New to me 6.5l turbo diesel

My advice (from having a '95 Chevy with the 6.5L turbo diesel and putting almost 170,000 miles on it) - before you even remotely think about any performance mods for this truck, you should be learning about what you need to do just to make it reliable. While I believe these trucks and motors were very good for what they were, the weak link was the DS4 fuel injection pump, specifically the Pump Mounted Driver (PMD, aka Fuel Solenoid Driver or FSD). This was the black box that ran the FI pump and was notorious for dying an early death from too much heat, and if you didn't catch it quick enough it would take the entire FI pump with it (FI pump replacement with a rebuilt unit goes for around $1800.00 from an independent shop, more from the dealer).

First, ask how recently the FSD and/or then entire FI pump was replaced. If it hasn't, then you're living on borrowed time. If one or both was replaced at the typical 75K miles, then it's coming up to the end of its average lifespan again. Either way, you're in for some big $$$'s. The FSD is mounted to the front of the FI pump located in the V of the motor under the front of the plastic "Turbo Power" cover. Remove the cover - it only holds in heat and prevents air circulation. The FSD generates a LOT of heat, and the theory is that this heat is transferred into the FI pump body and carried away by the return fuel flow. Good theory while the motor was on the test bench - not so good in real life. The FSD ends up having to deal with more heat than designed, and if you don't do something about it the excess heat will also cook the optical sensor inside the FI pump and then the entire unit will go south. Add to that the excess heat thins out the fuel in the pump and accelerates internal wear. Search for "FSD Cooler" on the net and you will get some good info and better explanations.

My recommendation is to install a device called an FSD Cooler and a new FSD. The FSD cooler is a finned heat sink mounted away from the FI pump with the FSD bolted to it. This allows heat generated by the FSD to be bled off into the air and not transfered into the FI pump body. Typical mounting location will let you use the stock wiring harness, but you can remote mount the cooler and FSD using a longer extension harness for even better cooling of the FSD.

As for chips and exhaust, the best bang for the buck for me was a dual cat-back exhaust with no mufflers. This motor was quiet enough not to need them. The most exhaust constriction is located in the exhaust downpipe from the back of the turbo to the catalytic converter if you want to spend the extra bucks to replace that as well. The turbo itself is fairly small, as small turbos spin up faster for better throttle response but don't flow high amounts of air at top speed for the best power. The size was a trade-off that gave this motor good response and acceleration but kept the power levels lower than the competition at the time. As for chips, if you replace the FSD you can use a high number resistor (located inside the wiring harness connector) to deliver more fuel and not even bother with a performance chip or new ECM.

There are some very good resources for this motor on the net, and if you have any other questions I'll try to give you a straight answer or direct you to where you can get good info.

Cheers - Jonathan

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One thing not fully mentioned in any of the upgrades for this motor is that the compression ratio for the 6.5L turbo diesel is around 21:1. While Banks typically offers on the Stinger exhaust system for the 6.5, when you get into doing things like increasing the turbo boost, putting in marine grade fuel injectors, and adding chip you need to start to think about running lower compression pistons. High compression = high heat, and 21:1 was about as high as it got for a light duty diesel.

My preference would be an intercooler, 15psi boost pressure on the turbo (i.e. - a performance chip), an FSD cooler, a 1998-style water pump with dual thermostats and crossover, 18:1 compression marine pistons and marine grade fuel injectors, and a new exhaust including downpipe from the turbo (getting rid of the cat and muffler). And don't forget a turbo boost gauge and exhaust gas temp gauge at the least. You'd better have a lot of discretionary income, however. At that point the motor will be very competative, but you'd better start thinking about reinforcing your transmission.

6.5's are quite popular as marine motors - compact, lightweight, good power and easy to work on.

Cheers - J>

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Mine is a 95 c1500 silverdo, 400 AT, 150k mi. I changed the alternator twice (bearing went out on the second piece of crap by around 80k). The inline fuel pump ($52 and easy to change) went out at 60k, not without warning although the brain surgeon at the dealer I asked about it said it would make that noise forever and still work. The starter stopped engaging fully when cold (below 10 degrees F) and got replaced at around 100k. (napa $150, the dealership in Scott City, KS changed it for $45.. that was a great deal).

I have considered the FSD. I?m thinking about leaving the factory one in place while it?s still good and relocating a new one on a remote heat sync.

I?ve replaced the stock air filter with a less restrictive one at

100k.

20mpg hwy.

This is a great truck.