Great news engine professionals and enthusiasts!

Because the first Engine Performance Expo was such an overwhelming success, we’re doing it again! The second annual event will be held October 14-16, 2021, and will once again be all online and 100% free to attend.

As with the first Expo, this one will include seminars, demonstrations, interviews, and live Q@A sessions with some of the performance engine industry’s most famous personalities. We’re also going a step further and covering a broader number of engine types (motorcycles anyone?), and adding more “how-to”, education and training sessions for those of you interested in improving your skills, or possibly starting a career in the industry.

We’ve posted more information on the Engine Performance Expo website here:

>> Engine Performance Expo Returns October 2021

Check it out and make sure to save the date!

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Written By: Ed Kiebler
Domestic Sales Manager, Rottler Manufacturing

To start this article, it is important to emphasize the extremely precise tolerances that surface finish is measured in.   When we talk surface finish, we are talking in microns or 40 millionths of an inch!  The example in this article puts that in relationship. The reason we need to understand this is that when you are getting weird or crazy readings on your profilometer you will understand that tiny things (a spec of dirt or lent or one larger than normal scratch) can affect these readings.

When we measure plateau finishes, the common Ra measurement isn’t anywhere near enough to understand the quality of the cylinder finish.  First, it doesn’t give us enough information.  Second, Ra only measures the average height and valley from the mean line.  The example pictured demonstrates why we cannot use the Ra measurement as our measurement for plateau finishes.

For a clear and accurate understanding of plateau cylinder wall finishes we use the Rk family of parameters.   These included RpK, Rvk and Rk which help define the proper surface finish or plateau finish we need for the application the engine is being used in.  The example here shows the main three parameters used in plateau finish measurements.

The key to plateau finishes is to determine what grit diamond abrasive or std abrasive you will need for your base finish. For instance if you require a RvK of 50+ a 400 grit diamond or std abrasive wont give you enough deep scratches once you have plateaued the cylinder. So the Rvk is the most important parameter to start with. A 50+ rvk is going to require a grit size ranging from 140 to 200 grit depending on the burnell hardness of the block.   In a nutshell, the harder the Brinell on the block the rougher the grit will need to be to obtain the base Rvk number you desire.    Similarly, To obtain a 50+ RvK in a Dart block, you will need a RvK number of 80+ before you use a fine grit abrasive to get the plateau.

Rvk is what the oil sees.  It is important to measure your finish each step of the way.  After honing with a rough base diamond, measure your surface finish to determine if you have enough roughness/RvK to obtain the desired RvK number after you plateau.  To reach your Rvk goal, you typically want at minimum 20 to 40 points higher on your roughness readings before plateau honing with a fine abrasive.

We typically try to keep it to a two-step process when plateau honing which makes it easier and less confusing.   It also gives you a true plateau that you can see on the traces of the cylinder finish.   I use a 600 grit CBN abrasive to plateau with.  Rpk is what the rings will see.  Most ring manufactures want between 8 to 15 Rpk numbers for their rings. This is why I use 600 grit. The CBN abrasive is a much sharper particle than diamond and cuts much cleaner than a diamond abrasive. With CBN you no longer need to use a brush or plateau brush to help with the finish. The CBN will remove all the torn and smeared metal from the diamond abrasive leaving a very clean and sharp peak and valley pattern.

The biggest misconception in plateau honing is the RpK will continue to get smoother or smaller if I keep honing. That actually isn’t true. The 600 grit CBN will leave between a 8 and 15 RpK number whether you hone 6 strokes or 20 strokes. We use the 600 grit CBN to determine RpK so if I wanted a rougher RpK I would use a rougher CBN grit abrasive – say for example something on the order of 500 or 400 grit. The CBN will also determine RvK numbers. The more strokes I hone with the CBN abrasive the smaller my RvK will get until I reach what I call a base finish which is the actual finish a 600 grit abrasive will create on a cast iron surface. The nice thing about this process is I can take a rougher grit diamond than I really need and simply use more plateau strokes to obtain a smoother or finer finish. This helps prevent the purchase of multiple different grit size of diamond abrasives.

I am typically only worried about the RvK and Rpk numbers. The Rk value is usually a combination of the rough base finish and smooth plateau finish. We can affect Rk by using a third step in the process. That can be done if  we use a rough (say 140 grit) base finish followed by a medium step (say 400 grit) followed by a plateau finish with 600 grit. This would maintain RvK, maintain RpK but reduce Rk values. 

The rough base finish is created simply by using a rough grit abrasive and honing the bore to size making sure it is round and straight. The plateau is a more defined process. We typically use pressure/strokes to determine our finish. So, it is important to apply the same amount of strokes and the same amount of pressure to obtain consistent results when plateauing. We want the hone head to almost immediately have pressure on it before it begins to spin so we maintain even finish thru out the bore. Typical process would be to use 6 strokes at 20% load on the 600 grit CBN abrasive.

A good example is honing a Dart block for general purpose use as defined by Total Seal:  I use a 170 grit diamond honed to size. I would then use a 600 grit CBN abrasive for 6 strokes ant 20% load. This should give you the required finish as defined by Total Seal for general purpose use. Those parameters are RpK of 10 to 20, Rk of 35 to 45 and RvK of 45 to 55. If your numbers on RvK are too high then use a couple more strokes with the 600 grit CBN. If they are too low then use a couple less strokes with the CBN abrasive.   Its really is that simple.

By using two steps we create a true plateau, we reduce honing time and reduce cost by needing less grit sizes of abrasive.

To serve as example, below are the surface finish parameters required by the ring manufacturers as I know them.

Total Seal

Thin Top ring

RpK        8 to 15

Rk           20 to 30

RvK        30 to 40

General purpose

RpK        10 to 20

Rk           35 to 45

RvK        45 to 55

High pressure/ forced induction

RpK        10 to 20

Rk           55 to 65

RvK        65  to 75


All rings

RpK        10 to 20

Rk           25 to 50

RvK        30 to 60


Good performance

RpK        8 to 12

Rk           25 to 35

RvK        40 to 50


RpK        3 to 5

Rk           12 to 18

RvK        20 to 50

Some sort of conclusions… something like…

I hope that this helps and gives insight into the critical role that surface finish plays in optimal engine performance.  At Rottler, we are always working to improve engine performance thru better machining.   I am always looking for new ways to ….  etc

WEBINAR: Cylinder Finish & Piston Ring Relationship Explained with Total Seal

Ed Kiebler of Rottler Manufacturing and Keith Jones of Total Seal team up Wednesday, October 21, 2020 at 10:00 AM CDT to discuss the science behind what makes a great finish. Ed will explain and demonstrate how proper honing techniques produce the right surface finish for optimal piston ring performance. Keith will package it all together from the ring’s point of view. This webinar will be done at location at Robert Yates Racing in Charlotte, NC .

After registering, you will receive a confirmation email containing information about joining the webinar. If you register for this webinar you will automatically receive a link to the recording whether you watch the webinar live or not.

You can access all 62 past recordings 24/7 at www.pera.org/webinars

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VIRTUAL EVENT: Engine Professional Expo

Mark Your Calendar & Register Today

Start 2021 with a one-of-kind, interactive, online event – The Engine Performance Expo. January 7th, 8th & 9th, 2021. No travel required, and registration is FREE.

This 3-day event showcases industry-leading engine builders, suppliers, machinists, and equipment manufacturers. The top people, parts, and processes in the high-performance engine industry will be featured each day.

From live panel discussions to detailed instructional demonstrations, the Engine Performance Expo delivers the “know-how” to go faster in 2021 and beyond. Connect with industry experts and see the latest products and processes.

Featuring engine builders from NASCAR to Diesel Drag Racing and beyond, the top names in the performance engine industry come together with leading suppliers to fill the “knowledge gap” left by the cancellation of PRI.

More details to come in the next few weeks as the schedule of speakers and demonstrations are confirmed. In the meantime, make sure to visit www.EnginePerformanceExpo.com to register and mark your calendar. These 3 days can change the season.

Tentative Schedule:

Day 1:
8 AM Opening & Featured Engine Builder Interview
8:30 AM Seminar with Q&A – Block Selection & Machining Considerations
9:30 AM Demonstration with Q&A – Block Machining
10:30 AM Seminar with Q&A – Surface Finishes & Sealing
11:30 AM Demonstration with Q&A – Surface Machining
12:30 to 1 PM – Break
1:00 PM Seminar with Q&A – Cylinder Honing & Surface Finish Considerations
2:00 PM Demonstration with Q&A – Honing & Profilometer
3:00 PM Seminar with Q&A – Rotating Assembly Balancing & Considerations
4:00 PM Demonstration with Q&A – Balancing Machine
5:00 PM Seminar with Q&A – Pistons, Pins, Clearances & Coatings
6:00 PM Demonstration with Q&A – Cleaning Equipment
7:00 PM Closing

Day 2:
8 AM Opening & Featured Engine Builder Interview
8:30 AM Seminar with Q&A – Engine Lubrication System – Pumps, Pans, Clearances, Filters & More
9:30 AM Demonstration with Q&A – Custom Parts Manufacturing
10:30 AM Seminar with Q&A – Cylinder Head & Manifold Porting
11:30 AM Demonstration with Q&A – 5 Axis Machining
12:30 to 1 PM – Break
1:00 PM Seminar with Q&A – Valves, Valve Seats & Guides
2:00 PM Demonstration with Q&A – Seat & Guide Machining
3:00 PM Seminar with Q&A – Valvetrain – Cams, Push rods, Rockers, Lifters & Valve Springs
4:00 PM Demonstration with Q&A – Spintron
5:00 PM Seminar with Q&A – EFI
6:00 PM Demonstration with Q&A – EFI Software
7:00 PM Closing

Day 3:
8 AM Opening & Featured Engine Builder Interview
8:30 AM Seminar with Q&A – Turbos
9:30 AM Demonstration with Q&A – Sleeving
10:30 AM Seminar with Q&A – Nitrous
11:30 AM Demonstration with Q&A – Bushing Installation
12:30 to 1 PM – Break
1:00 PM Seminar with Q&A – Diesel
2:00 PM Demonstration with Q&A – Diesel Specific Machining
3:00 PM Seminar with Q&A – Assembly Tips & Tricks
4:00 PM Demonstration with Q&A – Power Ring Filers, Bolt Stretch Gauge & Torque Angle
5:00 PM Seminar with Q&A – Dyno Testing & Health Checks
6:00 PM Demonstration with Q&A – Dyno Room Tools
7:00 to 8 PM Closing Roundtable

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Next Generation CNC Machining Centers

Rottler’s innovative EM Series CNC Machining Centers have been specifically designed to be the most technically advanced industry specific systems available. More than just a single machine, these new “Engine Machining” CNC Vertical Machining Centers are designed to give customers even more flexibility for engine parts machining, digitizing and porting, and custom parts manufacturing.

Rottler’s newest EM Series equipment is designed for maximum ease of use and efficiency thanks to our advanced 4C Machining Software. This advanced software lets users know they are machining with the most state-of-the-science equipment available.

Seamlessly integrating Computer Numeric Control (CNC), Computer Aided Design (CAD) and Computer Aided Manufacturing (CAM) in the industry’s most advanced Computer Measuring Machine (CMM), the 4C technology allows users to digitize, edit designs and begin cutting in less time but also requires less machining/programming expertise compared to many other systems. This brand new, revolutionary CNC machine CAD/CAM software allows 3D CAD Solid Models to be imported or created at the machine – the built-in CAM functions can be used to semi-automatically and interactively create complex 3D tool paths direct from the CAD geometry.

The advanced software design allows professional engine builders and head developers to maximize production and minimize preparation time. The next generation CNC control gives even greater capability beyond porting by letting users probe parts for duplication and modification all within the machine control – no external or third-party software or equipment required.

One of the main features is the EM series’ massive 32˝ touch screen – by maximizing screen size, Rottler’s CAM software allows unprecedented amounts of information to be displayed for the operator’s use. The user can choose the information to be displayed for incremental and interactive functionality. Rottler’s next generation CNC control found in the EM Series machines continues to give users unmatched speed of learning and ease of use when probing/digitizing without the need of additional cumbersome and expensive software.

Rottler EM69 Machine

Can’t find the parts you need for that one-off project? Make them yourself! More and more customers, after researching the real-world adequacy and challenges found in top-of-the-line industrial CNC machines, recognize the value and benefits of the parts machining capabilities built into Rottler’s equipment. Many of the EM Series machines can easily be programmed to custom create the parts you need when you need them.

Customers say it is the most user-friendly software they have ever operated because it allows even novices to be productive right away. Thanks to the speed and efficiency of 4C software, some machinists report being able to produce parts and port cylinder heads four-to-five-times faster than with other systems.

The software is only part of the secret to the EM Series’ attractiveness. These machines are designed to be up to the task of creating whatever our customers can dream up.

A lot of research and development has been put into sourcing and engineering the new high output spindle motors in the EM machines. CNC machine spindle motor power and torque is commonly given in two different ways – continuous and peak.

Continuous power and torque rating refers to the maximum cutting load that a spindle can sustain running non-stop, 24 hours per day without overheating. Advanced technology spindle motors are able for a limited time period to deliver substantially more power and torque before overheating.

Peak power and torque rating can be significantly higher compared to continuous rating but the limiting factor is heat. It is common when CNC machining that spindle motors are not running continuously (for example when changing tools). The depth of cut and feed rates will also determine to amount of heat that the spindle motor has to overcome. The integral spindle motors on the EM 5 axis models are liquid-cooled and the liquid’s temperature is accurately controlled by a special AC chiller unit allowing peak operation for longer periods of time.

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Building the Best, Using the Best

DFC Diesel, Alberta, British Columbia, Canada

When DFC Diesel first started rebuilding engines in 2010, president Matt Adams says the team quickly realized it wanted to build the best, using the best. “Thanks to brand new cutting-edge Rottler equipment we were able to bring an unrivaled level of precision machining to the Canadian diesel industry.”

Today, DFC uses a variety of Rottler equipment, including Rottler’s SG10XY for all of its 5.9L Cummins cylinder heads – “It can work on all 24 guides or seats while one of our machinists is able to operate other equipment during its cycle time,” says Adams.

“The rigidity of the spindle head and live pilot design gives mirror like seat finishes that are repeatedly cut to the same depth. This allows us to maintain strict quality control and have identical results on every cylinder head we remanufacture. Its automatic functions allow more production to be done and being CNC controlled gives repeatable results each time it is used.”

DFC received the fi rst automated hone from Rottler in existence and Adams says his workers are proud to showcase its abilities with every engine they remanufacture. “With a CNC controlled operating system it allows every engine to have the exact same crosshatch angle in every cylinder and with a load sensing honing head gets every bore within 0.0002˝ (two tenths of a thousandth inch) for taper and out of round with ease. Finishing off with a preprogrammed plateau mode gives our engines the same level of quality found when built in the OE manufacturing plants. These fi nishes are QC checked using a profi lometer ensuring the proper RA surface fi nish for proper ring seating and longevity.

“A welcome addition to our lineup of precision Rottler equipment, our EM69 was the fi rst one sold in Canada. This machine allows fast and precise digitizing and cutting of head ports and allows reverse engineering of existing port designs through the use of a Reninshaw probe. The ability to design intakes and produce custom parts as well as cut O-rings in cylinder heads raises the bar for precision engine machining equipment and further demonstrates our desire of bringing the most advanced machining equipment to the business.

“Finishing off our lineup of the most advanced automotive machining equipment in Canada is the SG9MTS seat and guide machine. The SG9MTS has all the same design features of the SG10X but in a manual version. The live UNIPILOT design keeps concentricity of seat cutting to above industry standard and the production fi xture combined with programmable cutter heights and speeds allows for precision machining with production speeds. Perfect sealing of valves is possible each time, every time.”

– Matt Adams, Owner, Alberta, British
Columbia, Canada

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VIDEO: EM69HP LS Cylinder Head Performance Porting

The Rottler EM69HP is Rottler’s flagship 5-axis machining center. Building on the strong foundation from previous generation porting and block work machines, the all-new EM69HP now incorporates Rottler’s next-generation 4C control as well as a newly designed 20,000RPM spindle. This allows the Rottler EM69HP to create race-winning ports faster and with a better finish than the competition.

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Customer Spotlight: Choate Engineering Performance

When a family puts their name on a product they produce you know there’s a lot of pride that went into that work; ensuring they have a customer who can trust what they are putting in their vehicle. Choate Engineering Performance is one of those companies that have put the years of experience, investment in equipment, and industry know-how behind creating a top rate product that will handle anything the customer wants to throw at it.

Born out of a frustration in being able to find a machine shop with dedication and pride in their work, Choate Engineering Performance made the investment themselves with a mission to keep all of their work on an engine build in house. This way they control the quality from start to finish. The capabilities of the shop speak for themselves; with 4 and 5 axis CNC machinery as well as flow bench and testing equipment the customers who come to Choate know what they’re going to get; excellence and performance.

A major component of the capabilities and the investment Choate has made in creating an elite machine shop is their lineup of machinery. The Rottler P69AHD Porting machine, F69ATC machining center, SG9MTS Seat and Guide alongside the added benefit a solid hone in the H85AY have given Choate Engineering Performance the confidence to put their name on their product and know their customers will be satisfied and returning again for their next project.

A project that Choate was able to participate in and sponsor was The Punisher Truck Build. Choate donated all of the machining, camshaft, cylinder heads, pistons and more – about 98% of that build and did all of the machining from start to finish. The Punisher is a 1964 F100 with a 6.0/6.4 hybrid. This thing hauls!! Check out full build details on Truck Trend by clicking here.

A changed approach

While operating as an engine rebuilder, Choate has continued to provide their services through the COVID-19 pandemic. While some business has slowed, they know that parts production and repairs statistically do well in this type of economic climate. They have focused their efforts on that work and know they have the foundation to keep going and come out of these challenging times as strong as ever.

Choate offers programming, or “Reverse Engineering”  for Rottler machines as well as cam technology. We at Rottler are proud to call Choate Engineering Performance a customer and trusted partner in the engine rebuilding world. Being family-owned and operated ourselves for over 97 years we know what it means to put our name on our product. It takes pride, dedication, and trust. We look forward to continuing to support companies like Choate in the future and are honored to have them as a strong Rottler customer.

Follow Choate Engineering Performance on Facebook and Instagram.

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VIDEO: Custom Part Manufacturing With Fusion 360

Here at Rottler Manufacturing we recognize that our customers come from backgrounds just as diverse as the types of products they produce. Therefore we are always looking to provide the most versatile platform possible. In this video, we demonstrate how the popular Autodesk Fusion 360 software can be used directly with our Rottler 4C Machine Control to produce and run edit-free G-Code programs.

The Rottler EM69HP is an all-in-one 5-axis engine machining center designed for producing race-ready cylinder heads and blocks. It also provides a great platform for creating custom parts such as mounts, spacers, brackets.


Rottler will go LIVE for the first time Wednesday, May 20, 2020 at 5pm PST, 7pm CT and 8pm EST to demonstrate custom parts manufacturing with Fusion 360! Watch live by tuning in to the Rottler YouTube Live channel. You’ll be able to watch along and send in questions as we demo!

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VIDEO: Automated Cylinder Head Machining – High Production

See how one machinist can produce a finished cylinder head approximately every 3 minutes in our new video showcasing Rottler’s SG10XY cutting valve seats coupled with the S86A surfacer. A dream team for serious production.

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