View Full Version : VNT Turbo with External wastegate
UnstableCable
28-02-2012, 13:13
Quick question about the above. i know with a normal turbo (non vnt) the external waste gate makes the actuator on the turbo redundant and it can be removed.
However Im not sure if this is the same for a vnt? Do you still need the actuator to operate the internals on the vnt?
Thanks in advance
Quick question about the above. i know with a normal turbo (non vnt) the external waste gate makes the actuator on the turbo redundant and it can be removed.
However Im not sure if this is the same for a vnt? Do you still need the actuator to operate the internals on the vnt?
Thanks in advance
Yes the VNT actuator controls the vanes so yes you will need to keep it you can't simply weld up the wastegate port like a conventional turbo and use external wastegate. VNT doesn't have a wastegate port. The VNT will always need the actuator to control the flow of exhaust gasses over the vanes. This is how VNT boost is controlled by restricting the opening of the vanes.
Unless there is another way around it to which i have not read or seen as yet, you could use the stadard vnt vane control actuator alongside an external wastegate if you wanted i suppose
UnstableCable
28-02-2012, 13:37
Thanks for the reply
I wanted to use the external wastegate to control control the spiking, Im a little confused as to how I would go about it??
If the vnt has the actuator plumbed in to operate the veins then when the boost reaches the pressure set by the spring in actuator (which is 14psi on mine) the vnt will dump its pressure right??
I wanted to us the externalwaste gate to run 16psi, how would I go about doing that?
You would have to use the two together having the external wastegate in place should assist if not fully remove any spiking that you are getting with the VNT but you will need to retain the vane control actuator purely for controlling vane movement. How bad is your spiking then?
I had all this grief when I went efi but managed to sort it, you need to plumb the vnt actuator in as normal so when it hits 7psi or so the vanes adjust, then you need to plumb in the external gate as per the instructions that come with it, now comes the hard bit, my vnt had a base pressure of 14psi approx so I fitted a 14psi spring in the external gate but if you Want more than 14psi at any time you have to menipulate both the vnt actuator and the external gate at the same time.
Basically when a vnt hits it's base pressure the vanes close up to control the boost, if you were to just raise the pressure in the external gate to say 20psi you'd still only get 14psi but you would start having spiking issues again.
On a side not, I had a 38mm Tial external gate and it stopped all spiking 100%
As Oli says, you use the external gate to catch the spikes, so to speak :) The external gate should open at just above, or about the same boost you've set the VNT too.
allanr5gtt
09-03-2012, 11:37
I had all this grief when I went efi but managed to sort it, you need to plumb the vnt actuator in as normal so when it hits 7psi or so the vanes adjust, then you need to plumb in the external gate as per the instructions that come with it, now comes the hard bit, my vnt had a base pressure of 14psi approx so I fitted a 14psi spring in the external gate but if you Want more than 14psi at any time you have to menipulate both the vnt actuator and the external gate at the same time.
Basically when a vnt hits it's base pressure the vanes close up to control the boost, if you were to just raise the pressure in the external gate to say 20psi you'd still only get 14psi but you would start having spiking issues again.
On a side not, I had a 38mm Tial external gate and it stopped all spiking 100%
did you ever get the vnt working with the efi?
did you ever get the vnt working with the efi?
Yep
allanr5gtt
09-03-2012, 13:08
would you advise any one to go down that route? i like the idea of have efi and vnt was there any issues with mapping?
im in the process mate of doing an efi conversion with a t3 vnt so i will let you know how i get on when scoff is mapping it
allanr5gtt
09-03-2012, 13:59
im in the process mate of doing an efi conversion with a t3 vnt so i will let you know how i get on when scoff is mapping it
t3 vnt? what's that like in size to the one the adam l sell?
I had all this grief when I went efi but managed to sort it, you need to plumb the vnt actuator in as normal so when it hits 7psi or so the vanes adjust, then you need to plumb in the external gate as per the instructions that come with it, now comes the hard bit, my vnt had a base pressure of 14psi approx so I fitted a 14psi spring in the external gate but if you Want more than 14psi at any time you have to menipulate both the vnt actuator and the external gate at the same time.
Basically when a vnt hits it's base pressure the vanes close up to control the boost, if you were to just raise the pressure in the external gate to say 20psi you'd still only get 14psi but you would start having spiking issues again.
On a side not, I had a 38mm Tial external gate and it stopped all spiking 100%
Dont mean to jump in hear but i was thinking of going vnt.
Was just wondering on adusting the boost on a vnt, do you ajdust it the same as a regular turbo and shorten the actuator arm?
what affect would it have? would it adjust the boost pressure or when the vnt will come in on the rev range?
would you advise any one to go down that route? i like the idea of have efi and vnt was there any issues with mapping?
It's perfectly doable I just personally wouldn't do it again as for similar money you could turbo an f7p and get more power reliably
Dont mean to jump in hear but i was thinking of going vnt.
Was just wondering on adusting the boost on a vnt, do you ajdust it the same as a regular turbo and shorten the actuator arm?
what affect would it have? would it adjust the boost pressure or when the vnt will come in on the rev range?
You'll find that the actuator does nothing but open the vanes once you go efi, once you hit 7psi the vanes will open and then the boost will just keep climbing, hence the need for an external wastegate.
The best way to do it would be to use an electronic servo to open the vanes controlled by a boost sensitive switch set at 7psi then use the external gate to limit the boost.
But to be fair I wouldn't do it again, too much grief and agro for what is only small gains for the large exspense.
t3 vnt? what's that like in size to the one the adam l sell?
It's quite a bit bigger mate
Tony Walker
09-03-2012, 22:04
How much is the VNT Adam sells?
It's quite a bit bigger mate
Yeah the compressor housing on Phil's was much bigger than my adam L vnt which had a T3 compressor housing on it and Phil's front was defo quiet a bit bigger, rear was the same I would say:agree:
As Oli says, you use the external gate to catch the spikes, so to speak :) The external gate should open at just above, or about the same boost you've set the VNT too.
hi Scoff so what would i need to get my raider converted to efi ? how much £ ? and who could fit it for me ? thx
Markey Mark (BD)
16-03-2012, 16:32
How much is the VNT Adam sells?
Don't believe he makes them anymore, been fair few years since made them
Remember him saying for the time it took to make one you could make 2-3 normal hybrid turbo's
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