Heating the transmission with engine coolant

[Daox]

Alright, I finally found some solid info on this issue, yay. Below is a link to a paper that tested this exact topic. I didn't read the whole thing, but I'll post quotes of the conclusion.

The effect of engine and transmission oil viscometrics on vehicle fuel consumption

Also note, these tests were done on a diesel engine, not gasoline. Ambient temperature was 25°C.

It was found that 495W of heating applied from the start of the drive cycle resulted in a 0.5% reduction in fuel consumption, while 1080W of heating yielded a 0.7% reduction. In order to demonstrate the maximum achievable benefit of heating the current production transmission oil, the oil was preheated to 70°C prior to the start of the cycle resulting in a 1.4% reduction in fuel consumption.

...

The fuel saving achieved by using an un*heated, reduced viscosity, transmission oil was found to be 1.1% compared with the baseline, which is greater than was achieved when applying 1080W of heating to the current production oil. Providing the reduced viscosity oil can satisfy durability and other production criteria, its use would be a less complex solution to reducing transmission churning losses and drive cycle fuel consumption than heating the current production oil. Heating the lower viscosity oil during the cycle yielded a further 0.4 % reduction in fuel consumption over the NEDC, giving a total improvement of 1.5% compared with the unheated ‘production’ oil.

Also of interest is this colder weather testing section:

Figure 13 shows that at an ambient temperature of -7C the transmission oil temperature naturally rises by 31C (from -7°C, to 24°C) over the NEDC without any additional heating. The increased warming over that seen at the 25°C tests is most likely attributable to the increased work done to shear the highly viscous oil at the very low temperatures. This increased work is a significant proportion of the extra parasitic load that, when combined with thermodynamic effects on engine combustion, and temperature dependant fueling maps, give a fuel consumption increase of 15% when compared with the results at 25°C. Another significant factor in this increased parasitic load is the increased rolling resistance of the cold tyres at *7°C.

Interestingly, the impact of the additional heating at -7°C is very similar to that observed at 25°C in terms of temperature rise and fuel consumption reduction, with a 0.6% saving observed over the cycle.

[Daox]

While searching for information on exhaust heat recovery, I found a paper yesterday (and can't find it now, grrr) that said that an automatic transmission saw a 2.2% FE increase from preheating the transmission on a 30 minute drive cycle test. Not bad for a 30 minute drive! The shorter the drive, the greater the effect the cold start has.

Edit: Yay, I found it:

https://etd.ohiolink.edu/!etd.send_f...osition=inline

Using a novel oil routing method, the transmission fluid reached its operating temperature in 40% less time than in the baseline set by a conventional transmission oil system: 15 minutes compared to 25 minutes. This resulted in a fuel economy improvement of 2.2% during a 30 minute drive cycle. As with the engine oil, although on a smaller scale, quickly warming the transmission oil has a decidedly positive effect on vehicle efficiency.

[oil pan 4]

Using a novel oil routing method, the transmission fluid reached its operating temperature in 40% less time than in the baseline set by a conventional transmission oil system: 15 minutes compared to 25 minutes. This resulted in a fuel economy improvement of 2.2% during a 30 minute drive cycle. As with the engine oil, although on a smaller scale, quickly warming the transmission oil has a decidedly positive effect on vehicle efficiency.

Thank you for finding that. Justification for building my transmission preheating and heating devices. I have already bought most of the parts, just need to install them before winter rolls around.
Thermostatic valve so I don't over cool the trans in winter or over heat it in summer, 400w block heater on 3/4NPT plug to preheat the transmission pan, direct coolant to transmission fluid heating to speed up warming times, thermoswitches to automatically and quickly attain operating temperature.

Since I live real close to work, about a 10 minute drive, more for me.

[Daox]

No problem. I'd love to see what you come up with.

[oil pan 4]

I will start getting some pictures going. The quick warm up stuff is going to be piggy backed on enhanced TH700R4 transmission cooling rig I am working on.

The only thing I don't have setteled is exactly how I want to enter the transmission pan with coolant lines. I think I am going to use 6AN or 8AN flare bulk head fitting and stainless steel line.

[stovie]

i was looking on ebay a few months ago and they had heat exchangers that i think would work good for what your trying to do. it will help warm the tranny and engine up but also cool the tranny if it starts to overheat.

also theres some stuff called nansulate that i've really been wanting to try. It has a r-11 insulation value at three mils thick, so it should do a good job keeping the heat in too. So that the radiator is the only thing that removes heat when needed. You could also coat the differentials if they don't get too hot also.

I was also thinking that using nansulate would reduce under hood temps.

[oil pan 4]

Underhood insulation has been proven to work. I was planning to install double OEM under hood insulating material to hold heat in better during cool months and sound deaden the nose of the diesel all the time.

[Daox]

I'm bumping this to add that I've started to modify the transmission on my 2000 Honda Insight to be heated with engine coolant. More info in this thread:

http://ecomodder.com/forum/showthrea...ant-35269.html