Add a little "power" to my DD engine

[Pettersen]

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.

[Mazdabater]

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.

[Pettersen]

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.

[TitaniumTT]

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

[My5ABaby]

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

[Pettersen]

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.

[My5ABaby]

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

[Pettersen]

Guess i will make it a priority then.

[My5ABaby]

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

[Pettersen]

I know, but every little bit helps

[Pettersen]

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.

[C. Ludwig]

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.

[Pettersen]

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?

[89Rotary]

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