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Moly Piston rings end gap for Turbo's
Posted by: 63turbo ()
Date: February 17, 2018 12:27PM

I've never tried gapping rings myself, I've always had someone else do it.
What's a good ring gap on a turbo car... "good ring gap" means what have you had good results with, not what you think should work smiling smiley

------------------------------------

Kevin Nash
Friday Harbor Washington
63 Spyder, Daily driver, EFI read about my project here: [corvaircenter.com]
first test start on EFI here:[www.youtube.com]
first official EFI boost test here:[www.youtube.com]
My new fan! [corvaircenter.com]
engine less 62 Spyder
Canadian 64 Monza Parts car



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Re: Moly Piston rings end gap for Turbo's
Posted by: jjohnsonjo ()
Date: February 17, 2018 12:47PM

I've done it 3 times on this engine and use the SM specs. My recent build was .040 over, with forged pistons that were fit tight. Then ends gaps were in the .018/.019 range, which is about center of SM range, so I left them alone. No problems and very low leak down after the cam burn in run.

J.O.

65 Corsa Turbo Vert
79 Honda XL 500S
69 Honda CL 160 D
2010 BMW F 650 GS
2003 Bounder 36D
2013 KIA Optima SX turbo-AKA ZIPPY (wife,s car)
69 Newport Holiday Sailboat
Baja 150 dune buggy cart
Coleman HS 500 UTV
2016 KIA Sorento SXL Turbo

Bethlehem,Pa

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Re: Moly Piston rings end gap for Turbo's
Posted by: vairmech ()
Date: February 17, 2018 03:58PM

How are you going to drive the car? Makes a difference on what to recommend!

Ken Hand
Handy Car Care
248 613 8586

Vairmech@aol.com

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Re: Moly Piston rings end gap for Turbo's
Posted by: v8vair ()
Date: February 17, 2018 05:57PM

With the heat of a turbo you could open the end gaps up a bit,but my choice would be Total Seal rings. I would check with them on whether to use it on the top or 2nd ring ? Mike

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Re: Moly Piston rings end gap for Turbo's
Posted by: joelsplace ()
Date: February 17, 2018 07:03PM

Total seal have gaps also.

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Re: Moly Piston rings end gap for Turbo's
Posted by: 63turbo ()
Date: February 17, 2018 07:33PM

Thanks for the replies! I'm probably never going to be boosting this engine
over 20psi (hopefully, crossing my fingers...) and ended up shooting for .019"
on the top ring and around .022" on the second ring.

------------------------------------

Kevin Nash
Friday Harbor Washington
63 Spyder, Daily driver, EFI read about my project here: [corvaircenter.com]
first test start on EFI here:[www.youtube.com]
first official EFI boost test here:[www.youtube.com]
My new fan! [corvaircenter.com]
engine less 62 Spyder
Canadian 64 Monza Parts car



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Re: Moly Piston rings end gap for Turbo's
Posted by: Vairismo ()
Date: February 17, 2018 08:11PM

Wouldn't the bigger gap be a positive for the top ring? More heat and expansion on the top ring, well I thought so anyway.

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Re: Moly Piston rings end gap for Turbo's
Posted by: Max Roeder ()
Date: February 18, 2018 04:13AM

Good basic information from Mahle. But read the notation at the bottom of page 21
and the exception of clearance for turbocharged 2nd comp ring. Also read on how to file the rings, from outside-in.

[www.mahle-aftermarket.com]

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Re: Moly Piston rings end gap for Turbo's
Posted by: vairmech ()
Date: February 18, 2018 05:12AM

20 PSI is a LOT of boost! Do you mean 20"? You also mentioned Mahle are you going 3.1? You ask for recommendations and all I see is standard answers when we don't know what you are building other than the 20 PSI? boost.

The details are the answer for what you are asking not the standard pat answer.

Ken Hand
Handy Car Care
248 613 8586

Vairmech@aol.com

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Re: Moly Piston rings end gap for Turbo's
Posted by: 63turbo ()
Date: February 18, 2018 09:16AM

vairmech Wrote:
-------------------------------------------------------
> 20 PSI is a LOT of boost! Do you mean 20"? You
> also mentioned Mahle are you going 3.1? You ask
> for recommendations and all I see is standard
> answers when we don't know what you are building
> other than the 20 PSI? boost.
>
> The details are the answer for what you are asking
> not the standard pat answer.


I meant 20psi of boost, and yes it is a bunch but I've
been there before, not a big deal if one is careful
and if not... I deserve a bunch of broken parts to
pay homage to the boost Gods for NOT being careful.
Actually it is not high boost that cause ring gap
concerns, it is temperature, and high boost for a
few seconds at high rpm is a far different thing than
continuous boost under a hard load at a lower rpm
and is different still from a Nitrous engine at approximately
the same cylinder pressure... the temps on the rings and
pistons get much higher in a hurry in the "continuous boost/hard load"
scenario and in the Nitrous engine. Those 2 conditions have absolutely
nothing to do with what I'm doing. I've looked at ring gap recommendations
from various sources and they are all over the place, but the
consistent take away is that for forced induction engines, that second
ring ought to have a larger gap than the top ring.

------------------------------------

Kevin Nash
Friday Harbor Washington
63 Spyder, Daily driver, EFI read about my project here: [corvaircenter.com]
first test start on EFI here:[www.youtube.com]
first official EFI boost test here:[www.youtube.com]
My new fan! [corvaircenter.com]
engine less 62 Spyder
Canadian 64 Monza Parts car



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Re: Moly Piston rings end gap for Turbo's
Posted by: jjohnsonjo ()
Date: February 18, 2018 02:24PM

>
> I meant 20psi of boost, and yes it is a bunch but
> I've
> been there before, not a big deal if one is
> careful
> and if not... I deserve a bunch of broken parts to
>
> pay homage to the boost Gods for NOT being
> careful.
> Actually it is not high boost that cause ring gap
> concerns, it is temperature, and high boost for a
>
> few seconds at high rpm is a far different thing
> than
> continuous boost under a hard load at a lower rpm
> and is different still from a Nitrous engine at
> approximately
> the same cylinder pressure... the temps on the
> rings and
> pistons get much higher in a hurry in the
> "continuous boost/hard load"
> scenario and in the Nitrous engine. Those 2
> conditions have absolutely
> nothing to do with what I'm doing. I've looked at
> ring gap recommendations
> from various sources and they are all over the
> place, but the
> consistent take away is that for forced induction
> engines, that second
> ring ought to have a larger gap than the top ring.

Kevin I am sure you have thought all this through and know what you are doing I am wondering what brand pistons you will be using. A lot of the forged pistons will crush the upper land and pinch the ring when above 16 PSI.

J.O.

65 Corsa Turbo Vert
79 Honda XL 500S
69 Honda CL 160 D
2010 BMW F 650 GS
2003 Bounder 36D
2013 KIA Optima SX turbo-AKA ZIPPY (wife,s car)
69 Newport Holiday Sailboat
Baja 150 dune buggy cart
Coleman HS 500 UTV
2016 KIA Sorento SXL Turbo

Bethlehem,Pa

Image and video hosting by TinyPic

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Re: Moly Piston rings end gap for Turbo's
Posted by: gnvair ()
Date: February 18, 2018 02:30PM

jjohnsonjo Wrote:
-------------------------------------------------------
> >
> > I meant 20psi of boost, and yes it is a bunch
> but
> > I've
> > been there before, not a big deal if one is
> > careful
> > and if not... I deserve a bunch of broken parts
> to
> >
> > pay homage to the boost Gods for NOT being
> > careful.
> > Actually it is not high boost that cause ring
> gap
> > concerns, it is temperature, and high boost for
> a
> >
> > few seconds at high rpm is a far different
> thing
> > than
> > continuous boost under a hard load at a lower
> rpm
> > and is different still from a Nitrous engine at
> > approximately
> > the same cylinder pressure... the temps on the
> > rings and
> > pistons get much higher in a hurry in the
> > "continuous boost/hard load"
> > scenario and in the Nitrous engine. Those 2
> > conditions have absolutely
> > nothing to do with what I'm doing. I've looked
> at
> > ring gap recommendations
> > from various sources and they are all over the
> > place, but the
> > consistent take away is that for forced
> induction
> > engines, that second
> > ring ought to have a larger gap than the top
> ring.
>
> Kevin I am sure you have thought all this through
> and know what you are doing I am wondering what
> brand pistons you will be using. A lot of the
> forged pistons will crush the upper land and pinch
> the ring when above 16 PSI.

That isn't necessary true as most high quality race pistons will have a larger distance between the top compression ring and the top of the piston. Off the shelf TRW type do not and duplicate the factory piston in this respect.

Lee J

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Re: Moly Piston rings end gap for Turbo's
Posted by: 63turbo ()
Date: February 18, 2018 03:18PM

My pistons are the same old "hi-tech" pistons that I've used before, except
that the number 3 and 4 cylinders are Clarks cast (unfortunately)... This might
be considered the "wrong way" to do this for Higher boost, but I know I'm not the only one that has taken stock cast pistons to such high boost without problems. There's much more margin for error with a good quality forged piston, but still, they ARE NOT a magic cure for detonation... bad detonation
with forged or cast pistons you will break something, and the cure is to fix the detonation. I know from past experience with stock, original 50 year old cast pistons that they can take a heck of a lot more abuse than most would think possible- Bad severe detonation from overly advanced timing and a hard load... I broke the top compression ring on cylinders #1 and #3, and the ring lands on all of the pistons were severely pounded out.
That failure was years ago, and came after three or four years and 18000 miles
of very hard driving and boosting as much as I could, with much more aggressive timing than most would think possible, on pump gas.

------------------------------------

Kevin Nash
Friday Harbor Washington
63 Spyder, Daily driver, EFI read about my project here: [corvaircenter.com]
first test start on EFI here:[www.youtube.com]
first official EFI boost test here:[www.youtube.com]
My new fan! [corvaircenter.com]
engine less 62 Spyder
Canadian 64 Monza Parts car



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Re: Moly Piston rings end gap for Turbo's
Posted by: vairmech ()
Date: February 18, 2018 06:13PM

OK, now there is some information to use! I would opt for a little larger than just middle of the road clearances. Yes, the consideration is the heat produced and if you are using factory style pistons I don't really think you need to stagger the ring gap numbers but I would run at least .020" gap. If you need to change the gaps spend the money for a ring filer, they are cheap.

Ken Hand
Handy Car Care
248 613 8586

Vairmech@aol.com

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