turbo motorbike! video now on youtube must see!!!

[tim_blair]

[tim_blair]

I would have thought the fuel bowl breathers would need to see positive pressure from the turbo otherwise the fuel will be getting pushed back into the bowl from the jets.

exactly right i have plumbed the float bowl breather pipes into the airbox so that the bowls are at equal pressure

[Lloyd]

Pressurising the bowls to the same as the airbox is a good start, but if you have equal pressure in the bowl and in the carb then how is the fuel going to get into the engine?

Carbs need pressure difference. If you have 3psi in a carb and vacuum in a venturi then fuel will flow. If you put 15psi into the intake and 15psi into the fuel bowl then fuel isn't going to go anywhere and basically wont go.


Suck through is just being lazy btw

[whynot]

ah so you have pressurised the air box as well. which makes sense thinking about motorbikes I was thinking air filter box like in a car.

[whynot]

there should still be a pressure difference between the intake and the venturi, it just has to be less pressure than in the fuel bowl and the fuel will be pushed out.
what about back pressure from the turbo? could that be messing with the amount of air flowing through the motor and hence the fueling?

[tim_blair]

yea that sounds logical i have put pressure adjustment screws on the pipes that feed the pressure to the bowls and to the tops of the diaphragms so that i can adjust the pressure but it seems to run at its best when they are at full open

i dont think that the back pressure is high enough to make a diff at 8-10,000 revs maybe when it gets up to 13-14000

but i cant get it there yet so ill cross that bridge when i get to it

yea by airbox i mean plenum it has a built in intercooler which is the large alloy bit on top of the engine in the pics

[Lloyd]

there should still be a pressure difference between the intake and the venturi

So why does a car need 3psi fuel pressure then instead of 0psi even though there is a vacuum present?

Getting around it with car carbs involved running restricters before the carb and venting the bowls to above those

[Rookie]

there should still be a pressure difference between the intake and the venturi

So why does a car need 3psi fuel pressure then instead of 0psi even though there is a vacuum present?

Getting around it with car carbs involved running restricters before the carb and venting the bowls to above those

You obviously dont know how a Carb works, look here http://auto.howstuffworks.com/question3771.htm

and here http://en.wikipedia.org/wiki/Venturi_effect

As I said earlier get a rising rate fuel pressure regulator and your problem will be solved.

[spencer]

As in that oldschool thread, do this

http://www.turbo-bike.net/Pressurize%20carbs.htm

No fpr needed

[Rookie]

No, you need a rising rate FPR to compensate for the boost which is now trying to stop the fuel flowing into the float bowl, the whole idea is to trick the whole system into thinking it is operating under normal atmospheric conditions, hence you need to pressurise all the different chambers on the carbs, AND have a rising rate fpr to trick the fuel pump.

[Rookie]

This guy obviously knows what he is doing seeings as he has the setup 90% correct he just overlooked the fact of filling the float bowl

[spencer]

yea you is correct

[Lloyd]

Sorry, was basically just trying to imply that the pressure in the carb needs to still be over what is in the intake.

And since I obvious don't know how a carb works then I guess I'm in the wrong trade. Both my old cars still went pretty sweet though. Black one was running 19psi with a T25, and anyone who came for a spin in that will tell you it went like hell







Anyway, point is you need to keep the fuel pressure a few psi over what you're getting in the inlet manifold

[tim_blair]

you make a good point lloyd im defo gona need more pressure in the fuel line than whats in the bowls

[jondee86]

You obviously dont know how a Carb works

Haaaaaaaaaaaaaaaaa..... OWNED

[tim_blair]

http://www.youtube.com/watch?v=eu3RqnuWtt8

comments?

[Paulio]

do a skid

[Rookie]

Sorry, was basically just trying to imply that the pressure in the carb needs to still be over what is in the intake.

This statement is still incorrect, and this is what I was refering to. If this was the case then the fuel would be blown into the motor through the jets and it would negate the need for a carb.

Anyway, point is you need to keep the fuel pressure a few psi over what you're getting in the inlet manifold

This is correct, the fuel pressure needs to be above the pressuse in the float bowl, this will feed fuel into the float bowl and then the vacuum from the venturi effect will suck it from the float bowl into the motor.

The Bike looks awesome by the way, good job!

+1 for "heCtik SKidz"!!!

[Akane]

No skids, no brownie points, no biatches.

[eskimo]

No skids, no brownie points, no biatches.

hahahah