LEARN How To Use PORTING and Rotor Scallops Efficiently - Rotary Engine Airflow is Everything

I learned a bunch of new stuff this week when a buddy of mine proposed a question about how scallops and porting work together. Diving deep into the rabbit hole of airflow and port timing lead me to have this conversation in my head.
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[@VictorMPR]

I thought I had a good grasp on these engines… then you throw in scallops. Scallops! Brilliant! Also I think you should clarify the “exhaust pressure” part. It is negative pressure. As the exhaust gasses leave the engine it creates a negative pressure behind the gasses which helps pull the intake air in during overlap… at the right rpm, of course (which is why we get the braps).

[@RADPotential]

Thank you! Yea...while editing I realized my description wasn't exactly perfect for the scavenging effect happening during overlap. I'll pin your comment!!!

[@swampyfox8688]

Yeah! scallops! I never knew there was such a thing. Going to bed smarter tonight thanks to Erich’s willingness to invest his time sharing his knowledge. Please don’t ever get married and have kids Erich! 😂

[@VictorMPR]

@@RADPotentialHoly crap! Super cool, thank you! Also of use/ importance, the Renesis has no overlap. None. All the magic happens from intake manifold tuning… for those out there who didn’t know, anyway 😅

[@neoanderson7]

I really do appreciate all this. Not common to see the younger gens take up where the older folk have left off.. maybe even teach the older gen a thing or 2.. 🙂 Can't wait to see more.. cheers!

[@blacksnakedotcom]

You are my favorite rotary youtuber. You never gatekeep knowledge like all the others. Pure knowledge and experimentation.

[@joogullae3456]

Dude you seriously are the best damn rotary youtuber on here. I'm saving up for a year to get about 12k to get my r3 and I'm learning everything I can from your channel.

[@Dudley_FD3]

These videos are worth their weight in gold. You’re awesome brother, keep up the good work

[@danielwood5318]

@RADPotential Excellent video... certainly activated my NZ dyslexic brain in to overdrive down the 'rabbit hole'. Question: When one considers 'Laminar Flow' vs 'Turbulent Flow', and then considers intake/exhaust 'porting'; I note that everyone utilises a 'smooth surface' approach to Porting. However, I wish to bring to the classes attention that a Golf Ball is dimpled on the surface to generate 'Turbulent Flow' upon the surface of the ball to create a 'Laminar Flow' around the Golf Ball, thereby lowering the surface friction of the Golf Ball to increase the golf ball's ability to travel further. Therefore, considering the desired goals of Rotary porting, would it not be more beneficial to create 'Turbulent Flow' within the 'Intake', be that by dimpling the intake housing of the RX plates, or the intake manifold, thereby creating a better environment for air/fuel mixture, creating a better/cleaner 'bang'. As well as creating 'Turbulent Flow' of the the 'Exhaust', be that dimpling exhaust housing, or the exhaust manifold to create the 'Turbulent Flow' barrier to increase the airflow efficiency of the lowered surface resistance (not unlike a golf ball), thereby increasing the airflow rate by way of the increased 'Laminar Flow' through the exhaust due to the 'Turbulent Flow' shielding? Has anyone done this in the past or looked at the science of this rabbit hole? or am I talking/thinking sht? FYI 'Laminar Flow' vs 'Turbulent Flow' link for those that may not be able to visualise my thought process i0.wp.com/theconstructor.org/wp-content/uploads/2020/02/laminar-and-turbulent-flow.jpg?resize=345%2C380&ssl=1

[@swampyfox8688]

RAD science…… love it!! Thank you! Even though my interest is working on my RX8 …. You made the video applicable and interesting to the wider rotary community. Bravo Erich! Appreciate ya!

[@BrianGochnauer]

I would love to see a NA engine with scalloped rotors sounds like; more interested in smoothness (not braps) with increased power on the high end. But that's just me and my 13B powered airplane.

[@DudeItsRobert]

I love the videos like this where you explain the science behind this stuff, keep up the good work 👍🏽

[@clintonlangerak7972]

G'day from Australia. Always great content, as an engineer myself I find the science interesting. If I recall correctly, Mazda won engine of the year award for the Renesis because they were one of the first companies back in the late 90s to computer model and simulate the engine. I imagine that would have included modelling the airflow too. Looking forward to more build videos.

[@RADPotential]

That is epic! I'll check it out for sure!

[@gregsnowsnow4017]

I have been watching your KZbin channel for years and it’s played a tremendous role in my never ending OBSESSION with rotary engines and the science behind them, thank you by the way🤜. I unfortunately live in an area with almost no rotary community and it sucks. Ultimately I want to start one here but, but that’s a future pipe dream at the moment. Does anyone in your rotary community that could help me find a machine shop closer to where I live? I would really like to personally interact with the shop in person to clarify exactly what I would like done. I live in the very northwest part of Arkansas ( birthplace of Walmart)🙄 any guidance would be greatly appreciated, thanks again for the content you have allowed all of us to absorb.

[@paulclarkson2583]

Thankyou for the time you spend making these videos, I thoroughly enjoy watching your content, its very informative and easy to understand.

[@donaldwoodardjr6595]

Very good information!!!!!

[@chadausburn4832]

Great video but I have to disagree with you. The side seal is what seals the port and is what port timing is measured off of, not the rotor side. Scalloping does not change port timing. It absolutely improves the efficiency of the port like you said 8:30 but the port does not open until the side seal passes. Scalloping the rotor is the same as changing the ramp of a camshaft but leaving the open/close timing (duration) the same. Scalloping is a great thing to do for air flow much like a roller cam has a more aggressive ramp and gets more air earlier in the port opening. More efficient airflow as soon as the port opens can only be a good thing either way.

[@pilotohernandez1569]

Really good content 🔥

[@Rx4Lyfe]

Never heard of scallops on rotors before😮

[@tonymunn]

I have a '74 - 13B that is street ported but has bad oil seals. It is getting ready to be rebuilt. It is in a 74 RX4. Should I try to source some higer compression S5 rotors and scallop them. I love the rotary engine content. I am in Albuquerque near Rotary Rehab. Brian is a cool guy. I love dropping by his shop.

[@jeremycollins3408]

It would be cool to see you and KMR do a live stream . Kyle seems pretty cool?

[@RADPotential]

Yea! He is an awesome guy! Tons of experience and a great driver!

[@Unix-cz9km]

Never noticed the RX8 had them till you showed them, and I compared it to my engine rotors, and there they were haha. Curious to know how the Renesis utilizes them, given the goal (According to Mazda's Technical data) for that particular engine was completely eliminating intake/exhaust overlap. Could just serve as additional intake space, and they already have 2 exhaust ports per rotor.

[@m0d.]

Thanks for sharing this!!! Say, if I had a stockport 12A engine with a 48 IDA Weber, could the addition of scallops help alot with performance? I'm trying to retain the 12A's strength by not going bridgy way.

[@ADudesRotary]

Maybe a static engine build with rx8 rotors to test the theory, something like the 1 your friend Charles has. Other than that maybe you can contact Promaz in Victoria Australia who conduct static engine testing and have extensive experience with RX8 motors and turbo charging they maybe able to answer the scalloping/streetport theory. Save you plenty dollars.

[@devultra1125]

Where did you get that ultra lightwight rotor from? Amazing how much material was removed here.

[@anarchy8263]

wonder what happens if you scallop the intake on the primary side only and scallop the exhaust on the opposite side?

[@thefastesttofuboii3216]

So I’m curious and just new to this really, I have an 85 s roller chassis that I’m putting a gslse 13b into, and since you have to replace fuel lines because there carb lines at the moment rather than efi, do you have to replace hardlines and softlines or just the softlines?

[@Mike-on8pz]

Like your channel and vids etc. Mazda has done all the testing on scallop. Why not use a modded rx8 engine for performance. Latest technology!

[@anthonysomics9073]

Been watching a long time ( roku TV ) , been giving likes . like what your doing had 2 rx7s , now down to 1 . interested in what's still available ( years later ), years cars I had , think '81 , & '89 , don't understand the acronyms \ initials like fc, , understanding that their models thanks

[@luisgil4351]

Hey Rad, I’m new to owning a rotary and I just bought a spare blown engine to practice rebuilding them do you have a list of tools I will need to open the engine block and re-assemble it again

[@user-bh8ze7eu4s]

Bro I want to do the same. I have so many questions on clearence the rotors 😢.. Im afraid to dumb my money having noone to show me

[@BrianGochnauer]

Love to see the graph you mention from ?vargus? (how do you spell that?)

[@jo-qp7mz]

I thought the scalloped rotors required scalloped housings to make the most power and the irons were kind of irrelevant

[@marcosalonga9410]

When you change the rew rotors to scalloped s4na rotors wouldnt you have to also change the flywheel and front counter to match balance with the rotors? Or would you just happen to already have lightened your flywheel and have an adjusted base map?

[@RADPotential]

I would have the rotating assembly balanced by the shop who does the scallop to the rotors

[@nathanwright8477]

From Australia here! Check out Pac performance for some info. I'm sure they'll have something

[@tylerneisinger206]

Broooo, i dont know who else to ask, please, lol. I got an 85 gs, gonna get a 350 swap and have it live at my local speedway for drift events. The only decent cheap wheels i can find online or around anywhere are some 4x110 14×7 5+2 "atv" wheels. Can i make these fit, or would it be a waste of time and money? Would like to have spare wheels with tires already mounted for when i take it sliding. And cant find a remotely decent wheel set for under 1000 bucks o:, lol.

[@tylerneisinger206]

I do weld and fab and whatnot, wouldnt mind having to pick up the fender flares and lip kit, but trying to stay away from cutting the quarters, as the car is decently clean.

[@RADPotential]

Best bet will be to find a good set of used wheels. Those ATV wheels aren't rated for the weight or speed for a road going car. You should be able to find some plus sign wheels or even waffles for cheap. 13 inch tires are cheap as well. Measure the diameter of your axle flange. You could always re drill the axle for 4x100 or 4x114 to have more options

[@tylerneisinger206]

@@RADPotential omg!! You're totally right!!! I forgot about that video i saw of yours, explaining how to drill the rear axle's. I assume the fronts would be the same, just drill the hubs. I got axcess to a lathe and press and all that, so this shouldnt be too bad. I really appreciate you man. You're like the ONLY dude with tons of great info on the web for these chassis. Thank you so much, lol.

[@TheLoca215]

Where can I find the template for street posting my 12a

[@ADudesRotary]

Mazdatrix

[@slcbuilds3687]

Great video and information. As I keep researching and finding new videos about porting these engines I came across a great video from SidneyCritic that shows flow testing of a whole bunch of different porting scenarios using a bridge port. The most interesting bit that I saw which nobody ever talks about was the shape of the port coming into the opening of the irons. Everyone talks about opening up the port for mild, aggressive, half bridge, bridge, but never addresses the shape of these. He has an outstanding video on this. It's linked and a great watch as well. kzbin.info/www/bejne/n5XFoHl3ic99i9U