I/H/E Mods
 

Do intake, header, and exhaust mods make a huge increase in hp numbers on an N/A? (Mazdatrix claims 28% hp increase to the wheels with their true dual exhaust system).

If it does, why such a big increase on RX-7's with just a dual exhaust system?

Re: I/H/E Mods
 

They sure do make a big increase in HP. You will be amazed by what a full exhaust will do for you. All you have to do for a rotary is to get it to flow good and you will make HP.

I can assure you that the dual exaust makes a very large increase in hp. The intake increases are marginal. I have a K@N. Its written in stone...DO THE EXAUST FIRST ..... Some else can explain just why it is more dramatic on a rotary than a boinger.

Rotary engines are inherently LOUD so Mazda made them quiet by installing a header designed to keep it quiet, it is very very restrictive. In this attempt to keep it quiet they had to sacrifice a lot of power.

Rotary engines are also bad from the standpoint of emissions, hence the multiple catalytic converters.

The combination of multiple cats and the stock header will give you a fairly quiet car, but it harldy makes as much power as it could. A good set of headers and a pipe to replace the cats get rid of all these restrictions, but make the car LOUD.

The reason the Mazdatrix dual uncollected exhaust is so good is because two pipes to two mufflers flows better than two header pipes collected and then split again. Unless you have an '86-'88 six port you don't need very much backpressure to operate the engine, if any at all. Heck, even if you have an '86-'88 six port model there are ways to get around the backpressure thing.

The reason the '86-'88 models need backpressure is to open the fifth and sixth ports on the intake, on the later six port models the air pump is used. If you have an '86-'88 you have options on how to get around this. People have connected the ports to the air pump, and some have gone as far as rigging up an electronic system that regulates exactly when they open. The cheap and easy way would be to simply wire open the actuators, the disadvantage to this is that you lose a little on the bottom end, but when you're trying to go fast it shouldn't drop below 6000 RPM's anyway.

Hope this helps. :)

Thanks guys, I had an idea of why the big hp increases with just a full exhaust, but I guess I just needed a more formal explaination.

Out of curiousity, has anyone tried the following dual exhaust setup?

Road Race Header(dual outlet) dual straight pipes collecting then splitting up again to two mufflers. Kinda like an 'X' shape after the headers.

Header
||
X
||
Mufflers

I was told this setup increases torque and reduces noise, compared to the Mazdatrix dual setup. This was recommended for my 87 N/A.

With a FULL free flow exhaust you'll gain lots of power...and lots of FUN!! No cats = FLAMES :D Go and get them...you won't regret it!!

KNO