This year I am re-building my "cheap" engine, and planning to go a bit more aggressive, but I have hit a roadblock. I am split between keeping the pistons sticking out of the hole, for the bit of extra compression, or having the P2V clearance for hotter cams.

My current setup is/was H23a1 crank and rods, with JDM H22A pistons, sticking out the hole .020, with 11.6 to 1 static compression, stock H22A cams. This made 197 WHP at 3400 ft elevation, with an ebay header and slight tweaking of a Neo.

I was planning to go with Type-s pistons this year, which if I keep them on the H23a1 rods, gives me 12.1 to 1 compression, but I am also planning on cams, and don't know if I would have the clearance needed.

The best option on that would be to go with the H23A rods, which are slightly shorter, and will bring the piston down to deck height, which should help with P2V clearance, but bring me down to 11.49 to 1 compression.

My big question in the end, if I drop the compression lower, will the ability to run bigger cams such as the Pro1, be of more benefit in the end? Hopefully I will break down and put a better header on for this year as well, to help it breathe more, and get the car well tuned to get the most out of it.

Thanks in advance for any/all opinions!

 

you should always check your P2V. You can go to type-s pistons with pro1's. Just make sure that you do the p2v. I had type-s pistons with crower 3's and ran pretty good

 

You gotta watch the dynamic compression, those type-s ring lands don't like lots of compression. There is a guy on here (can't remember his sn) that started with a h23 with type-s pistons and blew the ringlands. Just something else to watch, good luck in any case. for a build!

 

That is one plus I have, at 3400 ft elevation, I lose a good amount of compression, which keeps me safer in that respect.

I do plan to clay of course, just trying to figure out which route to go. Maybe I will just have the H23A1 rods bushed for the type-s pistons, and if I decide they won't work, use the shorter H23A rods instead.

Of course that means I need to decide if I am biting the bullet on cams or not. Pretty set on PRO1's, as they can still be used in a boost motor down the road.

 

<----- This guy right here!!!!

 

^^ Oh yeah thats right, I remember reading your build thread. High overlap cams SHOULD help with lowering dynamic compression, then its just making sure nothing hits ie p2v.

 

Never use type s bottom end as they weak for high compression.

 

When building an engine always remember the more turning mass the faster it'll go.

 

I built an identical engine to this, just used JDM H22A pistons instead of type-s.

That one was perfect, aside from the ring gap having tight oem spec, and I overheated the rings to the point of touching, and causing ringland failure on one piston with hot laps at the drag strip running a 100 shot.

 

I'm looking to do this same build in my H2B, hopefully in the spring ... snowboarding has been expensive though, so I'm not putting away the off season monies I had hoped to ... lol

I haven't decided on cams yet either, I was thinking I would need to fly cut the Type-S pistons for any cam bigger than a pro1.

 

Its not the CR I worry about, its the P2V clearance.

 

I hope to have all of my parts off to the machine shop this month, and get the valvetrain in the head in Feb. May have to wait a bit on the cash for cams, then I can clay it all and give some numbers.

 

This is a good option. If you clay it and it doesn't look good or you want room for bigger cams, you can always have the valve reliefs cut for a relatively modest price.

OP, neither Pro1's or high CR are going to be your friend if you want to boost down the road. Save your money if that's your long term plan unless you want to tear the bottom end apart again.

 

Yeah this is just a cheap build for fun, I have 2 more blocks in my garage to sleeve for a big boost build. I have heard that Pro 1s will be decent for boost, but I may just stick with valvetrain and the JDM cams at that point.