Wiseco P/W and ring end gaps...

[jareds]

Hi All.

I have not found much info on tried and tested piston to wall clearances / ring end gaps that work well on a 350+ daily drive.

The recommened piston to wall clearance is 0.025" as mentioned in the documentation that came with the pistons. can anyone confrim this?

What ring gaps should be used?

Hope someone can point me in the right direction.

This is for a EJ205.

Thanks,
Jared

* Registered users of the site do not see these ads.

[Storm]

The ring gaps should also be included with the documentation. It depends on the bore diameter and should be calculated.

Jay

[kakarot09]

I set the top ring gap at .017" and bottom at .020" when I used wiseco last on a 2.0. Yes the gap should be .0025" however the wiseco pistons have a coating and that gap is calculated prior to coating. So you can measure around .0015" clearance over the coating or go with the suggested bore diameter on the documentation.

[jareds]

Thanks for the responses.

The bore is 92.5mm (+/- 3.64").

I am looking at what guys have used and have made good power with, low oil consumption and little to no piston slap.
I am planning on running around 22psi with a large'ish turbo, (60-1 Twin scroll).

They dont allow for the coating? INTERESTING! Never thought of this.
Just to clear something up for me - when one states a P/W clearance, its actually 0.025 / 2 = .0125 on each side of the piston?

(Should it be 0.025 or 0.0025?)

Thanks,
Jared

[kakarot09]

Ptw clearance is diametrical. So you measure outside of piston, inside of cylinder, subtract the piston number from the wall number and that's your clearance. So yes each side would be half of that. Clearance should be .0025" can't really say for the power because this person was only using an 18g turbo. But those ptw clearances it shouldn't slap much. If I ever hear from the guy that bought the engine I'll add some oil consumption feed back.

[jareds]

Originally Posted by kakarot09

Ptw clearance is diametrical. So you measure outside of piston, inside of cylinder, subtract the piston number from the wall number and that's your clearance. So yes each side would be half of that. Clearance should be .0025" can't really say for the power because this person was only using an 18g turbo. But those ptw clearances it shouldn't slap much. If I ever hear from the guy that bought the engine I'll add some oil consumption feed back.

Great! got it, thanks!

0.0025 is as per the little piece of paper that came with pistons. I just need feedback as to when one goes larger.

Does Wiseco recommend the same PTW for NA, blown, blown and NOS engines? In other words, do they supply a different specification sheet with each piston meaning that the recommended PTW will differ?

Thanks,
Jared

[jareds]

Can any body add anything more?
I still don't know what piston clearance to go for.....
HELP.

[kakarot09]

For 350 whp I would follow the .0025 guideline.

[RealStreet]

Originally Posted by kakarot09

For 350 whp I would follow the .0025 guideline.

+1

It's important that you get the value you're requesting. If you don't have the tools to measure it correctly pay your machine shop for a hour of their time to verify everything before you walk out the door.

Thanks

[jareds]

Originally Posted by kakarot09

For 350 whp I would follow the .0025 guideline.

And if I'm aiming for 400HP?
What about rings gaps....?

[kakarot09]

Well I'm aiming for 400 on a 2.5L that has a little bigger bore and still using .0025. I've heard of people using .002 on a 2.5 but I don't know the results of that. I wasn't willing to go that tight on mine without a larger budget lol. Ring gaps I would say you are okay at .017 top still. Really this stuff is either a judgement call or its based based on an experience of "well I ran x gap and it seized at y power" many of the really experienced people will not tell you the clearances they would use because that's why they make money. If you're ever in doubt of ring gaps take the bore diameter in inches multiply by .0055 and you have a somewhat conservative top ring gap you can use. .017 is tighter than that. Maybe others will chime in with their gap suggestions.

[jnorth85]

I thought I would bump this, I recently assembled a block with Wiseco 99.5 pistons.

I ran .0030 P/W clearance.

The lowest top ring gap I could hit was .019, this was the nominal size the rings came in, I really wanted to go a little lower but had no choice.

The 2nd ring gap was set at .023

I installed the rings as instructed by Wiseco.

This motor will be going in an E85 car shooting for 550-600 WHP

[wrx1392]

the piston info tells you where to measure at too ,cause the pistons are cam ground. you need about .003 " per inch of bore for the ring gap.the more power you are making the gap should be bigger .i'll see if i can find the info.

[jareds]

Long story made short, I am using a Torque Plate, and I have all of the Bore tolerances within 0.01mm.

I have bored out the block to accept the Wiseco K588M93 pistons. 2.0L (92mm + 0,04")

However the PTW is a tricky one.

With the Wisecos one gets a piece of paper stating...
"COATED PISTONS: Piston to wall clearance is calculated before the coating is applied to the piston skirts. Use the recommended bore diameter of the piston kit, and install the pistons to that bore size."
And then, on the other piece of paper it defines the bore size (3.662" / 93mm), and then next to that it says PTW - 0.0025" (0.065mm).

Upon measuring the pistons with my Outside Mic (not a mitutoyo, but seems to be an OK brand...) i measured 92.97mm to the auto click of the Mic. If I give it one extra little notch over and above the auto click, I get 92.96mm.

Now, is one supposed to measure the Pistons and add the PTW, or, do we go on what paper comes with the pistons? I am SUPER confused!!!

Currently my engineer made the bore 93mm, so i have a PTW of around 0.03mm to 0.04mm (over the teflon coating)

I dont know where to go from here, does one use the 0.0025", or do we just bore it to the recommended bore?

[jchafee]

Mic your piston, lock the mic. Next put it in some wooden vise jaws, rock your bore gauge i. The mic and find you lowest value, zero the bore gauge. Now, rock the bore. The value you get there will be your clearance. This is how I do it to ensure accuracy because I don't have master rings for my bore gauge. As long as you're using accurate tools. All should be well.

[jareds]

I know how to measure the clearance.
My question is, which piece of paper do we follow that came with the Wiseco pistons?

[aboothman]

The "auto click" on my mitutoyo mics applies too much tension. You want to use a very light touch. Ask your machinist to show you how to properly use a mic, or check out some YouTube videos

[04ScoobyWtf]

I build a 25 with weisco and I'm running a .003 ptw and I believe .021 top and 23 bottom ring and I don't burn a drop and that gives room for the gaps to grow for we'll over 400 whp

[jnorth85]

Originally Posted by 04ScoobyWtf

I build a 25 with weisco and I'm running a .003 ptw and I believe .021 top and 23 bottom ring and I don't burn a drop and that gives room for the gaps to grow for we'll over 400 whp

I am running 0.019 top and 0.023 bottom but will be shooting for 600whp.
its more about the combustion temps that your motor will see than the actual HP number.

I am running E85 so my combustion temps will be much lower.

[ammfab]

I usually go off of the manufacturer's specs and then add some more gap depending on how much power the engine is expected to make. With 500-600whp in mind I'll gap them around .020" and the lower around .025". Sometimes ive gotten the lower rings out of the box already set Pretty high (sometimes higher than what i initially wanted to set them to) so then I end up matching them to lowest gap one of them already has.


Mike

[jnorth85]

Originally Posted by ammfab

I usually go off of the manufacturer's specs and then add some more gap depending on how much power the engine is expected to make. With 500-600whp in mind I'll gap them around .020" and the lower around .025". Sometimes ive gotten the lower rings out of the box already set Pretty high (sometimes higher than what i initially wanted to set them to) so then I end up matching them to lowest gap one of them already has.

Mike

Double

[jnorth85]

Originally Posted by ammfab

I usually go off of the manufacturer's specs and then add some more gap depending on how much power the engine is expected to make. With 500-600whp in mind I'll gap them around .020" and the lower around .025". Sometimes ive gotten the lower rings out of the box already set Pretty high (sometimes higher than what i initially wanted to set them to) so then I end up matching them to lowest gap one of them already has.

Mike

Mike that's sort of what I had to do. The uppers were at .019 as well as the lowers so I ended up just gapping the lowers.

Also to add fuel to the fire I gapped my rings with out a torque plate so I expect that gap to expand once the heads are torqued down.