I totally missed the turboed Ford diesel in your signature line. I sure hope I didn't offend you with my DI/IDI post. I apologize if I did. It sounds like you have a good knowledge of some of the weaknesses of the 6.5. I did read this thread as you posted, but I'm going to have to re-read so I can refresh my feeble memory. Having the cold air intake will be a big plus as long as it's big enough to not cause a restriction. Also, having the three inch downpipe and four inch straight piped exhaust puts you way ahead of the game. I searched on the truckstop forum for any CFM number, unsuccessfully. I then started a thread asking for info on the fan CFM. I'll copy over to here some of the replies I got. The first one is from a guy in West Jordan, Utah, not very far from you. He runs a lifted 97 Chevy K2500, and it sounds like he's done a lot of special work on it. It sounds like he does good until he tows, or gets into slow driving in the rough stuff. ---I have been running dual electrics on my rig. Flex-a-lite. They pull 5000 CFM combined. I have no problems running the ac or driving around town or highway. Its gotten hot climbing really steep grades going slow (5,000 to 10,000 ft in 5 miles) and towing up canyons. Other than that I love the freed up power with the clutch fan off. Since I switched turbos it has only helped the truck run colder and I see even less cooling issues.--- Here's a short one with a CFM number. ---10,000 is what I've read on here. never seen any numbers anywhere else--- Here's another from a guy who does hotshot trucking with his 6.5 vehicle in northern AZ, lots of towing on steep grades, and lots of experience with cooling and turbo issues. ---This number (referring to the previous post) is what I tried from a measured Trailblazer SS EV clutch fan in place and hood closed on a Trailblazer SS. That fan at 10,000 CFM does not have enough pitch for a 6.5 while towing thus doesn't move enough air. I tried and was heating up with the AC on pulling a decent grade. The 19" steel fan and Duramax fans move a lot more air in the 6.5's RPM range. We also have thicker radiators than the Trailblazer SS and this would affect the CFM number if I measured it on one of our trucks. Is he using AC? What part of the country or what is the summer temps? Planned use: DD or off road rock crawler? I would suggest using the biggest radiator that fits. Factory footprint and a thicker radiator. Gas HP radiator ratings are worthless for a precup in head diesel that has 2" radiator hoses vs. 1.25" gas engine hoses... Airflow in CFM and radiator thickness make a difference as separate variables. Lots of CFM with a thin radiator won't cool you off like found in a Stock Trailblazer SS. In our case (6.5's) we don't have enough CFM but plenty of radiator thickness. Going off road through deep water electrics can be turned off. I would look for some 2005+ 1500 Chevy fans or Ford Taurus/ Lincoln full size car electrics. Electrics I wouldn't mess with unless you have to. CFM just isn't high enough and electrical issues/problems including needing a big alternator always come up. Good fans draw nearly the same juice as the glow plugs. My preference is to use the 19" steel clutch fan and build a shroud for it as well as single t-stat HO water pump. 21" only if it will fit. To reduce the heat kept in the engine exhaust work is needed including a better turbo than GM gives us. The turbo makes a big difference in cooling needs.--- Here's another short one from GA. ---I have a Suburban and I don't even use a fan most of the year.--- Going by these posts, would there be enough room between the fan and the rad to use the three core aluminum rad with the stock 6.5 fan? Or even better than the stock 6.5 fan would be the 21" DMax fan found in 01 to 05 GM DMaxpickups and in some of the 06 to 10 GM vans. The DMax fan, which moves way more air than the 6.5 fan, would require upgrading to a fan clutch from a 97 -99 6.5. The fan clutches up to 96 had six bolts holding the fan to the clutch. From 97 and on up into the Dmax fans the clutch has four bolts holding the fan on. An even better upgrade, if you have the funds to do so, would be to go to the balanced flow water pump found on the 2000 model year 6.5. This would require changing to the 2000 fan clutch as the balanced flow pump has a thread-on fitting for the fan clutch. Another thing that will help with cooling and not yet even talked about, an aftermarket turbo. The GM4 turbo that is on that 94 has no flat spots or lag at low RPM. But, once you get above about 2500 it runs out of breath. There are some other turbos available out there that have been proven to reduce back pressure and improve higher RPM performance, MPG, and towing ability. The guy from AZ doing hotshot deliveries in northern AZ went to a specific turbo and improved his towing MPG and speed/towing capabilities on the steep grades there. Don
