:::RHMT::: Real Home Made Turbo

General Category => Forced Induction => Topic started by: ratcityrex on February 07, 2013, 02:22:32 AM

Title: ring end gap on a 4.06 bore....
Post by: ratcityrex on February 07, 2013, 02:22:32 AM

So I'm about to put the lower end of the 327 together and I'm gonna gap my rings out, but I'm finding mixed reviews on size. Manufacturer hasting says a minimum of .004 per 1" of bore.(.004 x 4.06 = .0162x) Now to me that sounds tight. Especially considering that this motor will see boost one day. And it will also see some pretty good rpms too. So I was thinking .023 for top ring and .021 for second ring. But just wanted to get a little input from some of you nogs first........

Title: Re: ring end gap on a 4.06 bore....
Post by: ratcityrex on February 07, 2013, 02:53:49 AM

so just looked into it a little more. Read up on the hotrod 4.8 turbo lsx. They took the factory gap on the top from .015 to .028, and left the second ring at the stock .028.


Now granted, they were going for broke. And Im not. SO im guessing that .025 top ring and .025 second would probably be fine.

Title: Re: ring end gap on a 4.06 bore....
Post by: crxvtec91 on February 07, 2013, 11:42:08 AM

Quote from: ratcityrex on February 07, 2013, 02:53:49 AM

so just looked into it a little more. Read up on the hotrod 4.8 turbo lsx. They took the factory gap on the top from .015 to .028, and left the second ring at the stock .028.


Now granted, they were going for broke. And Im not. SO im guessing that .025 top ring and .025 second would probably be fine.

Does sound fine and as long as you leave the oil control rings alone it shouldnt smoke.

Title: Re: ring end gap on a 4.06 bore....
Post by: bigdaddyvtec on February 07, 2013, 01:18:08 PM

Simple math. Use the standard gap equation... you can find it on CPs page for one  :O)

From CP AND Wiescos pages (Same formula):

Multiply your inch bore size by the “Bore x” column for your application to determine
the end gap.


Top ring multiplier is the left number... Bottom is right  ;O)


Dirt / ATV / Snow / PWC  .0040”  .0050”
High-Performance Street / Strip  .0045”  .0055”
Street-Moderate Turbo / Nitrous  .0050”  .0055”
Late Model Stock  .0050”  .0055”
Circle Track/Drag Race  .0055”  .0060”
Blown Race Only  .0065”  .0070”
Nitrous Race Only  .0070”  .0075”

The oil rails may be installed without modifying the end gap. The gap should be a
minimum of .010”.

Title: Re: ring end gap on a 4.06 bore....
Post by: ratcityrex on February 07, 2013, 02:20:48 PM

Ok, so I imagine that that is for a forged piston. Mine are cast, not a big deal, but Ill probably run them around the .023 mark then. Just to be on the safe side. Not to worried about a little puff here and there. And when it does see boost, it will be minimal amount considering this thing will probably shit itself around the 550 hp mark.

Does this apply for the top and the 2nd ring?

Title: Re: ring end gap on a 4.06 bore....
Post by: bigdaddyvtec on February 07, 2013, 02:32:24 PM

Think ring expansion, not piston expansion  ;O)

Piston expansion (material/power wise) is P2w clearance issue  ....   not ring gap....   :noel:

Title: Re: ring end gap on a 4.06 bore....
Post by: ratcityrex on February 07, 2013, 03:14:47 PM

Fml....lol don't mind me. I'm just a fucking retard.... My pistons are plenty sloppy I'm sure!

Title: Re: ring end gap on a 4.06 bore....
Post by: bigdaddyvtec on February 07, 2013, 03:32:44 PM

Quote from: ratcityrex on February 07, 2013, 03:14:47 PM

Fml....lol don't mind me. I'm just a fucking retard.... My pistons are plenty sloppy I'm sure!

LOL