Idk if I'll own a rotary engine, but I'm sure as hell gonna sit here and learn. 21 minute video!!

Learning by testing, trying to correct problems and making mistakes, them sharing with everyone. You are a good man Rob.

It’s an utter shame how the engineering world gave up on the Rotary engine so quickly. Had they gotten the same attention piston engines got, who knows where they’d be today. People like you are putting in the effort to bring it back!

The first new car my family had was a 1972 Mazda RX2. I remember how smooth that engine was and it never left my mind. Sadly, the car was totaled when it was three weeks old and we replaced it with a larger car. I thought that the rotary engine would be the thing of the future at the time. Here we are fifty years later and this video is a blast from the past for me. Well done, sir. You have earned another subscriber.

THIS! Sad part is, so many in the rotary community will deny and call you a liar because they don't want their customers to be wise and save money. Keep it up! So glad I'm learning this before I do my inevitable rebuild

Dahm just wants the rotary to live. Dahm does not care about secrets. This is the way.

We used to remove 3 thou off each side entirely not just the tips. We also machined the actual faces down on the rotors as well. You’d be surprised how different each casting is and how unevenly material removal was on those faces. Ran 13b’s with 58psi making 980+whp pretty much indefinitely for multiple drag seasons on customer cars. Just clearance and balance and run a good studded block and they’ll run forever. There’s no real secrets to be had or magic port work that hasn’t already been tried over the past 50yrs.

Man, I feel like you glossed over detonation, which is a bug issue for the FD. Detonation will destroy those apex seals and, like mentioned, will destroy the rotor housing and the turbochargers on the way out. Two necessary solutions here that weren't mentioned. First, the stock intercooler for the FD3S is laughably small. A larger intercooler will keep charge air temperature down to reduce the risk of detonation. Also, the factory apex seals come in two pieces. They do slide around and make somewhat of a better seal but machining the rotors to accept a larger 3mm single piece apex seal is a much better option.

The Dahm gods have blessed us with another video

Guys in the shop in one of robs car: why we goin do fuckin fast!? Rob sitting there, stationary: I knew I shouldn't have given them the torch

Really interesting vid, I've said this for a long time, tighter fitting components make much stronger motors. As long as clearances arnt silly tight like f1 motors and you warm things ups properly (2 stroke talk there) then your going to avoid so much hassle in the future. High hp builds are difficult, my daily vehicles are usually low tune massive reliability. My toys are high tune lower reliably... but in the same breath if you warm things up and dont just beat on them out the gate then higher performance motors can still give very respectable bang for buck. Thanks for being an inspiration for many years Rob, I'm genuinely glad it's worked out for you. I'm a bike guy through and through but your passion for rotary engines is genuinely inspiring!

Great video man, it's really nice that people like you keep the rotary alive and improve it.

Love the fact you’ve gone from starting with a basic knowledge of rotaries, to fully fabricating parts and successfully building and tuning them to 1000+hp. Dahm, take a fucking bow my friend.

When I discuss Rotary engines vs Piston engines with folks I always point out the difference in engineering efforts. The overall effort (engineering/testing/etc) to improve the piston engine absolutely dwarfs the Rotary engine. I often wonder what may have been if the Rotary had even 1/10th of the same effort applied to it. Great video.

Man the 2stroke idea is brilliant.

not sure if i will ever buy a rotary but watching your channel certainly makes me want to learn more about them, just like you said. i have not seen a clear video with all the rotaryproblems and fixes for them for, so this is an amazing video!!

“That’s what you get when you’re surrounded by guys who smoke weed in the shop” RIP Rob’s torch

I love the fact that Dahm is shitting on years upon years of shite mechanics (which are responsible for many cool cars having bad reputations in US, not just an engine, because of their incompetence) but also the "boutique" gate keepers. Rotaries are here to stay. Every day there's new rotary content and more and more people who learn that the bullshit is just that, bullshit.

I never have owned or driven a rotary, I still found this interesting. Thanks Rob.

This is a really refreshing 'explanation' video. It is like a magician that does a trick amazingly well...and then agrees to explain how he does the trick, step-by-step, so you fully understand what is happening, yet the next time you see the trick, you enjoy it even MORE. No smoke and mirrors and no BS. Great job!!

TLDW: treat your engine like a 2 stroke, E-85 with 2 stroke oil, replace the dowel rods with solid rods, get thicker tension bolts, run the oil through the blocks separately instead of through the single oil hole where the dowel is causing block cracks.

This has to be one of the most straight up legit gear head engine mod videos I've ever seen. This guy uses science to explain why he does each mod on the engine and not make it sound like hookum. Well done young man!!!

Awesome video, I’ve been tempted to buy an RX8 several times, but scared off by all the engine problems I’ve heard about. If I could find a local shop that could do all these mods, then I would seriously consider buying a used RX8

This guy is a REAL one!!! In an ocean of confusion and needless upgrades... it's refreshing to get realworld practical guidance with an accompanying explanation of the "WHY" supporting the recommendations!!! A Genius IMHO!!! Thank You for the great videos!!!👍💯🙏

That steak is rare. **the steak is* *Rob Dahm with* *a conclusive ending** Yes, that is quite rare.

I’ve always been scared of rotary engines. Just because everything is always such a secret. I really appreciate you taking the time to educate us

Good work bro. I don't even have a rotary but hearing someone sharing their learning experience with it is heartwarming. Liked and subscribed right now just because of the honesty. Merry Christmas bro.

Recently got an rx-8 and just so stoked to have a rotary to work on and fix up. Love this channel and inspires me to work hard to learn the ins and outs of these engines.

This is like $100K worth of information in one free video Rob spills some beans

Tearing apart a rotary engine, AND putting it back together, was one of the most rewarding experiences I've ever had.

The Wankel Engine has SO much potential. It defies belief that only one company was willing to take the risks to produce it. I remember coming to the exact same conclusion you did about the two-stroke oil. E-85...that's brilliant because it's a little bit counter intuitive. I always wondered why the apex seals would fail...which you explained beautifully. I just had a thought about a maranging stainless steel alloy. Such an alloy actually gets stronger as it gets hotter...up to a certain temperature. You may need some babbit metals alloyed with it to provide proper wear characteristics. You need to study metallurgy on your own. A smart guy like you may come up with the best alloy and solve that issue once and for all. Also, the spring under the apex seal, maybe there's some super unobtanium alloy that will last the useful life of the engine. I think you should focus on the aviation market...once you fix all of the issues. It's a good compromise between a reciprocating engine & gas turbine. The sky is the limit!

Thanks for the very detailed " long term " research like information ( degradation in general ). Learning this and adding new concepts for secondary thermal engines , I.e. using a rotor as a part of a steam machine and using the wasted heat near the exhaust to generate steam, may also increase efficiency a large step. Duration and overall efficiency can be improved a lot.

It seems to be time for you to have an engine dyno for testing.

Thanks Rob! Sad to say, you probably already have a target on your back. I can't wait to learn about the different compositions of the apex seals. I'm sure most of them are hot-work alloys. I've seen a 160k mile mazda seal under a metallurgical microscope. It's amazing what they did!

Great and practical advice. I feel like buying back my RX8 and ripping the engine out and fixing it. The stepped full length down pin idea is brilliant - typical Kiwi ingenuity. Thanks.

This made me shift interest to the rotary. With all the issues you hear, maybe this really will make me aim for it this time. Thanks for the great video and series after this one.

Man I just love that you’re just putting all your results and solutions out like this and I bet lots of rotary guys that watched this are making plans to sort out their motors now

As a tech this is hands down my favorite type of auto content. Diving into the mechanics. Analyzing what can and will go wrong. And then coming up with solutions, that may or may not work. And be able to learn from it and convey that knowledge to others.

It really shows you have a passion for what you do man. Great video!

Found out about rotary engines and ended up building a Lego technic one and sharing it on UKposts. The way they work is so awesome!

This is why i watch you Rob over most youtube creators. Informative and clearing up the BS, no one deserves to be ripped off with pointless modifications and i'm glad you are helping the community and enthusiast!

Wish your channel existed 15 years ago! LOL. I've owned and still am the proud owner of the 7, and on my 6th engine. Went thru tune shops that didn't know what they're doing, and engines that were poorly built. It was funny you mentioned the ripple water mod cuz I had that done to one of my engines, and it blew during tuning 1 week after it was put in the car. I too had serious carbon build up on rotors in one of my engines and a chunk of that came loose which ultimately killed the apex and the engine. Believe it or not, that build was by Amemiya and was only making 500hps. The engine lasted about 4 years and 30,000km. "Too much city driving" was to blame for the carbon buildup, but never thot that was the real reason. What you're doing is super awesome and helping rotary lovers globally while fulfilling our dreams at the same time. Good on you, thank you from my heart, and keep up the phenomenal channel! Can't wait to see your next video on apex seals.

I enjoyed this video so much, and it all made so much sense, and so simple to understand. Now I think I'm in love with rotary engines again. I've always thought mass continuing in a circle was way better then reciprocating mass. I've raced 2 stroke dirt bikes growing up (bean oil smells so good) and 2 stroke oil had gotten so good that we were running 100 to 1 mix ratio on synthetic. We just never ran lean on fuel - air ratio. Less oil in the fuel keeps octane higher, and a cleaner combustion chamber. Great video, thanks!

This is great, gonna rebuild my 13b-MPS 4 port soon and this channel has been a gem

I’ve never been interested in rotaries until I watched this channel. It was new territory for me, it was weird and foreign. Watching this channel has made me believe that building a rotary is like the next level in engine building like sure you can build an LS, but can you build a rotary? I hope more people will accept the challenge Rob has silently put down. I certainly will.

You're the Tesla of Rotary Engines. It's always fun seeing you push the boundaries of what we've all thought was possible with rotary engines.

Recently been on a rotary bug… this video was fed to me perfectly lol. Thanks for such a great deep dive.

What a great video! I’ve never owned a rotary, but knowing this kinda info is out there is a benefit to anyone wanting to get into them. Looking at the space between the bolt holding the plates together, and where they pass through them, would a machined tube that closes up the gap work to prevent torsional movement of the engine? It looks like there’s enough material to have a tube in the middle.

Real talk Rob , in my years I have learned the guy who is constantly bragging about how good their shit is , and won't share any secrets. Usually means they don't have a fucking clue and are too fat headed to admit it. Seeing you do this shit and prove yourself makes the world of difference. We learn from our mistakes, you take it to the next level. Keep being awesome and helping us make that reliable horsepower! Well reliable for a rotary .... Be safe Rob !

I love how you're changing the game for rotary engines. As a mechanic who has always hated how engineers cut corners to reduce costs it's so refreshing to see all the bs cut out and someone with the ability to redesign something the way it should be designed. Keep up the good work, I look forward to these more technical videos

I like you PMI'ed the seals . What about doing a hardness test with a echo-tip to see which ones have been heat-treated to different tempers. The harder the material the easier to break chip off . Great stuff on your channel . Makes me miss my rotary power pickup. I loved it so much . I could do a controlled smoke screen in 2nd gear that would have traffic stopped.

Hi Rob, I am installing an RX8 engine into a homebuilt aircraft and the sump metering oil system has been modified by installing an oil metering pump adaptor from rotary aviation. This unit cuts off the sump oil and takes from a two stroke oil container to do the same job still via the metering system. I have also changed out the plastic lines to braided stainless steel and high flow aluminium fittings.

New Zealand has some amazing rotary shops that have built some amazing cars be so awesome if you did a tour here.

I love the idea of testing all the different seals to the nth degree just to know and cut through community ambiguity. The custom keyboard community had a guy who would test all sorts of parts and build methods people swore by empirically and called it "keeb science". Love this stuff man, keep it up.

I want those solid dowels, they look like they help SO MUCH keeping everything together. thanks for the run down Rob!

I love Rob’s passion. It’s the best part of his channel

Sounds like the ideal rotary engine has two oil systems, the lubrication system and the combustion chamber system. The dowel tie rod issue I would be reluctant to put a one piece sized steel element through an aluminum block due to thermal expansion geometry. If anything you put a hex-shafted steel fastener through a shrink fit hex-broached aluminum dowel body. That allows your aluminum parts to grow together but retains decent unity between the steel and aluminum parts. Sounds like an expensive machining job though.

This is the way it once was, racers helping each other. Competition was left for the track. Started thinking of my Toyota. Loved My Rx3 station wagon until about 110mph. That's where it decided you needed to contact the ATC for take off clearance. Unfortunately for the rotary, 20,000 miles then was about the limit for the apex seals.

Hey there. I’m wanting to enter the rotary worm hole. Just watched your video about problem solving. I gotta say that you’ve got a avid fan here. Tons of information. I appreciate it.

Regarding the size of the ARP stud, you can buy bronze bushings with or without collars that can take up that slack. Aircraft supply stores carry a lot of different sizes, but they can be found on McMaster Carr and MSC and other industrial supply sites as well.

So I’ve never built one of these myself but I come from an engineering background. You have a very interesting point about how the engine is held together only using long screws and dowels, i think that the screws are the size they are because they didn’t want to compromise the structural geometric load dissipation of the end plates where it’s screwed in, larger holes exponentially come onwards or outwards. I think you bring up an interesting point about the screws and why the rest of them are thinner than the main holes, do you think that has anything to do with the way such a unique engine “block” expands based on heat? I hypothesize that those stock rods were carefully calculated to expand a certain amount when the engine is warmed up as to not become loose but not stay on too tight so the seals can function better while also keeping a safe retention between the engine “plates” during cold starts. Inserting straight dowels machined into the holes make some sense into making it more stiff but I’d argue that if it has a direct fit to the actual walls on the holes, then the heat transfer and the rate at which it warms up and the heat dispersion would be not worse per day but poor design, it would most likely stress the frame of the engine block in uneven ways and by completely trying to get rid of the torsion flex, it would beneficially save the apex seals and rotors during run time but making it too stiff will inevitably destroy the main shaft. This was actually the problem with the original mazdaspeed lemans 7 series race car, they made everything fixed with super proprietary seals and basically made a special mounting system for the engine plates and also made a custom engine block to hold itsself together. This led to more consistent performance and insane power numbers in a a variable NA engine of all things. Tho only thing that would fail consistently would be the central shaft, this is because like you said, at high rpm and insane power, the rotors will inevitably vibrate, if even a single rotors timing is off or has an ignition cycle that even 1/6000th of a cycle off, (between 4 rotors) it would repeatedly torsionally stress and vibrate the shaft. The engine they used for the VNA 4R 7series engines are super custom made and designed specifically to hold ideal power at around 350 or less hp, ( the kinda avg power number held during the entire 24 hour race) and even then, the central shafts failed. I love what you do but I think it’s simply impossible to try to hold together a 1200hp turbo 4rotor engine, especially when the original design was meant for avg power output of about 110hp and a peak of 280~hp at 2-3 rotors. I think that your engine will specifically suffer more of these problems because you rip around and sometimes race and just rev the shit out of it. Anyway, I think the ideal solution for that would be to use “dowels” and screws or whatever you use that match the diameter of the holes but keep the original thread diameter. I’m sure this is already what you do but the next step would be to specifically modify the exterior of the engine block plates, if you use the edges or extra mold pieces and weld a custom machined tab of some sort to increase the torsion stiffness from the exterior, hell, to make it really strong, you could Mount these exterior supports with an offset against each other so that it really locks. Well that’s all I have to say. You get a lot of comments so you might not see this but I would like your input on that.

-Diablo in a rotary shop- *chuckles* "I'M IN DANGER"

Living the dream, man! I keep going back and fourth between IT and Auto jobs.

I've always wanted to go rotary. But the closer I get to doing it, stories, rumours, horror stories, myths get in the way. I do most of my own wrenching and the more I see of rotaries, even with their problems, they seem to be so simple to work on and maintain. Even pulling the engine every few 10s of thousands of miles for seal replacement and inspection could be a simple routine. Burning 2 stroke oil is so simple and brilliant. Thanks for the video. I need to do a bit more homework that will include more of your videos. But a cheap RX8 project might be in my future.

Thanks for sharing

people like you need to spread more info of these engines like you, we are not far from end of life of the combustion engine and electric is taking over. We all need to try to keep these engines alive and others as long as we can.

Hey Rob, I believe those XRF machines will only give you a surface material reading. That should only matter if they're coated (like ceramic coated ones) I also believe most models do not list carbon content of the material.

So I’ve been doing a lot of thinking later about those tension bolts. What about a brass bushing kit? Use an ARP stud with a press fit brass bushing around it……. It’ll help keep the torsion down using a stronger and thicker bolt, and it’s a softer metal so it allows a little wiggle room for clearance issues. Plus it also doubles as an additional alignment dowl

You're doing wonders for the community! The honesty of this channel gives me hope for my own future rebuild.

I’ve never worked on a Rotary before, but I hope one day I do. But if I were to see that in person, it would be common since to me that those bolts have too much play to keep the engine steady. Everything else was absolutely awesome to learn about. Love the video. Love that if I get into a rotary, I have a lot more knowledge of them now. Thanks you, keep helping people understand.

I use to use Klotz Super Techniplate in all of my 2 stoke lawn equipment, line trimmers, blowers, chainsaws, mainly because I like the castor smell... until my line trimmer got hot and seized up one day after using Klotz for about 2 seasons. When I finally got the piston out of the cylinder, I was expecting to find them all galled up, but it was in fact a buildup of castor residue on the piston skirts that caused the seizure, the cylinder was perfect. The rings were literally glued into the lands so bad, I could not get the rings off the piston without breaking them. I finally got all the residue off the piston, replaced the rings, and used it for many more years... The Klotz made good brush pile fire starter fluid after that, lol! Awesome video Rob.

Hey Rob, have you tried applying Nikasil to the rotor sides and the side plates? If so.. how's that shake out? Have a look at the aluminum cylinders of the m70 BMW V12... aluminum-on-aluminum with *ZERO* wear. I have personally seen ~200K mile engines with the original diamond-honed crosshatch looking like they were just ground at the factory.

Hi Rob thank you so much for this in depth well thought out run down on Mazda's Rotary. I was fortunate enough to work in the USA (Albuquerque) in 1978 and being an ignorant Aussie thought I would buy a small compact fuel efficient car. And ended up with a Mazda RX4 Gorgeous car. (Didn't even realize there was such a thing as a "Rotary engine" Performance wise it was off the scale. The wife loved it too (Lead foot) Many happy memories.

Well, this was a surprise to see in my recommendations out of the blue. I haven't actively watched a car-related video in over a year, and then UKposts just says 'hey, you know that one neat but kind of obscure category of engine? have an entire video on it'. On that note, fantastic video- very well-explained, very little in the way of wasted time, and I learned a number of things about rotary engines in the process. I was already relatively familiar with them, but they haven't exactly been my main domain when it comes to cars, mostly down to the fact that they're not super common.

Awesome explanation, what if you counterbored and put drill bushings at every tension bolt?

16:35 that could so easily be fixed by mazda by simply including locating teeth on the outside edge of the plates so when the tension bolts pull everything together the teeth mesh with each other to eliminate that torque. Or heck with a bit of machining and some strong rings with teeth you could machine teeth into the outside edge of the plates that will mesh with the toothed rings almost like another gasket but instead of sealing its to stop the plates from trying to twist.

I've followed you since the beginning. I don't know why, but I was always a fan. You seem like a completely different person now. You went balls deep to learn shit and now you look like everyone I know that studied engineering. I love it.

I kinda feel like some of these shops stumble upon big hp numbers and thus think oh you need these mods where Rob is being more methodical which I'm here for.

I plan on fixing my 2004 Rx 8. She has been sitting for a little bit. I start her up once in a while. Everyone keeps on telling me to swap that boat anchor out and I refuse. ( yes I'm a girl that knows a lot more about rotary then the guys around me ) I've done most of the work on my car. I love 💕 working on cars. Can't wait to pull my engine and see inside and at the same time nervous. It takes a lot of money to rebuild. Good thing im about to start a job. Great Vid by the way. I'm going to prove them all wrong one of these days a rotary can be reliable. Hopefully sooner then later 13B

Fascinating - thanks for the in-depth look at this marvelous bit of engineering!

Rob’s drug references are hilarious, makes me feel right at home like hanging out with some old high school buddies lmao

Nice one brother ! 2 stroke/ rotor crew all the way ! hello from melbourne Australia!

Great great video. Rebuilding my first rotary, doing a ton of research, taking my time and going to see what happens. Basically bought the car for the sole purpose of learning how to build these engines, not gonna lie so far it's been fun we'll see how things come out lol

I mean, all of this makes so much sense. Love the content rob. Stock stuff, just some overlooked areas from mazda, and you have yourself a pretty sturdy engine.

"This is a corner seal in METH" Don't be a corner seal on meth

One of the best videos ever made on the subject of rotary engines. So much bullshit and fragmented info out there, you've squeezed the orange and presented the finest juice! Nice one Rob.

i've been considering rotary swapping my 944 but i didn't have the knowledge, so i might go along with it now because this video is just enlightening

I didn’t knew I was in rotary church and reverend Dahm was speaking!

I don't know what has more cuts, Rob's videos or his bandsaw.

Ended up here from watching Crighton's 700 CR motorcycle (200hp). That man is brilliant. Good interview with him available.

Super interesting and informative when I can’t sleep at 3am. Good stuff!

Rob: These are mistakes we have made and lessons we have learnt through experience. Also Rob: Don't drink the forbidden Coolant milkshake. It doesn't taste good. ...Rob, how you know that?

I think we need a spreadsheet that shows the composition and density of apex seals compared to stock ones if you could do that for us it would be amazing

I love your videos, you and your crew do incredible work! Such good information all the time.

I learned so much watching this video. I’m about to do a 20B on an FC, and I’ve been more concerned about reliability in terms of power upgrades.

Dahm, this could have been two hours long and I wouldn't have noticed. Great video, loved geeking out on the tech.

Excellent video! I've never had a rotary engine but they've always held my interest because they're something different. Maybe someday I'll have one to experiment on - if so I'll definitely come back to this video for guidance! Have you ever thought of running a liquid propane fuel system? Propane liquefies at 107 psi, which should also provide for more power out of smallish injectors. It also cools to well below zero as it vaporizes in the intake manifold. Plus, it has an octane rating similar to racing fuel making it a good candidate for high boost.

Genius! I'm looking to pick up a RX7.... I need to take it to you for the upgrades!

I really enjoyed this. Great info. Keep it simple and robust.

Rotaries are super reliable so long as you can pull the motor every time you have one of these extremely common problems. Seriously though, love rotaries and love you Rob, keep the videos coming.