Hi folks, I'm getting an F20B really cheap because the person had the tranny bought off them for the price of both engine and tranny. Plus it has a new stage 3 clutch attached. This is the main reason I'm not going H22 instead. H22's are expensive where I'm from....plus a straight head block swap isn't fun

I'm thinking about stroking it, and from what I'm seeing, an F23 crank works. They have the same main journal diameter (55mm). They also have the same rod journal size, but I'm not seeing the F20 rods working.

I've been reading up on it, but I'm not too sure how to calculate what rods would fit there, as well as pistons. I did a search here for some answers and saw an F20B parting out and it had some K20 pistons, so that's a start. I saw that the rods would have to go up into the pistons to help the RS ratio?

I need some help with this please. I did a fair bit of mods outside engines before, but never swapped around different parts to get a good result. I may not want to go high compression because most likely I'll eventually boost it. The car currently has an F22B (willing to use parts from it if needed) that runs good if that helps.

 

There is a lot of misinformation in your post.

If it comes with an eBay special "stage 3"clutch, put the clutch in the garbage and buy something quality.

The F20B rods will not work with the F23 crank for obvious reasons. Aside from the length difference, the rod journals are different. They are the same diameterbut the F23 journals are not as wide.

F23 rods/crank with K20 pistons will work fine in an F20B block but you will need to have the block bored. The rod/stroke is not that bad. You can't improve it by "having the rods go up in the pistons" as the pin height won't change the rod/stroke ratio without a longer rod. The K20 pistons have to be installed backwards with the exhaust reliefs on the intake side of the engine because the K20 spins the opposite direction and the pin offset needs to be corrected.

It's best to do a build like this with forged H beam rods or better since the stock F23 rods won't tolerate a lot of abuse.

 

The stuff's not obvious to me, hence the questions. Didn't know about the width, both journals and k20 pistons.

If the clutch turns out to be ebay I'm gonna run it till it breaks, then swap it out.

Interesting tidbit about reversing the pistons though. Thanks.

 

Not wise on the clutch. eBay clutches are garbage. You'll just end up spending the time to do it twice.

Either way a similar setup is the basis for my built 2.3L setup. There are other piston options available as well but you have to hunt for them and do research. There are some 4G63 stroker DSM pistons that will work if you want to stay 85mm for example. There is a compression calculator www.zealautowerks.com that you can plug the specs into and figure out your compression ratio among other things.

It's not a very common setup. People are scared to innovate or break the norm. Plus K series are all the rage nowadays. Only a few similar builds have ever been done that I know of. It is very potent and cost effective when done correctly though.

 

To add a comment on the eBay clutch thing, I would say it really depends on rpms your gonna spin it to and power level it will see. I used to run an xtd stage 3 six puck clutch in a 300whp ls turbo, it did just fine and didn’t cost much. I’ve seen them loose pucks at high rpms on a b16 some kid was reving
to 9500, stock b16 at that 😒. I’m currently running a xtd stage 3 and 8lb flywheel in my all motor d series and really like it, engages smooth, easy to drive and holds the power I need it to for cheap. I’ve seen some be super chattery but I’ve also seen that with name brand clutches and think it could be possibly the disc got bent when mating the trans to the motor.

 

They will hold some power, for awhile. I have run them in the past when I was young and didn't care. The longevity and just general poor quality of parts are main issues I see. The pucks are made of a subpar material and wear very fast. The throwout bearings are total junk and make noise out of the box or after a few hundred miles at best. I started buying quality years ago and never looked back. Everything just fits, works, and lasts way longer.