MATT BRANNON'S H-PRODUCTION FIAT X1/9

Fire Breathing Fiats is pleased to welcome Matt Brannon who brings us his SCCA H-Production X1/9. Surprised to see it on our pages? The notion was simple really and echoed numerous times in our emails: "Who said it has to be a twincam to be a fire breather...?" So with that sentiment we bring you Matt's machine. The first of what we hope will be many more "un-twincams" to appear on this web site. Read on as Matt takes us through the prep on his National level contender.

Thanks again Matt for your inspiring contribution. We'll be looking forward to seeing you on the podium at the Runoffs soon. jc

Building a limited prep Fiat X1/9 is a pretty straight forward endeavor, with a few exceptions.  The car is very well balanced and has excellent competition potential in this trim.

Without getting into all of the intricacies of SCCA production rules, the following give an approximation of the class differences

F-Production:  1500 carb or 1500 FI @ 1750 lbs, 4 or 5-spd trans, unlimited compression, port and polish allowed, dry sump, unlimited suspension mods

G-Production:  1300 carb @ 1900 lbs, 4 or 5-spd trans, unlimited compression, port and polish allowed, dry sump, unlimited suspension mods

H-Production:  1500 Carb or 1500 FI @2000 lbs w/5-spd trans, or 1300 carb @ 1900 lbs w/4-spd trans, 11:1 compression, no porting,polishing,dry-sump, or suspension relocations. 

Unfortunately, the 1300/4-spd combination in H-Production is simply not competitive.  The best performance you can find out of the motor in that trim is mid-80’s HP at the wheels.  The 1500 combinations, however, put the car squarely in competition, with significant HP and torque gains proportionate to the increase in displacement, making the car relatively equal with the power of other full-prep cars in the class.

The competition in H-Production is so varied now that the car has to be “on” in most every sense to be competitive.  The AH Sprites, with their 948 engines would seem like little competition, but when stuffed to 14:1 compression, dry-sumped, and ported to the max, these little buggers really put out power.  Coupled with a nearly 500 lb difference in minimum weight and unlimited suspension these cars are very fast and nimble.  The Limited Prep Triumph Spitfire, comes in two variations; dual carb 1300 and single carb 1500.  These cars, in the right hands, have excellent straight-line speed and very good handling, and are capable cars.  The Limited Prep Mk 1 Scirrocco, on the other hand, has terrible handling characteristics because of it’s front-wheel drive platform, but an incredibly powerful engine, which makes these cars among the absolute fastest on the track in terms of straight-line speed, regularly posting fast trap-speeds at the end of long straights.

All of that said, the X1/9 entered in HP has to be prepared from every angle.   The most important factors in generating speed and performance in this trim are, in order:

•  -           Engine and carburation

•  -           Transmission

•  -           Struts and suspension set-up

A digital programmable fuel injection system is required to get the absolute best power from the engine.  A stock FI system will flow about 8% more than a race-prep or stock carbureted configurations.  Several solutions are available on the market, from high $$ old-school names (Motronic, Electromotive) to build-it-yourself Megasquirt systems.  Bang-for-the buck, Megasquirt has the others beat hands-down, but can be a bit daunting to get put into place.   That said, a race-prep carbureted 1500 engine is not far off the mark (with a properly prepped carb) and will approach triple-digit HP numbers.

Exhaust headers are required, and a lot of performance can be found in the engine with a properly tuned header.  1300 and 1500 engines require different primary tube lengths!  Be prepared to do some dyno work to find the correct combination, although the 1500 header sold by IAP is not too far off the mark if the collector is cut off and opened up to 2 ½”. 

Contrary to popular belief, the X1/9 transmission, when not abused, is a very reliable gearbox.  The argument between open and welded differential is always in-play between X1/9 competitors.  I have been coached to believe that welded diff is not necessary if the car is well balanced and set-up correctly.  An open diff also limits the stresses and strain put on the gearbox, resulting in intrinsically greater reliability.   It’s biggest downfall is the gear ratio split between 3 rd and 4 th gear.  This split is very large and causes the engine to fall flat on 3 rd -4 th upshifts.  It is highly recommended to find a close-ratio PBS or Colotti gearbox (with matching limited slip differential), although the prices for these units in good condition ($5000+) will match the cost of nearly everything else you put into your car....  An aluminum flywheel is also essential to reduce reciprocating losses and improve throttle response but make sure that it is attached with high-quality fasteners and has been inspected for cracks or it will buzz-saw it’s way out of the bell-housing!

If using a stock 5-speed gearbox with 4.08 rear diff, you will be limited in your cam selections, as the RPMs required at top end on a long straight will be relatively low, requiring the engine to find a “working” peak range between 5000-7500 RPM.  40/80 seat-to-seat in this configuration with 260 degrees at .050 is about the high-end of cam duration or else the car will make it’s peak horsepower at an RPM that is higher than the usable top-gear range on the all-important long straight-away.  If the gearbox can be fitted with a lower-ratio rear diff, the cam duration can be increased proportionately.  A 4.42 rear diff will enable a working range that approaches 8000 RPM.  Even higher diff ratios or lower custom 3rd-to-5th gearset combinations will enable cam selection that approaches a 9000 redline.

Building the engine with 11:1 compression is not a big mystery and can be accomplished relatively economically with a set of wedge-dome pistons and deck/head milling.

Although the suspension or steering geometry cannot be modified in HP, strut modifications are essential.  A high-quality double-adjustable, coil-over with camber plate set-up is critical.  Expect to spend at least $2000 on a good coil over and strut set-up.

Wheels, track, and other parameters of the HP car is identical to that of G-Production, which make transition of the chassis between H, G, and F possible.

For wheels, Circle Wheel manufactures excellent-quality one-piece wheels at any backspace measurement.  They have the exact specifications on-file to manufacture a 13x6 wheel that sets an X1/9 within ¼” of maximum track front and ½” in the rear for G/H Production

With all of this said, building an X1/9 from scratch into a competitive H-Production car will total between $10-$15K when figuring the engine, suspension, wheels, tires, seat, fuel cell, gauges, roll-cage, flares, fire system, FI controller, and so-on.  A close-ratio gear box is extra!

Don’t be daunted, however, because a modestly-prepped car is still VERY fun to drive at the regional level, and depending on your skill, a potential winner.   It’s also a challenge to build your car faster season-after-season with modest investments.

Good luck!

Matt, Marnie, and Brayden Brannon

#22 H-Production

Midwest-X19.com

Columbus , Ohio