Hey guys,

Okay so my 12a is on it's way out and I have a 6port 13b sitting here out of a s4 FC. I just want to know what is the best carb setup on a street ported motor that will be used for daily driver and ofcourse the track? Also would there be a performance advantage to using the 6port 13b over building my 12a?

Should I just leave the EFI on the 13b and drop her in? Or should I strip her down and go carb?

I'm still new to rotary's as well as carbs :|

Any help is much appreciated. Thanks!

 

Fuel injection will always yield more power, better fuel efficiency, and better driveability. The con side to FI is making it work. You will have a fun time cutting up wireing harness to splice it all together. I am sure there is a wireing diagram that somone on here can point you too. If you decide to go carb I would go witha mikuni. They don't yield as much power as a Weber, however, they are easier to tune, and are more drivable. Holleys from my understanding have a tendency to cut out in sharp corners. Besides Mikuni's look cooler then holleys lol.

 

most carbs will out perform stock fuel injection any day!
i would go with a weber carb, a do it yourselfer wont have much trouble tuning a weber and they look great too
drop your 12a distributor in and your ignition is done, trow on a carb and your intake is done

the wiring nightmare has been avoided and you have a clean engine bay to show off that new carby

 

I did it and used a 600 cfm Holley w/ great results.

 

Honestly everyone is gonna have an opinion on this, Ill say Dellorto, but haven't even really experianced mine.. Id say just make sure you buy something that is mostly set up for a rotary engine.

 

I had a Dellorto on my 6 port... I'd have to say total thumbs up all around.

 

thanks for all the input guys, so what kind of power potential am I looking at with a carb+6-port setup? As far as fuel economy, yes I said it hehe, is a carb setup much worse than the FI?

I guess i'm just looking for pro's and con's from both sides.

Also what tranny do you guys suggest to mate with the 6port? I have the N/A tranny that came with it, plus the 12A tranny thats in the car.

Thanks again!

 

anywhere around 140-160 rwhp is a good guess I suppose. I would use the tranny that came with the engine, just swap out the tail shaft from your FB and put it on the FC tranny.

 

thanks dean, so now what would the advantage be to using the 6-port over my 12a? I have both motors, just need to decide which to go with. All that i've ever driven is my bone stock 12a with a stock nikki in need of a rebuild :P

 

holley

 

Go 13B and you will never look back

 

i kept mine FI with plans for a standalone later look at some of my posts and ones from fire85gslse we both have FI S4's in our cars run great he has more money invested in his though "if he hasn't sold it yet" than i do. he is running about 195 hp in it had its got quite a few exotic kills out there. im running about 165 hp and can only seem to kill imports of the Japanese kind. but i dont have nearly everything he has done to his yet on mine. id choose FI just because its highly tunable and you can be able to use fuel and timing maps to change everything and anything with the engine. this is always a hot topic but i stand behind my decision. case and point if carbs are so much better why dont new cars have them or even the high end race cars? thats why i go FI for now on.

 

Why don't new cars have carbs? Same reason they don't have pop up headlights. No taste...

 

 

i like that but carbs really tend to be cold natured and most FI setups from the factory with factory settings are not so cold natured the have computers to adjust for that. and when taste comes in to it they all got old and didnt want to play with chokes all the time or wait 15 mins for the car to warm up so the carb would act right this is the first FI system i have had the pleasure of playing with although it is testy it is a very good system. ive had 7 car now all were carbed then i swapped the last one to FI I was very hesitant but i havent looked back. it promises so much more reliability over the carb there is no way i would change it now and go mess up my low end just to be easy i wouldnt want to take out the 6 ports

 

your 12A tranny will be fine

 

Power output will all depend on what carb you choose to put on it. A Weber 48IDA will just about make the most, but it will not be nearly as drivable every day as say a Mikuni 44PHH or a Dellorto, which will make less power. Either way you will end up with more power than the stock FI will put out.

As for 12A VS 13B, no real question really if your looking for power. Without porting the 12A, your looking at 150hp MAX at the flywheel. With porting, you can get up to 175hp at the flywheel but your gas mileage will suffer. A 13B 6 port can do 165hp reliably on a medium sized carb and still get decent gas mileage and drivability. Overall, 13B>12A.

 

I thought carb generated more power than FI.

As for the topic, my friend's running his 6-Port with a Webber, though for now it's flooded lol...

 

YER GOD-DAMNED RIGHT!

 

I would go side draft with an upper than mates to the stock LIM and maintains functionality of the 5th and 6th port system. Combine this with the GSLSE heavier internals for good torque, a 12a centerplate (bigger ports). Streetport the end plates (I've always wanted to try this with bridging the 5th and 6th ports with a carb) and utilize pineapple inserts if you wish. Finish it off with a full racing beat exhaust. This would make an awesome daily driver.

 

thanks for all the input guys. I also have a 13B-RE sitting at my shop and i've been thinking about swapping that in too. Maybe make it N/A? Would that be better than the s4?

Just to confirm, I can swap the front cover from my 12a to any 13b so that it will mount up in my fb?

 

Either a carb or FI are capable of allowing your engine to produce maximum power. A properly designed carb can make that happen over an acceptably wide power band, if you're willing to work for it. But a fully loaded, programmable FI system can guarantee optimal mixture anywhere on the band, -for a price.
Most race applications can use a carb with great results because most any carb large enough for the engine can be made to deliver optimal mixture throughout a narrow RPM band, but wide enough for racing applications. Track cars are running from 4.5K-9K. What do they care about low end for?
Boost your engine to the max, and FI is the best way to ensure you don't break it. There's no guessing with FI. You set it and it does what you tell it to, regardless of the environmental conditions. It's electronic. A system shut-down can be wired in to the ignition to prevent catastrophe.
With a carb in super-boosted application, if one of the many mechanical parts of the carb decides to give you a problem, it could be bad.

On the street, identical cars, one with an absolutely perfect carburetor and one with an absolutely perfect FI system, the fulie wins. But the margin is small, and it's very expensive to overcome that margin. Your typical carb setup is going to be far less than optimal, though.
On the track, the carb can give the fulie a run for it's money, and sometimes win, too. That's a margin way too small for the cost.

 

thats kind of what i was trying to say but you were nicer about it.

 

Yes you can, now are you planning on using the factory oil injection. Or were you planning on blocking/taking off the metering oil pump (oil metering pump?)? The one for the 12a front cover only has 2 lines instead of the 4 for the 13b. My Dellorto had 2 places where the lines went in, and also held the chokes in place in the barrels, Im not sure what the other carbs had. Taking the intakes apart on a 200k engine, there was soo much oil crud built up it sickend me took alot of carb cleaner as well. If I were you, I would take out the MOP and seal up the front cover, while its not on the engine. And then just run 2cycle premix about 3oz per 5 gal or 1oz per gal mixtures.

 

Well I was thinking about blocking it off as you suggested, but I was unsure of the pro/cons. Obviously having to pour oil in every fill up is a bit of a pain, but besides that is there any difference in lubrication? Does the OMP do a better job lubricating than pre-mixing? Little off topic but i've been wondering about this.

Also i've herd that the ports on the RE motor are larger than any other 2 rotor, is this true? If I did go FI, has anyone had success with Megasquirt?

Thanks for all the great info guys!