Cast or chrome rings for B23 +T

[VB242]

Which is better for high boost application and why? Looking at Rock Auto Hastings brand rings. I want to gap them a little tighter to reduce some blow by when I put this motor back together. I think I went 028" last time.

 

[VB242]

Never mind, Google says chrome is the way to go.

 

[mikep]

You need a nicer finish for chrome.

 

[OttoB]

More Gap to 2nd ring

 

[dl242gt]

Never mind, Google says chrome is the way to go.

AI knows everything there is to know.

 

[culberro]

You need a nicer finish for chrome.

Generally rougher finish (180-280 grit stone) as the chrome is so hard you need the rings to break the peaks off and do the plateau honing for you. For a cast or moly ring you'd do some 400 grit stones as well for a few strokes to knock the peaks down.
A while back OEMs and machine shops were doing too fine of a finish and the bores would "glaze" and you wouldn't get good ring seal. Now it's a really rough hone, with a few (like 2-4 passes) with a finer hone to get the correct finish on most rings.

 

[mikep]

My apologies. I was thinking of moly. But i have always done a plateau, hadn’t heard of leaving a rough bore.

High Performance Piston Rings and Cylinder Finishes - Engine Builder Magazine

Today’s performance ring sets are thinner, lighter and more conformable than ever before. Thinner, low-tension rings reduce friction for more usable horsepower. Less weight reduces ring groove pound out. Narrower rings also allow tighter tolerances and less blowby. All very good things when...

www.enginebuildermag.com

 

[culberro]

My apologies. I was thinking of moly. But i have always done a plateau, hadn’t heard of leaving a rough bore.

High Performance Piston Rings and Cylinder Finishes - Engine Builder Magazine

Today’s performance ring sets are thinner, lighter and more conformable than ever before. Thinner, low-tension rings reduce friction for more usable horsepower. Less weight reduces ring groove pound out. Narrower rings also allow tighter tolerances and less blowby. All very good things when...

www.enginebuildermag.com

Hastings just updated their ring guidelines and just spec out surface roughness numbers for the bore. It’s up to the machine shop to get there. They used to have a stone grit guideline, and the chrome rings were rough.
Moly rings are great because they’re more tolerant of bore finish and it can be on the smooth side without issue, which is why OEM replacement rings are usually moly faced for quick seating.

But generally for most engines it’s a 220-280 grit stone, then just a few strokes (like 2 up and down passes) with a 400 stone and you’re done. You can also use a plateau brush or dingle ball hone as well. It’s funny talking with the ring companies and asking about bore finish, they all stress that you don’t want it too smooth which is very counterintuitive. We had some chrome rings on air cooled vintage motorcycles that would not seal. Talked to the piston company and they said to put the lightest coating (or none) of oil on the rings and then break them in hard. Never an issue with ring seal after that, but gosh dang that’s not the usually way!

 

[culberro]

Never mind, Google says chrome is the way to go.

Chrome is the way to go, but don't baby it on the break in and run a dingle ball hone through the bores at a minimum.
If you can't hone it, run the standard cast iron rings.