Air fuel ratio with exhaust and intake mods
 

I wonder, would i need to tune the fuel system if i were to add a full racing beat exhaust and intake on my car? these things run rich right? so if i add fuel i shouldnt damage the engine by running lean right?

Not likely to damage anything on a non forced induction engine.

The concern on a turbo engine is that the turbocharger is now able to breathe so well that it will spool up and "boost creep" way past the ability of the stock fuel system.

A stock fuel system on a non Turbo is good up to around 200hp (at flywheel)and that amount of power is about the max most na's will do , even with a good streetport getting more than that will be hard unless the street port is really nice as well as the tune on the dyno(safc/standalone), then beyond that for more power you're looking into a custom intake manifold.

S5 na's will breach this mark more easily than s4 rx7s.

S4 (86-88) stock port with full exhaust and intake wiol be around 160-170+ hp (more with a tune and/or street port)

S5 (89-91) with the same will be 175-185 (more with tune and/or street port).


Rotary >Pistons

Or make a cost effective difference. I've been in these shoes (as have many others).

For the money that you'd pour into most new full exhausts and intakes - and keep in mind that you may be slapping these $1000+ parts on a 100K+ mile engine... you could spend the money on a 13BT swap and make even more power.

So, you don't NEED a tune. You'd get a negligible (20hp?) gain in power on stock ports. I only say negligible because of the difference these mods potentially make in a turbo engine.

Think about it... 146Bhp + 20 is still FAR short of the 13BT's bhp

Been there, $3000+ invested into an s4 na with just mods and for similiar power of a stock t2.

Even without the rebuild were still talking $1500+

1)$1500 streetport na rebuild rotary resurrection
2)$300 borla cat back
3)$250 racing beat header,
4)$50 straight pipe in place of cat
5)$300 corksport aluminum intake piping,cnced Maf adapter and kn air filter.
6)$100 jacobs rotarymaster ignition
7) $400 racing beat lightweight flywheel
8)$200 centerforce dual friction clutch
9)$200 front/rear cusco strut tower bars
10)$50 dtss eliminators

Right now I'm working on a t2 and trust me I wish I bought something like this before instead of investing into my old na.

Rotary >Pistons

If you put a lot into the Chassis of the N/A,I would be thinking of swapping shells!That is if the old N/A was worth it.
Otherwise I would be selling parts off it to fund the TII!

Problem is no one pays much for stuff especially na.

I'd probably get 25-50% of what I paid for each.

Good thing I got a deal on my t2 project

Rotary >Pistons

Read ya loud and clear, thank you gents.

Let us know what you end up with.

No matter what you do, the stock exhaust system sucks, uprading to headers and catback it will give you a noticable difference.

I personally had the Borla catback which is a 2.5" before the y pipe and dual 2" after the split iirc , i had the racing beat streetable header and a straight pipe in place of my cat.

I was running without my 5/6 ports , they were removed, so to keep them working you will need to keep your main cat as the split air pipe that goes to the cat is used to open them, but maybe you can run without a cat with some fabrication but I wouldn't know

@ mystery - I ended up selling the car for $300 , the shell was in great shape other than a small rust spot on the wheelwell and some minor front end dmg from a 10-15mph hit in the front. The dmg wasn't very noticable unless you looked closely , and the hood was very tight against the front bumper

wthdidyousay, im purchasing the racing beat full exhaust slowly. got the header with the 6 port fitting already installed and just ordered the pre silencer. expensive exhaust for sure!

As for the intake i plan on fabricating something, i want it to be a true cold air not a hot air intake like i bought the car with.

As far as having an unrealistic horsepower objective,

no thats not what im trying for. as of right now the exhaust is falling apart and ive got exhaust leaks galore from just about every few feet of the exhaust so a new exhaust will give me a great and sealed exhaust system. If the engine goes out in the near future ill remove it and street port and rebuild then put it back in. i love this car and the power it makes is just fine. flip up headlight and go cart handling make me spooge!

I just dropped off my injectors at the local injection shop and they told me that i had around 19 ohms resistance on one of the primary injectors, this sucks!!!

Nice man.

This is my old car, got a lot of video views!


Rotary >Pistons

she sounded great! what type exhaust did you use? seems to make damn good power compared to mine as well. i guess that is the end result of 3500 invested in the motor?

Borla catback , racing beat streetable header, straight pipe in place of cat, intake and streetported engine

Rotary >Pistons

could you explain how you made the intake?

I bought a corksport intake kit, a cnced maf adapter, and kn intake.

I blocked off all the open spots.

You could get an eBay intake kit probably much cheaper , I had one before but the maf adapter was pretty cheap quality.

Rotary >Pistons