The C4 "A Fistfull of Torque"
by Tony Costa

When GM introduced the C4 back (seems like an eternity), in 1984 they forever changed the industry benchmark for high performance automobiles. In 1984 the C4 was declared by the media as being the most technically advanced automobile on the planet.

The 1984 C4's rock hard suspension and GM's infamous cross-fire injection gave way the following year to a more refined and streetable version of the C4. A radical redesign of a car within the first year of a new platform introduction is almost unheard of. GM was forced by its customers to fix its mistakes and by 1986 most of the production bugs had been worked out.

The C4 emerged as a true world class performance machine and forced most of the traditional hot rodders to go back to school and relearn a new language. That language was until that time reserved for computer nerds and rocket scientists.

Times have changed and the C4 has taken a back seat. The C5 and  C6 like all new toy's get the most attention. Well, C4 owners take heart because a properly set up L98 or LT1 will stand head to head with the new kids on the block.

The L98 and LT1 were designed as street machines. The C4 power curve is right where you need it. The power is emphasized in the lower rpm ranges (1500 - 3500 rpm) hey folks this is where you live on the street. I don't care what Porche owners or anyone may tell you, the fun factor of a high performance street machine is directly proportional to low end neck snapping torque.

In stock form the L98 puts out an amazing 350 lbs of torque that comes in under the 4400 rpm. Net horsepower was rated at around 250, that's net horsepower, if the auto industry was still using the gross horsepower rating system, like it did in the old days, the L98 would be rated at
around 300 horses. Thats nothing to sneeze at

The first time we got a chance to actually do some serious work on a C4 was back in 1986. Until that time we followed the time honored formula for hot rodders:

- Slap on a set of long tube headers and a 2 1/2" dual exhaust system with a        x-over pipe
- Install an Edelbrook hi-rise intake manifold with a Holley carb
- Port the heads
- Slap in a 3/4 cam
-Modify the timing curve by messing with the weights in the distributor
-Install 4:10 gears and hold on.

There were no computers to mess with on C3's, no fuel curves, no sensors no exotic fuel injection parameters. What you saw is what you got. A gas guzzling, bad tempered, bad ass machine that was hard to handle at high speed, tended to overheat and would not idle. It was a straight line rocket sled from Hell.
In short a thing of beauty for a hot rodder. 

The C3 had to be babied and tended to on an almost daily basis. The plugs had to be inspected, cleaned or changed out after a few weeks of semi normal driving. If you couldn't afford to install stainless steel brake cylinders, bleeding the brake system was a daily event. Yes we have come a long way baby.

In 1986 a customer brought in his spanking new C4, he told us he wanted more power. We knew then that it was no longer business as usual.
At the time we were lucky enough to have a very good friend who was a head mechanic at a local Chevy dealership. He had just completed a six month GM sponsored course that was dedicated to the new C4.
We convinced him to moonlight with us and at the same time pass down the new Holy Grail of GM C4 performance knowledge.

What we found was that you could meld old school hot rodding tricks with the new rocket science. The C4 in stock form was a revelation, it delivered incredible performance and at the same time was actually a real car. By that I mean it could be driven on a daily basis in all kinds of weather. It didn't break down,or overheat. It stopped and handled unlike anything that Chevy had ever mass produced.

A spanking new out of the box C4 was an impressive package for the mid 80's. Remember high performance was just emerging from the dark ages of tight emission and cost controls. The American auto industry had just come to the realization that in order to survive it had to offer something that was previously unheard of, "Quality".
GM actually performed quality control testing on the new C4. This the first time a major US auto manufacturer did not use its customers to quality test its vehicles.

A new C4 could do the quarter mile in about 14.2 seconds, 0 to 60 came in at around 6.3 seconds. Those were respectable numbers in 1986. Of course respectable is not what new C4 owners wanted. They had just paid top dollar for an American icon and were not enthusiastic about to getting dusted by four cylinder Porsche's.

The Solution
Like its predecessors the C4 will respond to the traditional hot rodding formula:

Intake + Exhaust + Ignition + Gears = More Power

The difference with this new computerized marvel is that after the mods are completed the car can still be used as a daily or long distance driver. You won't even have to listen to your wife complain about how you ruined your car.

With some planning and coordination the C4 will easily slip into the mid thirteen second 1/4 mile bracket. Computers are a wonderful thing, when high performance modifications are planned around sensor operating parameters the end result will be a very civilized and reliable touring machine. A machine that will deliver the same rocket sled acceleration of former Vettes while at the same time delivering a very street able ride while getting 25+ MPG.

If you are the proud owner of a C4 who is just a little tired about constantly being told that a C5 or C6 is the only way to go, listen up.
Upgrading the performance level of a C4 is pretty easy, with a little patience your car will keep up with and in most cases dust off unwary C5's. The majority of C5 owners are yuppie types that really never do much to their cars other then put gas in them. I hope I didn't piss off anybody with that last remark. Hey if you are a C5 owner and you are reading this, you don't fit into the, "I only put gas in my car" category and have probably ordered our ,(shameless plug) Corvette Performance Modification Manual

Seriously, if you want to increase your overall driving experience with a C4 or C5 for that matter take a look at our manual. It will guide you through all modifications to the major systems in your vehicle. It will also help you to make some sound decisions on the road to more horsepower while saving you money and the aggravation associated with mismatching performance parts.

The Vette Nut's

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