I have an 86 s4 NA with no emission controls( bought it like that). I would like to improve my gas mileage and make this car my daily driver. So my question is how would I go about doing this? Can I reactivate my 5/6 ports? I am unfamiliar with porting so I dont know where to begin. Thank you for anyone who has time to reply.

 

porting and the auxiliary ports will do nothing for fuel economy below 4k RPMs. leaving the auxiliary ports closed would probably improve economy slightly above that RPM.

to get any noticable difference the car has to be running properly first, which means a full tune up: service the injectors, adjust the TPS, check timing, replace plugs and wires and fix any vacuum leaks.

next step would be to add a piggyback fuel computer, like an SAFC to take fuel out of the maps which will save gas.

in the end you will be tripping over a dollar to pick up a dollar though, but the car might run/drive better. there is no easy/good way to improve economy, it always costs money to save money... and when starting with a car that gets about 12city/16mixed/20+highway even when running properly you aren't starting with a good economical platform to start with.

 

Thanks for the great reply. That helps a lot. Itll take some time to get all that done since im in school but ill get back to you when I am done to see if there is anything else I can do. How would you go about reactivating the 5/6th port though? Just curious in case id like to have better mpg below 4k.

 

on an S4 all you have to do is remove and cap the port to the split air pipe to deactivate them. on the S5 you can just disconnect the port lines to each vacuum actuator above the exhaust manifold. to reactivate them just undo the disconnect procedures.

not using the auxiliary ports for an extended period of time though may stick the auxiliary mechanisms which may require disassembly and cleaning. so it's not necessarily a good idea to ever deactivate them unless you can live with the consequences.

 

So I found out my lower intake is capped off permanently. That means i need a new one and i was thinking of getting a cheap one from the junkyard. Any problems with that or any better suggestions? Is it possible to check how good one is with out actually using it? Also when I put my new intake on and then the actuators do i have to put the air pump on with it? If i do what else needs to go one to get my ports to work again? Thanks for your time

 

if it's blocked off then the sleeves inside the engine may be missing, you might just want to pick up a set of those as well.

there's nothing wrong with second hand parts, just be sure the arms move freely and maybe lubricate them with marvel mystery oil before installing it. even sticking arms can be disassembled and cleaned, but you should replace the seals to prevent vacuum leaks if you are going to redo it.

 

Alright thanks man that helps alot. What brand of sleeves should I look for?

 

the sleeves are factory inside the engine, you can find a used set for a few bucks and just clean them up.

 

Another question, what are the vacuum line's set up for a na with no emissions? Or does anyone know a link that could describe how they are routed with no emissions on?