Hey guys. Im planing to get another car, 5th gen accord coupe, and im trying to do something a little different. I've been reading around on all different forums, and found out what I think id like to do. Im for sure thinking f23a1 swap, but make it a bit more performance oriented. I started researching and came up with a few results. First, I looked at the possibilities of k20a2 pistons with f23 rods. However, this would put me above a 12:1 cr, which is a littler high for me. I then thought about lower compression k20a3 pistons with f23 rods. That would yield around a 10.2:1 cr, which is a littler on the low side. So I got to thinking and started doing more research. What do you guys think about this: f23a1 block,crank, and head. Id use k20a3 rods, k20a2 pistons, and a factory f23 head gasket. From the research I've done, this should net me a low 11:x compression ration. Now I know there's alot of information there, and im sure it only half way makes sense. So sorry for that. As for the compression rations I listed, those are just what I've read on other forums and from what others have said. So if you disagree please feel free to tell me. Let me also say, im no engine builder. But I have alot of ambition to try things and I love hearing what others have to say. Im deffinately willing to learn if anyone want to pitch in some info. So if you guys can pitch in some info on what you think of this build and how you think it would work, id really appreciate it. Thanks!
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You'd be at 10.2:1 CR and that's deceiving. While the numerical ratio is decent the burn pattern with a piston 2mm in the hole would be crap. Even lower compression ratio pistons are at full compression height on their faces around the circumference because that surface drives the mixture toward the center of the chamber where the spark plug ignites it.
You either need to find a great tuner and get comfortable with a high CR or spend the money on custom pistons. Throw away whatever compression calculator you're using.My Members' Ride Thread - It's a marathon build, not a sprint. But keep me honest on the update frequency! -
Thanks for the fast reply. I wasn't using any calculator myself, just reading what other people have calculated. Would f23 rods and k20a2 pistons still yield a streetable compression ratio? Obviously a good tune is key, but they only have 91 octane around me and Im not sure if that's enough for that high compression.Comment
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It's enough with a spot-on tune. But a tune should be as accurate as possible anyway. Always go with someone reputable. Usually you have to pay a decent amount for it.My Members' Ride Thread - It's a marathon build, not a sprint. But keep me honest on the update frequency!Comment
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Yeah I got a few quotes when I was thinking about going turbo a while back. I was talking to john over at jk tuning in pa. It was 4-500 for him to chip a p06 and tune it. By chance, do you know of any other factory piston rod combo that will work but yield a slightly lower cr?Comment
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Alright guys, I've changed my mind. After more research and talking to some guys I've realized this hybrid isn't for me. I have however, decided on a much simple hybrid that has been proven to work and puts up decent numbers. Im planing to get a lower miles h23a1 complete motor and trans. Im then planing to get a set of h22a4 pistons and possibly an h23a1 rebuild kit (new seals, water pump, timing belt ect). With those pistons ill be sitting at a little under 11.7:1 cr. Add a good tune and I think ill be set. Whats everyone think?Comment
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If no machining has been done to the head or deck surface and mild cams are being used then you're in the clear. But because the piston has a .5mm higher compression height than the H23A1 piston you're going to be a bit above deck. Mill any off the block to get it flat and you're gambling. It's been done but be sure to clay your engine first. Since you don't have any VTEC lobes then the reading will be as accurate as possible.My Members' Ride Thread - It's a marathon build, not a sprint. But keep me honest on the update frequency!Comment
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Yeah, if I remember right the piston will sit .020 inches out of the hole. If machining is needed, I could always compensate with a thicker hg right? Like a 4 or 5 layer im thinking. Hopefully the block and head will be nice and flat though, which it should be as long as the motor wasn't abused before.Comment
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Honestly, if you are going thru the expense and labor of a full engine rebuild, don't fuck around with hybrids and mis-matched OEM parts. Buy a set of custom pistons made to match your block.Comment
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The reason im going with h22 pistons is the price. They're 100 bucks for pistons and rings vs 600 for new pistons.Comment
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Good luck building a hybrid engine with parts purchased with pinched pennies.My Members' Ride Thread - It's a marathon build, not a sprint. But keep me honest on the update frequency!Comment
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Ha, yeah I know. Never cheap out on an engine build. Its not the fact that im pinching pennies. Just the fact that it makes alot more sense to spend a fraction of the price on parts that will work just as well. Im still spending around 500 on a tune too.Comment
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F23 block, a6 head, h23 plenum, k20 pistons for higher ratioComment
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you guys do know base model rsx pistons put it at 11:1 and a safer piston to valve clearance. F23A1 block/crank/rods, k20A3 pistons, F22A6 head, skunk2 IM, 70mm TB, custom header, and a custom grind from web cams and you'd have a 230-240whp brawler.Comment
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