Thread: Running rich

Originally Posted by Finnius

Ahha! Thats how it works... BeeUtey.

Last job to do is to get an adjustable fuel pressure regulator. Are these kits any good: V8Wizard

How low can i take the fuel pressure to improve economy whilst still being drive able?

Can't help you with specifics, its more than 10 years ago since I did the last adjustable reg but the car I fitted it to worked a treat. The question for you is not to ask how low you can go but to fit an oxygen sensor and gauge so you can read the mixture as you drive. A gauge for a narrow band sensor for example:

Vehicle White 2" Digital Analog LED Air Fuel Ratio Monitor Racing Gauge AU Stock | eBay )

will give you some knowledge but a wide band one is better although much more expensive. Example of a wide band kit:

#3918 INNOVATE MOTORSPORTS MTX-L Plus Wideband Air/Fuel Ratio Gauge Kit | eBay

Fitting a sensor is not particularly hard, either weld on your own adaptor or get an exhaust shop to fit one to the y junction.

Ok thanks. That info helps a lot.

So basically to tune using one of those O2 gauges and an adjustable pressure regulator you would want the most of amount of air in the exhaust gas before it gets too lean?
What is the units on those gauges - is it PPM of O2? Or a percentage of O2 in the exhaust gases?
Is there a range of O2 values to use when tuning - how would i know it is in the lean range?

Thanks so much.

The gauges read air/fuel ratio. I'm sure they'll come with instructions or you can just drive the car with various a/f ratios and see how it goes.

Hey Bee Utey,

So i bought a nice wideband AFR gauge and will install it shortly.
I am looking at an adjustable fuel pressure regulator as well.

The problem is that the pressure regulator i am looking at says that although it is an adjustable regulator it also has a "power boost valve". This that apparently rises the fuel pressure under load more so than the standard regulator:
"On acceleration from standstill, the power boost valve fuel pressure will increase at 1.7 times the standard rate. This will produce a healthy fuel mixture strength which will instantly improve the drivability of your vehicle."

Does that sound like a good idea?
It goes on:
"By simply multiplying vacuum (load), enrichment of the fuel mixture when under moderate to heavy acceleration and in all other demanding driving situations too whilst maintaining a crisp lean mix for normal cruise speed driving & engine deceleration times plus at idle situations as well."

Do you have some tips on how best to tune the engine using a valve like this and an AFR. Would i set base pressure of 2.5bar, then get up to highway speed/cruise and then check the AFR for stoichiometric, if its too rich then lower fuel pressure and repeat etc.
Would i not tune it under load - as that sounds tricky as the "power valve" is going to multiply vacuum and increase max fuel pressure...

Cheers

Originally Posted by bee utey

The gauges read air/fuel ratio. I'm sure they'll come with instructions or you can just drive the car with various a/f ratios and see how it goes.

So i just finished installing the AFR gauge this evening after work! It is great to finally see exactly how rich/lean the V8 is running.
The gauge says that 14.7 is stoichimetric. Lower than that is rich and more than that is lean.

I still have to do some highway driving, cruising, up hills etc to find out how she is running - but does anyone know how lean you can run these Rover V8's before it is unhealthy for them?
I can adjust the fuel pressure and test the power getting up to speed, hills etc easily enough but i don't want to set it too lean and wear out the engine (excess heat i suppose?).