Opinions of Builders of Superformance Cars

[olddog]

For auto-cross the tires and chassis are more important than the engine.

For the average guy who just wants to have fun, the flatter the torque curve on the engine the better.

More CID and less cam is the easiest way I know to get a flat torque curve. A 351 Windsor aftermarket 4.125 bore block and a 4" stroke, would be my first pick. The heads make the engine. I would have to give that some thought. Craft sells a special CNC ported Brodix head that would be high on my list. Brent Lykins in Kentucky would be happy to custom build you an engine.

I have watched a lot of Cobras run at London Ohio Cobra show, both at the burn out runs and the Auto-cross. I see a lot of Carb problems with fuel sloshing away from the jets during acceleration and cornering. Some go so rich the pipes are pushing black smoke. You just don't see that with EFI. A good multi port EFI solves all types of problems. It can also be used to flatten the torque curve by pulling a bit of timing to kill some power at a midrange, if you desired.

Experts on here have done some pretty fair tests and proven that a carb will make more power than EFI. I do not understand why, but I do not question their attempt to do a fair test. I do not think that matters in your case, as you could easily build more power than you can use. You want good drive-ability.

[Mark IV]

Also if you are looking at a Superformance vs. a BDR keep in mind some the items standard on the SPF:

Limited slip diff
Heater/defroster
Chrome over brass windshield frame
Battery box integrated into trunk
No recycled parts
Oil cooler and hoses
Several others we can document if you wish further info

Some of the items we have such as the original style gages and seats may not fit with your build vision, but can be modified. It appears you are looking for a "hot rod" that visually apes a "Cobra" more than a traditional Cobra.

[Jim Vander Wal]

Brian,

To add to my earlier reply.

I added a full width roll bar to both of my SPF cars, #1855 & #2584. The factory bars are not track rated but most tracks will let you run unless the organizing group is picky. 2584 came with twin roll bars, I don't like these at all and changed to the wide single during the first year.
In 1855 I changed to the Torsen diff and 3.27 gears. Both are my preference.
Swapped belts to the cam lock variety rather than latch & link
Used the top twice in 60k miles between the two cars. It's easier to get wet and dry out and not significantly less effective.
I liked the glove box.
Used the tonneau a lot.
Ran 275/40-17 and 315 or 335/35 -17s. Started with 15s for 6 weeks before changing and never looked back.
Added a 2nd driveshaft hoop. The SPF hoop is marginal.
Headlights need an immediate upgrade. I like the Hella 7" H4 conversions.
Taillights are in need of an upgrade, properly designed LEDs can help.

The SPF can be very comfortable, I ran MI to CO to MT twice. MI to CO. MI to VIR twice and many other day trips.

On Backdraft, a friend has one.
Nice car, wider in the back and maybe longer. Might be a 92 or 93" wheelbase.
The BMW suspension is way different than the SPF suspension.
Similar brakes to SPF.
Seats are thinner than the SPFs
Build quality seems to be good but I don't think it's as good as the SPF.

My FFR isn't near finished so I can't comment on anything other than parts.

Jim

[moore_rb]

Originally Posted by olddog

Experts on here have done some pretty fair tests and proven that a carb will make more power than EFI. I do not understand why, but I do not question their attempt to do a fair test.

Volumetric Efficiency increases as air velocity increases, as engine RPM increases; and for some mythical, magical reason, carbs allow air to flow through the intake manifold faster than EFI does at lower MAPs, and higher RPM's...

I've likened it to watering your plants with a spray bottle, versus a watering can. If the plants need a low to moderate amount of water, the spray bottle does a better job of efficiently (and economically) moistening the soil, and increasing the humidity in the immediate area of the plant; but when the plant needs a LOT of water, even a super-awesome computer just can't pump that spray bottle lever fast enough to deliver a volume of air/water mixture at a velocity necessary to really soak the soil... When high-speed delivery is the goal, old-school watering cans rule...

However- Who cares about peak HP? By and large, EFI allows better volumetric efficiency at lower and mid-level RPM's (where it counts on a true multi-purpose engine) and Olddog has already pointed out the benefits of EFI for track use (especially autocross)

Peak HP is for bench-racers, and carbs are for guys (like me) who enjoy fiddling with their tune all the time.

For all the "just get in it and drive" types, EFI is the most rational option.

Regarding the question of Backdraft versus SPF- My only opinion there is that Superformance bodies, while still not perfect representations of csx3000 cars, still look closer to the mark than BDR bodies do (if that's important)

But, BDR's fatter rear fenders serve a purpose- Their cars are designed to wear wider, modern Z-rated tires, and to go racing-

JMHO, but if racing and raw performance numbers is more important than styling/originality, then BDR makes for a better foundation to build a more modern racecar. (unless you are considering Vintage racing classes, where originality in chassis and suspension design are important considerations, which would swing things back toward SPF...)

Regarding BDR versus Factory Five- for a race/performance oriented car, a FF is a great option to consider- Like them or hate them- FF's chassis design is the most rigid of the bunch.

The cost of a FF kit, combined with the cost of putting it together is right in line with the cost of a delivered BDR roller (every car has to be put together by SOMEONE, so you can't really escape the assembly cost)

Regarding the "show car" appearance... Pfft- You can't win that game, so why even play?

For every guy out there that hates your car because "a Cobra shouldn't have headrests, or an EFI Coyote in it" There will be another guy who looks at it and appreciates the workmanship that went into making it go together...

Kind of like the local guy out here in Az that put the mega-huge aluminum offshore V12 in his Kirkham. Purists hate it, practical hot rodders don't understand the cost-factor of all that effort, performance nuts don't understand what good a car is when it can only be driven at half-throttle... and in spite of all that- It's still one MEGA-cool machine.

Do your car, your way, work with your builder, and ignore the haters. That's the best advice anyone on here is going to give you.... The rest will all just be blathering and bloviating. (like I just did for half a page, hahaha )