This is my standard bore d16 block. If I do the math for the rings that came with a the SRPs i get about 11 thousandths. Min gap is .015 as per manufacture. (edit < that statment is wrong BTW)

Sooo I do the the top ring on 1,2 and 3 then I destroy #4 trying to square the ends. If I put the #4 ring in the #3 cyl I get a loose .020" gap it's a tight .021" in #4 cyl. This leaves the rest of them around .015-.016". Am I going to lose enough compression to matter with a .020: gap? any other problems I might have? I have read that .004 over is OK and my machinist says .005 is tolerable. Time is an issue, what would you do?


Modified by Bailhatch at 12:02 AM 12/2/2004

 

It's the hottest cyl so that should help...I hope

 

bump for people that know this...

 

For $25 you can have a new set of rings, I would never use that .020 ring, doing things half *** will not get you any were. And almost everyone makes the mistake you made on their first set of rings. The first ring I filed came out to be .016 like I wanted, but then I thought that it took too long, the next one came out with a gap of .038, I threw it out.

 

I agree about not half assing things, but I i'm skeptical about how much of a difference it will make.

 

If you don't want to buy new rings I would at least make them all the same.

 

.021" is too big. Get a new ring set for that cylinder. You really don't want the gap any bigger than .018" on the 1st or 2nd ring. On a stock bore d16 your top ring should be .014" and 2nd ring should be .016. Where does it say that the minimum is .015"? thats not correct.

 

you're right I miss read the .015" part. Can I just get any ring set and use just the top ring out of it since all the others are fine? does the brand need to be the same as long as the dimensions are identical?

 

Yeah titanDarin is right that is way to BIG for the compression ring, I am a b-series guy but i set all my comp. rings to .017-.018, and the second ring .014, thats till CP pistons changed it to .019-.020, i know thats a big increase,but i just finished a set in a turbo gsr and they dont smoke or have any issues. Also the rings came straight out the package really close to that tolerances, or i probably would have gapped them .014, just needed a very little grinding to make sure they would butt up evenly. any brand will work cp, je, arias, total seal, just check the ring width tolerances.

 

A little tip when you do ring gaps, just file one side only. That way you always have one side that is perfectly square and you can adjust easily if your other side gets on an angle.

 

good tip from Earl !

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by earl &raquo;</TD></TR><TR><TD CLASS="quote">A little tip when you do ring gaps, just file one side only. That way you always have one side that is perfectly square and you can adjust easily if your other side gets on an angle.</TD></TR></TABLE>

humm, wish I thought of that or read it before I started. Oh well, this is my first full build. At least the bearings came out good

 

Is there a formula to figure out what size gap we should do our rings? for instance, an 84mm and say 81.5 mm bore. I'm not sure if I've seen the discussion here before. Thanks. I have an 84mm b-series to build for a friend and maybe you guys can help out. Thanks.

 

Top ring - 0.006" of gap per 1.0" of bore

Mid ring - 0-0045-0.007 of gap per 1.0" of bore...dependign on your style, ring material, and building philosophy

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Enthalpy &raquo;</TD></TR><TR><TD CLASS="quote">dependign on your style, ring material, and building philosophy
</TD></TR></TABLE>

I would be very interested in knowledgable peoples "building philisophy". I know every thing is a compromise in this world of physics so I would love to hear some examples in ring gapping.

 

Oh yeah and by the way earl is the one i asked about the second rings .019-.020 gap being O.K., and guess what it was O.K and runs smoooooooth!no smoke. to earl, and dans machine work.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Enthalpy &raquo;</TD></TR><TR><TD CLASS="quote">Top ring - 0.006" of gap per 1.0" of bore

Mid ring - 0-0045-0.007 of gap per 1.0" of bore...dependign on your style, ring material, and building philosophy
</TD></TR></TABLE>
Hi Scott, this is Vic the one that came down there at Secret Service w/ Mase to tune my car. The one w/ one piece front end. By the way, My calculation on top ring for 84 mm is .0198 Is this correct? and the 2nd ring is if I"m using the .007 formula came up to .023. It's seems a little too big but I don't know, you're the man.

 

I wouldn't use the certain amount of gap per inch of bore formula, just because it is very general. I would search what others are running with, make a decision on how much power and how much boost you will run, make an educated decision from that. Also the second ring is not for holding compression, it is for scraping oil of the cylinder walls. I only have 145 miles on my fresh build but it does not burn any oil, and it does not smoke even though my second ring gap is at a whooping .024&lt;--- Earl and CP approved.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Bailhatch &raquo;</TD></TR><TR><TD CLASS="quote"> I would be very interested in knowledgable peoples "building philisophy". I know every thing is a compromise in this world of physics so I would love to hear some examples in ring gapping. </TD></TR></TABLE>

there are 2 popular schools of thought on mid ring sizing:

1) gap the mid ring at about 75% of the gap for the top ring becasue it wont see as much heat and therefor wont expand as much.

2) gap the mid ring the same or larger than the top ring to prevent pressure from building up behind the top ring and unseating it.

It also helps to know your particular application. Higher HP cars that see extended High HP use are going to need a bit more gap (top and mid) becasue the ring will heat up more during use and we dont want ht gap to close completely and bind.

it also helps to know your ring material. the mid ring on the CP's I usually use on SR20's that i build has a higher Coefficent of Thermal Expansion (CTE) than the top ring. so even though it sees less heat it will actually grow as much as the top ring. Informaiton like that should be available to you from your piston maufacturer. if it isnt...you should choose a different maufacturer.


<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by boostedb20vtec &raquo;</TD></TR><TR><TD CLASS="quote">My calculation on top ring for 84 mm is .0198 Is this correct? and the 2nd ring is if I"m using the .007 formula came up to .023. It's seems a little too big but I don't know, you're the man. </TD></TR></TABLE>

Vic, yes that is perfectly acceptable. On 86.5mm SR's i always run 0.020" top and 0.024" mid with my CP's. Compression numbers are always spot on and i have never had any smoking issues.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by leadfoot78 &raquo;</TD></TR><TR><TD CLASS="quote">I wouldn't use the certain amount of gap per inch of bore formula, just because it is very general. I would search what others are running with, make a decision on how much power and how much boost you will run, make an educated decision from that. Also the second ring is not for holding compression, it is for scraping oil of the cylinder walls. I only have 145 miles on my fresh build but it does not burn any oil, and it does not smoke even though my second ring gap is at a whooping .024&lt;--- Earl and CP approved. </TD></TR></TABLE>

HAHAHA...would it help you if I told oyu that i got those formulas from an old post by Earl?? i modified the mid ring formula a bit to reflect the different schools of thought though.

my question to you is why WOULDNT you want to calculate ring gap based off bore size? why do we gap rings?...to allow for thermal expansion. the ring is going to expand most around the circumference becasue that is it's largest dimension. circumference = pi*d where d= bore size. material in the ring expands x inches for every inch of length (which is what CTE tells us...how much grownth per length). so for a given ring and varying bore size calculating gap based off bore size will give us the most consistant final gap at temperature.

personally i liek to know the resons behind what settigns that other people are using...not just their settings.

if you give a man a fish he eats for a day...teach a man to fish and he eats for a lifetime.

such is true in this case....

 

I still wouldn't use that formula, a person making 500whp boosting 20+ psi on a sleeved 84mm block is not going to gap their rings the same as a stock B20 just because the bore size is the same. So to answer your question, I wouldn't calculate ring gap by the bore size because there is a lot of variables that may change the amount of gap required. It's a good place to start, but I wouldn't follow it dead on. Personally I wanted the smallest possible ring gap with out making the ends of the ring butt up against each other, I knew I wasn't going to boost over 15psi since it dosn't take much to make a CX hatch go like hell anyway.

 

Damn leadfoot78 i thought mines were gapped BIG, I thought i was seeing things when i opened the packages and every ring i took out was oversize! So i got on the old computer and IM'd earl to see whats up with it, and he told me it was cool , that CP changed them( but nobody told ME.LOL) cause i was using the JE caculator that they send with there pistons, and they were coming out ALOT smaller. It's good to know that some one else has had a bigger gap and it still doesn't SMOKE, Turn up the BOOST, leadfoot78. LOL!!!!!!!!

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by numba1 &raquo;</TD></TR><TR><TD CLASS="quote">Damn leadfoot78 i thought mines were gapped BIG, I thought i was seeing things when i opened the packages and every ring i took out was oversize! So i got on the old computer and IM'd earl to see whats up with it, and he told me it was cool , that CP changed them( but nobody told ME.LOL) cause i was using the JE caculator that they send with there pistons, and they were coming out ALOT smaller. It's good to know that some one else has had a bigger gap and it still doesn't SMOKE, Turn up the BOOST, leadfoot78. LOL!!!!!!!! </TD></TR></TABLE>

LOL, I've got a little black **** on the left side of the steering wheel, It's just for that.