Tiny turbo for 550cc motorcycle

[Speedfab]

Chances are it won't make enough boost to even need a wastegate.

[smackhead999]

Chances are it won't make enough boost to even need a wastegate.

I dont follow....  explain please

[Speedfab]

Chances are it won't make enough boost to even need a wastegate.

I dont follow....  explain please

Your

Setup

Won't

Make

Enough

Boost

To

Require

Controlling.

[smackhead999]

Oooooohhhh...... so thats what you meant.

[mefarri]

Ahhhhhahahaha

[smackhead999]

I was hoping for an education, but....

I felt very much like a Mexican there where the old white people that talk to non-English speakers really slow and loud, like it might help  them understand.

[zbrown]

lol

[WannaBeFast]

I felt very much like a Mexican there where the old white people that talk to non-English speakers really slow and loud, like it might help  them understand.

Awesome observation. It has happened to me and I am not even Mexican. 



 

[smackhead999]

Everything looks good so far.  Newest observations:

CR: 8.6:1

Ignition: CDI with twin VR sensors (not points) Surprised.   Not sure if this is good or not yet... specs online say it has serious timing advance

Oiling:  Nice Oil Gallery tap on the starboard side of head, stock place for testing oil pressure.  Plenty of space to return oil into clutch cover.

Induction:  Carbs are super clean, but metal/rubber flanges bolted to head for carbs are dry rotted and falling apart.

[sciff5]

So how do you add supplemental fuel under boost?
I never really understood how people turbo charged engines before EFI

With a draw-through deal this simple?  It does it itself.  Engine pulls in more air, carburetor supplies more fuel.  the carb meters fuel based on airflow and pressure drop across the venturi, it doesn't care what's downstream.  Draw through stuff does NOT need a boost referenced regulator, you only need that if you're pressurizing the carb (blow through).  Also realize this is a pumper carb, it has NO float.  It pumps based on crankcase pulses and the popoff pressure of the needle and seat.  When we did this with holley 4 barrels, we made an external boost reference to the power valve and drilled the passages larger for boost enrichment (there is a way to do this with a blow through as well, just more complex.)

Blow through setups, you need to raise fuel pressure in lock step with boost, otherwise enough boost can stop fuel flow entirely.  Boost reference the float?  WTF are you talking about?  In a blow through, the float bowl is pressurized just like everything else.  It HAS to be, otherwise the pressure in the venturi will push the fuel backwards in the main jet circuit.

Here is a VW turbo setup I built (actually a bunch of them) 20 years ago.  Dirt simple - rejetted holley 750 with powervalve boost reference, header, turbo, wastegate, intake.  Made stupid power on a good engine, and made well set up beetles easy 10 second cars:

[attachimg=1]

Here is a turbo ZRX setup I built maybe 10 years ago.  Sure, we had good EFI then, but why?  Too easy to use what was already there.  Build airbox for carbs then manipulate fuel as needed.  This had the fuel pressure controlled by a pitot tube in the charge pipe to raise it faster than boost pressure.  This Flintstone rig went low 8s:

[attachimg=2]
[attachimg=3]
[attachimg=4]

When I get time later I'll find you pics of my girlfriend's 10 second beetle STREET car.  Carbureted turbo.  Back when 10s were stupid fast and you hardly ever saw turbos lol.

Great info!

Thanks for the lesson.

So how do you chose an appropriate carb when FI is introduced into the picture and what fuel did you use on those cars? No intercooler, I'm assuming is less than ideal, but I'm also guessing having gas mixed in with the air cools the temps of the incoming air.

[Speedfab]

Shane I have a turbo for you.  PM me.