Hey James, wasn't replying to anyone in particular - just updating.
I mention engine on coasting because 1, I'm not quite ready to commit to something like a kill switch, and 2, my last car was an automatic so I feel much better about coasting in neutral with this manual car. It's so much nicer and seems to coast easier and farther too.
So these STi's have a cool feature called the DCCD or driver controlled center differential.
Through that, we can control the initial limited slip differential torque. The car's quick reference guide says this, "
This system adjusts the torque-distribution ratio between the front and rear wheels of the center differential to suit driving and road surface conditions."
The 4 pages in the owner's manual don't mention torque-distribution between front and rear wheels (although it does mention left to right). It's language focuses on how the car responds and what each mode would be best suited to (Auto + or manually increasing the initial LSD torque is for slippery or questionable traction situations and Auto - or manually reducing the initial LSD torque is for high traction conditions).
It does mention that "
A higher initial LSD torque setting gives the vehicle greater traction when driving straight ahead but makes cornering more difficult. Remember this when adjusting the initial LSD torque. In general, higher initial LSD torque settings assist driving on slippery roads and lower settings for non-slippery roads. When the vehicle is stuck in snow or mud, setting the initial LSD torque to the maximum [LOCK, if you're familiar with these vehicles]
will help to free the vehicle."
My question for you guys would be am I wrong to interpret that I can use this somehow to make the car roll easier aka get better mileage on the highway and/or city? (and being safe about weather and driving conditions and sticking to the Auto and + - when the drive might be questionable)
With a minimal amount of Googling, here's some logic from a 2008 post over on the iwsti.com forum:
Quote:
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Originally Posted by fry_ed
In a straight line (i.e. on the highway), DCCD AUTO will default to DCCD LOCK. There will be more friction (it's very easy to imagine this for an AWD car that uses a viscous type center diff to keep the fronts and rears rotating at the same speed), and therefore you will have to push the GO pedal a bit harder on the highway to keep up to speed, compared to having the DCCD in OPEN. You know, because friction = heat loss = more power loss.
In the city, there are lots of turns, and DCCD AUTO will default to DCCD OPEN. So it's not that much different than just setting it manually to OPEN. It seems very obvious to me that you should see a non-negligible mpg difference on the highway and a negligible mpg difference in the city, as CRASH1973 showed...
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Source Post,
Source Thread.
I like the simplified logic presented in that post (might be too simplified, and I think it's effective to make the point), but I'm probably biased. However, none of the people that were arguing against being able to influence MPG through using settings on the DCCD ever responded directly after that post beyond one person that was already in the pro-use-dccd-for-better-mpg camp agreeing with it. What do you think?
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