When it comes to piston rings, there is a whole lot of misunderstanding and/or outdated beliefs in the marketplace. So, in order to clear up any misconceptions, we asked you, the readers, for your questions for Total Seal to answer in this installment of Ask The Experts. You guys came up with some really good inquiries, diving deep into all aspects of piston rings and cylinder wall finish. You guys sent in so many questions that even we couldn’t stick to our self-imposed limit of 10 questions for Total Seal. So if your question didn’t get answered here, you can always reach out to Total Seal’s tech support. Read on for Total Seal’s answers to Ask The Experts.

Given that many machine shops use old methods to hone cylinders, how can a customer tell if a machine shop is up on the latest best practices in cylinder honing? – Neil S.

TS: The use of a profilometer such as the Mitutoyo SJ-210 or the newest model the SJ-220, would be a good indicator. These instruments accurately measure the roughness average (Ra), the core average (Rk), Average peak (Rpk), and average valley depth (Rvk).  A good machine shop should be able to provide you with those numbers.

A profilometer physically measures the surface finish of a surface (the cylinder wall in this instance) and can give you a “picture” of the machining performed. Besides ensuring there is enough valley to effectively hold oil, ideally, the closer you get to your target in the hone, the quicker the engine “breaks in” or “seals up” and starts making maximum power.

I have a heavily modified import V6 engine I’m building, and I’m at the point of trying every trick on this engine. Without getting too into the weeds, which would be a better choice, gapless or gas ported? I can’t use a ring with both. – Scott W.

TS: If it is for street use, we would suggest using a gas-ported top ring. If it is a dedicated race-only application, then we would suggest a gapless top ring. Keep in mind, they can be combined. When combined, we have seen as much as 30-plus horsepower over a conventional gap ring package. So, there are some real horsepower-per-dollar advantages in combining the two technologies.

I was watching a video where the presenter claimed to have recorded a 5-10 horsepower increase by lapping (by hand or machine) the fresh honing surface with red Scotch-Brite pads before assembly, which theoretically would provide better ring seal and longer ring life. He claims it also decreases the peaks without disturbing the valleys needed for oil retention. Have you ever investigated something like this? – Richard W.

TS: Yes, we have done extensive testing. Going over a freshly honed cylinder wall with the Scotch Brite cleans the junk or fuzz off the cylinder, and the rings simply come in faster, so we see a quicker result on the dyno. Ultimately, I didn’t see a power increase given enough run-in time to allow the rings and cylinders to completely seat up, which can take a lot longer than one thinks.

Besides piston rings, Total Seal manufacturers many tools related to piston rings, like power ring filers. Gettng not only the proper ring gap, but a properly machined ring gap is critical to getting the most performance out of your engine.

I am building a high-performance drag race engine that will not be dyno tested and won’t be run for quite some time. What should I put on the rings during assembly that will ensure that there are no problems upon first startup, which may be a couple of years down the road? – John M.

TS: Total Seal’s Quick Seat was developed for this instance. As a dry film it will not “flow” or “drip” down into the pan during long-term storage. You can also bag it up and use some baking soda (refrigerator box) in the bag and tape it closed. The baking soda acts as a desiccant to absorb moisture.

A nationally recognized, FSCA-winning engine builder has stated he only uses 1/16-inch rings in his medium boosted, high-horsepower street engines. With all the new metallurgy allowing thinner and thinner rings for better combustion sealing, is there a point of diminishing returns using thin rings below 1.5mm in medium boosted applications? – Roger R.

TS: Some of this is personal preference by the engine builder, which is fine, but there are horsepower gains to be found going with a thinner ring package. We have many engine builders using thinner rings, i.e. 1.5mm or 1.2mm etc, in very high horsepower builds to great success. Without knowing all the details I would consider going with a 1.2mm, 1.2mm, 3.0mm combination, such as used in our new TFX ring sets.

Total Seal’s Quick Seat dry-film assembly lube is a unique product in the world of engine assembly lubricants, as it is a dry powder. Not only does it protect the cylinder walls from excessive wear during assembly, and maintain its protection and lubricity under extended storage, but it can also accelerate the engine break-in process.

While I appreciate all of the high-performance piston ring innovations, what about for regular, run-of-the-mill engines, like a ’51 Willys, ’54 Chevy 235 Stovebolt, or ’80 Buick V6? What’s the “best” out there for those kinds of classics? – Bradley B.

TS: Our CR sets in the 1/16-inch, 1/16-inch, and 3/16-inch sizes are great for those early models, but it also depends on what you can find for pistons. Often, the choice of ring thickness is dictated by what pistons are available for a particular engine.

We don’t have a power hone; we are honing with a manual Sunnen cylinder hone using CAN 2 stone and felt sets without much success. At first, we were getting a larger diameter in the center of the cylinder and a smaller diameter in the top and bottom. We finally turned a sleeve to 4.030-inch inside diameter and trued the stones by honing the inside bore, and achieved better results. Is this an acceptable process? – Joe M.

TS: Running in your stones is super important. A couple of other things to consider when using the two-stone setup (N37) prefix you sometimes need to knock the guides down. There is also a four-stone set we prefer with the (NN40) prefix. One thing to note is that the more stones you run, the rounder the cylinder will be.

My question pertains to break-in and seating rings for optimal longevity. We have a J-tech crankcase/blowby meter that is helpful during ring seating, but I always wondered what the ring manufacturer would say the correct procedure is as far as how much load to put on at initial start, though the entire break-in process. A most typical application to address would be a pump-gas iron 540-572 BBC, hydraulic roller, 8.0:1, screw-supercharged and intercooled, making about 8-12 psi and 800-1,100 horsepower.

TS: On an engine like that, we would suggest running it for 15 minutes or so with about 80-100 lb-ft load, varying the throttle the entire time. Afterwards, check all the important things like valve springs, timing, etc, and then let the pulls commence.

For cylinders that have been plateau honed, is it possible to re-hone the surface when worn, without taking enough material to require oversized pistons and rings? – Vicente C.

TS: Yes, you can re-finish a cylinder safely by removing no more than .001 of an inch of material. That shouldn’t necessitate new pistons or rings.

A proper ring gap is an important part of engine assembly. There’s more to properly measuring ring gap than a simple set of feeler gauges.

If you’re tearing down an engine and plan to reuse rings, how important is it to make sure they go back in the same cylinder they came from? Are they broken in specifically for that cylinder? What happens if the rings were to go back in a different cylinder of the same engine? – Kent S.

TS: It is very important that they go back in the cylinders they came from, and even more important that they stay on the same pistons. Rings do wear into the ring groove like a flat tappet lifter on a cam. Once set, they don’t like to be swapped around.

I’ve got a couple of Nikasil-cylinder engines I’m working on. The first is an older air-cooled N/A Porsche flat-6. I’m interested in your recommendation for compression rings for a hot street engine, as well as having only one compression ring. Also, what about running boost with Nikasil cylinders; are there any special considerations with the ring set there? – Jay N.

TS: A two-ring or single compression ring piston is generally a no-go on an application like that, as it will use excessive oil. The second ring’s primary purpose is to scrape the oil that gets by the oil control rings. Therefore, two-ring pistons are not practical even in the best of scenarios, especially in street applications. As far as boosted applications are concerned, the tune is critical to avoid fuel washing the cylinders. They also need to be honed by a shop that can measure the cylinder surface with a profilometer. Nikasil has some advantages, but the piston ring seal can be tricky.