[purpleporsche]

<!--quoteo(post=78981:date=Aug 28 2009, 12:33 AM:name=stewhatch)-->QUOTE (stewhatch @ Aug 28 2009, 12:33 AM) <{POST_SNAPBACK}><!--quotec-->Is there a quotient for how many rotors are the approximate equivalent of "X" amount of cylinders? For example a 3 rotor Wankel motor may be comparable to having 8 cylinders. Just curious.<!--QuoteEnd--><!--QuoteEEnd-->
That's a much discussed subject in the Wankel world, but consider this fact: Each face of the rotor fires every time it passes the plugs....therefore, at 13B (two-rotor) has the equivalent power pulse of a six-cylinder piston engine and a 20B (three-rotor) pulses like a nine cylinder. Four rotors (26B) is, of course, similar to a twelve. Much more information is avaiable at sites like www.racingbeat.com and www.mazdatrix.com to name two.

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[Bognostraclum]

Didn't expect to see so mutch love for Wankels around here. That said, i love those engines. I really admire the design/concept of the whole thing.

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[Cloud9...68]

<!--quoteo(post=78983:date=Aug 28 2009, 01:17 AM:name=firefish)-->QUOTE (firefish @ Aug 28 2009, 01:17 AM) <{POST_SNAPBACK}><!--quotec-->Funny that you should mention this as a friend of mine is working on such a setup as we speak. Biggest issue so far is to score a strong enough tranny at a decent price.<!--QuoteEnd--><!--QuoteEEnd-->
Really?! That's very cool. I did a little searching on the topic of this engine, and swaps (real and contemplated) done with it, and found that adapting the electricals of the engine to the car is a real nightmare, not to mention all the mechanical adaptors needed (transmission, engine mounts, etc., although that is common to any swap). People were saying that by the time you got all the details worked out, the swap can easily cost $20 - $30K.

Also, I have to wonder, what are the advantages of the 20B engine, other than its sheer uniqueness, over, say, a strong V6 like Nissan's? Being a pretty old design, how much horsepower can realistically be extracted from it? Does it have to be turbocharged (the consequently much more complicated and expensive) to produce competitive power? How much does it weigh? I know rotaries are known to be compact, but from the pictures of the 20B, it doesn't look all that small.

Having said all that (I hope it didn't come across as too negative, because I still think it is a very cool idea, though probably very challenging to pull off), I'd be interested to see how your friend's project turns out.

I know this is off topic, but I'm thinking the MR2 might be the ultimate relatively affordable track car. The standard Toyota turbo 2.0l is stout enough to handle tons of boost, making this car a potential Ferrari-beater for a tenth the price.

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[PorscheDude]

It's not unheard of for a single turbo 20B to put out inexcess of 550 to the wheel.

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[Cloud9...68]

<!--quoteo(post=79123:date=Aug 29 2009, 03:20 PM:name=PorscheDude)-->QUOTE (PorscheDude @ Aug 29 2009, 03:20 PM) <{POST_SNAPBACK}><!--quotec-->It's not unheard of for a single turbo 20B to put out inexcess of 550 to the wheel.<!--QuoteEnd--><!--QuoteEEnd-->
That's definitely impressive, but there are plenty of piston engines of similar effective displacement capable of that and more. So, while, as I said, I really like the wankel (having owned a '93 RX7 twin turbo), I'm scratching my head as to the advantage of the 20B over a piston engine of comparable effective displacement. Seems like its uniqueness is the main thing.

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[Cloud9...68]

<!--quoteo(post=79106:date=Aug 29 2009, 11:22 AM:name=Bognostraclum)-->QUOTE (Bognostraclum @ Aug 29 2009, 11:22 AM) <{POST_SNAPBACK}><!--quotec-->Didn't expect to see so mutch love for Wankels around here. That said, i love those engines. I really admire the design/concept of the whole thing.<!--QuoteEnd--><!--QuoteEEnd-->
Yes, they defintely have some cool features (tons of power for the size, virtually no vibration, very free revvng, low center of gravity, design is simplicity defined), but the drawbacks are pretty severe, too - lack of low-end grunt, at least among the two-rotors, high oil consumption, and, the real nail in the coffin, abysmal gas mileage. My RX7 hardly ever got above 17 mpg, in a car that weighed less than 2800 lbs. I would imagine a 20B would guzzle gas lke a '65 Lincoln.

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[PorscheDude]

One big advantage is the light weight of the package.
Altough apex seals can be problematic, there's allot less moving
parts to go wrong.

A well tuned and maintained rotory can be very cost effective.

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[Cloud9...68]

<!--quoteo(post=79135:date=Aug 29 2009, 07:20 PM:name=PorscheDude)-->QUOTE (PorscheDude @ Aug 29 2009, 07:20 PM) <{POST_SNAPBACK}><!--quotec-->One big advantage is the light weight of the package.<!--QuoteEnd--><!--QuoteEEnd-->
I know that's true of the 13B, but the 20B is by definition a third again bigger, and therefore, heavier. In the searching I did about this engine, I saw a wide variety of quotes for its weight. Although, many of them seemed to be highly speculative, as you might expect for such a rare and unusual engine.

Edit: I just checked again, and a fairly credible-looking source put the 20B's weight at 315 lbs. Doesn't strike me as being particularly light...

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[purpleporsche]

<!--quoteo(post=79144:date=Aug 29 2009, 08:22 PM:name=Cloud9...68)-->QUOTE (Cloud9...68 @ Aug 29 2009, 08:22 PM) <{POST_SNAPBACK}><!--quotec-->I know that's true of the 13B, but the 20B is by definition a third again bigger, and therefore, heavier. In the searching I did about this engine, I saw a wide variety of quotes for its weight. Although, many of them seemed to be highly speculative, as you might expect for such a rare and unusual engine.

Edit: I just checked again, and a fairly credible-looking source put the 20B's weight at 315 lbs. Doesn't strike me as being particularly light...<!--QuoteEnd--><!--QuoteEEnd-->
The 20B is a seven-layer Dagwood "sandwich". The rotor housings are aluminum, but the mass-produced 20B (Japanese market) uses cast iron intermediate and end housings. I'll weigh each of these pieces individually, but I estimate the weight of the iron alone to be 130 lbs. Racing Beat offers aluminum replacements for the narrow intermediate and end housings that can reduce this weight by 60%. The "thicker" intermediate housing is required to bring the rotors into proper phase and an aluminum replacement is not available. An all-aluminum 13B "block" weighs 109 lbs, less the eccentric shaft (equivalent of a crank) and rotors (equivalent of pistons).

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[Cloud9...68]

So, from your description, the 20B is no lightweight, although if had continued in production, it may eventually have gotten lighter by replacement of more of its components with aluminum, including, I would imagine, the rotors.

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[purpleporsche]

<!--quoteo(post=79207:date=Aug 30 2009, 12:50 PM:name=Cloud9...68)-->QUOTE (Cloud9...68 @ Aug 30 2009, 12:50 PM) <{POST_SNAPBACK}><!--quotec-->So, from your description, the 20B is no lightweight, although if had continued in production, it may eventually have gotten lighter by replacement of more of its components with aluminum, including, I would imagine, the rotors.<!--QuoteEnd--><!--QuoteEEnd-->
I suppose it's not exactly LIGHT....but it's not bad for the equivalent eight-cylinder power, but it is compact; and because the "crank" runs through the center of the block, it sits low in the engine compartment. It's not a perfect motor.....that has yet to be conceived.

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[flash]

still lighter than our engine too

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