NB bolt on mods and tuning
 

have a '04 Miata LS with a stock 1.8L VVT engine. Performance mods include K&N CAI, RB header, FM hi-flow mid-pipe and RB power-pulse exhust. Timing is advanced to about +14 degrees. Car runs great.

I would prefer to stay naturally aspirated but would also like a little more HP...who doesn't. Would an AFPR, adjustable fuel pressure regulator, benefit me any to add a little more fuel, or will the ECU just over compensate for that. This mod is fairly cheap and easy.

How about Intake/Exhaust cams for the '04 with VVT? Also, I've seen a lot of talk about the flattop (square top) intake manifold and slightly larger TB. About how much HP gain could one expect from any of these mods?

Are these upgrades fairly easy to do and how about the best bang for the buck?

Philip M

If you want the most out of your naturally aspirated VVT motor, buy one of Reverent's MS2's, VVTuner, and EV14 injectors. With the proper tune, you should be able to make ~140-150 whp. Don't bother with cams. An adjustable FPR is a waste of money.

Reference hustler's build:
https://www.miataturbo.net/build-thr...ommuter-63231/

If you want to make more power with bolt on mods, you need to bolt on a turbo.

But yeah, a standalone ECU will be necessary to get the most out of your engine. More fuel won't help unless it's controlled (megasquirt) and there is more air to mix it with.

While its true that the JDM/UKDM/EUDM square top will give you some power, you are leaving a lot on the table with the stock ECU. the factory ECU is tuned for emissions compliance, not performance. Like everyone else has said, programmable ECU and good tune will unlock a bit. I've heard numbers like 10-15hp/tq across the board.

Go make an intro thread and tell us about the car, your mechanical ability and your goals for the project. Then go look up the 949Racing cars, specifically the old "Silver Rental" "Crusher" and the "94R." Emilio and co have posted more info on N/A modded and raced Miatas than anyone.