My thoughts exactly, my friend, but I don't think the existing ratios quite support it.  Might try it some day, like I say, if I discover a need for myself.  For now I think I'll just go forward with the OD box.  I too think that the granny low box with an added OD unit would be "the bee's knees" since the ratios leading up to 1:1 in that box are so nicely spaced.

LR's have a neat TC setup that allows them to bolt up an add-on overdrive in the place that was originally inteded for a PTO.  The G t-case doesn't support that, but maybe we could get an add-on one for behind the t-case.  It might make rear drive line angles too steep on a SWB, but it would probably work okay on a LWB, or even a SWB with CV rear drive shaft.  I know a guy in Canada (Ray Wood @ Wise Owl) who designed a new style of OD for the LR and he limited his risk by explaining the design with full scale drawings and all, and pre-selling 10 units to cover the initial set up, machining, and assembly costs.  If we got serious about doing it, there is of course always a way.

All the best,

-Dave G.

PS - lowered my exhaust temps about 100 deg yesterday when I changed out the air cleaner element that had become oil-soaked to the tune of weighing about 3x what it should have.  :banghead:   I fixed the leaky oil separator a month or so ago, but never changed out the filter.  I guess running an oil-rich air charge into the cylinder before spraying in the diesel could make it run a little rich and warm, eh?  I also bought a chunk of flex pipe and some clamps to try taking the muffler out this weekend.  I'll let you all know how that goes.

Intercooler is fun because it has a sort of compound effect.  The intercooler takes temps down that have been elevated by the air passing through the turbo which is hot due to contact with high temp exhaust (adiabatic heating by the turbo is negligible compared to conduction/radiation from the metal parts).  Reducing inlet charge temps reduces exhaust temps some which doesn't heat the turbo as much, which in turn means the air isn't heated as much by the turbo so the intercooler further lowers charge temp, etc. etc.

I'm also going to install a raised air intake of the cyclonic type like AMZ has, but I don't think underhood intake air temps are all that big a deal for me with the ceramic coated manifold.  Seems to stay quite cool under there.  I'm mainly interested in limiting the dust and water ingress.

Ceramic coating the exhaust housing of the turbo, and the exhaust driven impeller could significantly lower the ammount of heat conducted to elements that are in the intake path......Hmmmm.....I have a spare center section that needs rebuild.  I wonder if I could ceramic coat it without badly effecting the internal clearances, and then have it re-balanced at rebuild time....hmmm....

I need to install a temp monitor in the little tube between turbo and intake so I can monitor inlet temps and see how much gains are really to be had here....

-Dave G.

Well, I tried it yesterday and though I have no way to gauge how much "airflow" it bought me, it didin't do a thing for exhaust temps, at least as I'm  measuring them pre-turbo.  Bottom line was I spent about half a day proving to myself that those Timevalve guys build a pretty darned good muffler.  The "after" test was a whole lot louder, and no different in exhaust temps.  So the muffler went right back where it came from.

The upside was that I found some cracks in my muffler heat shield that had been leading to a once-in-awhile clanging from under there and was able to weld them up and reinforce the plate so it won't crack again.  I also found a loose hanger on the exhaust pipe that I was able to correct.  So the exhaust is generally in better shape for the effort, but no change to the exhaust temps. 

-Dave G.

Eek... I hope not...at least not as far as the turbo is concerned.  They like to say nice things about the ideal gas law like it "favors" high temperature and pressure, which is a nice way of saying it's not very useful for everyday folks.  :^)  But in reality means that it takes high temp and pressure for reality to approach an adiabatic (no heat exchange w. surroundings) process.

The turbo raises absolute pressure from ambient 1 atmosphere  to roughly 1.7 atmosphere.  A corresponding temperature rise in degrees K would be from roughly 310 to 527, or from about 37C pre-turbo under hood air temp to 254C post turbo.  I don't think my intake manifold is hanging out around 500F.  But I could be wrong and it sure would be interesting to find out exactly what IS going on there.  If the intake charge really is that hot, then I did absolutely the wrong thing in ceramic coating the intake.  My goal was to insulate the charge air from outside influences like heat soak from adjacent components, but if the charge air were 500 degrees, I'd want all the outside influence I could get as everything else under the hood is cooler than that, with the possible exception of the exhaust manifold.

Ideal behavior models are a good place to start, but the real world is so far from ideal that we usually end up reverting to the statistician's old mantra, "In God we Trust....All others bring data"  :^)  Looks like I'll have to get those temp gauges rigged up to find out for sure.  And then think of some experiments to try and distinguish between sources of heat.....one of these days.....in my spare time.....  :^)

I think a fun one would be to get in a situation under some load where you could spin the turbo up quick to full pressure from relatively low EGTs, look at the air temp rise right then as a "pressure only" sort of effect, and then see how the charge temp rises as I sit there at full boost letting the exhaust temps come up to 1100 or so, and the turbo soak out, etc.  Hmmm...see now it might be time to install that laptop after all.  I don't need it for GPS, but I could have some really cool instrumentation running!!!!

-Dave G.

I'm with you up to this point and this absolutely does happen.  The only place the heat comes from to ignite the fuel is from the air that surrounds it.  So charge air temp is absoluetly dropped when the fuel comes in.  Unfotunately, shortly thereafter the fuel does in fact ignite and the rest goes to pot.

The only way to have fuel work toward net lowering of the combustion chamber (and exhaust) temps is to NOT burn it, or at least not completely.  In a diesel that gets really ugly in the form of lots of black smoke, and doesn't increase power output beyond that which was achieved by the maximum ammount of fuel that could be burned.  The way to lower temps in the diesel as far as I can tell is to run it lean.  But before too long you fall off the other side of the curve where you're pumping in lots of air that takes away power for the engine to do the work of compressing, but doesn't contribute to power out because you didn't add fuel to heat that extra air effectively.

She's a fickle beastie.... 

-Dave G.

14 National Renewable Energy Laboratory, Biodiesel—Clean, Green Diesel Fuel

I didn't think it was an issue.  I just didn't understand where MazWest "showed a marked improvement in power" from biodiesel.  There is 11% less available energy.  Maybe it is a difference in lubrication properties or something?  It was just a thought.

Cheers,
Chad