Hi capacity Fuel Pump and Fuel Economy

[mtam22]

Originally posted by Sydneykid

...Dirty injectors restrict fuel flow, that would improve fuel economy and increase risk of detonation.  I have seen dirty injectors increase power as the car was running rich.

Wouldn't dirty injectors REDUCE fuel economy if it's "peeing" rather than spraying?

[Sydneykid]

Hi mtam22, "Wouldn't dirty injectors REDUCE fuel economy if it's "peeing" rather than spraying"

Not really, the lambda sensor would see the unburnt fuel and the ecu would reduce the flow. Plus the engine would run really badly as the fule would still be un-atomised at the time of ignition and would not burn properly. Missing and very poor power delivery are signs of this.

I have seen injectors so dirty that they stay open, this fills the cylinder/s up with fuel overnight. When you go to start the engine next, it hydraulics and bends conrod/s.

This is way past what is being described here, what what we seem to have is either a stuffed lambda sensor or very poor tuning. Both of which would show up with a 5 minute power run on the dyno with the fast and wide lambda sensor up the pipe. As I said, cost less than 1 tank of fuel to check.

Hope that clarifies.

[ed]

Originally posted by mtam22

Wouldn't dirty injectors REDUCE fuel economy if it's "peeing" rather than spraying?

they can, but I think SydneyKid is saying they get blocked and the amount of fuel being pushed through is less than a clean injector. Hence leaning out the mixtures and pushing more power.

[magic1]

i dont know all but we have a different state of tune. ie if i get more than 300km to a tank im happy, i would be happier if i got more.

I put it down to i few factors that some have over looked

1. advanced ignition timing

2. gt30

3. bigger fuel pump

4. tuned computer

5. 435rwhp, power is not free

[Cubes]

Generally with a blocked injector (one cyl leaning out) you will get less fuel economy as when cruising the o2 sensor measures the afr over the whole 6 banks. If you are getting one injector running lean then the rest will be required to run rich in order for the overall afr to be within spec.

Thats the way I see it but maybe I am wrong?

I have recently found that I have a leaky injector which causes the car to splutter the next morning for the initial kick.

If left for a week without a start the car will not start and will stall with anything less than 2000rpm on board.

I think the car does make good power as it accelerates hard and I think for an RB20 goes pretty well.

magic1,

It is very possible to get near stock fuel consumption even with 300rwkw.

It comes down to the amount of time spent tuning the computer (assuming powerfc) and how well the injectors atomise fuel at low duty cycles.

Headwork also makes a slight difference.

For example if they have polished the inlet ports or used an 80grit.

The rough inlet port creates a little turbulence which improves fuel atomisation hence power especially at low and mid rpm.

Then there's the combustion efficiency. If you have slapped a thicker headgasket on the car to reduce the compression then this will increase the squish gap which effectively reduces turbulence hence atomisation and power just before the fuel/air is ignited.

Lots of things to consider.

A bloke sky30, I think thats his alias.

He recently went a GT35 and has decreased his fuel consumption.

Second hand word is that he is now getting near 500km's to a tank.

Prior to the GT35 he was running a highflowed RB20 turbo that was making 240rwkw with all the boost on board by 2000rpm (RB30DET), I would like the know the fuel consumption prior to the gt35 turbo.