bobybeach

Hi guys, I ran into a problem with running lean on my 13b. I was only running 1 walbro intank pump, I was really impressed with how much that little pump could flow. Anyway something was running dry my injectors, stock lines or pump.
I have always been unsure of the flow limits with stock 3/16 lines. Some experts told me that this is the first thing to upgrade while others have said it can support 1000hp at the engine. hmm who do you believe?

So I decided to do a test with a......
2L container
Pressure gauge
Stop watch
Stock fuel reg
Syringe (to simulate boost on the reg)
Gate valve (to simulate a large injector)

I first tested a single intank walbro pump with the stock lines. What I did was turn on the pump on, I measured an instant base fuel pressure of 45psi then pressed the syringe to simulate 1.3bar boost. The fuel pressure rose to 65psi. I then open the gate slowly to see how much I could flow before the fuel pressure would drop.
The more the gate opened the more the pressure would drop.

I measured....

Base fuel pressure 45psi

60psi fuel pressure. 2L 36sec = 3.3L/min with 5psi pressure drop
55psi 2L 30sec = 4L/min with 10psi pressure drop

CONCLUSSION

from this I concluded that with one intank pump and stock lines assuming 5psi fuel pressure drop is acceptable, then this pump can support 375whp at 1.3bar boost.
I noticed that the pump would really start to struggle with flow as the reg pressure would increase with boost (simulated) and more than 1.3bar showed the pump flow slow dramatically. (I didn’t measure this just observed the flow from the gate as I increase the boost on the reg.) So I conclude that one walbro flow is only stable with 1.3bar boost applications.

My next test was with the two walbros installed. The results....

Base fuel pressure 65psi (stock reg is really struggling)

1.3bar boost simulated fuel pressures....

60psi 2L 25sec = 4.8L/min with 5psi fuel pressure drop
55psi 2L 24sec = 5L/min with 10psi drop
50psi 2L 22sec = 5.5L/min with 15psi drop.

CONCLUSSION

With 1.3bar boost pressure and two intank walbro, stock fuel lines are able to support 545whp. An aftermarket pressure reg is also needed with two pumps as the stock cant regulate accurately, with base pressure tested as high as 65psi.

OMGWTHFBBQ

thats amazing you did that testing yourself.
Good to know !

bobybeach

yes theorticaly though, yet to prove with dyno, i will need to upgrade the turbo and injectors now to test the max flow of this fuel system on a dyno. but the first test seemed to be accurate with the results i was getting on my set up as the turbo and injectors used were capable of 400whp, and i was just starting run lean at high revs and 1.3bar boost. this agress with the 375 measured with the single walbro.

rotorforce

That's genius even if it is in theory you have quite the intelligence.

bobybeach

haha! no just maybe too much time on my hands while my girlfriend is on holiday in Bali

Denholm

good job, thats some impressive testing!

iceblue

A+ bud, an excellent effort and kind of you to share.

You are gentlemen and a scholar

eriksseven

iTrader: (6)

A+ as well!

Turblown

iTrader: (12)

Not to knock your test or anything, however those tests don't factor in other variables that are IRL; for example acceleration Gs.

If you are going to run that much power, why cheap out on runner larger diameter lines? I know some people are going to bring up the debate on overkill and the necessity but still...

bobybeach

Ive never seen a dyno that has yet to include the factor of g-force.

and as far as cheaping out, why waste money on unnecessary upgrades like fuel lines if simple testing like this proves that stock are fine. id rather save that money and put in into tuning or real hp upgrades.

but still the dyno could prove me wrong.

snowball

nice work 10 forum $ to you.

The Wankler

iTrader: (14)

very nice work!

-Six-

iTrader: (10)

Awesome, thanks for sharing. You rarely see anyone provide some actual testing when they spout off theories on here. Nice work.

ggoldfingerd

iTrader: (1)

Thanks for the info, I better get a second walbro or bosch before I lean out my engine.

ilike2eatricers

cool. what kind of voltage was (were) the walbro seeing?