Most people can't pronounce it ( I-ZOO-ZOO ) and it's difficult to spell; however, Isuzu's reputation of strength and durability is well known world wide. In the US thousands of Isuzu NPR box trucks are on the road daily. General Motors, a large share holder of Isuzu, also sell and service the NPR trucks as a W4500 chevy and GMC.

Why use an Isuzu diesel ?? Well, Isuzu started building diesels in 1934. The 3.9L NPR engines are an "automotive" type design with less weight and inherently have more swapper friendly features. They are easy to find. Their 3,500 rpm red line and rated HP is more than engines of similar size. The engines are easily rebuilt and use liners. Parts and service are available if needed at every GM truck dealer.

Benefits include longevity and economy. Generally speaking a 10-14 mpg increase and 250,000 to 300,000 total miles are not uncommon. Rebuild it and start all over again.

Engine condition is very important. Usually miles and maintenance records tell the story but don't forget about good common sense. For example, Engine #1 shows 110K of in town deliveries and engine #2 shows 120K of road driving. Maintenance being equal what engine do you want? Calculate engine idle time, convert it to miles and add it to engine #1. BIG difference in total running time. The bottom line: Any engine with 130K or less, starts on the first turn, idles down and doesn't smoke is a keeper...

Flex plate spacers are machined to center to the crankshaft. Early adapters had to be manually centered.

4L80E/4L85E chevy transmissions are recommended for most vehicle conversions especially if you plan on towing. For a more basic conversion with less towing involved the 700R4 / 4L60 transmissions will work and requires no electronics. The progressive shifting cable attaches to the throttle lever. 

For manual applications we prefer the for zf5 spd or in lighter applications the M5R2.

Stock radiators provide maximum cooling for all applications.

After market gauges may be necessary for non GM vehicle conversions.

Record the VIN # of the Isuzu truck you engine came from. Sometimes it is required for parts or service.

Vehicles, transmissions and Ratio's
Vehicles: GM Tahoe's, 1/2 to 1 ton Silverado's, Suburban's, Astro's, 1/2 to 1 ton full size vans and the corresponding GMC line. Any RWD vehicle of similar size that can accommodate a rear sump engine and has enough space under the hood.

Transmissions: GM 200R4, 700R4, 4L60, 4L60E, 4L80E, 4L85E, Allison 1000 both 5 and 6spd NOTE: These transmissions are included in the GM vehicles above. They are also used for non GM conversions but require driveshaft modifications. Also, the "E" at the end of the transmission model indicates electronic shifting. All other models use a mechanical shifting mechinisism. We actually prefer the modern electronic transmissions for ease of tuning and with our transmission controllers instalation is very simple with only a few wires to connect to power and ground.

Final drive ratio's are critical for optimal performance and economy. Fortunately, The GM vehicles listed above use a 3.2, 3.4 or a 3.7 ratio. All work great. The middle is a good compromise. One step up = more power, one step down = more mpg. We try to get around 1800-2000 rpm's at cruising speeds in our conversions, this is a good compromise in mpg's and performance for daily driving empty and towing.

Expectations
Power and enonomy are inversely related. As power increases economy decreases or as economy increases power will decrease. The challenge is to balance the two depending how the vehicle is used. A 3.2 axle ratio would be great for an SUV people mover; however, a 3.9 ratio would be required for a 1/2 ton pick up pulling an RV or construction equipment. Economy also has other variables such as hills vs flat land and driving habits. Diesels do best when the driver "feeds" the engine and avoids "drowning" it with fuel.

The 3.9L diesel operates much like a gas motor. Simply turn the key and start driving. The glow plugs are only used below 20 degrees F. Remember, the engine will do everything the vehicle is designed to do with proper installation.

The USA has not produced a light duty diesel pick up or SUV in the last 20 years. Your conversion will be truly unique.

Driving is an expensive  privilege. The focus of this website is to reduce the cost of driving without sacrificing the comfort of a full size truck.