Cordt

Can you gain any noticable amount of power with an aftermarket or piggyback system on a stock motor N/A with maybe a free flowing exhaust and intake? I've heard leaning it out can yield some results but I'm curious as to whether it would even be worth it, or if it would compromise reliability at the same time.

RotaryEvolution

iTrader: (30)

yes

you can actually gain a significant amount of power by freeing up the intake and exhaust flow without massive portwork. moreso on the S5 than the S4 and also moreso with a standalone that you can adjust the timing with.

cut the split down a few degrees after peak torque(~5500 RPMs) and advance the timing as well as pull fuel out of the stock maps to around 12:1 by redline. i can envision a stock ported motor could probably produce about 180 wheel horsepower with a decent engine management system, intake and exhaust. for example, on a customers car with a mild streetport and exhaust port sleeve diffusers still in the exhaust, stock exhaust manifold, cold air intake and 2 1/2 free flowing exhaust and Rtek 2.1 on an S5 car made 190WHP with a little room to grow still. thats a bit of improvement over the ~140 stock wheel horsepower they normally produce.

j9fd3s

iTrader: (3)

the S4 runs a decent AFR stock (12.2@4000, 12.8@5500), and it seems timing is very conservative. so an AFC helps a little, but you really don't NEED it, although it is a nice addition

the s5 runs way richer (12.2@4000, tapering down to high 10's at redline), so just keeping the AFR flat @12.5 feels HUGE. AFC is really good on these.

Cordt

the only thing ive done to my car is replace the cats with a straight piece of pipe. do you think the stock airbox is OK or can it be improved by removing baffling?

and obviously a header would be nice but for now im stuck with the manibrick.

oh and it is an '86 base model.

RotaryEvolution

iTrader: (30)

removing the fins won't really make the airbox much more efficient if at all, a true cold air intake is the only way to really improve intake flow. at least with an n/a you can add more piping without really hindering flow, not very true with turbo engines.

Cordt

the stock intake is a true cold air intake...
you mean one of those ridiculous overpriced tube+cone filter things....i would sooner turn my car into a submarine than get one of those lol

RotaryEvolution

iTrader: (30)

i never said the stock airbox wasn't, nor that you can't fabricate a true cold air intake for the car. you can look around at other CAI threads for ideas, since there is no real kit for the FC that is a true cold air intake. but to get better flow the stock airbox is only going to get you so far.

Skidtron

iTrader: (1)

for the intake just get the airflow meter adapter and a cone filter. The stock air box is crap. even though its not a cold air intake it flows a lot more air

lastphaseofthis

iTrader: (8)

oh god. here we go, pandora's box was shut once, but i'm not shutting it this time. go suck some hot air.

Cordt

i am NOT making a hot air intake. stock airbox is fine for a stock engine. i was curious about tuning not increasing airflow by very minimal amounts.

Skidtron

iTrader: (1)

Your obviously one of those guys that thinks on a NA engine that 2hp from a cold air intake even matters. Who cares. The ability to draw air from 360 degrees is better than drawing air through his crappy stock tube above the fanshoud and around and down to the airbox and then through the flat filter that leaves a dirty mark on the filter where the air ACTUALLY goes which is like a third of the size of the air filter. Ya that's waaaayyy better. I also like to keep water out of my engine so I'm not gonna put the filter near the ground.

If you are worried about 2hp then you need to find something else to worry about. 2hp isnt even enough to cut my lawn.

Cordt

lol you realize 2hp is likely what you will gain from opening up the intake?

j9fd3s

iTrader: (3)

if you really want to make a difference in airflow then the exhaust system is the place to start.

Cordt

i have already replaced the cats with straight pipe

Skidtron

iTrader: (1)

Only 2hp I don't think so probably more like 5-8hp judging by lots of dyno testing I've seen on lots of different engines. It also depends on what all you have done. there's a point where certain modifications to the engine compound other modifications and make more power due to the neccessity of the first part later on. Say you put a intake filter on a fc and you get 5hp. Then you change the header and exhaust and get 20hp more so now you have 25hp more than stock. Now you take the filter off and put the stock airbox on. Now you dyno again and get the result of having only 18hp more than stock. PARTS DON'T JUST ADD AND SUBTRACT POWER! You can't buy hp in stages! Video games have destroyed critical thinking. Everything works in harmony to make the added hp it all matters and any part can add more power later on due to other parts added to the mix. I don't know how else to get this across. if people can't understand that then they are a lost cause. Remember the engine is an air pump so changing the size of stuff like piping and what not on either end of it effects the entire thing and not often in ways that people think it does. Velocity and volume are often mixed up and or ignored completely.

If your using a stock airbox it won't cut it when the engine needs to breathe like a streetported engine with an exhaust. The stock airbox is for stock cars.

Besides that, your just flat out wrong. Sorry you are I'm not trying to be terrible to you but its a fact.

The two hp I was talking about was say you put a cold intake on an engine and get 10hp and I put one in the engine bay and get 8hp. I don't care about the 2hp for the safety of the engine. I like being able to drive in the rain as well as dry.

Cordt

lol my car is stock.....hence using the STOCK airbox. the only thing that isnt stock is the absence of cat converters

Skidtron

iTrader: (1)

Uhhhmm... ya thats not stock then. Youve increased the flow of the exhaust dramatically. the cats are most of the problem for the rotary. I was just trying to help you out and yes tuning the factory ecu or whatever will yield decent results like the tiger man said. He speaks the truth as well.