Thread: VNT Turbo install

Hello,
Interesting that you got 32psi have you bypassed the modulator ?? This would cause the boost to go up that much it should be running the actuator hose directly to the outlet pipe before the intercooler. Mine peaks at about the 23psi mark and drops back to the 18 psi.
For the past month or so I been driving around in sport mode give it a try. As for fuel useage it is about the same if a lead foot or not.
I ran the VNT with a stage one map for a while and went good. Then got a TD5 Inside map and then you get the full advantage from went from wow to WOW.
Once you have a new map file there is a huge difference.
Ian

Ian,
The install was done by my LR mechanic as it was beyond my expertise. So I don't really know what you're asking me but I will ask the question. I think I need to get out on the highway and check out the high end performance. It was suggested i might need to go to the Td5 Inside map by my mechanic but I'll decide after a couple of weeks driving.

Originally Posted by Mundy

new (larger) maf, etc.

Details on the MAF?

Originally Posted by Mundy

the tuning was tricky (apparently) as when initially installed, it was generating max boost of 35psi and ultimately required a different maf to work smoothly. It’s now wound back to 23.

This seems strange as the wastegate is set by Turbotecnics when they put it together and is not meant to be adjusted.

How is the MAF sensor effecting the boost by so much (12 psi)?

The only time I have seen more than 22psi on my VNT is when the wastegate vacum hose disconnected so the wastegate was not getting the signal to open up...

I am wondering if the installer failed to disconnect and remove the modulator? These were only fitted to TD5 Discovery's and not the Defenders and are to be removed/disconnected/bypassed during the installation of the VNT.

Originally Posted by Mundy

don’t expect to change the intercooler but we’ll see.

Definitely worth fitting the larger intercooler in. You are robbing yourself of performance and reliability otherwise. Your running significantly higher boost pressure than the standard turbo charger, which means more heat due to the compression, the larger intercooler will assist in cooling the air temperature back down - cooler air is denser which is better performance wise.

Originally Posted by Mundy

I/we were a little surprised, too. But 35psi was way too high and now at 23 it works well as described. A new map and/or intercooler are options but from my part, if fuel economy is ok, low end continues as is now, there's no degrade of high end performance, and egt's aren't excessive, then it ain't broke and I don't need to fix it. If I am operating at a slightly less than peak output then hopefully things will last longer.

Not upgrading the intercooler will not help with reliability. If anything it may have the opposite effect as you are putting in hotter air resulting in hotter combusion chamber temperatures.

Originally Posted by OffTrack

The boost box + modified MAF route seems to be pretty common with the VNT upgrades. In many ways you'd be better off with the IRB dual channel boost box which gives you the ability to modify the MAF's output. It means you can use stock MAF's rather than relying on tuning companies for continued supply of the modded units.

IRB Developments

I went from turbo Boost Box and modified MAF to IRB product with genuine MAF. Much better. Issue was that took about three months to arrange the sale with IRB - international customer service is not their strong point.

Originally Posted by djam1

I find this part of the post interesting Pete Bell told me not to adjust it as it is preset and you shouldn't mess with it.
I think you will find if you speak to Jose and he does a MAP for the VNT you will have a much better result, the larger inter-cooler also helps.

This is correct, you are not meant to adjust the VNT wastegate as it is preset by Turbotecnics, the manufacturer.

I agree about Jose from TD5Inside's maps, this is what I run in my vehicle and it has been faultless.



One of the best things that you can do after the VNT, for an automatic vehicle at least, is to fit an Ashcroft Heavy Duty Torque Converter. This makes almost as much difference as the VNT upgrade and allows you to actually use the torque of the VNT diesel motor.

Originally Posted by Mundy

Ian,
The install was done by my LR mechanic as it was beyond my expertise. So I don't really know what you're asking me but I will ask the question. I think I need to get out on the highway and check out the high end performance. It was suggested i might need to go to the Td5 Inside map by my mechanic but I'll decide after a couple of weeks driving.

Hello,
Bit hard to explain but on the turbo there is a Actuator and small black pipe going in and a Long rod going out in the middle of the turbo. Follow the little black hose it should go to the outlet pipe of the turbo about in the middle of the pipe mid way between turbo and air box this is correct. NOT to the modulator with 3 small hoses on it near the air con compressor ....... The turbo should NOT be adjusted at all as set buy Turbo technics. I do not have any photo accounts so cannot put some pictures up maybe somebody else can.
Ian

Originally Posted by justfishing

Hello,
Bit hard to explain but on the turbo there is a Actuator and small black pipe going in and a Long rod going out in the middle of the turbo. Follow the little black hose it should go to the outlet pipe of the turbo about in the middle of the pipe mid way between turbo and air box this is correct. NOT to the modulator with 3 small hoses on it near the air con compressor ....... The turbo should NOT be adjusted at all as set buy Turbo technics. I do not have any photo accounts so cannot put some pictures up maybe somebody else can.
Ian

Thanks for the explanation, I think I can see what you mean. I have attached a couple of photos and I think the actuator has been connected to the modulator which I think is in the second photo. The hose in the top right going into the black box with the plus sign on it is coming from the side of the actuator.

What does the modulator do and why is connecting to it wrong for this turbo?

Car seems to work well. What is the ramification of the install as it is? Will I do damage if I leave or will it just work better if I move it?

Isn't "the pipe mid way between turbo and air box" the inlet to the turbo? Are you sure that's where it should connect?

the modulator should be bypassed using a vnt. connect the actuator at the turbo directly down to the pressure side of the turbo located at a point on the lower pipe going toward the front of the vehicle.

jc

Originally Posted by justinc

the modulator should be bypassed using a vnt. connect the actuator at the turbo directly down to the pressure side of the turbo located at a point on the lower pipe going toward the front of the vehicle.

jc

X2 ......You can see it in the second photo at the bottom the little black pipe on the outlet of the turbo is where it should be. At least you found out what was wrong, you will most likely have to re-adjust you VNT as this will be wrong. Very basically the Modulator is controlled by the ECU and adjusts the "pushing power" of the actuator on the turbo to control the boost. The VNT works differently to the waste gate turbo, so different principals work there as the vanes open only when max boost is reached then they release, very brief description. If you look up "How VNT works" on Youtube there are a couple of good animations there.
Hope it all works out for you .............I would be getting a new mechanic though !!!!!!! as it is quite clear in the instructions how to fit what and where..
Ian

Thanks to all. As has been said before by others, a great forum of knowledgeable and helpful people.