Article and video, from Road and Track

Rob Dahm 4-Rotor - How a Four-Rotor Wankel Rotary Works

 

Inspired by a guy with a non running 4 rotor. Seems legit. I do like EE though.

 

Yes EE does a good job explaining the unique rotor setup and firing order for a four-rotor. We will have to wait and see if Rob Dahm ever gets his four-rotor RX7 up and running.

 

Why wouldn't he not? It's not like this is a swap, the thing is hardly an Rx7 anyway.

 

Hey Legot, I am pulling for him to realize this car. I did some searching on the RX7 club site and it seems he has a history of great hype (other RX7 club members' comments, not mine) , but unfulfilled running four-rotor project cars. Let's hope we can see and hear this car soon. Cheers.

BTW, last year our NE region RX8 clubs met at a rotary event at Atco DragRaceway, in New Jersey. and there were many three rotor and one four rotor cars. The four-rotor was based on the RX7 body, though being actually a tube frame car, like the IMSA RX8s of the past. It was up and running. I will search for my photos and post here.

 

Photos of four-rotor tube frame RX7 from last year's rotary day event at Atco Drag Raceway in New Jersey. This car may have only been two-wheel drive, not four-wheel drive. Can't find my written notes, but I found the photos. Car was from Ohio and towed and then driven around the track for event.

 

Like the stickers on the car say, that's Defined Autoworks shop car, was built about 3 years ago.
IV-Rotor Build: 12 plugs/ 9 bearings/ 8 ports = 1 monster - RX7Club.com

Look for Logan C videos in YouTube, he just posted a new one about 2 weeks ago.

 

https://www.youtube.com/watch?v=pfdH...ature=youtu.be

Youtube of video I shot of this car, at same time. enjoy the sounds

 

I would but it's private

 

Ok, discuss with me, this is about the Defined Autoworks Car that Gwilliams posted, Rob Dahm's uses the standard R26B layout.

One thing I find a little weird about that build is that they used a 4 piece eccentric shaft instead of using the 3 piece configuration that Mazda used in the R26B honestly their configuration is very very very strange.


With Rotors #1-4, and #1 being the front of the engine:

The R26B uses this config
Lobe 1 + Lobes 2 and 3 on the Main Shaft + Lobe 4

This engine uses a weird config of
Lobe 1+ Lobe 2 + Lobe 3 on the Main Shaft +Lobe 4


My understanding is that having Lobe 4 separated from the main shaft is less than ideal, although it works. Most 4 rotors out there follow the R26B layout, but there is one with a pretty detailed build thread on Rx7club that has a 2 piece layout (Lobes 1 and 2+Lobes 3 and 4 on the main shaft).

The reason I think it's odd that they went with the 4 piece configuration is that as we move from the front of the engine to the rear of the engine there's an increasing amount of torque that's put on where the eccentrics interface with the main shaft. At the 1-2 interface there's the torque of one rotor, at the 2-3 interface there's the torque of two rotors, etc.

I can understand why the R26B has Lobe 4 as a separate part (so that Mazda could build a standard eccentric with a longer shaft and maintain tolerances without building new tooling to accomadate for the two additional parts that are necessary), but if you're going to build a 4 piece shaft why the heck would you choose to have Lobe 3 integral to the main shaft? It would be more effective to have Lobe 4 integrated to the main shaft, with lobes 1-3 as auxiliary parts.

 

Balancing purposes? He also used shaved center irons to save weight, so maybe the construction?

 

Sorry, I thought I had the youtube video tagged public. I checked, it is tagged public.


try it again, ok (shot handheld with Canon T5i DSLR, for any curious camera geeks )

 

Thanks for sharing, love the sound of a 26b.