Hey guys:

Continuation of a prev. question. I have gapped my top compression rings but doing them by hand has caused some problems. I tried match them to about .032-.037 range but one has ended up at .047! Now, I still think I can run this but what do you guys think? I have 4.030 bore Silv-O-Lite "hyper" pistons (355). Their website recommends .008 per inch of bore for their Hyper pistons at performance street use, so thats about .032. I have read on the forums to error on the open side if one must, esp. in high heat situations. I'll have about 9.8-1 (iron heads + ZZ4 cam) compression when all is said and done plus I was considering adding a 4-5 psi supercharger later on (low psi power-adder). With all this in consideration, will what I have my rings gapped at be alright? Thanks in advance!!



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1987 Trans am GTA
5.7 liter TPI / 700R4
Aus 9-bolt + 3.70 gear

 

you could go ahead and run it, probley will just be slightly less compression in the one cyl, its one of those you *could* run it but its a better idea to just get a new ring and gap it correctly

 

Buy new rings, start over. You're a full HUNDREDTH of an inch too big. That's like starting with 100,000 miles on the rings.

Rings are cheap. Don't start taking shortcuts now.

 

Try fitting that ring to the smallest cylinder and see where you end up. While under heat load full throttle boost the gaps are going to close up a lot. You might
try visiting an engine building shop and see if they have or can get ya another ring to use for a reasonable cost. On a blown/nitrous motor with keith black hypereutectics ya almost can't get too big on ring gap.

 

Thanks guys for your input. With all my research I found that I was in error! I was using the gapping for KB pistons instead of the regular Silv-O-lite charts. KB hyper pistons have even greater heat deflection and silicon content then a **** star's t1t's or even their own regular Silv-O-lite Hyper pistons! (...There wasnt an easy Silv-O-Lite chart but there was a KB hyper chart and I thought since Silv makes 'em both [chart was on Silv's web site] -- you know the rest...) Blah, so I am shelling out for new Hastings moly rings (All new top rings really) and gapping them at .025. Can never be too **** when building an engine! Thanks!



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1987 Trans am GTA
5.7 liter TPI / 700R4
Aus 9-bolt + 3.70 gear

 

If you're building for nitrous or a blower
even with the siv-o-lites you should add extra top ring gap or they could butt under load.

 

Buy another set of rings, mix and match. Most guys that do this for a living will have five or six sets of bearings and *** knows how many sets of rings. Build it right the first time, that way you will only have to do it once.

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--Spyder--

1992 Camaro RS
LO3, T-56,centerforce clutch, ported and polished 305 TPI heads, Edelbrock Performer Intake, 14X3 Open Element w/ K&N, custom cat back, AC delete, SMOG delete, alu drive shaft, 3.73 Eaton Posi, 160 stat w/ fan switch, Ed Wright Fast Chip, MSD Igniton Coil, STB, Subframe connectors, KYB AGX, Eagle GSC, and poly bushings.

 

I gotta a question regarding the ring gap in hyper pistons. I have a set of .030" over Speed Pro 4" bore pistons that I'm gonna put in my 350. They also have the coated skirts.

The website says.......

"....Our hypereutectic pistons operate perfectly with standard ring end gaps, and have conventional ring land locations. When compared to traditional cast pistons, which are not designed for performance use, the hypereutectics are significantly stronger, particularly in the highly loaded ring land, skirt and pin bore areas. Our FM244 Alloy contains 16.5% silicon, and has excellent tensile and fatigue strength. This material’s improved thermal characteristics, it’s greater hardness, and the increased resistance to scuffing permit tight bore clearances which help minimize noise on cold engine start up. This quiet operation, along with a lower cost are the primary advantages over a comparable forged piston......"

Notice the bold print. Why is it other companies require larger end gaps? Should I call their techs and ask them just to confirm that I don't need a larger end gap?

Thanks for any help,
AJ

 

That would be a good idea....
remember if your going to run nitrous or a blower or run the motor at full throttle for
a long time like a boat, the combustion
chambers and piston tops will run hotter regardless of brand and will need a little extra ring gap. the extra ring gap will disappear when the motor is under heat load.
If the ring gap closes up to 0 the ring will grab the cylinder wall and break the top ring land. The tech line of the manufacturer
of your pistons can help you with this.

 

the location of the ring groove to the top of the piston would change how much heat was transfered to the ring, plus differant alloys would have differant thermal expansion and transfer rates. if speed pro says you can run stock end gaps then i'd do it. i've never used speed pro hyper pistons so have no experience or knowledge with them, but have used a lot of their parts, pistons included with good results.

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ICON Motorsports
1st & 3rd
MM Black Diamond 538 F&AM

 

If I were going to run a blower I would use forged pistons. Last engine I built used forged pistons ,just in case I ever wanted to use a supercharger, and I didn't notice any noisy operation.