bokwus Posted May 10, 2007 Share Posted May 10, 2007 Several people have stated that the datsun chinook gets around 26 to 27 mpg as compared to the Toyota Chinook's 19 to 21 mpg. Why is there such a difference in performance? Is the Datsun as reliable as the Toyota? Thanks - John Quote Link to comment Share on other sites More sharing options...
keitholivier Posted May 12, 2007 Share Posted May 12, 2007 Anyone who makes such a claim is supposedly getting 32.5% better mileage with the Datsun. Considering that both vehicles are gas powered and from about the same era (thus similar technology), this would require the datsun to run on a significantly leaner air/fuel ratio, for which the technology just didn't exist that that time (hardly commonplace even today for that matter). For best specific fuel consumption (lb/bhp hr), an engine needs to be operated at its torque peak with the throttle wide open. With the weight of our motorhomes and the wind resistance and the relatively small size of the engines, one is very likely operating at close to the optimum engine performance, but depending at what speed you are travelling the engine RPM may be too high. Wind resistance increases with the square of the speed, so going faster is severely penalized. There are other factors. Tire pressure has a big impact on rolling resistance and thus fuel economy. The size of external apendages (like side mirrors) can have a significant effect on drag. What about driving habits ? On my relatively short commute to work (9 mi) I don't do more than 55mph, the engine is cold for about half of the trip and my average gas mileage with my chevy Colbalt is 28mpg. I would guess that the Cobalt weighs about 1/3 of my Dolphin. If I do highway mileage, once the engine is warm I reliably get 35+mpg. Instantaneous mileage can go up to 45mpg but that is quickly balanced by climbing a hill or driving a stretch into a headwind. From my experience, the only vehicle that will get 26mpg while dragging around one of our motorhomes is a diesel. Any of the modern common rail turbodiesels of around 2.0L should be able to do this. They may be a little more sluggish in the flatlands, but the turbo will make up for that in the mountains where performance will remain relatively flat instead of dropping by 50%. They also run cooler, have a lower RPM limit (thus lower max speed, but who cares..) oodles of torque and don't need to be thrashed. Because of the torque properties and lower top end, they would be a bad match for any gas auto trans, because the shift points would be all wrong. I have been pining for one of these ever since I movd here from Germany 3 years ago, but the ECU on these beasts is even more complex than what is on a gas engine, so someone very smart is needed to graft the controller into a foreign vehicle. Not a job for the intellectually challenged... That is a great pity since it used to be so easy dropping in a diesel motor that had a regular injection pump... Sadly, for the most part those days have since departed. Keith Quote Link to comment Share on other sites More sharing options...
86rader Posted May 12, 2007 Share Posted May 12, 2007 a few years back I looked at and test drove an '83 17 ft rear bath mini cruiser with the toy diesel and 5 speed. It was a very nice rig, but, just not big enough for a family of 4. It was painfully slow on the highway. Absolute top speed was probably around 60. On flat ground 55 was more like it. The owner said he got 18 driving it with his foot to the boards. He said it would do 24 if driven conservatively. Not sure how you could drive it anything other than conservative, though! It would be absolutely perfect for a single or couple, just so long as they weren't in any hurry. I wonder what that thing would have been like with a turbo? I'll bet with today's gas prices, it would bring pretty good money. Quote Link to comment Share on other sites More sharing options...
turtle Posted May 12, 2007 Share Posted May 12, 2007 a few years back I looked at and test drove an '83 17 ft rear bath mini cruiser with the toy diesel and 5 speed. It was painfully slow on the highway. Absolute top speed was probably around 60. On flat ground 55 was more like it. The owner said he got 18 driving it with his foot to the boards. He said it would do 24 if driven conservatively. Not sure how you could drive it anything other than conservative, though! It would be absolutely perfect for a single or couple, just so long as they weren't in any hurry. I wonder what that thing would have been like with a turbo? I have an 1981 2L 16 1/2' diesel mini cruiser and it gets 17-18 mpg in any driving conditions (around town or highway, up hill or down, it does not matter). You are the 1st person I have heard that has seen another Toyota diesel motor home outside of the one I have owned for the past 12 years. I got past the low HP issue by dropping the rear end gearing to 456 and replacing the stock 4 speed 5th overdrive gearbox with a close ration 5 speed. Now 65 mph is normal highway cruising. A 2.4 LT manifold and turbo charger will bolt up to the 2L engine and since the fuel injection is mechanical there are no other mods needed to turbo charge a 2L diesel engine. Diesel Mike Quote Link to comment Share on other sites More sharing options...
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