anyway.

 

It seems like there's a lot of support in the belief that a flat top piston will yield a little bit more power than a domed piston with the same compression ratio. Kind of makes sense for mixture and more even combustion.

I think you're kind of at a point where you have to decide if you're going to go forced induction or stay naturally aspirated. A 10 to 1 compression ratio flat top piston for forced induction would be a good choice in my opinion.
Not too high. Not too low. Unless your going to run e85.

Sounds like a mean build.

 

Flat top.

 

See I didn't say dome, I said reverse dome. It's like a regular f23 piston or most low compression Hondas. It's a dish with a little bump in the middle. You may have just misread. I don't have much knowledge on flat top pistons, that's the only reason I ask. I'd never use a dome unless it was my only choice. I know combustion isn't
as good with a dome as it is anything else. I use reverse dome with my turbo builds but that also doubles to lower compression.

Edit: Also does anybody know how deep the valve reliefs are cut on a k20a2 piston, h22a4 piston, or f23a1 piston whichever is deeper. I need to know because if I use aftermarket cams I'll cut them a bit deeper and use something with about the same specs as the most aggressive stock honda cam (I'll have to research, probably a k20a2, a k24a2, f20c, idk all the specs) maybe a little more aggressive since those cams are made for cars that are daily driven by a normal person. Just something in the ballpark, don't want to spend money on a custom cam.

 

opps my bad. reverse dome (dish?) or flat top. I misread..

 

Yeah reverse dome is basically dish, I think reverse dome has basically replaced a true dish so most of us might call it a dish. Or maybe I just haven't pulled a dish out of an engine, all of them have a small hump in the center. I see it more commonly used so that's what I've always used. Still the question still stands flat or reverse dome/dish?

 

Have you ever heard or read about setting quench clearance? Its kinda interesting.
It might answer which is better. Reverse dome or flat top.

 

I've never heard that... Sounds very interesting and right up my alley. You got any info? In the meantime I'll search Google.

 

Just what I've read. Basically piston to head clearance and how different quench/squish clearances affect combustion, power, knock resistance, and emissions.

 

Ok it's everything that I thought it would be, but a stock h22 head does not have much of a quench area.
Example:


I'll have to weld the head, deck it slightly, and put a lot into polishing the combustion chamber. I was already going to polish it but now I'll have to take the new material from the welds down and shape the chamber.
It will look like this:
This doesn't sound like a bad thing lol, but it's going to raise compression, that is bad. I don't want to run 11:1 compression and I'm still leaning towards a flat top with this build. Unless I get a custom piston with the shape of my combustion chamber, I don't see any way to decrease compression with a thicker head gasket and that is the worst option, only a last resort. I'm going to use a stock head gasket. I'm worried that making dished pistons the shape of my combustion chamber are going to be really expensive. Regular custom pistons from venolia are about $400 a set... I don't think I'll be spending more than $500. If I really needed to I could weld on the top of the piston and very very carefully shape it, but I don't know if I'm that skilled

 

A dish is just basically like a bowl whereas a reverse done is supposed to mirror the chamber shape. They're mass produced so it won't be exact, but it will be similar.

OHV Reverse Dome Piston:


OHV Dish Piston:

 

I knew the difference, I'm debating what is better.

 

So I take it the reverse dome is better since it has more "squish" area? More squish=more turbulence=better mixing? From what i think I understand this is a good thing right?

 

Exactly.

 

Never knew there was a difference between reverse dumb and dished pistons. I always thought they were basically the same. Thanks for learning me something new!

 

I'm pretty happy right now... If I weld my head all I need to do is make a mold of the combustion chamber and they can make any piston I could ever need for my combustion chamber. Now I just have to find out what compression ratio I want.