VNT control idea

[oldskool rich]

i just bort a GT2052 turbo for my project today,

i was playing around with the control leaver, normaly controled with a vacume pump, and then i came up with an idea, the whole point of a VNT is to get maximum boost from minimum exhaust gas. so it got me thinking, why not replace the the vacume pump with with an actuator valve? so the vains will be closed for maximum boost until the actuator opens at a desired pressure and opens the vains before there is too much boost

this way it will always be on boost, cud also be adjusted to be on less boost at idle.

am i on to sumthing, has anyone tried this before or have i just wasted my saturday :lol:

[jimfoo]

It can be done, but will probably reduce mileage some as it will always be restricting the exhaust as much as possible, where as the cable setup only closes the vanes when needed, and cycles them a lot more to prevent problems from carbon buildup.

[jtanguay]

for driveability go with the accelerator cable setup.  if you just want to drag though, that boost can will work.  you're going to be running max boost pretty much all the time unless you're light enough on the pedal.

[oldskool rich]

well it will be a daily driver but quater mile is very important

will this make my set up faster? if its always on boost it will be like having powerfull supercharger?

how much mpg will will i loose?

this set up will cycle the vains all the time too, everytime i hit my required psi they will cycle

the throttle linkage idea seems ok, but then how is that attached to the waste gate?

[jtanguay]

well it will be a daily driver but quater mile is very important

will this make my set up faster? if its always on boost it will be like having powerfull supercharger?

how much mpg will will i loose?

this set up will cycle the vains all the time too, everytime i hit my required psi they will cycle

the throttle linkage idea seems ok, but then how is that attached to the waste gate?

http://video.google.com/videoplay?docid=-8726487528543720960

http://video.google.com/videoplay?docid=3448331191659563820

thats all you really need to see :wink:

one way jimfoo 'pimped' out this setup is to have an override control lever under the dash or somewhere accessible.  it is useful for when you want full boost right away without having to mash the pedal.  i think this setup will be good for both street and track though without the manual control.

[DonGTI]

I have been chewing through most VNT posts on this forum and have to agree that some form of additional cable/throttle control is needed... Actuator only set-up, especally in city driving I would immagine would mean a lot of delay in the boost can to open hence you'd be getting boost in slow moving traffic and opening of aneroid pin dumping diesel in whilst doing 10-20 mph...

I saw in a post but can't remember its name that the throttle cable set-up can be modified to acheive full closed vanes even at 50% throttle by threading a spring around the cable which is harder than force needed to close vanes... hence at 50 % throttle you would have moved the cable and closed vanes without spring opening/extending. More than 50% throttle and the spring extends since the force of throttle pedal is increasing and the vanes are already fully closed with no more travel and hence the spring has to give way and extend reasonably... To open the vanes, a parallel system using the boost can is then used, and this application varies depending on wether the VNT is sprung to have the vanes "close" if the set-up brakes or "open".

Assuming that the vanes are closed when the lever is extended out, easyest way would be having the two systems running in parallel with the vane control leaver sprung to stay in the Closed, the throttle set up would be restraining it from closing, and the spring on the lever extends the lever as much as the throttle part allows it to move. Along side it and not connected directly to it, the boost can applies pressure to the lever and pushes it down when desired boost is reached, bypassing the throttle, and pushing in the vane lever opening the vanes.

I hope i did not mess up "closed and open" leaver positions... if yes the set up is reversed.    


I suggest you skim through all the litterature on this forum because there are a lot of different ways to go about this

[DonGTI]

Also watch out for the positioning of the turbo in its original application... read in another post that some have an oil drain at the base of either the center section or the vane carrier assembly, and this would need to be modified if the turbo has been "clocked" or turned... failure of which may lead to oil that gets past seals to accumulate in vane area coking up vanes or something like that...

some turbos have that problem whilst others do not... will open a thread soon to ask for confirmation re. which turbos are like that and in general what to look out for to say which turbos are like that when they have been opened. I bought a hybrid VNT15 with a 17 center section which the seller does not know what it came off... The 15's and 17's definitely have this hole but no idea about where it is or how to allign it ecc.

[jimfoo]

All VNT's need the drain to point down. It is also hard to clock the exhaust housing on some VNT's because of the vanes. Some have pins that go into the exhaust housing so they can only go on one way. The intake, you can turn whatever way you want. Your center section came off some Nissan Diesel, I forgot what exactly.

[DonGTI]

found the thread...

http://vwdiesel.net/phpBB/viewtopic.php?t=8065&postdays=0&postorder=asc&highlight=vnt&start=15

It shows two approaches, on page 1 uis the one by Libbybapa and page 2 another by Jimfoo... Libby's set up looks like its a factory item, and Jimfoo's set up looks infinitely adjustable...

There's also another thread somwhere of a vnt turbo'd merc, and although he does not have a VW engine on, he also had similar problems as to how to run the vane control system, and his solution is similar... but worth studying as well.

As a final note,i have to say how gratefull I am that these people decided to share their knowledge with everyone on this forum.

[oldskool rich]

ok sum fair points, i think you could rig up a cut off switch to the LDA so that you can have sports mode and echo diesel mode that way you would save more fuel in genaral. untill you want to race then ud have bare nuff torques

i can see why the cable idea makes sence. and im realy tempted to do it but im still thinking mine is pretty good, wud still be less lag

i might give it a go and if i dont like it ill go cable

i know this is a bit off subject but how long do you think a 1Z gear box will last with that sort of power? and what wud be a direct replacment upgrade that will take 200bhp?

[jtanguay]

i think the tranny will be good for 200bhp.  not if you're dumping it though.  the shock load of that much power will definitely kill it over time... how much time i dunno... 20 psi @ 2000rpm = carnage  :twisted:

[jimfoo]

One thing about just putting an actuator on, if I remember right, you have to put it on the opposite side from the stock actuator or it won't open the vanes, but rather close them with boost which is not what you want to do. Just make sure to check first.

[oldskool rich]

ill just have to take it easy

the actuator is just right

i can tell when the vains are open just by blowing down it :lol:

[MrDave]

Why not run the stock VNT actuator on full vacuum, then use a boostvalve to bleed pressure in to relax the vanes as you get to the target boost pressure?



-Dave

[jtanguay]

Why not run the stock VNT actuator on full vacuum, then use a boostvalve to bleed pressure in to relax the vanes as you get to the target boost pressure?



-Dave

you would probably bleed way too much boost air in there, and possibly disable any vacuum operated device on the car... such as brakes  :lol: