Trying to put my engine together today after so many problems. Its a b18a and I had it sleeved. I bought custom ross pistons 84.5mm and it came with rings(I'm sure I paid for them for what I spent). I did a seach on here and came up with .020 for a gap on the first ring. I checked mine and am getting .032. The book (Haynes) says for stanard b20 its .0014 to .0024 which for 84mm. Plan on running up to 25psi. Had it bored .0045 over piston for gap. Pistons are 3.328 and the bore is 3.3325. I'll try to find out the brand the rings are.

Talk to ross the other day and they thought the ring gap was too big also. So they ordered me a set of rings. When I got them the spec sheet I got with it said:
Cyclinder is 84.5
TOP Second Oil
Street, strip, circle Bore x .0045 Bore x .0035 Min. .015
Nitrous up to 150hp " .006 .0045 "
Nitrous over 150hp .008 .0055 "
Blown gas * .0055 .0035 "
Blown Alcohol * .0045 .0035 "
Blown Nitro * .0055 .0035 "

* indicates any type of forced induction system


Doing the math and: 84.5 .046 .30 or is it
3.3325 .20 .10

Does this sound right? Seems big??

 

You want ABOUT .020" for your upper ring gap and .018-.022 on your middle.
You cannot use stock specs on this. Your piston to wall (.0045") should be fine for a Ross piston.
I wish you would have contacted me for CP's as you can run them tighter for more power and they come in 84.5mm off the shelf.

 

Explain what you meant by different cp's? You mean for all out race version? I got the bore size from frank at sfp. It's a somewhat daily driver. Pistons are custom because I moved the wrist pin and had it coated.


If you need specs on what I have or idea's to give please ask. I think frank is closing and moving up north so need someone to talk to to finish everything.


Modified by integramic at 5:56 PM 5/8/2004