Tech Tips: 2017+ Fiat 124 Spider

[Editor's Note: This article originally ran in the August 2018 issue of Grassroots Motorsports. Some information may be different today.]

Photography Courtesy Fiat

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Brian Goodwin
Goodwin Racing
good-win-racing.com
(858) 775-2810

Replacing the restrictive crunch-bent exhaust system is my favorite opportunity to add both power and fun. The factory cross-pipe in particular is crunch-bent down to about 1.7 inches in places, giving enthusiasts a nice opportunity to bolt on an exhaust system to gain torque while improving turbo spool. The Abarth version already has a fun exhaust note and just needs the flow improvement; the other trim levels with no exhaust note at all-Classica and Lusso–can get in on the fun character this motor has when uncorked a little. In other words, you don’t need to buy the Abarth version for laugh-out-loud exhaust notes–you can easily add it.

Fortunately even the SCCA C Street drivers can replace the entire three-piece exhaust system, since the Fiata has just one catalytic converter and it is up under the turbo–unlike the ND Miata, which has a second converter in the mid-pipe that limits ND C Street competitors to changing just the axle-back exhaust section on the Miata. That also means the complete cat-back system of cross-pipe, mid-pipe, and axle-back is street smog compliant in all states.

The cheap factory diverter valve is inconsistent in operation: Some work okay and some stick and leak boost from new with resulting lumpy and inconsistent performance. In some early reviews of the 124, it is apparent the reviewer didn’t realize he got one of the particularly bad samples of this simple, cheap, little plastic valve that is easily upgraded. Our replacement choice is Go Fast Bits’s DV+, but SCCA competitors in C Street or STU are limited to trying another sample of stock item until they find one that works reasonably well. After doing more and more on the tune side, the benefits include faster turbo spool, better drivability, and more top end.

Fortunately the motor has been around for years in other applications and is pretty well sorted. We race ours almost every weekend, and it has never been back to the dealer for anything. The diverter valve is the most common source of odd power delivery. Upgrading the intercooler pathway and exhaust system for clean laminar flow into and out of the motor pays off for all owners in added power and consistency.

Watch the plugs and coils. High-rpm miss is common over time and usually comes back to fouled plugs or weak coils. Fortunately, good upgrades are available for both items from many sources, and we suggest that the harder drivers get in the good habit of just replacing these low-cost bits once per year for best and consistent performance. Oil changes every 3000 miles are recommended for the hard drivers–autocross, track, etc.

Track users need a real roll bar, and our top choice is Blackbird Fabworx. We love that Fiat gave their version of this great Miata ND chassis a thicker steering wheel and a slightly heavier feel to the assisted steering.

We also love that the Fiata gets a more stout Mazda transmission based on NC-generation internals instead of the delicate Skyactiv trans found in the ND.

The stock suspension is too floppy for much beyond the most mild track use, and coil-overs are a must for anyone with track day dreams as are the cat-back exhaust, intercooler upgrade, diverter valve and tune, and wheels and tires.

For mixed street duty, we like a light 17×8-inch wheel–17 pounds or less per wheel, while the stock Abarth 17×7-inch wheels are silly heavy at over 21 pounds. The max tire fitment is 235/40 in stock fenders with the right offset and camber; with a fender roll, 17×9-inch and 245/40 works great for those with coil-overs.

Those without limited-slip will want to add it. We sent our original housing to our friends at OS Giken in Japan when the Fiat 124 first landed here, and now that popular limited-slip is available from us. See our site for before and after autocross videos.

We think there is opportunity for the Fiat 124 in C Street and STU with the right driver, despite the Fiat being about 100 pounds heavier than the ND Miata and having some turbo lag. The Abarth version comes with a 13mm rear sway bar, while other trims come with a 14mm rear. The ND Miata only has an 11mm rear sway bar. Thus, for C Street, do a full cat-back exhaust, plus upgrade the front bar, and then apply the usual C Street treatment of adjustable shocks–Koni Sports are still a great choice for reasonable cost–and stiff bump-stops in stock lengths per the rules. If running C Street, I would consider the Abarth version since that comes with the Sport button that gives a little more responsive stock tune plus stock limited-slip. For STU, we would just start with a Classica since the Abarth package really gets you nothing you will be keeping.

We race ours almost every weekend, and it has never been back to the dealer for anything.”

We like the Classica with cloth seats for most folks-great car for the money. Beware the optional Recaro seats in upper trim levels. If you are serious about autocross or are over 6 foot in height, the Recaro seats may not be an upgrade for you. The Recaro uses the same seat frame, yet is significantly heavier and the driver sits higher in the car compared to stock cloth seats, yet the lateral support isn’t any more effective. As a result, several taller friends special ordered the Recaro seat option, expecting it would be an upgrade, and ended up replacing them with the standard cloth seats simply to get their heads low enough in the car so as not to rub the underside of the soft top.

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Comments
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mad_machine (Forum Supporter)
mad_machine (Forum Supporter) MegaDork
6/8/20 12:18 p.m.

One of the very few cars I would trade my 500 Abarth in on.

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