Thread: VNT TURBO FEEDBACK PLEASE

Originally Posted by OffTrack

You should be right with your current map, but you'd definitely get better performance with a remap to suit.

The bare essentials are:

Uprated Intercooler: £500
Boost Box: £100
Turbo: £700
total: £1300 + shipping

so probably just shy of $2000 plus any shipping charges.

Factor in another $800 if you upgrade to a reflashable ECU and remap.

cheers
Paul

Originally Posted by robbotd5

I have been thinking of the VNT for a while now because my biggest killer with my van in tow is the turbo lag. Exasperated by the fact that it is manual. My car is fairly moded as you can see by the info in my signature. Thinking a VNT may just be the icing on the cake???
Thoughts?
Regards
Robbo

I am very interested in a VNT. Spoke to my LR mechanic who was quite disparaging of the need for a VNT. He said much better value for money putting in 3" exhaust and removing cat. However, I see that robbotd5 has done this and the low rpm performance in a manual is still poor.

So, offtrack, $2000 for the bits, what about installation and remapping costs? I already have a rechipped 2004 manual.

Other suggested alterative from my guy was to install a new turbo which has a larger inlet and larger diameter impeller but which is a straight mechanical swap. Also needs mapping to be adjusted.

Fitting a VNT is a straight mechanical swap also.

Anyone with a few tools and time can do it at home.

Larger compressor will make more top end. But take even Longer to spool up.

Mundy.
I would not call my performance poor but the lag is still there but nothing like it was when the car was stock. Removing the cat is illegal.My van is a big one at 23ft which saps the performance as you would expect. If a VNT spools up to boost faster than the stock Garrett then I will eventually fit one.
Regards
Robbo

Just got a box delivered today from Bas with a VNT and NNN Ecu with the need to communicate with the immobilizor taken off as well.

I'll let you know how it all goes

Originally Posted by Mundy

I am very interested in a VNT. Spoke to my LR mechanic who was quite disparaging of the need for a VNT. He said much better value for money putting in 3" exhaust and removing cat. However, I see that robbotd5 has done this and the low rpm performance in a manual is still poor.

So, offtrack, $2000 for the bits, what about installation and remapping costs? I already have a rechipped 2004 manual.

Other suggested alterative from my guy was to install a new turbo which has a larger inlet and larger diameter impeller but which is a straight mechanical swap. Also needs mapping to be adjusted.

Not wanting to be derogatory about your mechanic but he doesn't know what hes talking about.
A 3 Inch exhaust and a decat is in NO way comparable with a VNT.
I did the larger intercooler decat and 2.5 inch mandrel bent with a 3 inch centre muffler as well as a remap
This combination was nothing like the VNT but all of it combined is pretty special.
I am also told that your mapping doesn't have to be changed with the VNT but you will benefit if you have it optimised

Originally Posted by djam1

Not wanting to be derogatory about your mechanic but he doesn't know what hes talking about.
A 3 Inch exhaust and a decat is in NO way comparable with a VNT.
I did the larger intercooler decat and 2.5 inch mandrel bent with a 3 inch centre muffler as well as a remap
This combination was nothing like the VNT but all of it combined is pretty special.
I am also told that your mapping doesn't have to be changed with the VNT but you will benefit if you have it optimised

^x2

and just to add to the above, a bigger turbo is going to result in more lag. The benefits of a bigger turbo that can flow more air are unlikely to be realised on a turbo that will only spin out to 4500 rpm, unlike a petrol engine that may get a chance to use the extra air at higher rpm.

Originally Posted by Tombie

Fitting a VNT is a straight mechanical swap also.

Anyone with a few tools and time can do it at home.

Larger compressor will make more top end. But take even Longer to spool up.

Thanks, I willing to give it a go. However, can someone explain what the boost box is for (ie why do you need one?) and how and where it is installed?

Also, is the upgraded intercooler really necessary?

The Disco Td5 ecu is programmed with a maximum boost limit of something like 22psi. If the ECU detects a boost level higher than this it limits fuelling until the boost drops to acceptable levels. You've probably read about the "kangaroo hop" that occurs when the wastegate modulator isn't functioning correctly - this caused by the ECU detecting an overboost condition.

A VNT produces high levels of boost of earlier than the standard turbo and this can result in over boost conditions.

A boost box plugs in to the line between the ECU and the MAP (Manifold Absolute Pressure) sensor and lowers the pressure reading sent to the ECU to a point that doesn't trigger over boost in normal driving.

I'm not sure if the larger intercooler is absolutely necessary, but all the major tuning companies seem recommend the intercooler upgrade as a prerequisite for the VNT install.

cheers
Paul