Pitot Tubes
Turbo Mini Forums

I know some of you guys are using them (Fab and Robert).
What kind of size should I aim for ? I've searched on the net and the sizes I've come across seem alittle big.
And how much pressure difference should there be between the boost pipe and the float bowl.? 3.5 PSI ?
Some guidance would be appreciated and I hope this post makes sense as I posted it using my phone.
Cheers
Dan

Edited by pinkyandnobrain on 13th Jan, 2011.

"So wat we gonna do tonight Brain?"
"Same thing we do evernight Pinky!"
"Try to take over the world!"

there's no guide to this, understand fully how it's working, then you'll learn how it does affect your mixture and so how tune it.
I would start with a 6mm tubing 45 ° to airflow, then depending mixture you can enlarge tubing or bend it a little more.
work from this it'll then all depend to your engin/boost specs.
idealy you'll need a wbo2 sensor to work on cleanly but the 6 tubing at 45 should put you near the ball park witha set of bdd/bfy/bdk needles in hands

Fab you are the man, thank you.

"So wat we gonna do tonight Brain?"
"Same thing we do evernight Pinky!"
"Try to take over the world!"

Well here is a pic of my home-made plenum with its pitot tube.


And a pic of it mocked up.

"So wat we gonna do tonight Brain?"
"Same thing we do evernight Pinky!"
"Try to take over the world!"

What exactly is the purpose of that ?

9.85 @ 145mph
202mph standing mile
speed didn't kill me, but taxation probably will

It's to pressurise the floatbowl, without the need for the restrictor ring I believe ?

WWW.TURBO-MINI.COM

The float bowl gets pressurised through drillings where the plenum bolts on anyway ?

At least mine did. There is an orifice with a small hole which applies boost to the float chamber. This is size matched to the "lean off tube" so that under boost it makes no difference as boost is applied from both sides. And on part throttle vac, this hole prevents the lean off tube creating a full vacuum in the float bowl, as it always bleeds off vacuum ( or allows air in, whichever way you look at it )

Edited by stevieturbo on 23rd Jan, 2011.

9.85 @ 145mph
202mph standing mile
speed didn't kill me, but taxation probably will

Im running a modified NA HIF as we didnt get metro turbos here so it doesnt have the drilling and i needed a different way to pressurise the float-bowl. The pitot tube picks up slightly higher pressure in the center of the flow path as apposed to the pressure at the sides of the main pipe, this higher pressure is then plumbed in to the float-bowl so that fuel is not forced back out the jet as the engine comes on boost.

"So wat we gonna do tonight Brain?"
"Same thing we do evernight Pinky!"
"Try to take over the world!"

Would it not be easier just to drill the body like a turbo carb ?

And surely a normal boost source is all that is needed. The design of the carb with the bridge etc will always naturally draw fuel from the jet under any circumstances with air flowing over it ?

Although I actually thought all carbs would have had a drilling into the air filter area. Whether boost or atmospheric, the chamber must have a reference to outside air or boosted air.

9.85 @ 145mph
202mph standing mile
speed didn't kill me, but taxation probably will

a few people with genuine HIF's have removed the restrictor and found the car went uncontrollably lean on boost, the restrictor creates a pressure differential over and above that created by the venturi to sook fuel out the needle (must be in the order of 0.25psi or something equally subtle) if you wish to remove the restrictor you need some other means of artificially pressurising the float bowl. dont understad the dynamics of why the venturi alone isnt sufficient, but if you wish to remove the restrictor, you need a pitot tube.

turbo 16v k-series 11.9@118.9 :)

Denis O'Brien.

The pitot tube doesn't pick a higher flow in the center of the path, it does convert kinetic velocity to pressure. primary it was used to mesure airplane speed.

I come tru this the first time I rebuilt my zx11 engine, I forget to plug back the velocity tube and bike was really bad with full trottle above 50 mph, I found the trouble and was amased that little tube to float chamber could make that much difference, looked how it was working, then ended into turbobikes world:
http://www.turbo-bike.com

I like it,
it seem that you'll find some serious power here

9.85 @ 145mph
202mph standing mile
speed didn't kill me, but taxation probably will

the ring installed into turbo pendulum chamber