Idiots guide to blown fuel systems............please.

[Furyous]

Ok guys,I will be wondering round the pits at the me, watching fuel crews do there thing, and whilst I fully understand the basics, I cannot for the life of me, work out the exact path of fuel into the motor.I was looking at one if Urs's heads in september, and it looked like that had injectors directly on top of the valve, as well as else where.

What I'd like to see is a very basic fuel path, from tank to..............etc etc.

Oh, and if the Turbo boys want to join in, thats just fine too.


Over to the experts please....

[blownalky]

your pretty much there jon.
normally have 6 to 8 nozzles in the hat.
8 to 16 nozzles under the blower/inlet manifold.
16 down nozzles in the heads ,exiting directly into the inlet port.
norm goes ,fuel tank to fuel pump to fuel shut off valve to barrel valve to nozzles .
but also returns from the barrel valve .to the fuel mangement system.
be it fuel solinoids or slide valve or alr timers or check valves.

nozzle configuration depends on fuel pump/fuel/blower and motor combos .
ie if you was running a screw blower on methanol,in a top meth fc.then you would run 20 nozzles.four in the hat and 16 in the manifold.
have seen sucess with 2 hat nozzles and 8 in the manifold.
think all the quick cars in the states are running the 20 nozzle deal.

a top fuel motor could run 38 nozzles when running a 80gpm plus fuel pump.
6 in the hat ,16 in the inlet manifold ,16 down nozzles in the heads.
setback stuff is different again.
just depends on fuel demands.

thats it im going to the peak proformance day.

Edited by blownalky on Friday 18th May 23:42

Edited by blownalky on Saturday 19th May 18:59

[Furyous]

Thanks guys.



How is the fuel pump rate adjusted ?



Can you vary the delivery rates of nozzles in different areas,ie more in the hat and less for the direct, or is it all set from the barrel valve ?



Jon, thanks for the offer, will deffo take you up on that.Do you plan on being out this year ?



F

[Tet]

Furyous said:

Can you vary the delivery rates of nozzles in different areas,ie more in the hat and less for the direct, or is it all set from the barrel valve ?

No, the nozzles come in different sizes, so you can vary the flow at different parts of the engine (varying the flow between the front and rear cylinders, for example).

[blownalky]

you cannot adjust the flow rate of a mechanical pump.
if when its flowed,it makes 8gpm/100psi at 4000rpm(cam speed).then thats it.
you can modify pumps to stop cavitation internally,which aids high pump rpm flow on motors running methanol.

or did you mean low and high side?
the way you adjust flow through the nozzles to the motor is by
changing the fuel pressure in parts of the fuel system by returning fuel to the tank via timers/slide valve/check valves.
either timed valves or pressure valves jetted.
hope this helps
cliff

Edited by blownalky on Saturday 19th May 19:02

[blownalky]

oops ,this all looks very confusing now.
its a fairly simple idea really.
honest.

[Furyous]

Not as confusing as you may think.Im pretty much with you on the above.I just need to see a motor to be able to relate a bit more to it.



Thanks guys.I really love the tech side of the sport, and when Im watching people working on cars, I dont like to interupt and ask what appear to be dumbass questions.

[john 215]

Hi,
That was really intresting gentlemen,i am same Furyous love the technical side of our sport but dont want to disturb busy crew.One thing as far fuel systems is concerned,when a fuel car go 'to high side' on the line and the idle changes, is this second fuel pump being used at this point?
Cheers John.

[blownalky]

only one fuel pump fella,
start motor ,trim pump too about 50/60 psi.
do burnout .
go to line then turn it all on.
cliff

[john 215]

Thanks Cliff,just the size of the pumps on a modern fuel engine and the pipe work give the impression of more than one pump.Thanks for sharing your knowledge.must take a closer look at fuel set ups this weekend armed with what has been writen above,Just read Lex's blog about set back blowers,didnt realise that 'back in the day' not only was different jets ran at the front of the engine but also different compression ratios!

love watching you guys at work,have a good W/E and thanks again.

John

[blownalky]

no problem,pop your head in hakan fallstrom,s pit and say hi.i will explain more with the car in front of me.

just ask for me and introduce yourself.

dont worry most of us speak english.

some much better than me.

cliff

[john 215]

Cheers Cliff your a real gent.

Best of luck over the weekend,

John.

[Nitrohaulic]

Like Nitro-Besty says and like Virgil Hartman has explained to us on classicfunnycarboard concerning our nostalgia cars using hat and port nozzles, once you're determined your required total area of fuel, it's up to you to decide how to split it up. More in the hat and your blower lasts longer and you make more power due to sealing the strips to the case better. More in the ports and you have better idle quality due to controlling more what each cylinder gets. Fascinating little thread here.

http://www.classicfunnycarboard.com/cgi-bin/ikonbo...

Just pay no attention to the sparks that are flying there at the moment. That only happens about once a month.

Edited by Nitrohaulic on Sunday 27th May 17:13