Can anyone help me and tell me what the differences in the 4 and 6 port on 13b.. I'm trying to find a 13b 6 port intake mainfold to buy? but I either can't find any or do not know which one to look for off on ebay.

thanks.

 

Well, one has 6 ports, and the other has 4. NA engines are 6 port, while turbos are 4 port. The lower intake manifold will have matching port openings (4 or 6) that go into 4 intake runners. All FCs have 4 intake runners, so don't expect to find 6 runners going into a throttle body.

Why are you looking for an intake manifold on ebay? Is your engine missing one?

 

RotaryRocket88, i am looking becasue this guy who runs a rotary shop in town that my best bet for more power was to ditch my fuel injection and all the efi stuff, if i were buy a 6 port manifold with a 650 carb. and he would install for 150

 

Uh, ok. What's the point of taking a step backwards into the 70s? What exactly are you trying to do? It's not going to be some miraculous power gain, if it in fact gets you any more at all. I'm no carb expert, but 650cfm seems to be the size used on heavily ported engines. I'm guessing you have a stock port engine, which would not lend itself well to a massive carb. How much do you know about carb and EFI systems, and how much are you just going along with whatever this guy says?

 

Agreed^

There has to be a reason as to why this "shop" is trying to convince you to ditch your (already working) EFI system. I've seen this done many times but it looks like a pain. Once you start changing minor things in the car, even something as small as altitude change, you'd have to tune the carb. not a lot of people can tune a carburetor...


I say stick with what you have.

 

I spent a few days trying to make a 650cfm carb run right on a stock 6port 13B. It will run great up top and just barely idle but it stumbles under part throttle. I'll be building a different engine for that car so it can use a carb that big. (Miata w/13B)

Keep the efi and find a different shop.

 

well i took it to the shop because my car keeps stalling on cold starts and has a bad idle... he said my problem is within the efi system and intake stuff because he said its known for it. and he said if i ditch the efi system my problem would not only be fixed but be better and be adding more power.....

so u guys mean to tell me i already have a 6 port intake mainfold?

 

Yes, you have a 6-port engine. But to run a carb you will likely need a custom manifold to replace the existing one. This guy sounds like a hack that can't fix a simple idle problem, and would rather tell you to throw everything away and use a carb that is way too big. Now's the time for you to start being a DIY'er and troubleshoot your idle problem on your own. The FSM and this forum will have all the info you need. Cold start issues can be related to the water thermoswitch on the radiator or the water temp sensor on the water pump. A poor idle is usually a vacuum leak or the variable resistor needs adjustment (S4 only).

 

Racing Beat has the carb and manifold set up you are looking for.

If this were 20 years ago, and there wasn't all the info on efi out there that there is now, I might agree with the guy. The system on your car has been studied and picked apart and your best friend is now a multimeter, not a carburetor hammer.

 

RotaryRocket, i replaced my variable resistor and then turn the screw both ways and it doesn't do anything in anything to change.

 

I also think there is something else majorly wrong with my rx7... it feels like no power and my gas pedal feels heavy or something and I can't win races agasint civic's with just headers and fart can, and i can't beat a hyduia with the same thing, and i also lost to a vr6.

 

Your "mechanic" is a hack.

Instead of repairing your car he wants you to pay him to reinforce his limitations.

Had he gotten the stock system(s) running properly and THEN said he could do better, that might be a different story but to claim that the stock setup is "known" for running poorly only indicates that he doesn't have a clue.

Depending on your automotive background, the stock intake- and all the associated subsystems- can appear daunting...scary to the point that a dumb carb seems like a good option, but it's really not.

There might be a lot of it (although for some perspective, look at a third gen sometime), but each subsystem is actually pretty simple. What they do, and how they interact, is quite logical and the whole enchilada can be understood with some persistence and sweat.

Your car is suffering from age and a series of owners/mechanics who didn't understand it.
Get it running right with the stock equipment before deciding you (or your mechanic) are smarter than Mazda's engineers.

 

Don't do it!!!!!!!!!!!! Just look into problems such as low compression, TPS, Timing, ect....

 

I'd say your mechanic is a tard. Are you sure you don't have an intake leak?

 

I think i fixed the problem.... I went out and adjusted the screw on the side of the throttle body and it seems better with idleing and doesn't stall while its trying to warm up.

 

What screw did you adjust? The TPS screw on the primary throttle? It'll move the plunger on the TPS, which is the black metal/plastic device on the TB. If so, you should set it, rather than adjust randomly. Here's a link w/ some testing info: http://howto.globalvicinity.com/gv_w...i=58&co=1&vi=1. You should use a multimeter and adjust the screw until there is 1.0V on terminal "A". The engine must be fully warmed, and the key must be in the 'ON' position, but the engine does not have to be running. There will also be a green 2-wire connector next to the leading coil (next to battery). A piece of wire needs to be inserted to connect both terminals on this before ANY idle adjusts are made. This is the initial set coupler, and it prevents the ECU from fighting idle changes you make.

 

alright thanks rotary rocket.. i'll try those other steps maybe this weekend but so far its better from just turning that screw.

so back the to the holley carb crap, so if i did do that it wouldn't add over 100hp like this rotary guy is saying????

 

maybe if you add a supercharger along with the carb....

 

haha so adding a 6 port manifold with holley carb it wouldn't add massavie power gain add on like the guy is telling me?

 

lolololololololol, does this guy sell ocean front property in Idaho too? Absolutely no way downgrading to a carb will add any power. Fix your EFI stuff. And get someone else to work on your car.

 

unless I'm severely mistaken, that is correct. It _might_ add a bit of hp, but not 100hp.
for comparison, the difference between a stock NA fc and a stock turbo fc is roughly 40-50hp.

 

so this so called city rotary guy isn'tsoo much a rotary guy what ya guys are telling me?

 

He's an idiot. Don't let him touch anything.

 

thanks rotaryrocket and other members... god damnit... ******* city of reading shop all spicks saying they run a rotary shop.. god damn *******!!!

 

well i guess all u guys were all are right... I"m a newbie and somewhat fixed my car just by turning a screw and that spick of rotary shop was all wrong... hahahaha.