If you checked out the picture page on the 1991 Corvette, you know that the car was 100% stock when I bought it. Although the performance of a stock Corvette is adequate for most, the acceleration of the car quickly began to bore me, especially considering my last Corvette made nearly 500 rear wheel horsepower, and over 600 rear wheel torque. It wasn't long after I got the car home that the modifications began.
The first modification I made was to add some Hooker brand long tube headers. After just buying a new car, I didn't have a ton of cash to throw at modifications, so I chose the cheaper, non-ceramic coated, headers. This picture is about 15,000 miles after installation. While there is some surface rust, the headers are still performing great. I haven't had any issues with leaks or cracking, so for less than $500 I am pretty happy with them.
Emissions equipment delete
The Hooker headers I bought didn't have any provisions for the emissions equipment on the car, so I deleted most of the emissions stuff. I removed the smog pump, EGR valve, and the AIR system. I register the car in my home state of Montana, so I don't have to worry about emissions inspections or anything.
Magnaflow mufflers and X-pipe
With the headers installed, I removed the catalytic converters entirely and had an exhaust shop fabricate the rest of my exhaust system. I used a Dr. Gas X-pipe and 2 Maganflow mufflers. I also had 2 exhaust cutouts installed so I can run the car basically open header for the track.
Air intake mods
With the exhaust system done, I turned my attention to the intake side of things. I was still struggling financially at this point, so I did the cheap stuff I could afford. I cut the stock air lid opening, installed an air foil, and installed a K&N filter.
Wide band air to fuel monitor
This is a wide band air fuel meter. It uses a 5 wire Bosch oxygen sensor to monitor the amount of oxygen in the exhaust. The rest of the system converts that data t an air fuel ratio, and then displays the air fuel ratio on this gauge. This was/is an invaluable tuning tool, and a must in my opinion if you plan to add nitrous or some other type of power adder.
After market igniton system
This is my aftermarket ignition box. The box does several things for me. It retards timing on start up, makes my stock tachometer much more accurate, retards timing when I engage the nitrous, has a built in rev-limiter, and a host of other things. Most definitely a worth while mod, and another one I consider a must if you are going to use nitrous.
All of the modifications so far had been leading up to the nitrous install. I had used nitrous on both the WS6 and the 92 Corvette with great success and I saw no reason not to use it here. The nitrous install is long and tedious, but it's covered in it's entirety in the nitrous install section.
After the nitrous installation, the rear tires didn't stand a chance of hooking up anywhere in the first 2 gears. I bought a set of Mickey Thompson ET street Radials and had them mounted on the stock rear wheels.
What happens when you try to hook up 500+ RWTQ
Well, the stock drive train components didn't take too well to nitrous launches on the new tires. I destroyed the clutch and replaced it with a McLeod twin disk. I also decided that once the clutch was in, the rear end probably wouldn't hold up too well so I started to strengthen it. I started by adding a cryo-treated drive shaft, then some cryo treated half shafts and spindles. I topped it off with some cryo treated Spicer U-joints. Turns out, the Cryo'd spindles were the weak link after all the work.
Time to get serious
After replacing the drivers side spindle twice due to breakage, I decided to send the whole rear end to Jeb Burnett of www.deepfreezecryo.com. Jeb runs what is probably the fastest stock style 6 speed C4 Corvette in the world, so the guy knows a thing or two about setting up the rear end to live under some serious abuse. After Jeb Burnett received my rear end components, he discovered that my drivers side half shaft was actually bent, and that is what was most likely causing the spindle breakage. I decided to have Jeb go the extra mile with my rear end and set it up to take life time of abuse from my car. When I get the rear back it should have an upgraded batwing, solid bushings, a new cryo treated stock half shaft on the drivers side, a new cryo treated spindle, a 4.09 gear set, and a spool. The spool will take away some of the streetability of the car, but with the amount of drag strip abuse the car sees, I really don't see another option.
The car is back together now. After some minor teething issues, I got the car squared away and have been busy ripping off mid 12 second ET's at the local strip. I have yet to spray anything more than a 100 HP shot of nitrous, but I am hopeful that with some more practice and the extra power a 150 shot would give me that I can manage a high 11 second ET.