Ring selection for street sbc

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Ring selection for street sbc

Post by gnicholson » Sun Mar 11, 2018 1:16 am

Im freshening an 11 to 1 street sbc with 4.200 bore diamond pistons. 1/16 1/16 3/16 . If i was starting over i would go with a thinner ring pack. This engine has a moroso 3 vane vacuum pump. Im thinking std moly filled top napier 2nd and std tension oil rings. Thought I would get some expert opinions on what rings I should use in this application

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Re: Ring selection for street sbc

Post by gnicholson » Sun Mar 11, 2018 5:08 pm

I guess what i would like to know is what tension oil rings would you run with a vacuum pump on the street. This is not a daily driver but will be driven a fair amount and i would like to keep oil consumption to a minimum. Also is a napier 2nd ring a good idea on a street car . I would say this thing will see 1 to 2k a year.

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Re: Ring selection for street sbc

Post by 1972ho » Sun Mar 11, 2018 5:17 pm

Why not call a couple of the piston companies or total seal see what they have to say,but for me if it not a race only and trying to get max hp I would just go with the standard tension ring pack I would even get rid of the vacuum pump.

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Re: Ring selection for street sbc

Post by groberts101 » Sun Mar 11, 2018 5:46 pm

Probably a bit biased here, but I like the medium tension stuff(sometimes grouped into the "low tension" catagory) for vac assisted street/strip type deals. Yeah you give up some extra power to parasitic losses but a clean combustion space still counts for something too.

I also like gapless rings since you end up with less blowby and may potentially find even more power by reducing pump requirements/drag. The total seal AP top rings are pricy but will worth it over the long haul.

However, with your much lower % street type deal I'd probably lean towards file fitting a medium tension set to end up with something in between a low and medium tension. Then adjust vac if needed from there. Little extra margin would be prudent, IMHO.

EDIT: sorry.. crossed some wires when commenting on street use%.

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Re: Ring selection for street sbc

Post by cpmotors » Sun Mar 11, 2018 9:09 pm

I run 8-11lb oil rings, Napier 2nd and AP steel or Moly faced with no issues on street cars, none with vacuum pumps though.
Not a fan of gapless rings.
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Re: Ring selection for street sbc

Post by engineguyBill » Sun Mar 11, 2018 11:25 pm

Go with ductile plasma moly (sprayed) top ring, Napier second and standard tension oil ring assembly for your application. "Moly filled" top ring typically uses a grey cast iron ring material which is very inferior compared to the ductile iron high performance top ring. Even better would be a nitrided or PVD steel top ring, but these are harder to find for 1/16" thickness rings. There is no benefit/advantage to using low tension oil ring assembly in a street-driven application.
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Re: Ring selection for street sbc

Post by In-Tech » Mon Mar 12, 2018 12:27 am

engineguyBill wrote:
Sun Mar 11, 2018 11:25 pm
Go with ductile plasma moly (sprayed) top ring, Napier second and standard tension oil ring assembly for your application. "Moly filled" top ring typically uses a grey cast iron ring material which is very inferior compared to the ductile iron high performance top ring. Even better would be a nitrided or PVD steel top ring, but these are harder to find for 1/16" thickness rings. There is no benefit/advantage to using low tension oil ring assembly in a street-driven application.
Totally agree with ya Bill, I was just asked to look at a broken(not completely, just hurt) combo and the first thing I saw was moly FILLED ring and not plasma, it did have a tapered second, I'd still use a napier second any day I could find one within reason.

I mean seriously, you have a LSX block NA making 600 fwhp and you're hurting stuff in 2000 miles? All I could say was, bad parts and bad tune(was that extra 10 hp worth the bad tune)? :(

When you don't have control over the entire engine, and you never do, you have to watch the breathers and that little thing in the front called a belt tensioner. When things are good, nothing comes out of the breather for that split second and the tensioner is steady. That tensioner is rattling for a reason. :wink:

Good oil control in regards to the combustion chamber is a huge thing.
Heat is energy, energy is horsepower...but you gotta control the heat.
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Re: Ring selection for street sbc

Post by gnicholson » Mon Mar 12, 2018 1:43 pm

Thanks for the replys. Thinner rings arent enough improvement to justify buying new pistons are they?

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Re: Ring selection for street sbc

Post by MadBill » Mon Mar 12, 2018 1:54 pm

No.
Here's a typical test. Going from 5/64" to 1.2 mm was worth ~ 8 HP @ 6,000 on a 450 HP 350. Worth considering only if you're already buying new pistons. https://www.youtube.com/watch?v=-29IWc-zrv8
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Re: Ring selection for street sbc

Post by Casper393W » Mon Mar 12, 2018 5:26 pm

On a street type build why would one look to give up durability for just a few hp.

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Re: Ring selection for street sbc

Post by gnicholson » Mon Mar 12, 2018 7:58 pm

Okay I called total seal and ordered a steel top ring Napier second ring and a 15 pound Oil ring. The bore size on this is 4.185 thanks for all the help

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Re: Ring selection for street sbc

Post by user-17438 » Mon Mar 12, 2018 11:07 pm

It all depends on how round and straight the bores are. You could run TS Gold rings on the street.

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Re: Ring selection for street sbc

Post by engineguyBill » Tue Mar 13, 2018 1:25 pm

gnicholson wrote:
Mon Mar 12, 2018 7:58 pm
Okay I called total seal and ordered a steel top ring Napier second ring and a 15 pound Oil ring. The bore size on this is 4.185 thanks for all the help
Excellent choice.
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Re: Ring selection for street sbc

Post by DCal » Tue Mar 13, 2018 1:39 pm

gnicholson wrote:
Mon Mar 12, 2018 7:58 pm
Okay I called total seal and ordered a steel top ring Napier second ring and a 15 pound Oil ring. The bore size on this is 4.185 thanks for all the help
In your first post you said the pistons were 4.200 Diamonds, do you mean just the oil ring expanders are for 4.185?

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Re: Ring selection for street sbc

Post by gnicholson » Tue Mar 13, 2018 3:09 pm

Its actually 4.185 not 4.2. I was going from memory and my memory aint what it used to be.

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