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Seeing as to how most G20s are automatic and all, I was just wondering what overdrive actually does and if it helps our car in certain situations to turn it off. Back in the day, I remember hearing that overdrive reduces gas mileage, but I don't believe that because nowadays lots of cars have it.

What I've noticed so far though (overdrive turned off):
1) well first of all, the little yellow light comes on "O/D off"
2) not much of a difference at low speeds/rpms
3) at higher speeds, the engine is at higher rpms than with O/D turned on
4) pressing/letting go off the gas has a lot more affect on the speed of the car (it feels as though i have more say on what goes in in the transmission)
5) the car feels more "sluggish" because the engine feels like it is revving higher than with overdrive turned on

I'm thinking that #3 is kinda a good thing because the SR20DE motor's powerband is somewhere around 4200~6800rpm (correct me if I'm wrong) so having the engine actually starting to run into that range is good (performance wise). For gas mileage however....
 

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You pretty much hit the nail on the head. What the OD button does is actually "engage" the 4th gear during normal driving conditions. If you have OD turned off the car will not shift into 4th and you can take it to the fuel cut off RPM.

I do a lot of highway driving so OD is great for crusing. It gives better gas mileage due to the gearing ratios and I turn it off when it automatically downshifts when going up a hill to maintain the "power" going up the hill.

I guess it all depends on what your driving style is like....Just dont turn it off when doing excessive speed.....just my two cents...
 

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If you want to lower your 0-60 times turn off the o/d. It actually makes a noticable difference in your launch and your car will gain speed faster. Just be sure to turn it back on when hit 60-65mph or you wont be able to go faster than like 70mph.
 

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When exactly would you need to launch an automatic car ? I mean I guess you could take your car to the track but I think you'd get smoked .....
 

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You definatally can go past 70 with the OD off but you won't get there faster. Above 90 if you turn it back off it will kick the RPM's close to redline and you'll hit 100 faster than with it on

Jim
 

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sup alright so lets say i'm racing someone...
in the begging i want to keep my overdrive off right? and then
when i hit 70 exactly i want to turn on the overdrive so i can hit 100 faster...

thats what i summed up from what you guys said so tell me if its true or not and why is it that it would go from 70-100 faster w. overdrive on
 

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Yeah basically and if you're really laying into it turn off overdrive again at about 110 and you'll prevent the car from downshifting until about 120 but make sure you watch the tach otherwise you'll hit the rev limiter...try not to do that
 

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that is tight man .. i ran into my car and zoomed down the street and yea a lot faster then b4 thaks...

audi a4 here i come!
 

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i remember I hit that once, and the engine feels like it wants to switch, but it cant, and it starts skipping gears, or at least its what it feels like

Bopper359 said:
Yeah basically and if you're really laying into it turn off overdrive again at about 110 and you'll prevent the car from downshifting until about 120 but make sure you watch the tach otherwise you'll hit the rev limiter...try not to do that
 

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whats the 1/4 mile time if we do all that overdrive on and overdrive off stuff that u talked about above..in an automatic 2002 g20
 

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What about the auto tranny's power/comfort switch (do p11s have this too?) does this switch realy give any preformence gains. i remmber hearing it forces the transmission to change gears at higher rpms when set to power or somethin like that.
 

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Stealth said:
What about the auto tranny's power/comfort switch (do p11s have this too?) does this switch realy give any preformence gains. i remmber hearing it forces the transmission to change gears at higher rpms when set to power or somethin like that.
Precisely=) . It'll give you a little better acceleration. Most of the time I just keep mine in comfort. Very seldom do I ever floor the gas and when I do the transmission goes into the power mode(which makes me wonder why it's there in the first place:confused: ).
As for the P11, I don't know if it has a switch.
 

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Yeah, the P11 does have an OD switch

Jim
 

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What the hell?Do I understand this correctly

Ok wait I just read this whole O/D on O/D off thing and Im confused how the hell does all this button pushing make your car go any faster? any way lets say I driving my G20 automatic and want to go fast from launch if i put the auto in 1 instead of D and turn off O/D and mash the gas and right before I hit redline in first I switch the tranny into 2 and take it almost to redline again and switch to D and turn O/d back on before redline again so the tranny could go to 4th gear by it self that should make the car faster Correct?
 

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Re: What the hell?Do I understand this correctly

Twiggy said:
Ok wait I just read this whole O/D on O/D off thing and Im confused how the hell does all this button pushing make your car go any faster? any way lets say I driving my G20 automatic and want to go fast from launch if i put the auto in 1 instead of D and turn off O/D and mash the gas and right before I hit redline in first I switch the tranny into 2 and take it almost to redline again and switch to D and turn O/d back on before redline again so the tranny could go to 4th gear by it self that should make the car faster Correct?
Look at it this way guys. If your auto has 1, 2, and D, heres what happens when you keep the gas pedal floored.

1 - Will keep the car in 1st gear all the way till redline (or rev limiter kicks in) and will not shift into 2nd

2 - WIll keep the car in 2nd gear all the way till redline (or rev limiter kicks in) and will not shift into 3rd (or D)

D - WIll keep the car in 3rd gear all the way till redline (or rev limiter kicks in) and will not shift into 4th (or OD)

OD - 4th gear.

So, yes, *shifting* from gear to gear will keep the car from shifting prematurely and fully use the cars powerband much better, and may give you faster times...(I dont street race and dont condone it either, so I wouldnt know how this would affect that)....Keep in mind that if you choose to do this and run the RPMs up to 7000 you are pushing the car pretty hard.

I dont know what this does to the tranny or torque converter, but Im sure its not good to be doing it all the time.
 

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i don't understand how taking the overdrive off will affect your launches in any way at all. can someone explain this to me?
 

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flyg20 said:
i don't understand how taking the overdrive off will affect your launches in any way at all. can someone explain this to me?
There is no way that this helps...its all in your mind if you think it does. The only thing that button does is lets you shift into fourth gear.

As to the power/auto/comfort button...that changes your shift patterns. If you are in power it will let the revs go higher before it shifts...auto will keep you in comfort mode most of the time and comfort should always keep you in comfort mode...low shifts.

Leave it in auto (middle position). This is becuase when you are normally driving around...you just want to shift that places the least wear on your parts and saves the most gas. When you press the throttle down to WOT it automatically switches to power mode and gives you the highest shift setting. Have a friend watch the button...it will start blinking orange and return to normal after ur done punching the throttle.
 

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Over drive only works when in drive. It does nothing by turning it off when in 1st or 2nd gear

I'm almost positive on that one, correct me if I'm wrong
Jim
 
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