rollin road RESULT!!!!!!!!

yeap kjet, no electronics allowed!

ta for the models v. usefull!

what do you think to the shim in the metering head thingy then?

cabriaulait said

yeap kjet, no electronics allowed!

ta for the models v. usefull!

what do you think to the shim in the metering head thingy then?

Well, the system pressure should be 4.5-5.2 bar, I'd be tempted to measure and set it to 5.2 bar but not higher.

dave do you think youll make vw action at the pod would be a awesome meet if we could get a few of the mk1 boys hooning up the strip

give you a good idea off how well you can match other cars with your new found bhp

oh and the bumper cars are pretty cool

paul you camping again?

right can i get this straight
injectors need 49 ? to open or is that their maximum
metering head keeps UP to 5.2bar
fuel pump produces ?

this where the lm1 would come into its own it would awnser all your questions you just drive gentle hard and thrash datalog then go over the results and it will show you where your leaning out

k-jet is pretty crude but very tunable bigger pump is good but like paul said dont hike the pressure to much id leave the shim out then play around with the pump first

also isnt there bigger injectors you can get ?

no really  

49psi = 3.5 bar

The system pressure is (say) 5.2 bar, the fuel pump will deliver >5.2 bar if it were to 'pump' against a greater pressure restriction. But, instead of a single line and some kind of variable rate pump, the pump runs at a constant rate and the control pressure is regulated by a restrictor, the other end of the restrictor flows into the return line.

Remember, a pump can only generate pressure when its pumping against a restriction. If the fuel line is in open air (eg when you're measuring a volumetric flowrate by allowing it to run into a lemonade bottle) it is in fact pumping at 1 bar.

The fuel injectors are mechanical and they open at anything over (approx) 3.5 bar and close at anything below 3.5 bar. When they are fed fuel at 5.2 bar, they open, and this makes the fuel flow unrestricted into the manifold/combustion space, during which the pressure drops and drops very quickly, so it closes very quickly. The pressure then builds up again, the injectors open again, then close. This all happens so fast that they make a 'squeaking' noise while they operate, since its 200-300 times a second.

You could have a pump which can generate a high pressure, but then its volumetric flowrate  at high pressure isn't that good. And it could flow really well at low pressure, when you do your volumetric flowrate test.

That's why doing a volumetric flowrate test is only really a basic indicator that the pump's not broken or you have a serious issue with the filters, etc. Also when you connect the fuel pressure gauge and run the engine, you can actually observe if the pressure 'stays up' when you rev the car. Unfortunately (well, except when you're on a rolling road) when you simply rev the car on the drive, its under almost no load.

Measuring the air/fuel ratio is better, since you're measuring the thing that affects the power more directly, rather than one of the variables which contribute to it. For example, if your head didn't flow that well at high speed, you'd see the AFR remain good, but the power and torque drop off. If you see the AFR drop off as you rev higher, at least you know the head is flowing the air into the engine nicely!

but am i right in thinking that the air plate rises as it is sucked and for it to lean out means that the plates at its highest position?

cabriaulait said

but am i right in thinking that the air plate rises as it is sucked and for it to lean out means that the plates at its highest position?

Mostly but not entirely, fuel flowrate is a function of manifold pressure as well as fuel pressure.

aaaaaahhhhhh

diamond!!!

p/p head it is then!

how can manifold pressure vary apart from down?

cabriaulait said

how can manifold pressure vary apart from down?

Manifold pressure would be low (vacuum, under 1 bar) at closed throttle and approach 1 bar at WOT. It would also vary with rpm, according to the volumetric efficiency of the engine.

wot is WOTops: ?

really

what is  : WOT

i dont know
honest!

Wide Open Throttle  :wink:

how can u have pressure with nothing pushing apart from the atmosphere

cabriaulait said

how can u have pressure with nothing pushing apart from the atmosphere

Huh? You mean in general?

with boosted cars the map sensor reads from 0 to 250 kpa which is the basicaly the vacume in the inlet so say 250kpa 23psi

you would only get 100kpa tops iirc being n/a

so when you cruise it will be say 30 to 50 kpa then when you boot it the vacume rises to 90 to 100kpa so more vac more fuel

so vacume is important no vac no fuel lean time

paul correct me if im wrong im only used to boosted kpa charts so not 100% sure

''approach 1 bar at WOT.''

aaaahhhh
got it 1bar IS normal atm pressure!

no 0.7 ish bar is atmosphere pressure 100kpa i think