Race Engine Forum UK

Jenvey and KMS sell fixed pressure regulators. I have a KMS one and had my fuel rail modified from one end being push on to threaded end. I wanted as few joins as possible. As you can see I also had a temporarly fuel pressure gause installed, but that's off now.

Following on from this, I am now trying to size the fuel pumps I require so can someone with expert knowledge to check my calculations please:

Current LP pump: Facet silver top 476087: flow rate 30 US gal/hr = (3.8x30) = 114 l/hr (1.9 l/min)

Injectors: Siemens 60lb @3bar above base pressure (660cc/min)
Flow rate = 0.66 l/min
duty = 85 %
Injectors = 4

Reguired flow rate = 0.66 x 0.85 x 4 = 2.244 l/min = 134.64 l/hr (35.43 US gal/hr)

HP fuel pump required flow rate of 135l/min at 4.5bar (1.5bar boost + 3bar)

Although the LP supply pump is not deliverying the full rate required at 85% duty I have calculated that with my 1.5l swirl pot it will take 175s (just shy of 3 minutes) to reduce the level in the pot to 0.5l.

or am I on completely the wrong track and is the idea of the swirl pot to keep it full to the brim all the time?

Thanks
Chris

Sorry for overdue reply. Phill too busy so here goes!

The swirl pot is there to ensure the injector pump does not run dry. Given your calcs - which look OK to me, you might be better off with Facet 'Red Top' pumps feeding the swirl pot which are 45 (Imperial) gall/hr compared with (Imp) 25 on the Silver Top units. The swirl pot should have a bleed-off line back to the tank (cannot remember if you covered this) so it will never overspill.

Hope that helps,

G

Thanks for the reply Guy,

I bit the bullet and bought the red top just to be on the safe side, I managed to get the engine & gearbox back in over the weekend so I have now got to try and fit everything in the engine bay! Roll on next weekend...

Chris

Bit of an update, after a lot of deliberation, list making, sketching etc... I opted for speedflow fittings because they are only 30odd miles from my house and they were very helpful on the phone, not quite finished yet but please see the photos for progress to date.

Nice!

I do like a bit of color!

GC