My best friend and I always are talking about "future" car projects and building a 20B Rotary came up.
Has anyone built one? Are there even parts available in the US?
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April 12, 2011 11:18 p.m. SyntheticBlinkerFluid Reader
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April 12, 2011 11:38 p.m. RexSeven SuperDork
You can get 20B parts through Mazdaspeed Motorsports and many aftermarket rotary vendors, both US and Japanese. However, the cost of entry is STEEP. A 20B fresh from a JDM wrecker will cost you $3500-$4000 easily! I'll stick with S4/S5 13BTs unless I come across someone stupid enough to sell me a 20B for cheap(er).
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April 13, 2011 12:21 a.m. amg_rx7 HalfDork
Various people have done it at rx7club. Parts aren't too difficult to find depending what you are looking for. Not cheap though.
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April 13, 2011 1:55 a.m. Rustspecs13 Reader
My friend has a 470whp NA 20b. Revs to 10K, makes power EVERYwhere its kinda awesome. Sounds AMAZING.
Theres only a few 20B specific parts like the eccentric shaft, a middle housing or two and the dowl rods that hold it together. Every thing else is pretty much 13b stuff so you can get parts for them.
Shop around for prices, I think you can get them for cheaper, like 2-3K. Or maybe thats because they are iffy shape and should get a rebuild, which my friend does obviously to make awesome power. But they are expensive.
A turbo 20B can easily get 500-600whp. And because its 50% more displacement then a 13B it spools super fast. A mild 20B turbo with a standalone and medium turbo shouldn't be too expensive if you can fab up stuff yourself. When you have to pay some one else is when it gets expensive.
A REALLY good 13b can be just as awesome, and can be less expensive but its all in what you want. Look up defined autoworks, and call them and talk about 20B options if you want. They can either build you a whole turnkey setup, or supply you with parts and anything inbetween.
~Alex
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April 13, 2011 7:08 a.m. tuna55 Dork
So why can't you just bolt 2 13b's together and have a 26b?
Seriously... why not? Sounds easier.
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April 13, 2011 7:24 a.m. 92CelicaHalfTrac SuperDork
tuna55 wrote:
So why can't you just bolt 2 13b's together and have a 26b?
Seriously... why not? Sounds easier.
You can...
Gotta have a custom eccentric shaft made, though.
I had a site awhile back that gave the basic run-down. The cool thing is that with rotaries.... putting two and two together make 5. (OH man, more math!!
)
You end up cutting your effective flywheel mass/motor ratio in half.
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April 13, 2011 7:32 a.m. tuna55 Dork
92CelicaHalfTrac wrote:
tuna55 wrote:
So why can't you just bolt 2 13b's together and have a 26b?
Seriously... why not? Sounds easier.
You can...
Gotta have a custom eccentric shaft made, though.
I had a site awhile back that gave the basic run-down. The cool thing is that with rotaries.... putting two and two together make 5. (OH man, more math!!
)
You end up cutting your effective flywheel mass/motor ratio in half.
Why? I mean, if I was bolting two V8's together I wouldn't make a new crankshaft, I'd just make a piece such that I could bolt them together out of phase. Couldn't I just do that with two 13bs?
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April 13, 2011 7:33 a.m. 92CelicaHalfTrac SuperDork
tuna55 wrote:
92CelicaHalfTrac wrote:
tuna55 wrote:
So why can't you just bolt 2 13b's together and have a 26b?
Seriously... why not? Sounds easier.
You can...
Gotta have a custom eccentric shaft made, though.
I had a site awhile back that gave the basic run-down. The cool thing is that with rotaries.... putting two and two together make 5. (OH man, more math!!
)
You end up cutting your effective flywheel mass/motor ratio in half.
Why? I mean, if I was bolting two V8's together I wouldn't make a new crankshaft, I'd just make a piece such that I could bolt them together out of phase. Couldn't I just do that with two 13bs?
Well now you're just way over my head so i have no idea. All i know is that every "26B" i've seen had one e-shaft, 4 rotors.
But i'm learning! I recently bought a V6! So i'm moving out of my comfort zone!
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April 13, 2011 8:22 a.m. JamesMcD New Reader
tuna55 wrote:
So why can't you just bolt 2 13b's together and have a 26b?
Seriously... why not? Sounds easier.
It wouldn't be a 26B, it would be two 13Bs in the same car.
Just like those crazy tractor pull contraptions with 8 V8s on them are not referred to as having a single 64 cylinder engine. And also, if you geared the flywheels of two 4-cylinder engines together, you probably wouldn't say to people that you had a V8.
Another thing, there's really nothing on the front of the Mazda rotary that would accept this coupler you are thinking of.
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April 13, 2011 8:30 a.m. tuna55 Dork
JamesMcD wrote:
tuna55 wrote:
So why can't you just bolt 2 13b's together and have a 26b?
Seriously... why not? Sounds easier.
It wouldn't be a 26B, it would be two 13Bs in the same car.
Just like those crazy tractor pull contraptions with 8 V8s on them are not referred to as having a single 64 cylinder engine. And also, if you geared the flywheels of two 4-cylinder engines together, you probably wouldn't say to people that you had a V8.
Another thing, there's really nothing on the front of the Mazda rotary that would accept this coupler you are thinking of.
Sorry, until I searched a bit, I didn't realize there was such thing as a 26b. I just did 13+13 and kept the b. Nothing on the front? Really? No balancer or accessory drive or anything?
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April 13, 2011 9:11 a.m. JamesMcD New Reader
There is stuff on the front (like most everything else, there is a main pulley hub, which may entice you), but I personally would not feel comfortable attaching another engine to it.
tuna55 wrote:
JamesMcD wrote:
tuna55 wrote:
So why can't you just bolt 2 13b's together and have a 26b?
Seriously... why not? Sounds easier.
It wouldn't be a 26B, it would be two 13Bs in the same car.
Just like those crazy tractor pull contraptions with 8 V8s on them are not referred to as having a single 64 cylinder engine. And also, if you geared the flywheels of two 4-cylinder engines together, you probably wouldn't say to people that you had a V8.
Another thing, there's really nothing on the front of the Mazda rotary that would accept this coupler you are thinking of.
Sorry, until I searched a bit, I didn't realize there was such thing as a 26b. I just did 13+13 and kept the b. Nothing on the front? Really? No balancer or accessory drive or anything?
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April 13, 2011 9:45 a.m. carguy123 SuperDork
20bs have a crazy sound. They sound more like a Ferrari V12 than the Ferrari!
Is it possible to build a Renesis 20b?
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April 13, 2011 10:05 a.m. JamesMcD New Reader
The Renesis has the exhaust ports in the irons, not the housings, so no you can't make a Renesis 20B from existing Mazda parts.
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April 13, 2011 10:05 a.m. Sofa King Reader
Someone please correct me if I am wrong, but if you connect 2 13b rotaries, you are actually making 1 four rotor motor. You use a custom crankshaft and bolt the housings together. When tractor pullers use 2 engines, they are just using an adapter to connect two separate engines. They don't end up with one 16 cylinder engine.
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April 13, 2011 10:06 a.m. oldeskewltoy Reader
carguy123 wrote:
Is it possible to build a Renesis 20b?
Talk to Rob over @ Pineapple Racing
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April 13, 2011 10:19 a.m. weedburner New Reader
JamesMcD wrote:
There is stuff on the front (like most everything else, there is a main pulley hub, which may entice you), but I personally would not feel comfortable attaching another engine to it.
tuna55 wrote:
JamesMcD wrote:
tuna55 wrote:
So why can't you just bolt 2 13b's together and have a 26b?
Seriously... why not? Sounds easier.
It wouldn't be a 26B, it would be two 13Bs in the same car.
Just like those crazy tractor pull contraptions with 8 V8s on them are not referred to as having a single 64 cylinder engine. And also, if you geared the flywheels of two 4-cylinder engines together, you probably wouldn't say to people that you had a V8.
Another thing, there's really nothing on the front of the Mazda rotary that would accept this coupler you are thinking of.
Sorry, until I searched a bit, I didn't realize there was such thing as a 26b. I just did 13+13 and kept the b. Nothing on the front? Really? No balancer or accessory drive or anything?
I did it around 15 years ago, wasn't a turbo version though... homemade 4 rotor
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April 13, 2011 11:16 a.m. Armitage Reader
weedburner wrote:
I did it around 15 years ago, wasn't a turbo version though... homemade 4 rotor
Wow, neat stuff. You knew more about building cars and clever solutions to problems 15 years ago than I will ever know in my lifetime.
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April 13, 2011 11:27 a.m. tuna55 Dork
I saw that page just today by searching about, weedburner. Nice, sounds fun.
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April 13, 2011 12:38 p.m. Brett_Murphy Reader
In reply to Sofa King:
Sort of. Going from a 2 rotor to a 3 or 4 rotor is more like going from a 6 cylinder to and 8 cylinder engine, in that it is all in the same block. You could theoretically have an infinite number of rotors in a block if you could make your eccentric shaft both rigid and strong enough to keep it from deflecting.
4 rotor engines done by Mazda were the 13J and the R26B. The latter is the one they used to win LeMans, if I recall correctly.
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April 13, 2011 3:38 p.m. weedburner New Reader
In reply to Brett_Murphy:
The tough part is designing it so that it can be assembled. I don't know of anyone that has not used a multi-piece e-shaft to build a 3 or 4 rotor. I know of a japanese guy that made his 4 rotor e-shaft as one straight shaft that had seperate bearing and rotor journals that slide on and were pinned to each other. His engine ran too, just another way to do the same thing...
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April 13, 2011 7:57 p.m. Conquest351 Reader
Pineapple Racing.
I was on the verge of closing a multimillion dollar real estate deal a few years back. My commission was to be over $1.3M. I was looking at a house and buying my dream car. I was going to build a Race Car Replica's Superlite Coupe with a twin turbo custom built 4-rotor. I contacted Pineapple Racing about building the engine for me. They quoted me about $16k for a full turnkey twin turbo peripheral port 26b with all associated manifolds and injectors and all. I was going to run a FAST stand-alone ECU. I was going to be out about $80-85k for the whole car.
Anyway, needless to say, the deal fell through, the "buyer" ended up being a scam artist who wrote me over $6M worth of bad checks. He's currently wanted from what I understand. Writing hot checks for that amount is pretty much a felony. LOL
Back to the thread... The 4-rotor can be done. The major cost was all the turbo specific hardware. To build a NA 26b it was like $8500 ready to bolt in IIRC. There is a guy on GT40s.com who's building a 20b turbo Superlite Coupe. Of course he's a rotary nut and had one "sitting around".
Sorry to ninja the thread...
Brian
