Engine upgrades


Registered User
I read an article from the Supercoupe Club of Iowa, but it was taken down. I’ll write what I remember/what I’ve heard over the years. Please correct me if I made a mistake.

Remove your air silencer. Tiny HP gain, but its free. Located under your airfilter, you’ll probably need to jack the car up, remove the front-passenger-side tire and passenger-side plastic inner fender to reach it. Just buy 3 replacement bolts, nuts, and washers to hold your air filter box down. You might also get a nicer K&N airfilter while at it.
If you want a cone-shaped air filter, you’ll want a heat shield for it so you dont end up with a hot air intake. Probably need to fabricate your own heat shield unless someone has one for sale.

Maybe getting a 10% OD pulley for your Supercharger or Jackshaft (accomplishes the same thing, but the OD JS pulley is more desirable because it probably wont have as much belt slip as the smaller OD SC pulley).

Some people insist a more free-flowing exhaust upgrade helps, but haven’t gone for it myself. Seems expensive, but is probably necessary if you are serious about performance. Go with stainless.

If you do a bunch of engine and Supercharger upgrades, you’ll probably want a Front Mount Intercooler. Magnum Performance made some a long time ago, but they can be hard to find. Double Intercoolers help, but aren’t as helpful as Front Mount Intercoolers.

Probably the cheapest way to get the most HP is to drop in a 5.0 V8 engine from a donor car :D

I shared basically all that I think I know. My 1990, 1991, and 1993 SCs are all basically stock (except for the OD JS pulley and removing the air silencer). So I’d love to see what other members have to say. I’m willing to spend a few bucks on some modest HP gains.

Any opinions here on Seafoam in our cars? Cuzz I’ve heard good things about it. Might squeeze a few more ponies out.

David Neibert

SCCoA Admin
All sounds okay except the part about installing a 5.0 motor. Unless you are doing a power adder with the engine swap it will be slower than the SC motor.


SCCoA Member
"Measureable" gains? Open up the exhaust, overdrive the blower, and do an intercooler upgrade. No, I don't have real world HP gains.

Seat of the pants? Gears and shift kit if you have an auto.

Whats your goal with the car? A cruiser that's a bit more fun? Or drag strip monster? And then decide a budget.