May 3, 2000 update to the Mazda Miata project car

Dyno Daze

In
Out

This past weekend we did some dyno testing at Engineered Performance in Smryna, Ga. (http://www.engineered.net). First off, we need to mention that owner Ed Senf has put together a great crew that was great to work with: Glenn Affourtit, operations manager; Chuck Manning, fabricator; Aaron Ha, turbo guy; Damon Waguespack, Honda tech; Ramona Burkett, Nissan tech; and Aaron Montell, tuning apprentice. Chuck spent most of the day with us, and all we can say is that he rocks—nice guy and an excellent fabricator.

Engineered Performance is a rather large shop located on the north side of Atlanta, just a few miles from the I-75 and I-285 interchange. What makes their shop extremely interesting was the wide variety of cars present during our visit: a Jaguar sedan awaiting a frame-off restoration; an E30-chassis BMW M3 BMW CCA Club Race car; a first-gen Toyota MR2 getting a supercharger install; a Mitsubishi Mirage that was receiving a 276-horsepower, Japanese-spec Lancer engine; a pair of extremely clean Honda CRXs; a few TR7s stuck in suspended animation; and a Datsun Z car that was in for some Electromotive tuning.

Besides the Dynojet chassis dyno and their custom work, they also do routine maintenance and work on street cars. They also have a Crosley Super sitting out back.

Many customer cars also showed up during our testing day, including several turbocharged early Z cars, with Eric Chapman’s turbo 240Z posting 376 rear wheel horsepower on the dyno. (Eric also helped us work on the Miata, making him a good egg.) A fleet of Hondas and RX-7s also showed up, including the supercharged, four-door Integra GS-R featured on the Engineered Performance Web page.

Our first item to be dynoed on our Miata was a set of NGK spark plug wires. Our original wires were pretty junky, as Miatas are notoriously hard on spark plug wires. They were brittle and easily came off (sometimes too easily, like while we were driving the car).

Well, the dyno showed that the NGK wires performed about the same as the old ones, but at least they won’t pop off the coil pack as often.

A popular Miata trick involves bumping up the initial ignition timing from 10 degrees to 14 degrees. This free modification gave us a few more foot-pounds of torque below 5000 rpm, while slightly increasing horsepower throughout the rpm range.

Next up on our list was a Jackson Racing Cold Air Intake (http://www.jacksonracing.com). The Jackson intake replaces the entire, convoluted stock system with a one-piece air scoop. Where the stock setup inhales through the back of the engine compartment, the Jackson intake grabs fresh air through the mouth of the car.

Installing the intake was no big deal, although there is a spacer that must be placed just above the thermostat housing. To save on time, we installed this piece before heading off to the dyno. The hood prop rod must also be repositioned, and this too was done before going to the dyno.

The air bag sensor must also be temporarily removed during the install, but it too is not a problem. Before buttoning up everything, we “port matched” the plastic Jackson intake to our air flow meter.

Within an hour we had the new intake installed and were ready to go.

Our max horsepower increased from 92.1 to 96.5, with max torque rising from 85.6 lb.-ft. to 89.7 lb.-ft. What the numbers don’t show is a nice increase of botton-end torque. Like Ed pointed out, the gains in maximum torque and horsepower are for the magazine articles; the increases in low-end torque are what makes a difference in real-world driving. Plus, in theory, the Jackson piece will make a bigger difference at speed, as the system will allow our engine to ingest nice, cool air. Look for before-and-after 0-60 times to be posted soon.

Next we ditched the stock exhaust system for one from Jackson Racing: header, high-flow catalytic converter and complete exhaust system.

The exhaust system ($499.00) features stainless steel construction, a high-flow muffler and excellent construction. Installation was as simple as removing the old one and hanging the new one. The Jackson system fit as designed and features welds that are probably too nice for something that will never been seen. Like the factory system, the Jackson piece features a center resonator.

We also replaced our catalytic converter with a new, high-flow model. Our stock, 79,000-mile cat wasn’t clogged (yet), but we did manage to break some of its studs while removing the exhaust system. Replacing the cat along with the exhaust is probably a smart move, as a fresh cat will help your engine breathe better while keeping our precious atmosphere clean. Plus, as we found, the studs on the stock one like to snap. The Jackson Racing cat is ceramic coated for good looks and long life. They retail for $179.95—significantly less than the stock part.

Our final mod for the day was a Jackson Racing header—now we could see how their whole intake and exhaust package works together. This tuned, 4-2-1 header features CNC-machined flanges and a ceramic coating. It perfectly mated to our new cat, too.

With everything on and buttoned up, we were now making a max of 102.9 horsepower and 92.4 ft./lbs. of torque—a 12-percent gain from our original numbers.

While not measured on the dyno, throttle response is way better than before—tip-in acceleration is better, and the car is simply more fun to drive. The exhaust note is not that much louder than stock, although after seven hours on the highway, any Miata starts to get uncomfortable.

During our testing, it was interesting to see how the exhaust and intake gave us increases at both ends of the rpm range, but left a dip in the center; the header filled in that dip. It’s almost like they designed these parts to work together as a system.

Once we get all of our dyno numbers back from Engineered Performance, we’ll post them here. Plus, after a week or so with our new mods, we’ll probably have lots more info (and impressions) to share with you.

During our Atlanta weekend we did encounter one semi-major problem, which now needs to be addressed: the throw-out bearing in our clutch has passed on. Later this week the car heads over to Daytona Beach’s RML Automotive (http://www.rmlautomotive.com) for a new one. While we’re in there, we’ll replace the clutch and install and aluminum flywheel. The car should be back on the road in time for this weekend’s TSD rally. (Did someone say rally??)

Check back soon for more updates on this car, and for some photos from the day, click here: http://www.engineered.net/miata.htm

Before ending this segment, we also need to thank Randy Stocker (http://www.solomiata.com) and Rob Ebersol (http:www.ebersol.com/RR) for helping out with moral support while at the dyno. If you’re looking to buy any Jackson Racing parts, please check out Moss Motors’ home page (http://www.mossmotors.com/miata/catalog/tblofcontents/onlinecatalog.html). For good, general Miata info, don’t forget to visit Miata.net (http://www.miata.net) and the Miata Forum (http://www.miataforum.com).

Sometimes it’s nice when performance modifications actually make a real-world difference. Before installing our Jackson Racing header, intake, exhaust and high-flow cat, our Miata took 8.9 seconds to accelerate from zero to 60 mph. After our first round of mods, the car now needs only 8.0 seconds to accomplish the same feat—and this was with a slipping clutch.

Our Miata also now has a seven-pound aluminum flywheel (stock is 18 pounds) and fresh Jackson Racing Stage I organic clutch. So far we have only put about 50 miles on the combo, but around town, our butt-dyno says the engine pulls much harder than before. The clutch engages as soon as your foot comes off the floor, however, which takes about five minutes to get used to.

Once everything is broken in, we’ll run some acceleration numbers and compare them to our earlier ones.

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