VNT turbochargers and control
Turbo Mini Forums

ah i was wrong fab ! its not compounded its sequential . j
mine was set up compounded it would start at 1600 rpm , small turbo running uo to 3000 at 12 psi ,then big turbo giving 8 psi by 4000,unfortunately at 4600 odd it choked due to the small turbo being toooo small.good luck with the setup j ,i have to say id run it intake turbo super intercooler engine with no valve ,but it should be interesting
regards robert.

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM

The problem with going
intake - turbocharger - supercharger - engine

Is that the supercharger dosent reference what pressure it recieves, so if its set up to provide a 2:1 pressure ratio then it makes 15psi without the turbo. But as soon as the turbo comes on boost to say 15psi, then the supercharger compresses that 15psi to 30psi! This is where the engine goes bang!

I would like to run it with the turbo before with a bypass valve, but i would need a very sensitive pressure switch to control a solenoid that then pressurises a wastegate type affair, bypassing the supercharger all together - complex.

I would have kept those two turbochargers, sounds like an ace setup! To stop the choking i would provide a secong intake the the big turbo that has a one way vavle in it, so as soon as a vacuum is seen it pulls the valve open and allows more air in.

Cheers

J

yes i know what you mean i think i would run the 30 psi !! 7 :1 and away you go ! also im not sure but i think i read about this setup and it didnt actually go 15 turbo 15 super , i think i remember the super flopping over a bit and doing less boost as the rpm went up ,this was on a 3 litre toyota v6 .hey time will tell ,its all good fun .

j with mine i was running the small turbo into the plenum ,and the big one into the small one through the ic ,, the solution was to run a bigger small turbo like a t3/t4 or a gt30 ,and that would then have not choked it and also pumped up the second stage even sooner , but in the interim , i thought it would be interesting to run the big one and design a valve to cut out one side of the split a/r turbine housing , this in thoery would give me a half sized a/r and kick that bad boy in with a veangance!! then valve opens and it goes to a low backpressure high rpm setup . time will tell if i persevere or stick on the t3/t4 hybrid iv got knocking about ..
regards
robert

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM

That sounds ace, half the divided tang turbo for lower RPM spool then wack on the second half for lower pack pressure. Some excellent lateral thinking there, ill be watching avidly to see how it turns out!

J

came across some pics of vnt turbo's from some guys ebay shop, some have the numbers visible thought i'd post them here just in case anyone was interested.

http://s50.photobucket.com/albums/f305/joericambi/?start=0

I have just been examining a VNT actuator,

It has a vacum port and a 3 pin electrical connector on it, initially i assumed it had some kind of solenoid in it, but on removing the electrical module it appears to be a linear acuated Potentiometer to feed back to an ECU the position of the vanes.

This could be useful as it can be connected to a simple voltmeter to give a readout of how far the vanes are open.

also found this, some iterestin actuator bodging on pages 2&3.

http://www.vwdiesel.net/phpBB/viewtopic.ph...der=asc&start=0

Edited by Joe C on 27th May, 2007.

Thought this may be of interest,

I have converted an actuator from single to twin port buy using a valve guide seal to seal against the actuator rod and soldering in an exra fitting.