wastegate line input?
 

Ok normally from what I read the wastegate line goes pre tb post turbo compressor outlet.

Now say you setup your car with the TB infront of the turbo. Where would you look at tapping in for the wastegate line at?

how in the world did you manage to setup the tb before turbo?
and more importantly, why?
I don't think anyone here has done that before.

techsalvager likes to do thinks the hard way ;)

hmm maybe just into the piping but using a one way check valve to keep vacuum out but only allow pressure to get in.

after talking to someone else I think there is problem with that, being the pressure will get stuck in there possibily and hold the wastegate open.

So thinking about a check vavle that locks pressure in but when it sees vacuum can shut close and opens the other side to atmo to release the pressure

so you're overcomplicating things quite a bit.

may I ask why?
what benefits are you looking to gain from doing things weird like that?

Just let it pull vacuum on the WG, itll help keep it closed. Just beware that you could overspin the turbo if you throttle it in boost.

Also, Pre-turbo TB is epic.
http://www.gurneyflap.com/Resources/DSC05996.jpg

Turbo doesnt slow down when you close the throttle because its spinning in a vacuum.
No need for a BOV.

Thats how they did it in Formula 1, and they wouldnt do anything like that for no reason.

hmm, sounds pretty cool.
so how come no one I know has this? a PITA to set up and make work properly or what?

Subscribing for supreme interest.

Its a pretty unknown thing, and like you said its added complexity that most people wouldnt bother with.
Also, Im not sure if its true with all setups like this, but most of the ones Ive seen in F1 also had normal ITBs with a plenum in addition to the pre-turbo TB.

Whats funny is as many badass turbo setups we see today if you go and look at the setups in use 20+ years ago on rally cars, formula 1, and Lemans youll see that even with new technology were still way behind them.

overcomplicating what, I don't see any more complication than post turbine tb.

antilag

I thought from other posts that vacuum to the wastegate would eventually destory it, maybe I was wrong.

I think I'll look around on how the old carb setups did it.

wow...thats...kinda smart.

You shouldn't need to change your wastegate source. Source it anywhere between the turbocharger and the intake ports. It will still open when you reach target boost, and as soon as you go throttle off, it will immediately force the wastegate closed which should continue to help the compressor spin quickly under the vacuum condition. You might have issues tuning your idle (similar to single TB supercharger setups), but beyond that, I don't see any major complications.

I would source it from the manifold (unless you are going to have a second tb) because it seems like you are shooting for little to no lag and this is where you would have the least amount. I think anywhere you put it you are going to continue to build pressure (as much as the opening of the throttle will allow) in the system at part throttle. I agree a check valve seems like a suitable solution for putting a vacume on the wg.

Info from another web

"This was first used at the Monaco GP in 1982, and developments of the same system are still used in Formula One. But because Boudy defected to Peugeot with his ideas, the 205T16 was the first turbocharged rally car to use his system (The T16 being out before the final evolution R5 Turbo – The Maxi 5 Turbo). Which Renault calls DPV, or Dispositif Pre*rotation Variable (Variable Pre-rotation Device).

"At the very beginning we had made the decision to use it on the Group B R5 Turbo. It's not really necessary for road cars and a little expensive for them, but it's not so complicated". It may not be "so complicated" but the DPV system is an 'extremely effective way of ensuring near-instantaneous throttle response from a competition turbocharged engine’. The system provides for variable air areas and direction angles at the intake to the compressor wheel in advance of the rotation period during which the compressor turbine will require those conditions.

It's not a by-pass system, it's essentially a multi-variable nozzle arrangement which is mechanically linked to the throttle and which changes the direction and area of air which hits the compressor wheel according to throttle position. The rate of change of air flow area and direction is not exactly linear, but it's progressive and always increasing toward full flow at maximum compressor wheel speed.

This irregular mid-compressor-speed flow, which constantly changes the way the air hits the compressor vanes in the mid-range, improves the compressor's efficiency under part-load, because it is arranged so that the turbine will idle at a higher speed than it would given a fixed intake air direction and area. And of course, the higher the compressor idle speed, the shorter the time it will take to reach its important operating RPM. Result: less lag.

The DPV is inoperative at each end of the turbine's speed range. Under pedal-to-the metal full boost conditions it has no effect because there's regular full flow to the compressor, and with the throttle closed the DPV is shut down as well. But it is not just retained inertia and completely eradicated turbocharger lag which form the real benefit of the DPV system, because there's another major advantage in that as a result of there being no by-pass or blow-off to atmosphere, and because it's an internal function to the turbocharging system, there is no pressure wastage in the all*important part-load condition (ie. The blades don't stall during gear changes, or on/off throttle movements). "

Patent for the design
http://www.freepatentsonline.com/4471616.pdf

Wow, that's great, sounds like a piece of cake to design and implement. Yah.

Techsalvagar, do you have any details or pics of your setup? Parts etc?

doesnt look like its a throttle body from the patent its more of of what i would relate to a fan inlet vane damper from hvac.

example:
http://www.ruskin.com/catalog/servefile.aspx?id=558

Just implement a TPS based EBC instead.

nothing yet, I've still to figure out what turbo I want to go with.
I will need a turbo with a carbon seal to keep oil from being sucked out of the turbo.

Right now I"m working on my engine managment part. It can do fuel if I wanted to do that, but I really want to get it doing both fuel and spark, unfrountaly I have a problem with spark output. Spark breakup is happening

I'll probably use a stock TB, rip out the butterfly and the IAC, plate off the sides and the iac area.

time to get the parts, just scan the stuff slowly for deals, etc, also need to get the car in nicer shape before turbo, new motor mounts, bushings, etc


Just posted incase anyone knew off hand or had an idea.

braineack is knows I'm crazy

With that setup there would be a high level of suck if the tb fell apart.

Subscribing.

What would happen if you close the throttle while the compressor is spinning at 100,000rpm? Instead of compressor pressure surge would there be something like a vacuum surge between the throttle body and turbo inlet?

Like for instance say as soon as you close the throttle, there is 200kpa post turbo and 0kpa before. Is that a problem or does the engine quickly suck that 200kpa up.

From what I have been reading, 2 throttle bodies are recommended, 1 before, 1 after, because there is a fraction of a second delay of power reduction when the throttle is closed

The twin throttle bodies is nearly a paradox. (Not quite, but nearly)

You want a second throttle body to better regulate your off throttle engine operation, but adding the second throttle body quickly negates the effect you're going for regarding spinning the compressor in a vacuum...so as soon as you add the second throttle body, the entire setup defeats its own purpose. (Well, there will still be a vacuum, but the vacuum wont quickly form off throttle)

You might want to figure out how to route the Idle air control valve in such a way that the idle air doesnt pass through the turbocharger. Possibly mount a second throttle body at the intake manifold without a throttle plate/tps/etc, and use it soely for idle air control through the external air intake port, then remove the idle air control assembly from the pre-turbo throttle body. Just gotta figure out a 1-way valve setup for the assembly to keep boost from getting out to atmosphere through the idle air control.

A lot of carburetted turbo setups were of the draw-through variety, where the turbo (and thus, the throttle) were located at the inlet to the compressor.

One common problem with this arrangement was that when the throttle plate was slammed shut at high engine RPMs, the resultant vacuum present inside the compressor tended to cause the oil seals to blow out, or at least leak severely.


What will happen when running at partial throttle under load? Will the compressor be trying to run at a very high PR with a very low mass-flow? That would push you up and to the left on the map, beyond the surge line.

Check valve to shut under pressure. and to open under vacuum.

That way it doesn't throw off MAF readings

great question, more research needed, appreicate it.

I was under the impression that this could be partially solved with a properly setup TPS based EBC.

I think it maybe possible as well to solve it like that.

Your doing a less efficient design of this

http://www.aerocharger.com/index.php

http://www.engineeringtoolbox.com/fa...rol-d_198.html
and
http://www.epa.gov/apti/bces/module5.../principle.htm
this explains how inlet vanes move you on a map.

I say go for it if you have turbos to spare. Have fun and maybe you can come up with a good results.

I'm aware of those, they are alos 2k a turbo and up

thats not doing the same thing at all

I also question your definition of "efficiency"

Joe do you know if these were stock setups or aftermarket. From what I've read and learned you need a Turbo with a carbon seal to keep oil from leaking out if the compressor will see vacuum.