Pistons

[prballer16]

so i read this forum on some dude taking some weisico pistons for an h22 and cutting them toi raise his compression to 13.1 useing an f23 crank and f23 crower rods. what is this dude talking about actualy shaveing the pistions?

[oyajicool]

I have no idea.

If you post the link to the thread of that forum, knowledgeable members may be able to help with your question.

[deevergote]

I can barely understand what you're saying

Without precise machining equipment, modifying the tops or skirts of pistons is something only an idiot would do.

[Jarrett]

There are many things wrong with this inquiry but I'll focus on just a few points.

The F23A uses a 22mm wrist pin, 86mm bore and 30mm compression height. The K20A2/Z1 piston uses the same dimensions only with a 4.25cc dome on the piston to cause very high compression ratios whether the F23A head is used on the F22A head instead.

Any H-series piston is going to fit an 87mm which will mean you'll have to bore the block. If you're not starting off with an 86mm F23A block then you can forget about it as the F22A won't go that far. It will only go large enough to accept the 86mm pistons. That piston is also 31mm high which is likely why whoever you saw post about the piston is grinding it down.

If you were going to get aftermarket forged pistons then it would only make sense to get them for the application you want and not for something else that then has to be modified in order to work.

What are you even trying to achieve? Or did you just want clarification on something you saw?

[mugencivic4dr]

i'm assuming by shaving the piston the individual meant to fly cut the edges do to hitting the head. only reason for me assuming this is because a similar build ( usiing a VQ3O block, VQ35 crank and VQ30 pistons) required this "fly cut". some time when you build a hybrid motor you have to "modify a couple of things.

[deevergote]

When building a hybrid motor (something I am strongly opposed to with the engines commonly used in our cars, as there's very little benefit), you should be using custom aftermarket pistons made to the correct specs.

[wed3k]

you should be using custom aftermarket pistons made to the correct specs.

bingo.

exactly like what i did in my vw. avoided paying 600+ for a set of rods made for my "8v" motor, used scat rods made for a scirocco that has a different rod length and a smaller wrist pin (which means less weight) and just had a custom set of pistons made from ross. out the door price was 850 and that was with total seal gapless rings and completely coated.

I spent about 250 more than a shelf stock piston but i reduced a lot of the reciprocating weight which equates to faster acceleration and the ability to rev higher.

[prballer16]

lol im sorry guys i was watching youtube at the same time. ok so im working on an h22 build. n/a all motor looking to achive about 300hp. i read this thread some guy posted stateing he was going to take type s pistons and cut them to achive 13.1 compression i think its jus bull or he has machineing equipment. i basikly am looking to achive the maximum compression this engine will handle withought the risk of it blowing up on me the first time i decide to cut it loose. reliable but fun is the key.

[deevergote]

Why do you want the maximum compression?

[SOHC-FTW]

300whp N/A might aswell go big or go home (Aftermarket). People have made 250-275whp N/A on stock H22a block's but it takes work.

[wed3k]

Why do you want the maximum compression?

you can always just run 14+ and use alcohol or e85. e85 is a big deal nowadays but you need proper fueling setup and e85 doesn't really have much lubricity in the fuel