Aftermarket Regulator use

[immortality]

I was thinking about this last night when trying to get some shut eye.

Back in the day when I did a bit of flying I remember the use of fuel densities when calculating fuel requirements/weights for a trip which got me thinking about how much fuel density changes with temperature. This chart is for aviation fuel which is a little different (petrol is about .737 @ 15° C) but no doubt the density change with temperature would be very similar. I have tried touching the fuel rail on the L67 after a decent trip and it was very hot so large changes in temp are normal which would effect fuel density.



Using that chart (for 100/130 grade fuel) you have approx a 5.3% change in density with a 32° C change in temp

You should probably also take into consideration that Holden allowed a fairly large space within the fuel tank above the filler to allow for expansion.....

edit: which gets you thinking about fuel density and how it effects the engine tune. Obviously when in closed loop mode the O2 sensors will adjust the injector PW to achieve the correct AFR but when going into PE and open loop things are a little different. We know that from the factory things are tuned on the rich side which would negate any temp changes but what if you were tuning on ragged edge?

[Gareth]

I agree with the above

I remember reading about most aftermarket regulators not being linear, could have swore it was on here but couldn't find it. I remember it pointing out that factory ones where most reliable in reguards to correct regulation.

[The1]

this is a good read, you get what you pay for.

http://www.adaptronic.com.au/fuel-press ... ifference/

[immortality]

Good read, it's a shame he didn't list the individual regs results. I would have considered the Turbosmart 800 FPR.

These issues with varying fuel pressures would be worse with a batch fire system. For larger engines it also common to see each fuel rail having it's own fuel feed (in parallel) rather than the one feed for both rails (series).

It probably also shows the importance of having and FPR that matched the fuel pump flow.