Carb: Pros, Cons?

Rx-7fetish · 08-28-2011, 10:20 AM

86 sport coupe, NA, thinking about carbing it. I've got my turbo already so I'm set for fuel injected and forced induced , I'm itching to do some more work to this one without swapping the whole motor, what kind of gains or losses could I expect? Which carbs are better for street versus track, any reason I should not do this if I drive it often?

FC Zach · 08-28-2011, 11:35 PM

I think its purely just personal preference on your decision between EFI or Carburetion. I have had a carbed FC since 2004 and I love it. I'm not opposed to fuel injection, I just want wanted to keep it simple at the time and have had it that way since. If your just wanting to just throw a carb on it and that's it, I say do it. If you want a turbo charged set-up then I wouldn't recommend a carburetor, but that's just me offering my thoughts and not saying there is anything wrong with it because people do and have done it for years. I want to turbo charge my set-up one day just to do it, but there are some issues that need to be addressed first. Turbocharging a carbureted engine can be expensive and after all the required components are purchased and after the buying spree is over you'll look back and then you may as well have just purchased a programmable EFI kit where the tuning abilities are almost limitless.

To me it sounds like you're wanting a turbocharged rotary, if that's the case then I say stay EFI and the reasons for this is there are limitations to the carbed set-up. One big one being timing. With a distributor (I presume you'd be using) you limit yourself to whatever adjustment is necessary to not detonate during whatever boost pressure you're at.

Rx-7fetish · 08-29-2011, 06:06 PM

No, no. I have two running 7's. One is a tenth Ann. So I have a turbo, fuel injected car to play with, then I have the sport coupe which I'm debating to carb, I want more info before I do to make an educated decision as to actually doing or what parts to use.

j9fd3s · 08-31-2011, 11:51 AM

the biggest con to the carb is that you have to buy it, and spend time tuning it.

there are also a bunch of other things you need to buy to get it to work.

you need a low PSI fuel pump, a regulator, intake manifold, the carb, jets, air filter, etc etc. basically take the price of the carb NEW and double it.

there are basically two styles of intake, and two styles of carb.

the street setup, is the RB upper intake and side draft carb. http://www.racingbeat.com/RX7-1986-1...ake/18101.html this keeps the stock lower intake and 6 ports. since the intake is long like stock you can expect a nice broad power band.

you can also go IDA, which is a downdraft. intake is shorter and straighter, so top end should be better. http://www.mazdatrix.com/r-idamanifolds.htm

08-28-2011, 10:20 AM	#1
Rx-7fetish Blue Blur Join Date: Jan 2009 Location: Windsor iTrader: (0) Posts: 211 Rep Power: 0	Carb: Pros, Cons? 86 sport coupe, NA, thinking about carbing it. I've got my turbo already so I'm set for fuel injected and forced induced , I'm itching to do some more work to this one without swapping the whole motor, what kind of gains or losses could I expect? Which carbs are better for street versus track, any reason I should not do this if I drive it often?

08-28-2011, 11:35 PM	#2
FC Zach RCC Loves Me Not You Join Date: Mar 2008 Location: Eagleville, TN iTrader: (2) Posts: 2,267 Rep Power: 19	I think its purely just personal preference on your decision between EFI or Carburetion. I have had a carbed FC since 2004 and I love it. I'm not opposed to fuel injection, I just want wanted to keep it simple at the time and have had it that way since. If your just wanting to just throw a carb on it and that's it, I say do it. If you want a turbo charged set-up then I wouldn't recommend a carburetor, but that's just me offering my thoughts and not saying there is anything wrong with it because people do and have done it for years. I want to turbo charge my set-up one day just to do it, but there are some issues that need to be addressed first. Turbocharging a carbureted engine can be expensive and after all the required components are purchased and after the buying spree is over you'll look back and then you may as well have just purchased a programmable EFI kit where the tuning abilities are almost limitless. To me it sounds like you're wanting a turbocharged rotary, if that's the case then I say stay EFI and the reasons for this is there are limitations to the carbed set-up. One big one being timing. With a distributor (I presume you'd be using) you limit yourself to whatever adjustment is necessary to not detonate during whatever boost pressure you're at. __________________ 1993 Yamaha GTS1000 1992 Celica Turbo AllTrac 1987 RX7 Sport 1979 Yamaha G1, KM24 powered 1975 Dolmar KMS4

08-29-2011, 06:06 PM	#3
Rx-7fetish Blue Blur Join Date: Jan 2009 Location: Windsor iTrader: (0) Posts: 211 Rep Power: 0	No, no. I have two running 7's. One is a tenth Ann. So I have a turbo, fuel injected car to play with, then I have the sport coupe which I'm debating to carb, I want more info before I do to make an educated decision as to actually doing or what parts to use. Last edited by Rx-7fetish; 08-29-2011 at 06:21 PM..

08-31-2011, 11:51 AM	#4
j9fd3s Rotary Fanatic Join Date: Mar 2008 iTrader: (0) Posts: 123 Rep Power: 17	the biggest con to the carb is that you have to buy it, and spend time tuning it. there are also a bunch of other things you need to buy to get it to work. you need a low PSI fuel pump, a regulator, intake manifold, the carb, jets, air filter, etc etc. basically take the price of the carb NEW and double it. there are basically two styles of intake, and two styles of carb. the street setup, is the RB upper intake and side draft carb. http://www.racingbeat.com/RX7-1986-1...ake/18101.html this keeps the stock lower intake and 6 ports. since the intake is long like stock you can expect a nice broad power band. you can also go IDA, which is a downdraft. intake is shorter and straighter, so top end should be better. http://www.mazdatrix.com/r-idamanifolds.htm