Long John Silver
I'm not much of an expert on Quad 4's, i just built one of the (if not the first) Fiero conversion in 1991, and raced it until this past season. Since then, Greg Duncan has been running it in the Tucson/Phoenix area.
That being said, first I would never try this conversion with anything but the HO version, the 180 or 190hp versions (if you can find a 190hp W41 engine somewhere - and bring your checkbook!). I think you said it was an early engine, then it must be either the 140 or 150 horse version. These have head and head gasket problems, a lot of overheating, amonst others.
Now - for FieroJP
Custom exhaust? When my engine was built, we had it on a dyno. It originally produced a peak of 256 horsepower at 5800rpm , but no torque (150ftlb, or so at around 4400 - less than stock!). We went from the IMSA headers back to the stock manifold, ported the first 3" and port matched it, and the hp dropped to 248, but at 4900RPM and the torque went to over 190lbft at 4200. Do you realize how much that would improve both 60' and 1/4 mile times?
Then we shitcanned the racing cams, and went to the W41 cams with a 2 degree cam kit, and the horsepower dropped to 238, but at an amazing 4200rpm peak, plus the torque jumped to 208lbft at 3800RPM with a relatively flat torque curve all the way to just 5700 RPM.
With 18 less horsepower, and over 50ftlb's of torque, I probably lowered my 1/4 mile time by close to a full second (the car ended up in the low to mid 13's, but it wasn't built for that, it was a GT-2 car at first, then became an autocrosser).
No, if you are into the numbers game, go with your custom headers and get horsepower. But at the low end (remember this is a multi valve small displacement engine, the power is at high rpm's anyway) your Fiero will be a total slug until you get it wound up.
Remember, horsepower sells cars, torque wins races.
Let me know how it comes out
Cadero2dmax (formerly quad4fiero)
