ok first question is has anyone bored out their f23 to put h22 pistons in it and if so what needs to be done to the head also.....and can someone give me a link to where i can compare the intake manifolds of the f23 and h23....thanks

 

You can infer interchangability of intake manifolds by the gasket they use. If both engine utilize the same gasket, the two manifolds should bolt up.
If you have other issues, it will require a direct comparison.
As far as the piston question goes, try the aftermarket supplier route. You can get a far better piston for camparable pricing for the correct application without all these mental gyrations.

 

search - there is thread where somebody is putting a h23 IM on a f23. lots of pics and details.

PirateMcFred put h22 pistons in a f23 bottom end. they sit out of the hole and require machining of the head as well. There is a huge thread over in the prelude forum. I believe he was motivated to make that choice due to parts availability and cost.

If you want an off the shelf honda piston, K20 pistons are a MUCH better choice for a f23. same bore, compression height, and pin diameter.

 

So it would take no machining to use K20 pistions? They're the same exact size, where or how would they effect the performance?

 

essentially, yes.

depends on which k20 pistons you use. They have different dome sizes. K20a2 pistons on stock f23 rods, crank and head will put you right around 12:1 CR




If you want to build a motor, you need to do A LOT of research. Especially since it is unlikely that most engine builders will touch an oddball combo like this. Check out the Hybrid/Swaps section of the following link. You need to read a lot of the information in them. Even the stuff you think might not pertain to you exactly. Thats how you start to figure out the parts interchange.

https://honda-tech.com/forums/honda-prelude-4/faq-faq-faq-99%25-your-answers-here-2168311/


fun calculator to play with different engine combos.
http://www.zealautowerks.com/hfseries.html

 

The R40-A00 (R40-A01 0.25OS) K24Z3 pistons out of the 08 Accord EX-L will work. 87mm boar, 10.5:1 CR, same compression height, Floating writs pins and pin diameter. Pistons are fairly cheap but if you go with the 0.25OS pistons the rings will cost ya.

I looked into it for my build and the 08 K24Z3 cast OEMs were the way I was going to go. But forged won me over.

 

so if i use those pistons off of the k20a2 would i need to do anything to the head of the f23....and also what rsx do those pistons come in.....the type s os stock ones?

 

anyone?

 

bump

 

02-04 Acura RSX Type S or 02-05 Civic Type R (EP3, EDM)

Not sure about the head question though. I do know,

F23 = 50cc combustion chamber
K20A2 = 50.5cc chamber.

F23A*
intake valve = 34mm
Exhaust = 29mm

K20A2
intake valve = 35mm
exhaust = 30.5mm

I'm not sure of the valve angles entering the combustion chamber. So far that would be the only thing that may lead you to having to modify anything. And that would be only to have the valve reliefs angle cut in the K20A2 pistons. But with the reliefs being 1mm larger on the K20A piston already. I would say your pretty safe... clay them to be sure.... or wait for someone else to chime in.....

Cheers and happy Holidays

 

I've put an angle gauge on the f23a1 head valve faces and the valve reliefs on a k20a2 piston and they are the same.

I would still clay it to be certain.

 

why not just do it the easy way and put the entire H22 Head on the F23? It should fit no problems