OH my god. u need to see this if you like engineering

[billinjah 0]

Does anyone know how you manage the transition from supercharger boost to turbo?

 

your midrange is a mix of the two im sure thats how lancia did it.

[gibber 0]

There is 3 ways of doing it, super charger in to the turbo joined in series, but this limits the top end as the turbo has to suck air through the supercharger.

or you can do it the opposite way.

But as you say the best way is to run them in parallel but I want to knw how you actualy swap them over, which is the bit that lancia had the problems with.

[Henny 0]

As I understand it, the typical way of doing a compound charged engine is to have the turbo and the supercharger plumbed in with seperate air feeds, (although normally from the same air box/filter) feeding into a boost pressure or RPM controled valve system. This way you're not forcing air through either the turbo or the supercharger at any point in the rev range/ boost provision.

 

Below a certain number of revs the turbo is simply venting allowing it to spin up freely. At this point the supercharger is operating normally and is providing the boost to the engine giving plenty of low down power...

 

At a certain boost level/RPM limit a valve operates which should give a seemless transition in boost pressure (if set up properly!) from the supercharger (which then vents) to the turbo providing the boost instead. The supercharger normally has a magnetic or centrifugal clutch operated pulley and around this point this starts slipping/disengages to prevent spinning the supercharger too fast and damaging it.

 

Over the boost/RPM threshold the turbo is then providing all of the boost with the superchargers clutched pulley slipping enough to keep it from spinning too fast.

 

On the way back down the revs, the valve will swap back to the supercharger to provide the boost as the clutch re-engages drive to the charger meaning that, again, there's no sudden change in boost pressure or any points where no boost is available.

 

If it sounds complicated in theory, try actually setting one of these things up... definately not an easy task! :lol:

[A20 LEE 0]

don't know why, but that car looks better on LM's than any other Mk4 i've seen. Awesome.

[Kevin Bacon 5]

Agreed. Nice choice of offset and width.

[bristolbaron 10]

Renault had a crack at that some years ago, as part of their pulleyless engine research, dunno how they got on with it though.

 

But anyway, it would be easier to do in a Golf though as there's more room!

 

Love the way thats written in the 'Started reading the article in Car, but got bored when it mentioned Renault' way!!

[Kevin Bacon 5]

LOL! It was quite fascinating (at the time), there was a big write-up about Renault's work in some mag some years ago. They were working on 24 Volt electrics and an engine of 1.6cc with a twin scroll turbo that produced 250hp. It had no pulleys or belts at all. Steering, air con and water pumps were electric, flywheel, starter and alternator where one unit and the valves were actuated with solenoids. The engine was just one big square lump with a huge plastic cover on it saying "Renault"....at that point, yeah, I got bored, LOL! Apparently it was almost silent in operation and the only servicing it needed was oil every 20K and plugs every 60K.

 

Shame BMW beat them to it with Valvetronic :-) Don't underestimate those French (or Italians for that matter) they're clever bar stewards....it was a Frenchman after all that invented the G Lader and the Spaghetti eaters invented the VR engine ;-)

[gibber 0]

This is how lancia did it, note the by-pass on the SC, and a re-circ valve

[chrishill 0]

just stumbled upon this page while looking for something entirly different!

 

http://geocities.com/motorcity/lane/1231/twincharging.html

[Bally 0]

so nice... drool..

[biggerbigben 0]

WOW, me loving that...

[biggerbigben 0]

As I understand it, the typical way of doing a compound charged engine is to have the turbo and the supercharger plumbed in with seperate air feeds, (although normally from the same air box/filter) feeding into a boost pressure or RPM controled valve system. This way you're not forcing air through either the turbo or the supercharger at any point in the rev range/ boost provision.

 

Below a certain number of revs the turbo is simply venting allowing it to spin up freely. At this point the supercharger is operating normally and is providing the boost to the engine giving plenty of low down power...

 

At a certain boost level/RPM limit a valve operates which should give a seemless transition in boost pressure (if set up properly!) from the supercharger (which then vents) to the turbo providing the boost instead. The supercharger normally has a magnetic or centrifugal clutch operated pulley and around this point this starts slipping/disengages to prevent spinning the supercharger too fast and damaging it.

 

Over the boost/RPM threshold the turbo is then providing all of the boost with the superchargers clutched pulley slipping enough to keep it from spinning too fast.

 

On the way back down the revs, the valve will swap back to the supercharger to provide the boost as the clutch re-engages drive to the charger meaning that, again, there's no sudden change in boost pressure or any points where no boost is available.

 

If it sounds complicated in theory, try actually setting one of these things up... definately not an easy task! :lol:

 

Apparently that valve your on about was designed by HKS and is called a 'foofoo valve'! Its a friend of a friend who designed it!

[Henny 0]

I'll add that into my vocabulary then...

 

Foofoo valve... someone was taking the pi$$ when they named that weren't they! :lol:

[24V Renshaw 0]

Apparently they named it after they had had a few jars, so the story goes, from the same friend of a friend. I might even be right in remembering that there were in the FuFu bar in Bournemouth, but I am not sure...

 

Awesome MK4, to keep on topic.

 

Jay