re: disabling supercharger

[como]

Originally Posted by goldluderay

im thinking about running a push button switch at the base of the gas pedal this way the only time my s/c will kick on is at complete wot,,,,, im thinking about useing this set-up with a nst pulley along with a afc - wideband street tune

I'm no expert, but don't these things have to warm up before you run them, and cool down before you shut them off?

[Benesesso]

Originally Posted by como

I'm no expert, but don't these things have to warm up before you run them, and cool down before you shut them off?

Turbos need a cooldown for their bearings, but blowers don't. A turbo continues to spin after the engine stops, thus no more oil.

[goldluderay]

this is true i dint think about that you would not want the s/c to inguage late in the rpms good thinking,,,,my bad,,it would cause more wear that it is worth

[traintech86]

I know i am dragging up a thread thats old as hell but i want more info. I am looking into getting a SC or N/A and I was wondering about this. It seems like if you turned off the charger and using some mod, tell the car to use less fuel, you could get better MPG. I also read using the c tans? what about a 6 speed? just how far can you stretch this out? I will be making commutes from reno nevada to the SF bay often.

[328FTW]

Get a 20V then

And turning off the supercharger is going to do nothing cause it's normally off anyway unless you drive like an ass in which case you don't care about fuel use anyway.

[328FTW]

double fail

[traintech86]

What kind of MPG do the 20V guys get?

[328FTW]

40 if they push it. It has sequential injection so it is a better refined motor. Generally it's a few mpg better than a plain 4age, not astounding but significant enough.

[toyotaspeed90]

on my untuned gze I get around 45mpg on the freeway when the s/c is off.... guessing if I actually tuned the car & leaned it out a bit at cruising rpm/throttle response then I could get upwards of 50.....

it doesn't take much power to keep a car in motion.... so if you have an engine production 50hp at the given speed you're running you're probably wasting 15-20hp and the fuel required to make that power. The gze actually works well at not making power when the s/c is off.... the intake design is horrible and whether going through the bypass valve or if the air is just flowing straight through the sc12 either way it's a large obstruction.... equalling less power. Add to that the lower than n/a compression ratio....

my mr2 is slower than a 4afe when the s/c is off.... but as I said I get around 45mpg

[Griff]

45? Holy crap!!!! I'm lucky to get 25 outta my gze, and that's like 95% highway driving.

[traintech86]

Originally Posted by toyotaspeed90

on my untuned gze I get around 45mpg on the freeway when the s/c is off.... guessing if I actually tuned the car & leaned it out a bit at cruising rpm/throttle response then I could get upwards of 50.....

it doesn't take much power to keep a car in motion.... so if you have an engine production 50hp at the given speed you're running you're probably wasting 15-20hp and the fuel required to make that power. The gze actually works well at not making power when the s/c is off.... the intake design is horrible and whether going through the bypass valve or if the air is just flowing straight through the sc12 either way it's a large obstruction.... equalling less power. Add to that the lower than n/a compression ratio....

my mr2 is slower than a 4afe when the s/c is off.... but as I said I get around 45mpg

I remember reading about this somewhere and i was curious how you pull this off? i mean in my N/A i shifted pretty early when on the freeway unless i wanted to hear it roar lol. What other things could help out with this? would a 6 speed gearbox change anything? where could you cut weight?

[asdfg68plus1]

Unless my common sense fails me, a 6-speed would only make a difference if the ratio for the 6th gear is taller than the 5th gear on the 5-speed, so I would say it depends on which 6-speed you use.

[traintech86]

I don't know much at all about transmissions but can't you switch gears out? it would be awesome if i could get something like that. Have 1-5 normal and then 6 be for cruisin at 60mph...

[asdfg68plus1]

As long as the transmission you get the gears from are compatible to the one you have, then yes. I don't know which transmissions are compatible with each other, though...

[Oteck]

why not try un-plugging half the injectors? surely that will double your mileage

[traintech86]

Oteck, that sounds like a bad plan(i am assuming you're not serious). I am just curious if you can with the flick of a switch or 2 go from having all the performance of an mr2 to switching and being able to get good MPG.

[Oteck]

sarcasm is hard to detect i see. this kind of thing only works well on +6 cyls and during cruising. I recall some yankee tech would shuts off half V6/8 head to increase MPG. This is where vvt comes to play and allow air to pass through the block instead of creating resistance (pressurizing the chamber)

[toyotaspeed90]

Originally Posted by Oteck

sarcasm is hard to detect i see. this kind of thing only works well on +6 cyls and during cruising. I recall some yankee tech would shuts off half V6/8 head to increase MPG. This is where vvt comes to play and allow air to pass through the block instead of creating resistance (pressurizing the chamber)

oddly enough as far as I can tell this type of technology actually started at my college.... back in around 2001 or so when I took my first tour of the WWU VRI they were building a small (around 3.2?) carbon fiber v8 in which they wanted to both supercharge and make a ton of power but were working on using only 1 bank when cruising on the freeway. Unfortunately I never followed the project through and saw what became of it (the same school has a baja team, FSAE team, and they've competed internationally with their hybrid and non-conventional powered cars. Actually all of Subaru engines are decendants of an enguine built by them when Subaru actually hired WWU to create an engine for them in the early 80's....)



as for my car.... it's on megasquirt.... so the tuning is 100% up to me. I can turn the s/c on/off with the flick of a switch on the dash.... when it's off the car is really limited and in n/a form making very little power.

it would be possible, though, if you were on an aftermarket ecu, to install a barrell style throttle body *before* the stock throttle body... this would allow you to put a pretty bad restriction within the airflow -- reducing power.... you would have to put it far enough ahead that it doesn't cause a disturbance with the airflow through the regular TB.... but when you want to perform have it fully open and there's zero restriction.

[traintech86]

I understand that it runs like garbage withouth it so this is why i would like the option to turn it on/off. Its all still on paper though. What other stuff have people done to increase MPG?

[mr2tim]

Personally I like and have a loud car and I enjoy the hell out of chugging around in 4th or 5th gear and listening to the car under boost. I'd describe it as a booming sound and kind of awesome when in enclosed spaces.

Being that peak torque under boost is 2,500RPM has alot to do with this booming sound.