NA6 Intake/Exhaust Mods

zephyrus17 · Postby **zephyrus17** » Wed Jul 20, 2011 5:05 pm

I have a fully stock '90 NA6. I've been tempted to get some more growl in my NA and I was wondering what's a good place to start? I don't want to invest a lot at one time but try to do it step by step and prefer (of course) performance over noise.

I've been considering a Mania CAI or a X-Force Header, but one post here says getting a catback muffler is a better alternative than the header. So I'm a bit lost and wondering what's a good start for some boost?

Postby **NitroDann** » Wed Jul 20, 2011 5:14 pm

There is a LOT you can do. And lots of products that put style over performance (like the mania cai).

Going to a cat back will do SFA (this is an acronym for a rude saying that means not much) unless you get a high flow cat, as the cat will become a bottleneck.

How much performance increase do you want (as a percentage) 10% more grunt, 20?

Dann

zephyrus17 · Postby **zephyrus17** » Wed Jul 20, 2011 5:24 pm

Thanks for the quick reply. I know there's the turbo option, but I think I'd like to keep it NA. I wouldn't want anything too flashy or too loud and 'bogan', but something with a nice noticable acceleration boost.

When I bumped the ignition timing up to 14 BTDC, the dyno said I had around 65kW, which is, a third down from the original power. Either I give the engine squeaky elbow grease, or think of other ways to get more power back. I'm not looking for a 200Hp monster, since the MX5 is my DD. Nothing drastic, probably the firewall cut is the most I'll go. Around 90kW at the end of the whole process would be brilliant!

So from a stock setup, what's the component that's the first bottleneck?

Postby **NitroDann** » Wed Jul 20, 2011 5:30 pm

65kw is not a third down. Its about normal.

So you want a 30% increase is that right?

Dann

zephyrus17 · Postby **zephyrus17** » Wed Jul 20, 2011 5:37 pm

Well, I meant compared to the original power from the factory floor. Ok, maybe 20-30%, then.

Postby **NitroDann** » Wed Jul 20, 2011 5:44 pm

65rwkw is how much power a brand new na6 makes.

Factory power figures are measured at the engine not the wheels. A 317kw 6L SSV makes 250 rwkw not 317rwkw. The 317 is flywheel kilowatts (fwkw) not rear wheel kilowatts (rwkw).

If your after a 20-30% increase... Well tell me.

Does you car have power steer, air con, a big subwoofer etc?

Dann

Hjt · Postby **Hjt** » Wed Jul 20, 2011 5:51 pm

Does you car have power steer, air con, a big subwoofer etc?

'

before it's mentioned, he wants to increase power not decrease wait ;)

isn't full exhaust, aftermarket intake and a aftermarket ecu with a good tune a start ?

zephyrus17 · Postby **zephyrus17** » Wed Jul 20, 2011 5:52 pm

Ahh, my bad. I guess Wikipedia was a bit misleading.

I have none of those, well I have an aircon, but never use it.

@Hjt, of course that's a good start, but that's a bit too much cash for me at one go. It'll have to be one step at a time

Hjt · Postby **Hjt** » Wed Jul 20, 2011 5:53 pm

weight* (long day)

Postby **NitroDann** » Wed Jul 20, 2011 6:03 pm

Well he has typed that he wants 30% more power but id bet what he means is 30% more grunt.

For example if his air con is stuffed and thats why he never uses it he would probably not realise that it alone could contribute 2-3% of his 30% m0re grunt goal. If it works but he doesnt feel he needs it he can remove it and sell it, giving him his 2-3% plus some more budget.

I am just trying to find a way he can get to 30% without going to big things.

Its easy enough to get 10% or even 15% if your careful with the little details. but the jump to 30% takes either a big step or 2 (ecu and cams) or some weight saving, which is free.
The jump to 30% more power cant done with poorly designed cheap bolt ons like any cat back or the mania intake.

Which is it then?

Dann

zephyrus17 · Postby **zephyrus17** » Wed Jul 20, 2011 6:08 pm

Ok, let's take a step back. What'll be involved for the 15% increase, then?

Postby **NitroDann** » Wed Jul 20, 2011 6:18 pm

Assuming your motor is in good nick (at 65rwkw id say so.) Youll need a set of decent extractors, port matched if the matching is bad. feeding a big cat (buy a good nick second hand one for an xr6 falcon or v8 commodore from a wreckers for cheap as chips) into a 2-1/4 exhaust, with a pretty decent flowing muffler.

Then a PROPER cowl style intake, with heat shields on both the exhaust, and the intake, but not touching the intake. along with heat reflective tape all along the factory intake pipe. The intake needs to be completely sealed. Every air gap sealed with silicone, including the hole in the firewall. Also you will need a good firewall bonnet seal so get a new one if it isnt in good nick.

And keep a nice quality lightweight synthetic in it.

This will definately get you 15-20% done properly. with the 15-20% measured at road speed.

30% starts to become a big task.

Dann

Postby **NitroDann** » Wed Jul 20, 2011 6:39 pm

Dont be scared that this sounds complicated or expensive, it need not be. But just slapping some brand name stuff on guarantees you nothing. Getting these small percentage increases takes care. The devil is in the details.

Dann

tbro · Postby **tbro** » Wed Jul 20, 2011 7:03 pm

Give it a good service including fuel filter, good oil not cheap stuff. Have a tune done and run min of 95ron Caltex fuel.
Make sure your tyres are at least the tyre placard and try from there.
Upgrading the exhaust will benefit by all of 3 to 5 hp WHOOPY big gain hey????
Upgrading the inlet will usually loose power(ask Ben)

You have an underpowered car that can be bloody quick point to point as long as you drive it as such.
Don't allow the revs to drop too far under 3000rpm and keep it on the boil!!!
Don't worry that some claim their getting 100rwkw etc.
Love you car and enjoy what it was designed for,as I think Guan has proved big numbers mean squatshit!!!!!!

Terry

Postby **NitroDann** » Wed Jul 20, 2011 7:07 pm

I agree with what tbro says but it doesnt help someone who think his car is sh*t at the lights or overtaking etc.

i disagree with the intakes dont help.

Poorly designed intakes dont help of course. And just because its brand name or popular doesnt mean it isnt poorly designed. But I get air in almost 50c cooler compared to stock, and pressurized not under vacuum.

Dann