Carbuerated Vs. Fuel Injected
08-17-09, 03:20 PM
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Carbuerated Vs. Fuel Injected
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.
08-17-09, 03:28 PM
#3
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)
(2200lb vs 2680)
08-17-09, 03:40 PM
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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...
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08-17-09, 03:41 PM
#8
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.
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.
08-17-09, 04:34 PM
#13
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.
08-17-09, 04:38 PM
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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.
08-17-09, 04:56 PM
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[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...
Its not that I think that. This is what I heard, hence the reason for the thread...
08-17-09, 04:59 PM
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[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.
Also, is this on a stock manifold. Wouldnt a aftermarket manifold be better seeing as how they already thought to make it bigger.
08-17-09, 05:08 PM
#18
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.
08-17-09, 05:30 PM
#20
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.
08-17-09, 06:15 PM
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- 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.