i am going to bridge all 6 ports of my 12a and have the 5&6 open full time is it possible for me to use two 48ida Webber by making a custom intake manifold ???



one 48ida for each rotor ?? always wanted to know if this was done before any ideas views on this idea would be greatly appreciated

 

corky bell used to sell a dual weber IDA intake/turbo hat, its been done. a single IDA would probably be quite enough NA though

 

The Patent for the engine was submitted and granted to Bernard Maillard an Engineer for truck builder Adolph Saurer, in 1943 as an air compressor. So, you see all Otto cycle engines can also be air compressors. Wankel was searching for a device to form an engine with prue rotary motion. So he collected thousands of Patent drawings, both before and after the war. So he saw a modified compressor as his answer. But the engine is not called the Maillard, or the Saurer, is it? Wankel did not pass along this data to NSU. NSU found out when they applied for their Patents. Oops.



Maillard, then NSU invented the engine you use today. Mazda made it far more reliable.



In any case, the Wankel was a compressor first like nearly all engines. So the abillity to intake, compress and exhaust a specific volume of air per revolution is a known function. And so, that same volume as a mixture of fuel and air will produce a known amount of HP per revolution right up to the mechanical limits of the device.



A single 48 IDF with 44MM chokes on a 12A should get up to 270 HP in ideal trim. This would be at 10,000 RPM or a bit more. It might be possible to get to 273 or 274 with 2 48 IDFs, but I wouldn't bet on it. Two carbs would be more than twice the airflow required.



Has it been done before? Yes many times, with both Webers,and Holly 4 barrels, and giant throttle bodies. It will be done again. You can bet on it.



You can do 250HP on a single 48IDF with 38MM chokes.



Lynn E. Hanover

 

 

On my 79 12a I am running two S&K's, which are similar to ida webbers. I have a "stock" manifold from a company out of CA that was made in the early 80's, so it is possible. I have had a lot of trouble getting them to run right. I am running it as an N/A.

 

There is always a supply of people who will reinvent the wheel. One of my Government jobs (yes I admit it. I worked for the Government) was to help young engineers with any problems they might have. Mostly it was where to look things up that had become extinct. Early on in life the basics are often overlooked. Number one is that you cannot fool Mother Nature. Or basic physics.



While on the one hand, since more throttle pedal makes for more cross sectional opening in the throttle, and that make more power, would not doubleing the opening size then double the Power?



A seductive thought. And well worn path since many have been there before you.



The engine is a compressor, and its mechanical limit RPM gives you the maximum amount of cubic feet of air you could ever need to feed fuel air mixture to. So you can deduce the CFM or, Cubic Feet of Air you need to service with any specific carburetor choke size, or throttle body size.



In the case of the throttle body size you have a great advantage over the carb in that the computer in one revolution can come up with the correct answer to the question, how much fuel to inject on the very next revolution. The carb only responds (slowly) to the local atmospheric data. So when you snap all of the throttle you own open at once the low pressure in the intake manifold is satisfied by a sudden inflow of air, and the low pressure in the choke lasts only a few milliseconds, so the amount of fuel that can be dumped into the flow to maintain a flamible mixture, is so far below enough that the engine falls flat going over-lean. So about one second after full throttle the airflow through the double carbs or just too big a carb, drops to near zero, and how much fuel flow do you get out of a carb at zero airflow? Zero.



So when carbs were still the only answer, we saw two throat carbs with a little tiny throat like the Weber DMSA-100 with the low speed throat at 23MM and a vacuum operated secondary (high speed)at 27MM. So the second hole could not be opened by the owner at all. It opened automatically only when there was enough engine RPM (Manifold vacuum) to operate the vacuum diaphragm, that pulled open the second hole. This was also done on American cars with 4 barrels carbs, where the carb had two small holes, for 99% of the time, and two vacuum operated giant secondaries for showing off when the RPM was high enough (High manifold vacuum)(high RPM=high airflow).



There were many hop up pieces that seemed like great ideas. Used to open all of the holes at the same time. Like a gear set with a gear on each shaft so it all happened at once. Good for one weekend of fun. You had to tease the engine up to RPM (say 4,000) before using full throttle, lest it fall on its face over-lean. All very popular, and all removed after about one weekend.



And that was on 5 or 6 liter engines. Now comes a dual Weber like setup for the rotary, at 1.147 liters. What would be the outcome? With half of the stock airflow through each carb, the tuning range has been moved down to right off idle. So your midrange tuning will now be the idle curcuit. Transition will now include a very rich emultion tube set. And high speed tuning will have to be alcohol sized mains and airs. The alterative would be to rev the engine to 18,000 RPM to get both carbs the airflow they need to operate properly.



You may have noticed that the many companies who produced this and similar products are extinct.

But hope springs eternal.



Lynn E. Hanover