So I'm getting ready to gap my rings on my b18c5. I have supertech pistons w/ p2w at .004" and I'm looking to make between 4-500hp it WILL be a DD pump gas. Now I have the spec sheet from supertech on their sugggested piston ring gap calculations.
Now they say for top ring multiply bore by .005" for moderate turbo and .0065 for turbo race only
When doing the calculation I use the total bore right with my p2w clearence which is 3.21"?
Ok so when doing the math for moderate turbo I end up at
Top ring: .016"
Second ring: .02"

Now my question is I should be calculating for moderate turbo correct?and not race only?
Next do those numbers for my rings look good at those numbers? I don't really want it smoking on start ups.

TIA

 

You never stated your bore size. The ring gap is always factored by your bore size and nothing else. The piston has nothing to do with this number. What you should run depends on a few factors really... If you are questioning what is right for you I would call the manufacture. To better help you understand:

http://www.evans-tuning.com/forums/v...r+engine+build

 

Thanks for the reply nevaevasatisfied
I did state my bore it was just in inches
81.5 mm w/ .004" p2w, total bore 3.21"

Like I said I went off supertechs spec sheet and I got those numbers

For calculating ring gap I use my total bore right and not just 81.5?

 

Ok using the formula off Evans tuning and not supertechs I get
Top ring: .018"
Second ring: .022"

Supertechs sheet said min. on the oil ring gap is .015" so do I just have to be looser then that?
When I was searching I seen people saying don't gap the oil rings rings and leave them how they are is this true?

 

I just measured all of them to see what they are at and I got
1st cylinder
Top ring: .014"
Second ring: .021"
1st oil ring: .02"
2nd oil ring: .017"

2nd cylinder
Top ring: .017"
Second ring: .024"
1st oil ring: .02"
2nd oil ring: .021"

3rd cylinder
Top ring: .016"
Second ring: .023"
1st oil ring: .02"
2nd oil ring: .021"

4th cylinder
Top ring: .017"
Second ring: .023"
1st oil ring: .022"
2nd oil ring: .023"

 

Top ring: .019"
Second ring: .023-.024"

So would this be a good number to go with? Or would it be loose and get smoke on start up and have a lot of blowby?

 

I gapped my rings at 0.018" for the top and 0.024" for the second ring on my 81.5mm bore turbo B series

 

Thanks for the input. What hp are you at and are you on pump gas? Do you have any smoke on start ups or anything? I guess I don't really have a way to be any tighter then that on the 2nd ring.

For your top ring I think .018" sounds better then the .02" but on the formula posted in the link it says have a .004 difference between the 2 rings. So .018" and .024" is safe?

 

motor is still on engine stand, but this is what I usually gap 81.5mm bore to without problems

 

ok. thanks again for the input

 

I am sorry - I missed that you slipped the bore size in there on me. Damn these old eyes!

Oil control rings are fine at 0.015" MIN for all engines. They constantly are covered in oil so they don't have the same environment as the top two rings.

Just be sure to remember to NOT add Piston to Wall clearance in. That is for the PISTON and not the piston RINGS. You must understand that your bore is your bore. It's not going to get "bigger" because you are trying to add other clearances that are measured SMALLER than your actual bore. So if your cylinder measures 81.5mm exactly then times that (in inches of course) by 0.00XX to get your ring gaps. Do not add or subtract any numbers to this. The purpose of gapping the rings is to make sure that when they heat up in the cylinder, the ends don't come into contact with each other. The other side of that is to make sure you don't lose compression or burn a lot of oil and the likes.

What I find the most interesting is that your measurements were that all over the place. Were you sure to square the rings in the bore? Also, to square them again if you bumped them with the feeler gauge?

 

i think those are the gaps without filing any of the rings??? you are right they are pretty far off if not.

i used like .0065 and then .0075 for my multipliers on my rings and my car has good compression and does not smoke on startup.

personally in your situation id bring all my 2nd ring gaps up to meet that .024" and bring my 1st ring gaps up around .020". just be careful to file a tiny bit off at a time, and watch the 2nd ring it files off quicker than the top ring.

you will be ok with those oil ring gaps but be sure to stagger them so the 3 oil rings dont have any gaps on top of each other.

 

That's the answer I was looking for. So I DON'T add p2w clearance in when calculating for gap.
I didnt use a ring squaring tool but I took the measurement, pushed the ring down a little more and recheck, then put it in another cylinder to make sure I got same reading all 3 times.
Do I need to get a ring squaring tool?
Thanks for your reply. Yea those are the measurements without filing anything. I thought it was weird that they were all over the place to. Im probably going to go around the measurements you said at Top ring .02" and second ring .024". Just not sure if I should keep it a little tighter then that on top?

 

flip your piston pointing down and use that to square the rings in the bore.

 

Should my gaps be the same for all the cylinders without filing? Like should all my top rings have the same gap and second rings have same gap without filing?

 

That's how I did it. Then I'd push down a little farther and measure twice to make sure. This works right? Or do I need to get a ring squaring tool?

 

You should be fine using the piston to square your rings.

 

I have never heard of a "ring squaring tool". Use the piston - just be sure to go in enough that the skirt is inside the cylinder.

Something that caught me off gaurd: Do NOT mix the piston rings in different cylinders!!! Keep each set for each specific cylinder seperate from each other! When you gap the rings you are making it fit that cylinder and that one only. You gap all the rings to the same measurement but may not be taking off the same amounts to get to that measurement.

It's like cutting wood. If you want to get 4 pieces to 10 feet long but you have one 11', 12', 14', and 18' piece each - you would cut different amounts off to get the end measurement. The only problem here is each cylinder appears to be different.

With new quality rings and a fresh bore the rings usually measure extremely close (in reference to starting gap) to each other. This is the reason I made my statement earlier. Just do as I mentioned and you will be fine.

 

I know your not supposed to mix the rings up and I didnt I just said I checked the measurement then measured it in a diff. cylinder to make sure they were the same. I have all rings seperated for each cylinder. So the cylinders are all exactly the same size, as I said my total bore on each cylinder is 3.21"
I understand how to gap them, i know you have to take diff amounts off each one.
So your saying they should all be closer together in measurements? Maybe ill try to recheck the measurements today but I'm pretty positive I measured them right

 

Guess its just like using the piston to push it down
http://www.google.com/search?q=ring+...B8O8iwKJltnPCA

 

Top ring .02"
Second ring .024"
Does that look good? Or would a little tighter on the top be better like .018" or .019"?

 

I have Arias pistons and their tech support told be for around 450whp .022 for the top ring. So im guessing .02 sounds about right.

 

By the way my pistons are also 81.5mm.

 

Whats your gaps for top and second ring? Is motor running?or you still putting it together?

 

I am still in the process of putting it together.