Something I was wondering. ( I'm only 16 and learning haha). I want to get a stage 1 closed loop chip from motorsport development. It's going to run 15 for that chip. With my boost controller. Would I save fuel if I ran only like 8 -10 psi as low boost and flick it to high when I want more power. Or would it use the same amount of fuel at low boost as at high as it's ment to run that amount. Or will the ecu reload this and use less fuel?? Thanks heaps

 

have it on a switch for lo and hi boost - you will use less fuel on less boost.

I had a hi/lo boost switch in my car which was great.

 

id be interested in this answer too

 

so it wudnt just overfuel the engine?

 

Basic rules:
a) for optimum power you need 300 grams of fuel (petrol) for each Kilowatt the engine produces for an hour.
b) more absolute pressure in the inlet manifold is more power.
c) the further you depress the throttle, the higher the absolute pressure is in the manifold.

So, if you need 10 Kilowatt to drive a certain speed you need 3 kilograms of fuel per hour.
If you need 100 Kilowatt to drive a certain speed you need 30 kilograms of fuel per hour.

Back to your stage 1 chip: most chips I know will also use an increased ignition advance. That means you get (a little) more power from about the same amount of fuel. So, a stage 1 chip running at 10 psi could use a little less fuel then the standard chip with the same amount of boost. How much? You would have to try that.

As to overfueling the engine at low boost: if the chip is setup the right way, the answer is no. Remember, before you reach 15 psi, the pressure is 14 psi, and before that 13psi, etc. etc. You always run a small amount of time on 8 and 9 and 10 psi. If the fueling there is incorrect, the car will not accelerate very nicely.

Now, I wouldn't use a boost controller. I would let the chip control the boost pressure.
If you want high and low boost, all you have to do is put a switch in one of the electrical wires connected to the amal valve. I use a switch with a key, looks like an ignition barrel.

 

Yea that's what I was wandering because there would be no point otherwise running low boost

 

So yes I would save fuel by having it set at low boost when I don't need it? I have a electronic contoler that I can adjust with a knob inside to set the high boost and then flick a switch for the set high boost.

 

If you are on "high boost" but at part throttle just cruising down the motorway or whatever, you will only be making very little boost anyway, so fitting a switch that limits the MAX boost from 15 down to say 8 would have NO difference in your economy at 2psi when cruising along.

If you want to save fuel, dont accelerate hard and dont cruise at massive speeds.

 

Really?

 

Yes the more boost, the more fuel you will use, however as said under normal driving you won't make no boost anyway, it's only under acceleration/low gears or high speed you actually make higher boost.

All the "Hi-Low" boost switch does when open is cut power to the amal valve and so you run lower boost, when the switch is closed you will be able to run the maximum boost your setup permits.

Basically as said the best way to save fuel as with any engine don't accelerate hard and don't hold onto lower gears longer than necessary or go high speed.

You need to be careful with boost controllers you don't adjust the boost to high otherwise you will have a meltdown.

The ECU fuels accordingly for the amount of air present at any given time so no it wouldn't overfuel.

When you start to increase airflow etc (I.E with a higher boost pressure) the ECU cannot fuel for this change as it is not calibrated for it hence it would run lean, this is why you need a remap/chip that has been calibrated to the spec along with different ignition curves etc.

Also good mapping will give better fuel economy.

Martin

 

If you want better mpg, buy a vacuum gauge, and watch it and learn it, don't waste your money with closed loop, it's ace at protecting cats but a correctly mapped car doesn't need it, but you won't have optimum fuelling from an off the shelf chip, if you could get this there would be no point in live mapping as there would be no gain to be had!!
I don't run CL and can get 40mpg without problem, and that was on a 200,000 miles worn engine, correctly mapped CO was 0.97% on greys and 137ppm.
tabetha

 

The problem with not running closed loop is there is a fairly finite number of cells available on the standard ecu for these cars, and while the ecu does of course interpolate between them, with the best mapping in the world it will never be as accurate as real time adjustments.
So im kind of at a loss as to what disadvantage you think closed loop brings tabetha?

 

I am impressed with the average mileage, 40mpg with a tuned 2.0 turbo-engine.
I have a small and light 1400cc car for shopping, but I don't come close to that number.
Besides in other posts the mileage is a lot less than 40, right Tabetha?

 

Maybe his speedo is out and telling him he has done more miles than he actually has