RS Cylinders 2nd Hand

[matty74]

I want to purchase these cylinders they are RS cylinders/Pistons and have only done 50K miles.

They need a polish, what to you guys reckon for 2nd handers any good?

[Wayne 962]

RS Cylinders = same as any other 2.7 CIS cylinders = nothing really too special.

The pistons are low compression 8.5:1 - I typically don't recommend rebuilding to RS specs, but instead bumping the compression.

-Wayne

[matty74]

So on my stock CIS 2.7 motor I can put in s cams and MFI?

[KobaltBlau]

no you cannot use s cams with your CIS pistons. You can use JE pistons at 9.5:1 or so with single plug, but will need good nikasil cylinders. note that alusil cylinders can be replated. That RS piston looks kind of scored but it might just be the flash.

[svandamme]

Originally posted by Wayne at Pelican Parts
RS Cylinders = same as any other 2.7 CIS cylinders = nothing really too special.

The pistons are low compression 8.5:1 - I typically don't recommend rebuilding to RS specs, but instead bumping the compression.

-Wayne

weren't RS cyllinders Nikasils par default

wile the regular 2.7's could be Alusils or Nikasils?

[KobaltBlau]

Yes, Stijn

[cnavarro]

I thought the pistons looked a little scored myself. Just go with some JEs and bump up the compression per Wayne's recommendation.

[EPorsche]

Matty74,
Almost finish with a rebuild on the same type engine with RS pistons. If you follow Wayne's book you will probably have trouble with the valve/piston clearance check. That's with stock CIS. If you fail that check you have to pull the pistons back off and get them shaved.

[911pcars]

Also check the condition of the cylinders. At 50k, they should still have the cross-hatch pattern on them. If the pistons look okay (skirt wear pattern is suspect), compare specs with measurements for piston ring side clearance and piston OD (and thus piston-to-cylinder clearance). I've seen new sets for $1500-$2500. If all is okay, add in the cost of a new ring set, then price these accordingly.

Some say the life span of JEs is not on par with the factory Mahle's. Same with piston clearance. The more clearance, the more noise, especially during warmup. More clearance at normal operating temps. creates more ring wear as well.

Don't polish the pistons (only the crown, if desired).

MHO,
Sherwood

[obrut]

"You can use JE pistons at 9.5:1 or so with single plug, "

as a data point - i used 10.5:1 JE's and had no det'n problems with our (ie. aussie) premium fuel (nb: GE80 cams). however, the engine runs much much better (particularly under 4000 rpm) now we've converted it to twin plug.

[Henry Schmidt]

If the pistons are still in spec, you can use the scratches to hold dry film lubricant.
The rougher the surface the better it (dfl) holds.
Dry film will not bring back missing material but if they're in spec. I'd use them.

It is hard to diagnose anything from 5000 miles away so check for cracks and measure, measure, measure.

All Mahle piston have a size group designation so if they show a little ware you could put the piston in a cylinder that is one size group smaller.

I.E.: put a #2 piston in a # 1 cylinder.

Of course new is better and more money.

[Carrera3.5L]

Mahle Motorsport also makes a 90mm RS piston/cylinder set with a 9.5:1 CR instead of the standard 8.5:1. These would work fine should you ever decide to install MFI and "S" cams.

Unfortunately, you can't buy the pistons individually and reuse your cylinders, you would have to spring for the whole piston/cylinder set. Not cheap, but at least you would have Mahle quality.

Ralph