turning down boost to save on gas

[Robotnik123]

My 8G Legnum VR-4 is a mega gas guzzler - 3454lbs curb weight, power loss thru the AWD drive train and slushbox 5sp tiptronc all have an effect. Around town I usually get MPG numbers in the low teens. Granted I am rather lead footed, but anyway: I am thinking of installing an HKS or similar electronic boost controller.

I understand such a device lets me turn up or down my turbo boost. So obviously I can turn my boost up temporarily for a race and back down to stock (which I believe is 8PSI for a 6A13TT) for normal running. I want to know though, if I can reduce boost below stock levels? What if I turned my boost down, to say 4PSI if that is possible. Could I do that and would it make my car more fuel efficient for ordinary driving? I mean I don't really need any boost at all for running up and down to work and to the supermarket.

[bradc]

It won't make too much of a difference, remember you're only on boost when you are actually flooring the car anyway. If you just accelerate slowly you will use a lot less petrol.

[Wodjno]

My 8G Legnum VR-4 is a mega gas guzzler - 3454lbs curb weight, power loss thru the AWD drive train and slushbox 5sp tiptronc all have an effect. Around town I usually get MPG numbers in the low teens. Granted I am rather lead footed, but anyway: I am thinking of installing an HKS or similar electronic boost controller.

I understand such a device lets me turn up or down my turbo boost. So obviously I can turn my boost up temporarily for a race and back down to stock (which I believe is 8PSI for a 6A13TT) for normal running. I want to know though, if I can reduce boost below stock levels? What if I turned my boost down, to say 4PSI if that is possible. Could I do that and would it make my car more fuel efficient for ordinary driving? I mean I don't really need any boost at all for running up and down to work and to the supermarket.

Hi

No an Electronic Boost controller will not allow you to decrease the stock boost, only to increase it above the standard. :happy:
I think it is possible with a Piggy back ECU, but involves a lot of work to achieve it and money.
If you don't need boost round town then don't put your foot down to far on the gas peddle. :inquisiti If you get a Boost gauge you will be able to see when you are on boost or not. If you keep it in vacuum all the time then you should be running efficiently at 14.7 afr.. This is the optimum for fuel efficiency without running to lean. :2thumbsup

[BraindG]

i run on 1.1 day in day out.. still get over 241~275 Miles on a full tank on long runs, and about 200 when just going to work and back...

don't think it makes all that much difference, vs fun.

[Wodjno]

i run on 1.1 day in day out.. still get over 241~275 Miles on a full tank on long runs, and about 200 when just going to work and back...

don't think it makes all that much difference, vs fun.

Are you running a fuel cut defender Barry :inquisiti

[BraindG]

Are you running a fuel cut defender Barry :inquisiti

Nah, never had any problems with that, the only time it moans is when i ease off between 3000 and 3500, just at its spooling up.

[Wodjno]

And you never get fuel cut ??

[BraindG]

And you never get fuel cut ??
Nope, admittedly i don't floor it from standstill. 1. clutch isnt good, 2. it spikes badly.. so i ease into it pushing harder and harder.

[pezza]

Hmm :thinking: will refrain from any comments mr Brain

I ran at standard boost from 1 bar for a month or so and did not notice much if any difference in conusmption... Like its been mentioned before its open throttle which seems to do it. (quick acceleration, kickdown etc)

I struggle to get over 190 full tank, but thats a lot of stop start landahn taaan driving..

[Nick Mann]

As has been said - very difficult to turn boost down. The easiest way is to not press the loud pedal so hard.

Get a boost gauge and you will see what difference you can make yourself.

Alternatively, get a piggyback ecu and trim the fuel levels back. Our cars run so rich that you can save quite a bit of fuel and gain power if you have it set up properly.

[conaboy]

Noticed a HUGE difference depending on the type of journey. Never been on a decent long run in the car until a couple of weeks ago. Around town Im averaging 150- 180 miles a tank/help

Went up to Fort William ( 200 mile round trip) and came back with almost half a tank:2thumbsup

Agree with comments above, more down to how heavy your right foot is than the boost you run.

If you do install a boost controller, when you up the boost you wont want to put it down again:evil2:

[zentac]

Hi

No an Electronic Boost controller will not allow you to decrease the stock boost, only to increase it above the standard. :happy:
I think it is possible with a Piggy back ECU, but involves a lot of work to achieve it and money.
If you don't need boost round town then don't put your foot down to far on the gas peddle. :inquisiti If you get a Boost gauge you will be able to see when you are on boost or not. If you keep it in vacuum all the time then you should be running efficiently at 14.7 afr.. This is the optimum for fuel efficiency without running to lean. :2thumbsup

Its not possible to turn the boost down with an after market ECU the only way to turn the boost down is to fit weaker springs in the 2 actuators, or replace the 2 actuators with lower boost ones.

[bradc]

Zentac, even if you do change the actuator spring, don't you still need to have a boost controller to keep the boost controlled correctly?

[mpau009]

Hi

No an Electronic Boost controller will not allow you to decrease the stock boost, only to increase it above the standard.

Are you sure??? :dizzy2: :o iv got mine set up with three settings, 5.5, 8.5, and 13psi(approximately), all of which hold their set boost according to my gauge. It was my understanding that the wastegates start to spill close to .4bar, so if your using a replacement solenoid either there is the potential to decrease boost slightly, or my factory boost is way down.:thinking: Of course it spikes over that setting, but it always settles at less than 6psi. Might be that the gauge is faulty, but the dyno seemed to match closely my readings.

I could see why maybe if the factory control was in parallel it might keep boost up.. but mines completely bypassed.

But to answer the original question, it makes no difference, it still builds boost as quickly, so unless you are driving everywhere at full tilt it will make next to no difference (except when you try to pass someone..)