Greetings. This is my first post so please don't kill me. I am putting a 13b engine into my VW Bug. I am going to get a RB intake for a Holley carb. I cannot find any info on the site regarding the best carb for the rotary engine. It seems like most people are running Holley carbs with mechanical secondaries. Will the stockish 13b behave better on the street with mechanical secondaries verses vacuum? Also, is the concensus that a stock or mildly ported 13b will need ~600 CFM? The car will be a daily driver and anything will be better than my old 60HP air-cooled engine. Thanks for any advice.

ADJ

If your motor isn't ported, then I think 600 is too much. The RB catalog lists the non-ported application at 465 CFM. And you're going to want a header along with the intake to take advantage of that much fuel. You pretty much want to stick with a tried-and true setup like the RB, and get the right intake, carb, and header for your engine. A mismatch is not going to give you the gains you're looking for, and at worst, could be nearly un-driveable.

I may have a different catalog than you do. The one I have recommends:

18045 All 6-port 13B engines 84-92 (uses 600cfm carb.) Not for streetport.

I can't find anyone that makes a pre-fab header to fit a VW Bug application so I'm going to have to build a custom header and exhaust but I expect will be very free-flowing when it's complete. My original question was regarding the carburetor application because most of my experience has been with Jeeps and V8's which tend to like vacuum secondaries when driven on the street. It seems like most of the carbs used with the RB intakes (that I have seen) have mechanical secondaries. Is this becuase they work better across the board with a rotary or are people using them becuase they are better suited for racing applications?

I would guess that mechanical would be a better choice so that you are not relying on engine vacuum.

I dont know what kind of vacuum these motors generate, but most racing applications use mechanical, usually only

really tame street cars use vacuum.



when I went from a 600 vac to a 750 mechanical it felt like a totally different animal- but that was on a BBC, not a rotary.

racing beat sells a 600 cfm mechanical secondary. what year 13b do you have 86-88 13b 146hp or 89-91 160hp either way 600cfm will be plenty go mechnical R.B. does If you opt to not buy the racingbeat carb just get 600 cfm holley thats for a chevy because I head something about the metering blocks and emulsion tubes are more suited for our applications. hope this helps wish i had more technical info