SR20det ring gaps and bearing clearances

[Garage Skidz]

I cant seem to find any info on what ring gaps and main/rod bearing clearances to run. if there is a solid thread on this stuff please let me know cause I haven't found one yet.

So does every one just run OEM clearances and gaps, even on their higher power builds?

Build: s14 notch top sr20, 87mm bore Eagle rods, CP pistons, ACL bearings, 2871r .64 a/r, JTW s3 cams, and shooting for 350-400whp.

so I'm just thinking wouldn't you wana run a slightly bigger bearing clearance and ring gap for more than stock power? I plan to up the power later so I would like to accommodate for that before I put it in.

the ring set I have for the pistons (wiseco 8700XX) comes with instructions that gave me a formula for the ring gaps. they came out to be .0017 for the top and .0018 for the bottom ring. I believe these are within the stock spec, is this good or bad? I just don't want to crack a piston.

if this is something I can find in another thread I apologize just looking for some definite info on my particular setup. Thanks

[lucas240sx]

Bump this up
I too am curious

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[sidewaysil80]

Its all covered in the “engine mechanical” section of the FSM.

[lucas240sx]

Its all covered in the “engine mechanical” section of the FSM.I have the s14 fsm printed out.
It says .008-.012 top ring
Untouched my wiseco top ring is it .008

Wiseco wants 86.5mm / 25.4= 3.405
3.405 x .005 = .01702 top ring
3.405 x .0055 = .01873 2md ring

I've read ppl say 2nd ring needs to be .004-.008 bigger

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[tuzzio]

I've read ppl say 2nd ring needs to be .004-.008 bigger

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Call wiseco and see if they recommend this and proceed.

[sidewaysil80]

As far as bearing clearances it's pretty well documented that unless you are line boring, stick with factory nissan bearings/specs.

[lucas240sx]

Call wiseco and see if they recommend this and proceed.I'm gapping to wiseco spec

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[sidewaysil80]

I'm gapping to wiseco spec

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I would call CP, I'm pretty sure the piston:wall clearance would have an effect on rings. Since it's their piston and subsequent measurement, it wouldn't hurt to double check. BUT, if both Wiseco and CP have the same clearances, that's a moot point. But really ring gap is only part of the equation.

[lucas240sx]

I would call CP, I'm pretty sure the piston:wall clearance would have an effect on rings. Since it's their piston and subsequent measurement, it wouldn't hurt to double check. BUT, if both Wiseco and CP have the same clearances, that's a moot point. But really ring gap is only part of the equation.Im using wiseco.
I just bumped this dude's post

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[gaz_moose]

not saying that I know what im talking about but,for ring gaps I would go on the large side as at worst it would just give you abit of extra blow by. too tight and you would get the rings binding up. I would use the piston/ring manufacturers settings.

that is assuming you plan on beating on the engine regular.

[jedi03]

+1 on following the piston manufacturers suggestions...I followed CPs with their pistons...2nd owner still beats on the engine over a year and a half later...they look at how the piston is normally used and calculate to make sure ring landings don't crack (binding piston ring)

[codyace]

+1 on following the piston manufacturers suggestions...I followed CPs with their pistons...2nd owner still beats on the engine over a year and a half later...they look at how the piston is normally used and calculate to make sure ring landings don't crack (binding piston ring)

Correct. Unless specifically noted in special applications, always follow what the piston manufacturer suggests.

[TheRealSy90]

Correct. Unless specifically noted in special applications, always follow what the piston manufacturer suggests.

Do you personally tend to go to the looser or tighter side of the tolerance?

[RalliartRsX]

Do you personally tend to go to the looser or tighter side of the tolerance?

Depends on end goal. Lots of track use (trackdays, long drift session) slightly looser in general terms due to the major buildup of heat and expansion

JE pistons has all the calculations and recommendations on their site. Just select which piston and it should have all the info (including bearing clearance if you also bought their rods). There is some math involved which take into account bore dimensions for instance.

[Garage Skidz]

Thanks all for the replys. Im probably going with the .017 top and .018 bottom gap. that should be good for 15 to 20 psi with a 2871r for street use.

[TheRealSy90]

While we are at it, what's everyone's preference for rod/main bearings as well as clearances? I know there's a lot of variables involved such as if certain machining steps are performed or not.


Personally, I'll always go with OEM Nissan bearings, sized off of the markings that are stamped into the block and the crank, preferably WPC treated. But once any of that gets machined those are moot and needs to be properly measured out. However, i'll never personnaly run a crank that's been machined on the bearing journals as I believe they are surface treated and hardened, and you then lose that hardened material.


I've never been a fan of those ACL "race" bearings that just come one size fits all, no wonder people spin rods so often with those.
A friend of mine that builds fwd sr's often always goes with "calico" bearings?

[hanzbrady]

While we are at it, what's everyone's preference for rod/main bearings as well as clearances? I know there's a lot of variables involved such as if certain machining steps are performed or not.


Personally, I'll always go with OEM Nissan bearings, sized off of the markings that are stamped into the block and the crank, preferably WPC treated. But once any of that gets machined those are moot and needs to be properly measured out. However, i'll never personnaly run a crank that's been machined on the bearing journals as I believe they are surface treated and hardened, and you then lose that hardened material.


I've never been a fan of those ACL "race" bearings that just come one size fits all, no wonder people spin rods so often with those.
A friend of mine that builds fwd sr's often always goes with "calico" bearings?

Calico is a coating company. They're the company that Mazworx uses. Also worth noting every Mazworx and almost every Real Street build runs ACL Race bearings including my own engine, hell my SR even has a cut crank. The race bearings also come in 3 sizes STD, .025mm, and .25mm. These bearings are obviously most at home in a perfectly round hole that's machined with an aftermarket bearing in mind.

At the end of the day with modern manufacturing processes every bearing from every company is damn near identical in performance. I would comfortably use any of the big 3's (ACL, King, Clevite) race bearings interchangeably, it's all personal preference.

[TheRealSy90]

Calico is a coating company. They're the company that Mazworx uses. Also worth noting every Mazworx and almost every Real Street build runs ACL Race bearings including my own engine, hell my SR even has a cut crank. The race bearings also come in 3 sizes STD, .025mm, and .25mm. These bearings are obviously most at home in a perfectly round hole that's machined with an aftermarket bearing in mind.

At the end of the day with modern manufacturing processes every bearing from every company is damn near identical in performance. I would comfortably use any of the big 3's (ACL, King, Clevite) race bearings interchangeably, it's all personal preference.

Thanks for explaining all that lol, been a while since I've shopped for bearings, I remember now that Calico'd Clevites were his preference.

In regards to Calico and WPC, I assume if one was planning to get their bearings of choice WPC treated, then there would be no gains from having them Calico coated before the WPC treatment? Even though WPC says they can treat wear coatings as well and that it's more beneficial than non-treated coatings.


I haven't actually had parts WPC'd yet but it's super appealing, would love to do a new build with WPC on every internal part haha.

[hanzbrady]

Thanks for explaining all that lol, been a while since I've shopped for bearings, I remember now that Calico'd Clevites were his preference.

In regards to Calico and WPC, I assume if one was planning to get their bearings of choice WPC treated, then there would be no gains from having them Calico coated before the WPC treatment? Even though WPC says they can treat wear coatings as well and that it's more beneficial than non-treated coatings.


I haven't actually had parts WPC'd yet but it's super appealing, would love to do a new build with WPC on every internal part haha.

Hmmm that's some internet science that's a bit over my head to be honest, thinking about multiple treatments and coatings and how they interact with each other hurts my head.

[RalliartRsX]

King is what I will recommend (And what is going in my VET build). Crank and mains have been measured and in spec, so the standard size should suffice (in my case)

[hanzbrady]

King is what I will recommend (And what is going in my VET build). Crank and mains have been measured and in spec, so the standard size should suffice (in my case)

Nice!

I personally have ACL mains and King rods, I was more worried about what was in stock and available haha.

The King bearings are great and what we almost exclusively run for Subarus since they're the only company that makes an oversized outer diameter main bearing with a standard inner diameter for straightening the line bore without having to mill the faces of the case halves flat.

[RalliartRsX]

Not knocking ACL, as it seems they work. But I am concerned with the QC on their bearings. According to the internet, they are hit or miss (or in Mazworx and a litany of other (SR20) cases like yourself hanz, they seem to be on target more than off target). However, I have seen first hand the quality and measured/consistent specs of the Kings, so they will be the bearing of choice for me. Just going to go with what I have experienced :)

In addition, the King bearings are not much more expensive in the grand scheme of things. So that is my choice

P.S The internet is a shitty place which sway opinions (and not necessarily rooted in facts or without bias) too far one way at times hahahahahah!

[TheRealSy90]

Slightly on topic but also off topic, cool read about how they made bearings for old engines that don't use a shelled bearing: http://www.roadandtrack.com/car-culture/travel/a11388689/babbitt-bearings/


In regards to piston rings, it blows me away how many people throw rings on, install pistons and send it. Never thinking about ring gap.