Hi Guys

brand new to Hondas as I’ve been working with minis most my life (so please go easy and let me know if I’ve posted in the correct area). I’m about to put a 98 spec B18c in my current mini but need to rebore the block to around 82mm. (Will bore match when I get the new pistons)

So I’ve just visited the the zealautowerks calc to get an estimated compression ration and this seems very highly from what I have seen other people suggesting. (Pic attached)

Compression calc


I have a stock head and stock bottom end from the ITR 98 spec DC2 and will have 82mm rebore and using 82mm PCT pistons. The calc is coming out at 13.3 does this sound right?

If it is correct I’m guessing I would have to upgrade my Valve train at this Compression are there any other mods I should add before putting it all back together. Just want reliability not looking for much extra power as the car only weighs 800kg

 

Too much compression for pump gas. Reliability will be questionable. I would put an ITR contour piston into your engine instead.

 

By the way... your calculation is a bit high because you selected the GSR cylinder head instead of the ITR cylinder head... but you still come up with a compression ratio of 13.00:1. It is still too high for pump gas... so if you intend to run it on corn or race gas... then send it.

 

Ah ok I was unsure of which codes related to my head.
would the pump gas be less of a problem bearing in mind I’m n the UK with 99 RON fuel?

I was looking for standard pistons but am struggling to find a UK supplier that stocks 82mm ITR pistons. Does anybody know where I can pick up a set?

thanks for the advise.

 

Has anybody successfully attempted to shave a few mm from the dome of the PCT pistons to bring down the compression

 

99 ron is only a bit better than the 93 (r+m)/2 we have in the US, so no, I wouldn't try to run that with 13:1 CR. E85 is ~108 (r+m)/2 which is like 113 ron.

Amayama will ship worldwide so I'd look there if you want to buy new.