After 9 years of owning a 1.6TD IDI CY powered Rabbit pickup which I absolutely love driving, I decided my 4x4 choice would be a Suzuki Samurai due to my loyalty to VW diesel engines & their fuel mileage a common, widely suported engine swap choice), love for old Suzuki motorcycles, and the cool factor and aftermarket support for the Samurai platform.
My wife traded her 81 Mercedes-Benz 300SD turbodiesel for an 82 Rabbit pickup when we first met, and now has an AAB 5 cylinder diesel powered VW Eurovan Camper as well...
I was contemplating converting the lightweight 175lb aluminum Suzuki 1.6L to a 16v head + 4 motorcycle carbs, as those engines are pretty great, but fuel mileage is a big goal for this, and pushing even "smaller" 45lb 265/70R16 aggressive extreme terrain tires will require a good bit of torque to not be pedal to the floor at highway speeds.
Some Samurai owners with diesel swaps are reporting mid 30's or even 38mpg with a VW diesel. Mine is lifted a pretty fair amount (more aerodynamic drag) and is running about the maximum tire size one can expect to knock down any respectable mpg, so an engine with lesser output will be pedal to the metal trying to maintain highway speeds and not get run over. This may kill the fuel efficiency, so more torque and at the right cruising rpm with gearing selection is crucial. Cruise rpm at peak torque, 2800-3200rpm.
What I really started realizing is that with further enhancing the gasoline engine's power output, the mpg was not likely to improve any...yet with a good performance diesel build that was well tuned, I could both increase my power substantially, and retain respectable fuel economy. The gas engine made the same peak torque, 98 ft-lbs, as the stock CY 1.6TD, but at 4,000rpm instead of the diesel's 2500-3000rpm range, which is broader and more preferred especially in a 4x4 application.
I am considering buying:
91 Jetta 1.6TD Eco engine with 220,000 miles and K14 stock turbo, and a regular full turbo 1.6TD pump with LDA (needing rebuilt), $800 semi-locally.
-vs-
shopping for an AHU to build as a 1.9 mTDI. I realize this will cost a bit more, and is definitely heavier by at least 60lbs. Searching AHU weight gives me numbers all over the place, so I am uncertain.
Factors I need help deciding on:
1.) COLD WEATHER STARTINGI have read mostly people stating that the TDI's are much better at cold starting. It's no fun to rely on a vehicle, and then not be prepared for leaving your vehicle unplugged overnight in sub-zero (Fahrenheit) overnight temps, and not have it start in the AM. Or even leaving it outside at work all day. I read one argument that the IDI glow plugs have a significantly smaller area to preheat, and therefore will start better than the TDI.
I have experienced a lot of difficulties in the past decade with the 1.6's not starting or not starting well in frigid temps. The Samurai does have dual battery trays which I could utilize in the winters if the IDI really needed more than 2 or 3 glow cycles.
I have not used 5W30 or even 0W30 (Just a Canadian winter weather thing?) in the winter, I always use Shell Rotella 15W##. I now realize 5W is the way to go for winter starts. Perhaps this and a stronger battery will make an IDI start well enough? And 2 batteries will give me confidence down to -10F temps even?
I have a feeling most will say the AHU TDI will start far easier. Does stock e-TDI vs m-TDI have any effect on cold starting difficulties?
I also predict some will say they can get their IDI's started in frigid temps well enough with special cares taken (winter fuel or additives, strong battery, garaging it - not always possible, oil viscosity, pump timing, etc) & others especially TDI lovers will say the IDI is very troublesome in the cold. Please share!
2.) FUEL ECONOMY vs POWER OUTPUTI understand that by design of the IDI prechamber vs the direct/swirl injection head/piston, the TDI is at least 10% more efficient than the IDI, if not 15%.
Weight is a big factor, as adding a 1.6TD is already 100lbs heavier than the all-aluminuim Suzuki 1.6L engines, and one of the biggest attributes to the Samurai off-road are it's size and very light weight. The AHU has a cast iron head as well, vs the 1.6's aluminum head, as well as being bigger displacement and hence slightly bigger bottom end components.
If I drop a well-spent hefty sum on a Giles 1.6TD Super Pump build, I was told that I could make up to 150hp and 225ft-lbs if boosting up to 20psi... HOLY SMOKERS, This really renewed my interest in the 1.6TD!!!!!! Granted I would want more durability, so I would probably keep it at 12-14psi boost and hope for 110hp & 160ft-lbs.
If I were to shoot for the same target power out of a TDI build with an mTDI (TDI-M?) pump, what kind of fuel economy numbers could I expect out of these two? Or rather, what differences in fuel economy could I expect comparing them as theoretically installed in the same vehicle? Is the 1.6TD going to be real close to the mTDI if both set up well and same power output? Or is the mTDI able to knock down significantly better mpg at the same power output?
3.) DURABILITY - high output 1.6TD IDI vs closer to stock 1.9 m-TDI AHU with similar powerIs the 1.6TD IDI MF code engine block, head, rods, crank etc up to the task of making 110-130hp and 150-180 ft-lbs RELIABLY?
Is there a lot more concern on the IDI of head cracking or warpage since they run an aluminum head? The IDI runs a lot hotter and therefore requires a larger radiator to keep it cool. Therefore is more sensitive to cooling system issues without a doubt, and may result in a warped head if a fan motor failure occurs, or a coolant leak. I remember some cracking in between the valves that was common on the 1.6 mechanical n/a heads at least, from when the wife's n/a rabbit pickup engine went through a couple head gaskets over the years. I was told this was common and the cracks do not go all the way through, and it was commonplace to put them right back in service. I think the block deck was .002" distorted at the head bolt thread areas from past overtorquing. Within VW spec, but I suspect it was a cause of 2 head gasket failures since she owned it. the 11mm block is not as tough in this regard. It has head studs and a Gaskets-To-Go MLS gasket in it now.
Again, the 1.6TD IDI "MF" is far lighter than the 1.9TDI "AHU" by 60lbs or even 100+lbs according to some accounts. I am pulling for the 1.6TD IDI to be able to last 200,000 or MANY MORE miles with nothing more than regular service and timing belts, but am not sure in boosted fueled modified form, if it will be up to this task. The AHU, I will assume can handle this durability concern with no sweat at all.
Eagerly awaiting your commentary. Thank you,
Chuck Lambert
Columbus, Ohio, USA