Boatally Insane

iTrader: (1)

I'm building a supercharged 555 and am wondering what ring end gap I should use...

I'm using Manley pistons (696660-8) and Manley rings (46456-8)

According to Manley's specs..

Blown Gas* Top Bore x .0055" Second Bore x .0035"

So with a 4.560 bore that would put me at .025" and .016"

I also contacted Total Seal who supplies the rings for Manley (Total Seal # CR9130)

They said to put the top ring at .025 and the second ring at .023


Thanks,

Doug

FIXX

iTrader: (2)

return what you have and get a set of total seal rings top ring gapless ..they are worth the money,,this is the part of the motor you dont want to spimp..

mike tkach

iTrader: (3)

a gap that is a little loose wont cause damage,but a gap to small can stick the ring in the bore ,then break rings and scratch or gouge the bore.like fixx said,espically on a blown engine,go with the gapless top rings,they just seal better.

Unlimited jd

iTrader: (5)

I found an article through a google search with back to back testing of the recommended ring gap, and then a grossly over sized gap .030 or .040 bigger. The oil loss was so minimal it couldn't be counted and there was no loss in power.

MER Performance

Ring end gaps: Such a loaded question with so many different opinions.
I will tell you what I do, that does not have blow-by, under boost or consumes oil.
This is over 10 years of doing this way.
Hell Fire top ring for forced; induction, moly for naturally aspirated. Napier 2nd, and lower tension oil control rings. Gap the 2 ring .006 -.010 larger than the top. You do not want to piss-off, the top ring, by causing pressure from the bottom side. This will make the ring deflect the opposite way, this will also cause the 2nd ring, not to scrape the cylinder wall properly.
You will regret using a gap-less 2nd ring, it looks good on a leak-down; but with the engine running and under boost, you will be blowing oil out of your valve covers or back into the induction system, depending how you do things. I have used; Total Seal and Childs&Albert gap-less @ least 10-11 yrs ago. My engineer @ CP Pistons, gave me the wake-up call on the problems with using them.
Insure your machinist is using a torque plate, either cast iron for cast heads or alum for alum. heads. Torque loads and fasteners must be utilized, to simulate deck surface deflection.
I use a rough-in stone, take out the last .001 with a #525 stone( this is not a 525 grit, it is a 220) then plateau hone the sharp edges out. The most important thing is oil on the cylinder walls @ start -up and the fuel mixture is not washing the cylinder walls of oil. You will vertically groove the rings and if the block is not a higher nickel, the cross-hatch will be scrubbed away by the rings.
You should not notice any blow-by, at least after the engine is up to temp ( meaning dyno, break-in, and pulls)

Hope this helps,
Mark

Budman II

iTrader: (1)

Don't know anything about the gapless rings, but the engineer from Mahle kind of echoed what Mark (MER) said - they are now generally recommending a slightly larger gap on the SECOND ring to prevent flutter from gasses building up behind the first.

mike tkach

iTrader: (3)

mark,i remember back when 0 gap second rings were all you could get in gapless,i did not like them,i have had great results with the 0 gap top rings and i totally agree,the hone job must be done correctly.

MER Performance

Mike, I have not used a gap-less, top ring. I take it is designed the same way as the 2nd type. I talked with CP, about this a little, I know the ring lang width, must be correct and the groove is very important to the machining of it. Using the oil control ring as the bottom section and the second, being different materials, concerns me with the expansion rate with combustion temps. I will ask; CP what they have seen in the long term use; with a gap-less top ring.
If it works with no issues; it's good to know for a future option. Have you pulled a piston after 100-150 hrs. and have had the piston inspected, that could give you hard facts, on the ring lang, conditions?

Mark

Boatally Insane

iTrader: (1)

Thanks,
LOTS of great info...
I'm going to stick with a convential ring this go 'round...
I'll likely make more power than my Eagle crank can handle anyway..


MER,

I'll have to check with my machine shop about his honing procedure. I know he used a torque plate but I have no idea on the actual finish..
I picked the Moly rings over the Hellfire as It'll be a season or so before I'm able to add the blower and I was worried about the Hellfires seating N/A...


Still amazed how ring gaps are all over the place depending on who I'm talking to...
My original thought was .028" on the first and .030" on the second..


Doug