Simple torque/power improvements for NA

[Noddycar]

Hi all

Apart from changing the timing on the NA, can you please suggest some simple changes to improve the performance of the NA (especially torque at lower RPM's)? Is it worthwhile (for example) to remove the standard paper filter and change with something like a K & N filter? Is the Mania cold air intake effective at increasing torque and is it hard to fit?

Until my exhaust system dies (it is very good at the moment), I will focus mainly on the engine bay for now.... I don't want to take the car too far away from stock, as I quite like the idea of having a relatively stock Limited Edition... Having said that, if changes are simple to make and reverse if I need to, that would be quite an attractive option.

The car is great on the open road, but a bit sluggish around town, so I am really trying to improve performance at lower RPM's. I know that the simplest solution is to push a little harder on the accelerator before taking off at the lights If most of these performance enhancements are more effective at higher RPM's, I probably won't bother.

Thanks

Noddycar

[project.r.racing]

being a na motor, any thing you do to it will move the torque power band higher up the rev range. and further away from usable street use.

if you have hanving issues with low rpm power, then it is best to leave the engine as is and not modify it.

you say your exhasut is good? is it a very large diameter pipe? as too big pipe normally kill bottom end performance.

[emx005]

I just got mine back from MX5 Mania the other week. Mania and enlarged intake, full exhaust, new rotors/brake lines/pads and a new cloth soft top with glass window.

The exhaust and intake made a noticeable difference right through the rev range. All I wanted was another 10-15% and from a seat of the pants feel I'm well and truly there. The biggest difference is how smooth the power delivery is now and I'm loving it. You'll never get great power gains staying NA without spending a shitload of coin but I'm happy with the way it's going now. Next up will be suspension and a respray of the rear end and mirrors.

The Mania intake sounds awesome but be aware that it is really loud and angry at wide open throttle.

[Mr nanotech]

Thanks for putting this up! I'll have to keep watching it as I've got an NA as well!!

[DaveWA]

Drop a LS2 motor in.....

[Mr nanotech]

Drop a LS2 motor in.....

Because that totally won't gimp the handling and weight distribution..

[bruce]

Like people have said, the easiest is the IN and the OUT (intake and exhaust).
As your exhaust is in good condition, you can fit an aftermarket exhaust and keep the original in storage if you want to return it to stock.
Not much more can be done to the little motor unless you go radical (turbo).

[Guran]

Have you tried 18 degrees timing with 98 RON? Does that do it for you?

Playing around with cold-air intakes and exhaust mods usually has the effect of increasing power output, but sacrificing low rpm torque. Generally, you don't get both with natural aspiration. If you want more low rpm torque, you're probably looking at forced induction. Or a Commodore/Falcon.

Further reading:
http://www.miata.net/faq/faq4.html#improve
http://www.miata.net/garage/turbos.html

[Noddycar]

Thanks to everyone for the replies.... After taking my new (old) toy over Mt Glorious today, I won't ever complain about the power of the little donk.... It pulled like a truck up the hill and handled perfectly. I drove it up mountain and tossed my wife the keys for the drive down. It was a hoot! I had a worrying little vibration noise coming in between 3000-3400 rpm after some hill driving. To me, it sounded like a transmission noise, but it disappeared when I hit around 3400 RPM.... Hopefully I was imagining the source and there is something loose elsewhere in the car.

Thanks again for the replies. As opinion seems a little divided on this issue, I may just leave it alone for now.

[Steampunk]

As Guran suggested, advancing timing works, there is NO doubt about that. 18degrees is good for low to mid-range increase, but top-end will suffer.
If you don't live past 6,000RPM often, you can be adventurous and go for 20degrees BTDC, but, once again, top end with suffer even more.

Try it, it's free and simple to do and if you don't like it, change it back.

[Noddycar]

Advancing the timing seems to be recommended by nearly everyone, so I will see how that goes... I always use BP Ultimate or similar premium fuels, so pinging should not be an issue. I don't tend to rev out more than around 5000 RPM (according to the tacho - don't know if it is accurate), as the engine starts to sound really "tinny". This might be related to my noise at 3000 RPM.... Ignoring my 3000 RPM grinding/rattle, when I hit around 5000 RPM I am hearing a higher pitched noise that sounds like a very high pitched vibration from the exhaust, but it seems to be coming from the engine bay. I am not sure if the two are related. I have not heard the 3000 RPM noise before today, after running it over Mt Glorious and then sitting in first gear after hitting the traffic from the music festival. Once the car sat and cooled for a while, the noise at 3000 RPM disappeared, which made me start worrying about issues with hot components somewhere in the transmission..... I will give it a good run sometime this week and if it is making the same noise, will drop it into the mechanic for a check-up. I can get the timing changed while it is there....

In regard to setting the timing, can I do this with a standard timing light and tacho, or do I need specialised equipment? I have a few MX-5 books waiting for me in my post office box, which I am sure will shed some light on this..

[Noddycar]

Forgot to mention, my "3000 RPM" rattle sounds like the gear shift knob is loose and vibrating (it isn't).

Going back to air filters for a moment. In regard to items such as the cold air intake or K & N filters, are there any other benefits from fitting these apart from performance? For example, does the engine run a little cooler or do they filter the air better?

[Mr nanotech]

Not sure about pod filters but I can tell you first hand that K&N replacement filter will do nothing. The main restriction in the na's intake is the airbox itself. So if you want any real gains, piss that off and find another solution like a cowl intake or pod.
Just make sure you don't do what I did because you'll lose a lot of torque. Pod's seem to kill torque I've noticed and you only get the gains top end.
What I did was ditch the airbox and put on the pod but since my flange doesn't fit over the extractors, the pod is right next to it sucking up all the hot air. Bad idea but I really can't be bothered putting the box back in since I'm making my own cowl using an enclosed pod and pipe through the firewall. Apparently those give you a gain right through your rev range.
Though that is conjecture really since I have no dyno prints to show.

Oh and if you want a cheapish way to get a little more torque, throw some stainless steel 4-2-1 extractors. They should get you going a little harder off the line and more pick up mid range. Apparently xForce are pretty good, they are still an entry-mid range product but at only $500 or so fitted you can't really complain. Since pace makers aren't available for mx5's and Genie only make mild steel for us, I'd be inclined to go for those. I personally have an Apex'i 4-1 setup. I put it on as an experiment/cheap replacement for my cracked manifold. But to be honest, that killed my torque for a lot more top end.

The 1.6L in the na is hard to get really going unless you do something drastic like forced induction. I agree with all the other posts but I will say that it's a very revvy engine so try to adopt a driving style that accounts for it. You'll notice the car has a lot more guts than you thought if you learn to keep the revs high. But like the others said, more top end is better for the track but for an every day driver, you don't really get the benefit of using it. Should make mountain passes fun though!

Hope I've helped you mate

[Steampunk]

Air filters are very subjective, Matty (was it Matty?) did a little write-up/test as to the restrictions of various elements in the intake system. It's this:
http://autospeed.com.au/A_110680/cms/article.html

From experience, I have dríven two cars that have different versions of the Loch Stewart intake, (one genuine, one knock-off copy) that is fed from a hole in the firewall, and I say they do improve low end.

Changing filters will not make the engine run cooler.

Make sure your spark plugs and leads are in good condition as well.

Igntion timing advance is easily done, with the only specialised tool needed is, as you mentioned, a timing light.

Your rattle can be many things, loose exhaust components (header heatshield, catalytic converter innards), loose gearstick turret bolts, etc.

[Noddycar]

Wow! Great answer Nano! I am filing all these answers away and assembling my wish list...

1red5.... Thanks for your experience with the intake. I think I will order the Mania CAI. Can always remove it, if it doesn't help.

I will definitely bump the timing as well. If the rattle persists, I will get Mazcare to take a look at it. The clutch got a fair workout today (mainly while stuck in first gear after the mountain climb), so I would prefer to play it safe.

Lots of conflicting views, but everybody's cars are different and so are the drivers. That's what makes this so interesting!