Honda D Series Forum banner

SOHC high comp pistons

6K views 33 replies 12 participants last post by  FarmerD 
#1 ·
Hi everyone,

i've been building a JRSC DOHC ZC which has been running for a while, but i've taken it off the road to go with forged rods/pistons as well as some head work and aftercoolers.

Anyway i'm trying to find a piston to suit my application. What i've found so far is the 75.5mm Wiseco d16a1/ZC piston which drops the compression to 9.1 in a d16a1 (i'm waiting from specs from race engineering to confirm what compression ratio i'll get in my ZC). If it's a 9.1 CR in a d16a1 though, my guess is i'll be getting high 8's CR in my blacktop ZC which is too low IMO.

Another alternative that i've read you can use it high compression SOHC pistons. Specifically, i've got my eye on CP Carillo D16a6 pistons 11.0:1 CR, which if i'm using the online calculator that's floating around yields me a 9.5:1 CR which is what i'm after.

Does anyone have experience with using high compression SOHC pistons in the blacktop ZC? I wish thezcr was still around.... :(

Pics for attention:





 
See less See more
3
#8 ·
very nice set up, i respect clean and proper builds, youve accomplished that for sure.

i have no info as far as what pistons are the right pistons for a dohc zc.

i run je 11:1 pistons in my built a6. acid beaver would be the guy to ask about what pistons you can and should run.

can i ask who makes that header ? did it fit with the factory crossmember or are you running an aftermarket crossmember/traction bar system ?

have an instagram ?

stratton.
 
#11 ·
Yep, you can find me on Insta my tag is the same as my plate 'efb055'.

The header is an eBay special for a B20, it's a stainless construction and the pipes seem to be put together ok. The flange was mild steel though which didn't matter, because i cut it off and plasma cut my own header flange to suit the ZC





New flange, the pipes needed to be pulled with clamps... The port spacing is noticeably different between the two motors. The dohc zc has equal ports, whereas the B seems to have the outer two closer to each other.



And I had to modify the downpipe to clear the 4wd transfer case:

 
#14 ·
for good quality high comp pistons, you could try PG6 honda pistons and shave the head down to match your wanted compression.

I think there are still one or two companies making adjustable cam gears to match the head shave.
 
#20 ·
as you reduce the head height via shaving, you want to adjust the cam gear so the center stays lined up, but the gear teeth are allowed to slowly roll clockwise as it gets shaved.

generally its less than 2 degrees of affective movement, but that can make a significant impact (positive or negative) on how you can time it.

and I pulled that 2 degrees movement out of my ass. it can be smaller or larger obviuously based on how much is shaved.

but then, shaving the head tightens up the combustion chamber and generally improves chamber burn events
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top