Anniversary Miata - Cheap Power Gains

I have a good friend who just picked up an anniversary edition ('99) miata. He was really looking for an S2000 but didn't want to shell out that much money, so my brother and I convinced him that he'd have at least as much fun in a miata.

Now he's looking to do some inexpensive upgrades to the engine and I was wondering what suggestions you guys have.

He's planning to start with some beefier plug wires, a new set of spark plugs, and a K&N drop-in filter. He doesn't want to touch the exhaust, and doesn't want to spend more than a few hundred bucks. I'm not that familiar with where the the big (or small) power gains can can be made with this engine, so what say ye?

Some things I was thinking of, but don't know enough about:

• CAI

• Re-tuned ecu

• aftermarket intake manifold? (does this even exist?)

It's a 99, so the good news is that it's got a better flowing head than the NA.

Basically, he won't get much in the way of power gains for cheap, especially if he doesn't want to touch the exhaust. I don't think there is an aftermarket intake manifold for NBs and most CAI kits haven't got much of an effect apart from drawing in warmer air than the OEM one. FM has an intake that - according to their measurements - actually gives you a little more power at the top end, but the gains aren't that high either.

It seems that people over on places like miata.net had some decent results playing with cams and/or a remap, but you'll need a proper aftermarket ECU for remapping, you can't just reflash the existing one.

TBH this side of a VVT install/turbo kit/supercharger I'd simply concentrate on the following:

• Upgrading the suspension, especially if it's still running the old OEM one. If it's got > 40k on it, chances are it's shot
• Stiffen the chassis
• Maybe upgrade the brakes

The last two might not be in the correct order, depends a little on what's already been done to the car. Actually the above is pretty much my plan for my NA that I'm slowly executing.

In reply to BoxheadTim:

I was expecting to hear this sort of thing. I didn't recall anyone getting a lot (or even a little) more power out of the NB without exhaust work, or something more expensive/involved.

Check that he doesn't already have the factory sport suspension. There will be a sticker on the passenger doorjamb that will read "Hard S" if he has it.

Barring that, as Boxhead said, your few hundred is better spent on some Koni yellows, and call it a day.

That's pretty much my understanding, too, but I guess we should wait for Keith to show up and tell us the same thing .

Oh, and I forgot - there are aftermarket intake manifolds for ITB setups. Cheap those aren't, though, and you're unlikely to see much in the way of power gains from a standard engine. Plus I'm guessing that you probably want/need to stick another ECU on, too.

The 10th Anniversary already comes with the sport suspension. It's the best factory suspension,but it's not as good as some of the aftermarket options And I agree, with a budget of a few hundred bucks, you'll get a lot more out of some handling upgrades than you will from chasing power. You can make a dramatic difference in handling or about a 10% increase in power.

Of course, the first rule is "fix what's broken". If it's rolling around on the original tires, putting on any new suspension parts will be a waste. If it's on the original shocks with 200k, then shocks are first priority.

Assuming everything is healthy, go with a set of sway bars and a good alignment. That will make an obvious change to the car and give your friend the ability to tune the oversteer/understeer balance.

As for power, you can put on a Randall cowl and pick up 5 hp. Next easiest is doing something with the exhaust, but that's out. So I'd be tempted to shave the head a bit to bump the compression. Plug wires and plugs will only bring back power that was lost due to age (see "fix that's broken" above) and the drop-in panel filter won't make any difference. When looking at air, pay more attention to temperature than to restriction.

In reply to Keith:

Great thanks. I think he'll be very interested in the cowl. Do you have the dyno plots for that on the NB? The link isn't working on the FM website (http://www.flyinmiata.com/index.php?stocknumber=05-28000).

No dyno plots for the NB, but it's not really a different engine from the NA in any fundamental way. Here's the NA chart: http://www.flyinmiata.com/tech/dyno_runs/Stinky_091900.pdf

Run 3 is stock, run 7 is with the Randall (hood closed), run 10 is with a fan aimed at the base of the windshield and the hood closed.

I just installed the Eibach sway bars and I can affirm what Keith stated....Sway bars are a major bang for your buck upgrade for any Miata. I have 140K on my 91 and I'm in the process of a SM build, so the shocks will be the Bilstein HD, but thats just my $0.02 really. Also, have the idea for adjustable endlinks in mind if doing a sway bar upgrade. Thats the next on my to-do list. I have the factory end links in place still and the front pushes while the back likes to get loose under corner out. Can't wait to change that.

Thanks for the advice! I talked to my friend about this yesterday and was telling him it might be best to focus on suspensions mods. I think he's going to keep it pretty close to stock for now though.

Miataman, there's nothing wrong with your endlinks. They don't affect the balance of the car. You're saying you have oversteer and understeet at the same time?

Yes, Keith. The front seems to understeer while the back wants to break loose. Could be my shocks though. I plan on getting those upgraded along with a NB transmission swap (hopefully, 5X Racing can help me with that at their shop). The shocks are factory still shutters at 140K. Would the Bilstein HD shocks be too stiff for street? I ask because the 91 DD is in the works of an SM build. The thing with the under/oversteer sounds strange, but it only occurs under hard cornering. I also have a roll bar installed. That stiffens up the rear end a bit.

Just curious - why no exhaust changes? It's possible to have a better flowing exhaust without making it painfully loud, and is one of the best ways to get a little (key word: LITTLE) more power out of a Miata.

In reply to miataman86:

If you're still on the original shocks, they're probably to blame. I just swapped the tired stock suspension (~130k) for a set of used MSM shocks and springs on mine with about 40k miles on them and the difference is much bigger than I would have expected.

BTW, did you get the alignment checked over by someone who knows what they're doing? That could well contribute to the handling.

I also wouldn't bother with a lot of troubleshooting until the shocks are changed. Oversteer and understeer at the same time just sounds like low grip to me. Oversteer is when the rear has a greater slip angle than the front, and understeer is when the front has a greater slip angle than the rear. Both at the same time means both ends are sliding more than the other

If you're building the car into a Spec, it doesn't really matter what's best - you have to do what's required. If that means Bilstein HD, that means Bilstein HD. Personally, I'd only install a Spec suspension if I was building a Spec Miata - or if the alternative was 140k stock suspension.

Exhaust changes won't pick up a lot of power, but they'll make the car sound more like a sports car. That'll make it seem faster. And if nobody's got a stopwatch on you, that's just as useful as making the car actually faster.

Wait, so he didnt want to spend money for the s2k, and now he wants to spend money trying to make the miata faster?

This is one of those things.. if you (whoever) have to ask how to make the miata faster, you should have bought the s2k, because you PROBABLY dont have the skillset to bridge that performance gap without also bridging the price gap.

Not everyone is an expert in all cars. Some respond well to a header. Some to an aftermarket intake manifold. Some to a chip. Others may not respond to the above one little bit. If you don't know the car, there's nothing wrong with asking.

A good intake on a non-Mazdaspeed Miata will gain you about 5 hp. A good intake on a Mazdaspeed will net you at least five times that.

I'm surprised nobody has mentioned swapping the cast-iron stock manifold for the '01+ tubular.

In reply to MCarp22:

I think that was because of the OP's requirement of "no exhaust changes".

When I get the Bilsrein HD shocks installed, along with the bushings for the control arms, I will go to a competant shop and have them do the alignment. The caster, camber, and toe will be set to SM settings. Not too worried about the factory springs as I've read that the HD shocks works well with the factory springs. The rims and tires will be purchased at the same time as the suspension work, if not right after.

You might find the car a bit oversteery with SM alignment but stock springs. SM suspension has a lot of front spring relative to the rear, and the sway bar/alignment settings are designed to take that into account. You could probably soften the rear bar or put the stock one back in temporarily to compensate.

I plan on setting the rear bar to a softer setting to help compensate for the oversteer. The front SM springs are too stiff a rate for the street, but I plan on getting the street springs that Eibach has. I may opt for more of a performance "street" alignment as to a SM for the meanwhile. Time will tell on that one.