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Discussion Starter #1
I'm all about the classic roadster experience and love the sweet song played by a highly tuned dohc 4-cylinder breathing through 4 air horns. The question is, which is more RJDM: Kehin FCR carburetors or IRTB fuel injection? If someone popped the hood at your local Miata meet, which would impress you the most? I understand the limitations that come with using carbs but it seems so Road&Ster to do it anyways. One of the Joyfast cars has some sweet looking FCRs.

My car is toy, not a daily driver and I have no emissions testing requirements where I live. All I care about is the weekend experience e.g. back roads, HPDEs, local club autocrosses (no classification necessary modification unlimited within bounds of safety), car shows, etc. I figure the flat slides can be purchases for much less money than IRTBs but are more troublesome to tune. I have limited experience with carbs - much prefer to stare at a laptop and press buttons. Having said that, how easy is it to tune the FCRs as compared to Webers DCOEs or S.U. carbs?
 

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Probably easier to tune than Weber DCOE's, if only because the flat slides have far fewer parts than the DCOE's!

If you run DCOE's today you're probably doing it for nostalgic reasons. Whereas Keihin FCR's are still a legitimate all-out performance choice. In terms of atomization , the Keihins and Mikunis are supposedly better than port injection even.
 

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Mufasa in Training
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I'm strongly considering IRTB's, but mostly because I know nothing at all about dealing with carbs...
 

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I've heard that carbs are a pain to use because you have to retune for everything. Meaning tune for the street, tune for the strip, tune for changing track conditions (e.g. weather), so on and so forth. If your ride's sole purpose is track only, then it should be ok...
 

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Mufasa in Training
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to alot of people that tuning is part of what makes carbs fun.
That might be true, but I am one of those people who would rather spend his time driving a tuned car than continually tuning said car, if that makes sense. It's one of the big reasons I haven't changed the engine; I'm neurotic enough about the rest of the car! #-o
 

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Discussion Starter #8
Keihin CR are more readily available and less expensive than FCR. Anyone familar with tuning either one on a bike or Miata?
 

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carbs don't adjust to elevation levels like EFI can, plus i wonder about fuel starvation in a car that corners like a miata.
 

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Discussion Starter #10
There are hundreds of vehicles that can out corner a Miata that run carbs so I don't think fuel starvation is a big concern with a properly designed carb like a Weber or Keihin. The nice thing about aftermarket EFI is that if one is so inclined and willing to put in the effort and extra sensors it can be made to work well at a variety of elevations and temperatures without need for user correction.
 

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I guess it don't matter if one decide to go carbs or fuel-injected itbs, just as long as it's done right and it hauls ass not only straight, but around corners!!! 8)

Just do it and inspire others...make us believe! =D>
 

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Hi guys.. im from the UK and am considering buying some mikuni twin chokes that are already on a manifold.

What else will i need to get them up and running as im a complete noob when its comes to carb tuning.

Please help.. i need as much info as possible :)

Edit: This is also my first post here!! So, hello!!! 8)
 

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I think all you need is a fuel pressure regulator and some ignition box to control timing, then you are good to go. Someone please correct me if I am wrong. Of course, you have to jet them correctly. Carbs are definately more impressive to me just because they are old school and I haven't seen many done.
 

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I have a customer locally with a 1.6L that wants to do OER carbs. Now this car is bone stock except for the 4-1 header. We will get a before & after dyno result.

Jimmy
FujiRacing
 

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Update from yesterday. I was able to pick up a used OER carb from an individual in Japan. I will first install it on my 1.8L Miata that still has the stock internals. The current IRTB setup uses a FREEDOM ECU on just a base fuel map and we were able to get a 14.1 1/4 mile mile. I will Dyno that first to see what numbers we have. Then the carbs will go on & we will do some 1/4 mile runs & get you a Dyno result to see how they compare. Then the carbs will go on the 1.6L.

Jimmy
FujiRacing
 

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Woah, MAMA!! Jimmy geting into carbs too, maybe?!

You ARE the man!

=D>
 

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Hi Tim-Thanks & not a maybe but carbs will happen. I believe you met Raul at last years Mazda natl. day event. He is the big reason that it will happen. Bring him any carb. Weber or Holley & he can do it. It is no secret that Webers will out perform just about any carb out there. As Jesseclee said and he is correct Weber parts & OER parts are interchangible. Raul will first set it and we will see how reliable it is & share exactly what parts make up a kit & also the install process.

Jimmy
fuji-racing.com
 

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Talked to OER last night and I will be putting a set of New OER carbs on my car this fall. The used OER carbs were passed on to a friend in Japan. I did a Gainesville FL.Solo Trials(Hi-Speed event) last month and Bill Coffey that I have known for about 15 years has side draft Mikuni's on his 240Z and man his car is fast. I am convinced that a carb setup has potential and now I can put the side by side (Dyno-1/4 mile) numbers up. With stock internals I was able to show what an IRTB can do and now we'll see what a carb set up can do. It will be a fair comparison since CFT that Dyno tuned the IRTB is one of the best anywhere and Raul is one of the best when it comes to carbs.

Jimmy
FujiRacing
 

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Thomas-OER is confident that on the straight the carburetor will make more power than the IRTB but the best way to find out is to put it on my car. And yes I have seen a FCR carb smoke the best fuel injected IRTB on the straight but had fuel starvation in the corners which an IRTB setup doesn't. I didn't see that with Bill Coffey's Mikuni carburetor setup. Do you know his 240Z? On another note you should get your stuff today.

Jimmy
FujiRacing
 
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