Ok, so I am interested in carburating my 13B. Any thoughts on this? I have heard differences between them both. Some argue its better some argue it isne. Any thoughts. Did I spell carbuerated right??? LOL Thanks. Oh and the car is a 91 RX7 N/A of course, S5. Thanks.

 

efi > carb

 

I've been toying with the idea myself. A friend swears by it and he's built some fast carbed cars. I have a street port with bigger secondaries but I don't think they're helping any. Prob overkill. I want more power though and another buddies ported FB which is about 500lbs lighter kicks my *** all the time (2200lb vs 2680)

 

Ok, your thoughts???

 

My buddies argument is carbed cars breath a hell of a lot better so you can feed them more fuel.

 

How many cars in the last 20 or so years have rolled off the assembly line with a carb on them? Carbs are outdated and whatever you might be able to gain in peak HP, you'll lose in driveablity and the overall powerband.

 

So that would mean more power right, for N/A?? I understand they dont make them any more but are they more reliable as far as parts go... Meaning: injectors and wiring going bad... Stuff like that...

 

EFI is way better than a carb for a street car. The FC's intake manifold and AFM is the choke for top end power but since most of the time you are in the 2-6K rpm range I'd stick with the manifold at least. The throttle body will flow enough air to feed the engine. A stand alone that gets rid of the AFM will help a lot.

A street port NA with stock manifold and TB will make about 240hp. You might get more from a carb set up but it will be inspite of the carb not because of it. The manifold design is where the top end power will come from, but mid range power will probably be sacrificed.

 

so using a Racing beat headers and protect intake manifold would be good too...I have a Holley 600...

 

My friend built a ported 12a carbed and got 260HP out of it.... but in the end he still had a pull choke sticking out of his dash.... Stay EFI, get your motor tuned with an Rtek or something and build it up right you should get some decent power.

 

I just think that Carb is cheaper and has the least amount of chances of having issues.

 

Cheaper almost never = better.

 

Injectors and wiring going bad? You're worrying about things that very rarely happen.

An increase in peak power that you might get is useless without torque in the mid-range. An NA already has very little torque to begin with, and you're considering sacrificing it? That's a good way to get a slower car. Peak HP numbers are largely meaningless.

 

If you really think that, then just go with the carb.

I'm sure that your buddy means well, but he couldn't be more wrong. The carburetor's venturi, by definition, is a restriction. Were a venturi so wonderful for flow, auto manufacturers would add them to EFI intake systems.

 

Let's see what Mazda had to say about this question back in 1984:

 

[QUOTE=Evil Aviator;9433003]If you really think that, then just go with the carb.


Its not that I think that. This is what I heard, hence the reason for the thread...

 

[QUOTE=arghx;9433044]Let's see what Mazda had to say about this question back in 1984:



Also, is this on a stock manifold. Wouldnt a aftermarket manifold be better seeing as how they already thought to make it bigger.

 

The larger the diameter of the intake runners, the lower the air velocity at low RPMs. Too big and the engine will only make power near redline. Too small and the engine will have better low-end torque, but struggle to reach redline. The stock manifold on an NA (especially an S5 NA) is very well engineered to strike a good balance between the two.

 

LOL, that is classic. I'm going to save that to my favorites since nobody ever listens to me when I rag on the POS venturi.

 

The Rx-8's use a single butterfly on the TB as opposed to a 3 barrel, two stage on the FC). The '8 keeps the runners for the secondary ports closed until the ECU opens them up with the secondary shutter valve using vacuum. Then the auxiliary ports are opened with a duty/feedback controlled motor. Finally, the VDI opens using vacuum.

 

It's amazing how many arguments you can settle using documents from the manufacturer, isn't it?

 

So why do we see so many N/A carbed monsters out on the tracks?

 

^ because they're race cars, or at least they are built much more like race cars.

 

True, I anticipate a carbed, ported N/A for my track days in the future. But I must agree, for street daily driving, or even semi-aggressive driving, EFI is better.



2000th post by the way. woot!

 

I am still waiting for some idiot drag racer to say that the Mazda engineers don't know what they are talking about, lol.

- Some race classes ban EFI so as not to be unfair to cars with carbs.
- A variation of the above is a weight penalty for EFI in order to make it fair.
- Shiny aftermarket carb kits are big money, and advertising dollars go a long way in influencing race rules and race teams. The same goes for Roots blowers, which have been outdated for about 50 years now. If Holley gave me a million dollars a year to use their carb kit as opposed to EFI, the only place you would find any of my EFI components would be at Ebay, lol.
- Carbs are iconic, and spectators like to see them (or at least know that they are there) on NASCARs, monster trucks, dragsters, etc. Even I admit that I like the look of a lot of the classic, outdated stuff.
- Many mechanics are good carb tuners, but are totally lost when it comes to new technology that involves complicated things called "computers". As outdated as it is, a well-tuned carb is still better than poorly-tuned EFI.