This 1984 S-15 2WD pick-up has a 1989 305 Tuned Port Injected (TPI) V-8 engine
from a Camaro/Firebird. The transmission is a New-Venture five-speed from
a 19881995 full-size 1/2 ton truck. This truck is smog legal in California.
The interior appears stock.
With the .73:1 fifth gear and 3.08 rear axle ratio, the engine turns 1700 rpm at 60 mph. Fuel mileage approaches 24 mpg at 65 mph on level roads. Normal trip mileage is about 22 mpg. Driven conservatively, overall fuel mileage is usually 18-21 mpg. It runs the 1/4 mile in 16.0 seconds at 89 mph.
As shown, this truck weighs over 3500 lbs and gained about 270 lbs from the
conversion: 160 lbs on the front axle and 110 lbs on the rear axle. The V-8
added about 190 lbs, the five-speed weighs about 35 lbs more than the original
5-speed, and the dual exhaust weighs 35 lbs more than the original exhaust;
the battery was relocated to the rear to improve weight distribution. This transfers
about 35 lbs off the front wheels and onto the rear wheels. A gear-reduction
starter and an aluminum water pump reduce engine weight (and front-end weight)
by about 15 lbs.
We have seen magazine articles which state the V-8 conversion only adds about 100 lbs to the vehicle. You should realize that these claims are not true. Most people do not realize how much weight the conversion adds because with the correct heavy duty shocks, it is barely noticeable in normal driving.
After the V-8 was installed, the front of the truck (which is equipped with the 1500 lb payload option) dropped less than an inch, the rear dropped about the same. The ride is slightly softer than stock, but most people do not notice much difference. The handling is not adversely affected. The most common comment made by people who drive the truck is not how powerful it feels, but how smooth and quiet it is. When the V8 conversion is done properly, the vehicle will feel stock, until you step hard on the gas pedal.
The vehicle is shown at the top of this page going through the Burn-Off Test (a registered trademark of JTR). It basically consists of revving up the engine, dumping the clutch and flooring the gas pedal (an MSD Soft Touch® rev limiter makes this test much safer by keeping the engine speed within safe limits). As you can see, the stock 7-1/2" rear-end (fitted with an Auburn limited slip differential) is up to the task. 1988 and newer 4.3 S-Trucks are equipped with even stronger 7-5/8" rear-ends and stronger axles. All 1993 S-Trucks have the 7-5/8" rear-ends.
The stock 7-1/2" S-Truck rear-end will handle a lot of power and is sufficient for most V8 conversions, but if you are running a "built" V-8, or have tall or sticky tires, you will need the 7-5/8" rear end, or a custom built rear-end. Incidentally, the V-8 Camaro use the same basic differential case as the S-Truck, as do 1978-1987 V-8 El Caminos and Monte Carlos. In fact, the V-8 El Caminos and Monte Carlos only came equipped with the 7-1/2" ring gears and the smaller axles.
At the time of this writing, this truck has over 205,000 miles, and the V-8 swap has been driven over 75,000 enjoyable miles. One of the reasons this truck is so enjoyable is that the suspension has been modified with Bell Tech 2" drop spindles, de-arched rear springs with air shocks from a 1993 Typhoon (the softest riding air shock for the S-Truck), a 1-1/8" front anti-sway bar from an S-10 Blazer, and a quick-ratio power-steering box (2-3/4 turns lock to lock) from a 1997 S-10 SS. All of which have added greatly to the enjoyment of the V-8 conversion.