Add a little "power" to my DD engine
 

So i got a stock S4 N/A engine i use to DD while i'm building a Semi PP N/A engine.

And since i'm fairly new to rotaries i wonder if there is anything i can do with the S4 engine that would gain me some extra power without being expensive, since i need to put all money in to the Semi PP build.

Already have uprated exhaust,TB mod and a previous owner changed out the filterbox with an open filter, anything else i could do? My only idea is to build a proper CAI, since the setup now probably isn't optimal.

Nope, given whats done that's about all you can do. I don't think theres anything really wrong with the factory airbox. Even if you did change that your not going to get a noticeable result.

hmm, to bad. Will just need to get the semi pp engine finished as soon as possible then, tho i doubt it will be done until the summer of 2013.

Full exhaust is the best thing to do. A header will gain you the most power on an n/a engine

CAI will help some. Biggest gain would be from going to an aftermarket computer, eg Haltech.

I have an rotaryworks 2,25" header, and the rest is more or less straight 3" pipes with 2 mufflers, and one buttplug from hell(to keep the noise down on the norwegian version of emissions, and i haven't bothered removing it yet since i suspect the car is way to noisy without it, but i'm planning on building a new muffler with a bypass/cutout valve)

I'm going to buy Haltech sport 1000 for the semi pp build, but i guess i could make that a priority, since i plan on using it on both engines anyway.

You'll be able to lean it out some but also make the timing more aggressive.

Guess i will make it a priority then.

All that said, I still wouldn't expect much from the engine.

I know, but every little bit helps :)

How much of a difference would itb's make on the stock engine?

I'm thinking i would loose hp, but not shure how much.. Either way, this won't be for performance reasons but because i'm going to run itb's on the semi pp engine, and i want everything as similar as possible, since it will make it easyer when i change engines in and out of the car. Plan on having one big plug for everything on the engine, and one harness on each engine, that way i don't have to take a single piece of the engine, just unhook the cable, motormounts and it's out.

ITBs aren't going to give you much, if anything. The big bottle neck with the NA engines is always the exhaust. If you're running a silencer in the tail pipe as you described, it's knocking down a good deal of top end power. Very hard to make NA power without having a ridiculously loud car.

ITBs should give you a little crisper throttle response, if setup properly. Maybe a couple HP up top, depending on how everything else is matched. Probably lose a small amount of power through the low and mid range. All in all, I would be surprised if you saw +/- 5 HP anywhere in the curve.

Great, sounds like there isn't any realy big downside to it then :)

I realy need to figure out how to build a sound dampening but very little restrictive muffler.

Would a cutout valve solve any proplems, like opening it when i want to drive fast and closed for city driving. Or would i need one map for closed and one for open, or having it controlled by an rpm switch?

you could try 6 Port Sleeve Inserts. Like from pineapple racing or i believe Atkins and Racing beat sell them too. the New Rx8's come stock with em. and its a simple install. all you gotta do is remove the LIM and toss em in. and supposedly its an instant 5 - 10 hp increase. i can't vouch for the HP increase. but it makes sense since your smoothing out the airflow from your 5/6 ports :)