ok so i have a wonder. what is the largest fuel injector you can put in a stock 13b? and how large are the injectors in a stock 13b? i have an 88 s4. just wondering. and will i have to re tune for a 10 cc larger? the reason why im posting this here is cuz i dont have enough post to put this in the correct category. i have looked throw the first 3 pages of faq and have not found a conclusive answer. any help would be great! thanks...

 

welcome to the board.

you can put as large an injector as you want, but the question would really come down to why? if you're not moving any significant amount of additional air, then more fuel is just more hassle and inefficiency.

stock = 460 cc

when you start looking around, you'll find people usually make more power by REMOVING fuel from an OEM setup (engine + ECU). it's pointless going larger.

 

ok i under stand than. but i was just wondering. now is that 460cc prim and 2nd or just prim? the main reason why i asked the question is i have a few idea for a few different builds. and one of them require knowing how large of injectors i could go with out getting into the ecu. i guess i should of added that in the original post... sorry hind sight is a *****! but thanks that gives me a start.

 

and another odd question. when one ports and rotary, its only done to the exhaust port right? now i thought that the difference between like j- street and bridge port was just size of work done to exhaust port.

 

You'll have to do some searching around for specifics as the answers are here in abundance, but the easy answer is, no. Porting is done to both intake and exhaust ports not just the exhaust.

Look at it as changing the cam in a piston engine. Changes open/close time, lift and duration. Porting the intake acheives the same thing. A street port is like a mild street cam, a peripheral port is like a drag spec cam. Then there's a ton of choice in between.

 

460 cc for both

See injector information here:
Rotary Resurrection home of the budget rebuild.

Generally, the ECU will not work properly with anything other than the original injector sizes. If you change any injectors, then you will either need to buy a reprogrammed ECU like an RTek Stage 1, a piggyback fuel controller like an S-AFC, or replace the stock ECU with a standalone EMS. The piggyback fuel controller and standalone EMS options will also require professional tuning. Aftermarket fuel control products typically have certain fuel injector requirements (flow rate, impedance, etc.), so always buy your fuel injectors AFTER you decide on the fuel control device.

One can port the intake, or the exhaust, or both, depending on the desired effect. It is also common to port the wastegate on Turbo II models.

Engine Porting