Power Mode Selection

[redlightningsvx]

wouldn't keeping it in power mode most of the time hurt the tranny? hurt gas milage? or do any harmful things overall?

[nextse7en]

Originally Posted by redlightningsvx

wouldn't keeping it in power mode most of the time hurt the tranny? hurt gas milage? or do any harmful things overall?

Since we don't have any hard numbers concerning power mode and the 4eat, we have to rely on common sense to provide us with an educated guess.

The transmission is operating at a higher rotational speed more of the time in power mode. As others have said, at lower throttle points, the transmission shift points are just a little higher than they are with power mode off. Shifts are made proportionately higher the more the throttle is depressed, and it seems to follow a linear curve. with your foot halfway into the throttle, for instance, the 1-2 shift is done at 4000 rpm, the 2-3 is done at about the same. 3/4s of the way in shifts move to 5500 rpm.

With that said, our transmissions do not fail because of weight or power applied, they fail because heat breaks down gaskets and such in our trannys, and the resultant material clogs the fluid paths, causing further heat... ad nausium, until the transmission fails. With the transmission rotating at a higher speed, fluid is pumped through faster, and cooled faster. Also, at lower gears there is less rotational stress on components. (think of a high gear on your bicycle vs. a low one, which one do you think puts more stress on the chain/gears?)


This causes me to believe that power mode has either no impact on transmission life, or a positive effect.


As far a milage is concerned, I have noticed no drop in mileage at all. There is some voodoo math involved here to figure out which is more economical, as when the engine is spinning the transmission faster, less torque is required to achive the same speed, so engine load drops, but injection becomes more frequent. I don't think you will suffer a significant milage drop (except for the small fact the power mode makes it more fun to keep your right foot smashed against the firewall.)

These are just guesses, but I feel they have merit.

-Patrick

[Trevor]

Originally Posted by nextse7en

With that said, our transmissions do not fail because of weight or power applied, they fail because heat breaks down gaskets and such in our trannys, and the resultant material clogs the fluid paths, causing further heat... ad nausium, until the transmission fails.
-Patrick

For a very long time I have been awaiting advice concerning an exact and proven key issue involved in the failure of the SVX transmission. There have been many here alleging expertise, but nothing definite has been posted. Many have had hands on experience, but no one has posted an absolute diagnosis after repairs have been affected.

Early on the stories revolved around debris from faulty clutch material blocking the OEM radiator associated cooler. However something else must be involved at this later period. Heat as such, is much too simplistic an answer.

[nextse7en]

Trevor, I am simply posting my experience while my transmission rebuilt. My filter was completely clogged with various clutch and seal detritus. The blockage was total. Whether debris cause the heat, or heat causes the debris, I feel we can be fairly sure the heat a debris contribute to the failure of the transmission.

LAN also has a few ideas surrounding heat and debris contributing to failure, his performance transmission build thread in the mod section is excellent reading for anyone curious about 4eat weaknesses and eventual failure. I am not questioning your admittedly exhaustive knowledge of automotive engineering, simply citing that I do have first hand experience and some research in this area. Simply because the knowledge of what kills this transmission is old, does not mean that it need be necessarily revised.

-Patrick

[b3lha]

I was just thinking: The SVX is not the only Subaru with a 4EAT gearbox. This mod might also work on Legacies and Imprezas. Somebody should tell those guys.

[Trevor]

Originally Posted by nextse7en

Trevor, I am simply posting my experience while my transmission rebuilt. My filter was completely clogged with various clutch and seal detritus. The blockage was total. Whether debris cause the heat, or heat causes the debris, I feel we can be fairly sure the heat a debris contribute to the failure of the transmission.

LAN also has a few ideas surrounding heat and debris contributing to failure, his performance transmission build thread in the mod section is excellent reading for anyone curious about 4eat weaknesses and eventual failure. I am not questioning your admittedly exhaustive knowledge of automotive engineering, simply citing that I do have first hand experience and some research in this area. Simply because the knowledge of what kills this transmission is old, does not mean that it need be necessarily revised.

-Patrick

Thanks Patrick for the additional Information.

I was in no way questioning what you had advised and was hoping for more information on the subject.

Working on advice from my specialist, I have refrained from fitting a filter and only a cooler. What you reported confirms the advice I was given, but contravenes what has so often been recommended here.

This topic in general requires much greater publicity, in view of the importance of the subject.

[svxistentialist]

Originally Posted by redlightningsvx

wouldn't keeping it in power mode most of the time hurt the tranny? hurt gas milage? or do any harmful things overall?

No
No
And er, no.

Originally Posted by nextse7en

This causes me to believe that power mode has either no impact on transmission life, or a positive effect.


As far a milage is concerned, I have noticed no drop in mileage at all. There is some voodoo math involved here to figure out which is more economical, as when the engine is spinning the transmission faster, less torque is required to achive the same speed, so engine load drops, but injection becomes more frequent. I don't think you will suffer a significant milage drop (except for the small fact the power mode makes it more fun to keep your right foot smashed against the firewall.)

These are just guesses, but I feel they have merit.

-Patrick

I agree here and I have been saying this a long time.

Phil runs his jdm with the Power switch on all the time. I used also do so when I had the Claret.

As I check all tanks of fuel from brim to brim, and record it [sad, or what? ] I know from driving that running with the Power shift map only makes little or no difference to consumption of fuel. From my own records 1 mpg worse or no difference is typical. I can't say if in some cases the Power map caused improvement in consumption, but this might be unrealistic, as gains could be cancelled by the fact you would enjoy driving in a more sporty manner, and so use more fuel.

Also, redlightning, BMW autos also have a "sport" button to run a more sporty shift map on theirs. This switch does not come with a warning about gearbox destruction.

I rest my case.

Joe

[redlightningsvx]

Originally Posted by svxistentialist

No
No
And er, no.



I agree here and I have been saying this a long time.

Phil runs his jdm with the Power switch on all the time. I used also do so when I had the Claret.

As I check all tanks of fuel from brim to brim, and record it [sad, or what? ] I know from driving that running with the Power shift map only makes little or no difference to consumption of fuel. From my own records 1 mpg worse or no difference is typical. I can't say if in some cases the Power map caused improvement in consumption, but this might be unrealistic, as gains could be cancelled by the fact you would enjoy driving in a more sporty manner, and so use more fuel.

Also, redlightning, BMW autos also have a "sport" button to run a more sporty shift map on theirs. This switch does not come with a warning about gearbox destruction.

I rest my case.

Joe

thanks, i was just hesitant about the whole thing now i'm gonna have to hook it up

[svxistentialist]

Originally Posted by redlightningsvx

thanks, i was just hesitant about the whole thing now i'm gonna have to hook it up

You won't regret it Seth.

This mod will not break your tranny, if it happens to eventually break it will be because of natural wear and tear.

I will go further and agree with Patrick about the sport/power mode probably being beneficial; in my own case I always took the view that power mode let the engine rev up more before it called for a gear change. Consequently all gear changes would be happening with the pump spinning harder and line pressure at max value. Changes are a fraction stiffer, but cause less clutch wear.

I have no evidence to support this theory, unless you count the fact that when I rebuilt the gearbox and drove it this way [using power mode], it stayed fixed. I drove it for years and sold it with the gearbox still good.

Joe

[Nomake Wan]

Originally Posted by b3lha

I was just thinking: The SVX is not the only Subaru with a 4EAT gearbox. This mod might also work on Legacies and Imprezas. Somebody should tell those guys.

I was actually lamenting not owning my Legacy anymore. Though I've not heard of any other 4EAT cars besides the SVX having a switch (JDM or otherwise) for Power Mode, it would be interesting to see if grounding that pin has an effect.

[Johnybeas]

well.. I miss my little green power light.... seeing as that I no longer have an auto tranny and probably the "POWER" mode does nothing with my WRX 5 spd.... can i still light up my light to show the uber power that the WRX tranny releases from the EG33???

[SubaruSVXCrazy]

Originally Posted by b3lha

The switch enables you to keep power mode on all the time - even when you're not "mashing the gas". This makes the car much more responsive and gives it a sportier feel.

Nomake, I'll check tonight whether the pins I removed from the stereo plug when I made my SSM interface, will click into the empty space on the TCU plug. If they do then I'll send you a couple, since I have no need of them.

The JDM power switch is at the back of the gearlever. As far as I remember is just uses one of the grounds nearby.

Wait what that button is it?
http://www.subaru-svx.net/photopost/data/538/1571.jpg

What happens if you chip it? Then its even quicker or what?

[Nomake Wan]

Originally Posted by SubaruSVXCrazy

Wait what that button is it?
http://www.subaru-svx.net/photopost/data/538/1571.jpg

What happens if you chip it? Then its even quicker or what?

The photo you linked is a photo of the shifter of a German SVX, not a Japanese SVX. That's why you can't find the Power switch (notice also that the shifter is LHD, not RHD).

If you ground pin A4 on your USDM SVX--as has been said in here--then you'll get a snappier throttle response. Or to be more precise, a more responsive transmission. It's a little hard to explain... the best way is to just try it out yourself and see.

[immortal_suby]

How did I miss this thread? I am doing this tomorrow. Thanks guys!

[svxistentialist]

Go for it Matt!

Be sure to put in a switch, so you can turn it off if you want.

[I only say this knowing you will leave it on full time]

Joe