Most bang-per-buck I can get for $500?

[91 V-Spec]

I'm running a stock 1.6 NA auto which I'm mostly happy with, but if there's anything quick and easy and obvious I can do to round up a couple of the horses that have run away in the last 19 years, I'm game.

What would you fellas put $500 towards? (An arbitrary amount that I wouldn't feel too guilty about, but that's hopefully worth my while!)

I've just bought new rims and tyres and I always run Mobil 98 octane.

Air filter? And if so, ducted to somewhere besides the engine bay? (Not the lights please!)

A new chip?

A new muffler or exhaust? (Though I reckon mine sounds great already!)

Spark plugs?

Something I haven't even thought of?

She's getting a new cambelt and water pump soon, so now would be a good time to get in there...

Fire away!

[91 V-Spec]

Or just direct me to a previous relevant topic I may have missed!
I've found a lot of gold on here already...

[Euen]

Peersonally, the first thing I would do is replace the auto with a manual but that would probably cost a bit more than $500 but I think you would find it would transform the car.

With regards to your list of suggestions

Air filter? And if so, ducted to somewhere besides the engine bay? (Not the lights please!)
Quite a few owners have ducted cold air in from the void betwen the firewall and the rear of the bonnet. There are differing views on how much of a performance increase this gives. Some have also replaced the airflow meter with one from an early RX7.

A new chip?
Not possible on the MX5 ECU. There are a few "snake oil" devices out there, I think they have even started to pop up on Trade Me, but they are a waste of money.

A new muffler or exhaust? (Though I reckon mine sounds great already!)
Possibly an option. You may be able to find an aftermarket performance exhaust from one of the MX5 specialist dismantlers (Mazline or MX5 Mart).

Spark plugs?
Depends on the state of your current ones. However, don't forget the plug leads. they do break down as they get older and can have an impact on performance.

I'm sure others will suggest further performance enhancements but getting significant improvements cheaply is a bit of an oxymoron as far as the MX5 is concerned.

Good luck

[91 V-Spec]

[quote="Euen"}

"replace the auto with a manual"

I knew someone was going to say that! Not an option, though I'm keen to try a manual MX5 in future...

Quite a few owners have ducted cold air in from the void betwen the firewall and the rear of the bonnet.

I've heard that one before. I assume its not very structural if people are happy to go knocking a big hole through there?

There are differing views on how much of a performance increase this gives. Some have also replaced the airflow meter with one from an early RX7.

Yeah, and probably not worth the shame of a dyno run to test it on my budget!

A new chip?

Not possible on the MX5 ECU. There are a few "snake oil" devices out there, I think they have even started to pop up on Trade Me, but they are a waste of money.

Good to know. My Dad just dynoed and professionally chipped his EF XR6 and is amazed with the results, which is why I ask. But when you're starting off with 3x the displacement the gains are obviously a lot greater...

A new muffler or exhaust? (Though I reckon mine sounds great already!)
Possibly an option. You may be able to find an aftermarket performance exhaust from one of the MX5 specialist dismantlers (Mazline or MX5 Mart).

A better exhaust would require better intake as well right?

Spark plugs?
Depends on the state of your current ones. However, don't forget the plug leads. they do break down as they get older and can have an impact on performance.

How do I tell if they're up to scratch or not?

I'm sure others will suggest further performance enhancements but getting significant improvements cheaply is a bit of an oxymoron as far as the MX5 is concerned.

Lightening the car up is free of course, but there's not much you can remove on an MX, and I need most of it!

Thanks mate!

[poison]

I have to agree 100% with Euen's well thought out comments.

If I may add my 10cents. save your money and spend it on a manual MX5, it
will greatly improve the performance, corner control and general fun. I have
an automatic company car and I spend 45mins+ in the traffic twice a day in
Auckland, this is the only time I would consider an auto.

Here is an option. If you buy another MX5 before you sell yours you will be
able to swap your new mags & tyres, plus all the best bits between cars. I
had two Celicas for a weekend as I was trading up for a model with a more
powerful engine and I got a little carried away and swapped about 60 parts
from shocks, chrome trims, dash knobs etc to rusty nuts and bolts. If you're
not comfortable with a manual and enjoy your car that's also fine. But you
will get more pep out of a manual.

[Posted via external email]

[sprsta]

the car is almost 20 years old your best bet is to replace all of the suspension bushes for urethane before you even think of looking at power
if you can do without your car for acouple of days and have a bench vice it wont cost you too much more than 500 i did every bush in mine for 570 inc alignment (i did all the labour myself (about a full day with a hoist))

this will be the biggest improvement you will ever make trust me

[sprsta]

but if you want power back

plugs
leads
fuel filter
air filter
etc

all of that general maintainance stuff would be a good start

[blackbetty]

slightly off topic but with the rx7 afm is there a difference between the na 13b or turbo afm.which am i supposed to use

[sprsta]

unless you spend most of your time at redline or have a turbo its not worth it. the factory afm will be sufficiant

or get a link and do away with the afm all together

a quick google will help alot

join the miata.net forum that is a welth of information

usually you will need to search miata rather than mx5 (usdm spec mx5)

[91 V-Spec]

Thanks for the advice everybody!

Good to know about the bushes sprsta, I had never thought of that, but with my current novice driving skills, I doubt I would notice the difference anyway.
What I do notice however, is the occasional struggling when attempting to overtake uphill. Yes I know a manual would help, but that's not going to happen!

After all this though, it dawned on me last night that I have enough power, I just need to get it down a bit better.
Merging onto the motorway in the wet, my right rear tyre (new GT Radial Champiro 50) lit up at 90k on the upshift to third and sent me a bit sideways. Unexpected and a bit unnerving, and I think that 5 hundy would probably be best put towards a LSD, wouldn't you agree?

Also, our friend Ross at MX5 Mart kindly pointed out to me that my exhaust has encountered something immovable at some stage and has a big kink in it ahead of the muffler, hence the odd downward angle of my tailpipe. That'll be getting replaced soon, which should give me better exhaust flow...

[sprsta]

you will definately notice the bushes itll drive like a new car and have less road noise

i have my old muffler hanging arround if you want it

you should get a viscus lsd for abit less than 500

[SLYDIT]

get GOOD tyres instead of an LSD. I am running the turbo and just have some 205 toyo t1rs and they have just the right amount of slip in them. Doing an autocross around cones i had no traction issues that werent controllable. A stock 1600 is never going to need an LSD if it has good tyres on it. in fact an LSD will make the rear end MORE loose than standard.

[91 V-Spec]

OK, my GT Radial Champiro 50 82V aren't that good then?

The GTs are definitely way harder to break loose than the crappy Chinese ones it came with, but any slippage is just a waste of power and rubber when you're going in a straight line...

The thing is, I currently have enough power to spin the inside tyre, which is easily controllable but gets annoying if you're not intending to and there's a cop nearby. I doubt the 1.6 auto could ever spin both with the LSD, even in the wet...

The cheap and simple solution is to not plant the accelerator but sometimes you have to when merging with traffic.

[Stevo]

A stock 1600 is never going to need an LSD if it has good tyres on it. in fact an LSD will make the rear end MORE loose than standard.

I have to agree with slydit on this one.
Cheers Stevo

[Gravelben]

I had some GT radials for a while (came attached to some cheap trademe wheels), they were crap - the least predictable tyres I've had, sometimes they'd grip and sometimes they'd slip, but it was very hard to predict which. Kingstars are crap too, but at least they're consistent - you know that if it rains they have no grip.

[91 V-Spec]

I think it must depend which GT Radial you go for and the application.

My Dad drives and tunes his XR6 hard, and after years of experimentation has settled on GT Radial HPZs. He reckoned the Champiro 50's were pretty good as well though.

I had a look at the Toyos, used and recommended by many MX5 owners, but from memory they were well outside of my price bracket...

Never mind, I've resigned myself to driving sensibly until I can afford to upgrade

[sprsta]

gt radial gave 3 types hpz's are a hell of alot better than champeros