VNT turbos

[Clio GTT]

Sorry if this has been repeated many times but the search function won't let me search for VNT as it's only 3 letters :scared:

As I understand the VNTs that people have used/are using have come from diesels.

Are there any issues with EGT killing them?

Anyone used one for a long period of time?

Much appreiated :niceone:

[Markey Mark (BD)]

I've had one myself and know of a few others that have used the VNT turbo for quite a few miles, no real problems with them.

[Sparkie]

i managed to kill 2 in the space of 6 months, but i'm lucky like that.

[Markey Mark (BD)]

i managed to kill 2 in the space of 6 months, but i'm lucky like that.

Thats not bad going mate :D;)

Got to say even though i've had one wouldn't have another one

[Clio GTT]

i managed to kill 2 in the space of 6 months, but i'm lucky like that.

Do you know what killed them?

[Clio GTT]

Thats not bad going mate :D;)

Got to say even though i've had one wouldn't have another one

Why not? :cooter:

[Markey Mark (BD)]

Why not? :cooter:

I just got fed up of them mate.

[Clio GTT]

I just got fed up of them mate.

elaborate :popcorn:

Fed up of having problems? or setup?

[Markey Mark (BD)]

elaborate :popcorn:

Fed up of having problems? or setup?

Set up of it and the general pissing about with them.

They were quite hard to get working well with the carb, my old 5 ran slightly rich all the time to compensate for the boost spike it had.
It has been a while since i've had mine and a few people may have solved the problem but to be honest the thought of putting the turbo in the car then spending about 2hrs (which was as long for the last time i fitted one) setting the vains, then doing carb didn't appeal to me anymore.


I prefer conventional turbo's over a VNT now.

[Clio GTT]

What would you recommend for a low comp, lightened and balanced engine with a 285 cam ?

[Markey Mark (BD)]

What would you recommend for a low comp, lightened and balanced engine with a 285 cam ?

Honestly mate i'd recomend not fitting a VNT, but thats just my personal opinion.

I had in my engine slightly higher comp (8.1:1), MSM cam, flywheel lightened, head done with bigger valves, etc.
I've fitted a few other VNT's too to other cars, all with standard comp but varried mods, one with just a different cam and another with abit more work done, still have to spend ages playing about with the turbo.

Go for a conventional turbo, T25/T3 or something like that depends what boost or power you want from the engine.

Another thing also, i don't really like low comp so i'd be changing that back to standard if it were mine.

[Clio GTT]

I meant what other turbo would you recommend?

GT28?

[Markey Mark (BD)]

I meant what other turbo would you recommend?

GT28?

Yeah something along those lines mate will do, what you want to use the car for as if its more track/fast road i'd prob go for something slightly smaller on the back end to keep the lag down.

[Clio GTT]

Yeah something along those lines mate will do, what you want to use the car for as if its more track/fast road i'd prob go for something slightly smaller on the back end to keep the lag down.

Purely a track/drag car.

I've got the derv for day to day and I'm dropping r5 rich's engine into my williams with some sorted suspension.

What sort of exhaust AR should I look for?

[Markey Mark (BD)]

Purely a track/drag car.

I've got the derv for day to day and I'm dropping r5 rich's engine into my williams with some sorted suspension.

What sort of exhaust AR should I look for?

Ah you bought R5 Rich's engine, goes well that lump.

If its for drag then i'd stick with how it comes if its fitted with the .64 rear housing, think its been used a few times before by some members, but not too sure how it will feel if you want to use it on track think it'll be abit laggy for that.

[Clio GTT]

Do you track your car? or is it purely a drag car?

I don't think I can stretch to 2 turbos and 2 carbs so I'll probably have to compromise on the drag setup as I'll do more track days than pod runs.

Do they do such thing as a T28 front and T25 rear?

I'm not too clued up on turbos as you can probably gather :ashamed:

[Markey Mark (BD)]

Do you track your car? or is it purely a drag car?

I don't think I can stretch to 2 turbos and 2 carbs so I'll probably have to compromise on the drag setup as I'll do more track days than pod runs.

Do they do such thing as a T28 front and T25 rear?

I'm not too clued up on turbos as you can probably gather :ashamed:

I got 2 cars now, one for drag and one for track. The engine with the VNT got sold on years ago i am going to use a Volvo engine for drag now.

Yeah they do somthing that can meet in the middle, have a word with Adam L and i think he can knock up some sort or T25/T28 or even T25/T3, something along those lines will do the job and be a compromise between the two

[Clio GTT]

With the engine being low comp, does that mean I have to run more boost than std comp?

[Markey Mark (BD)]

With the engine being low comp, does that mean I have to run more boost than std comp?

I find you will to get the same sort of power, you also loose low down torque too, i'd always run at least standard comp in any engine i do.

[markey b]

i bought my 5 in aug 2005 with a VNT, its still going strong :agree:

[Clio GTT]

i bought my 5 in aug 2005 with a VNT, its still going strong :agree:

How many miles have you put on it?

What sort of boost levels are you running?

[markey b]

no idea of mileage, it was my daily drive for the 1st year!

run 14psi normally and 27 when i want to **** my pants

[Clio GTT]

no idea of mileage, it was my daily drive for the 1st year!

run 14psi normally and 27 when i want to **** my pants

fairly robust then?

whats the spec of it?

[markey b]

markeymark is probably more clued up than me, or adam l as he probably built it!

i know its one of the early ones, makes boost very quickly and brings it in very hard

[rs250nut]

Purely a track/drag car.

I've got the derv for day to day and I'm dropping r5 rich's engine into my williams with some sorted suspension.

What sort of exhaust AR should I look for?

Your replacing the F7R with a C1J:scratch:

[Clio GTT]

Your replacing the F7R with a C1J:scratch:

I bought it as a bare shell and I'm building it up into a track car, an F7R would just bore me, I love the character of the C1J :)

[Os8472]

I've had a VNT from brand new for nearly 3 years, been the most fun I've ever had and its showen up alot of exspensive motors :D

Alot of peeps will say there a pain in the arse and yes they can be but mine had near as damn it the perfect settings from new and needed very little adjustment to get it working well.

Yes some will also say what I'm trying to do running a VNT and efi won't work but I've already worked it all out and had it working albeit for a short while till an oil pipe got caught by the aux belt and dump the oil everywhere, but it did work so a big middle finger to those who said it wouldn't :upyours:

[HAndy]

is that why your now going back to normal turbo again ?:laugh::laugh::wasntme::D
......only kidding;)

[Os8472]

is that why your now going back to normal turbo again ?:laugh::laugh::wasntme::D
......only kidding;)


Nope its because to get it working 100% right 100% of the time would cost me a further 600quid and I can't afford that now I've bought a house, besides with the money I'll get from selling the VNT, I'll have paid for the new turbo, all the new bits needed to fit it, a few other new engine bay bits and still still have 200quid left over.

[HAndy]

those engine items are still sat there in the black beast if your intrested?:cooter:
let me know;)

[Os8472]

those engine items are still sat there in the black beast if your intrested?:cooter:
let me know;)

Only need the down pipe and the head to come back from the machine shop after some special works

[Big Jim]

I'm not sure how many times I've said this, but if you have one of my actuator set-ups on a VNT you won't have any problems with setting up or spiking.

[Os8472]

I'm not sure how many times I've said this, but if you have one of my actuator set-ups on a VNT you won't have any problems with setting up or spiking.

Go on then, whats your actuator setup involve and how much?

[Os8472]

Just reread my post, looks like I'm having ago, sorry didn't mean it to sound that way.

I'd like to know how your actuator setup works compared to the standard actuator they come with and if it would sort the stable boost upto 4000rpm wher it goes nuts, going past 25psi without any sign of slowing

[philr5t]

this maybe it

[Os8472]

Ok looks like a T3 actuator, but how does that improve things?

The actuator I had worked fine on the carb but the second I went efi it didn't, maybe because it was no longer restricted by the carb, not sure

[MFaulks]

I'm not sure how many times I've said this, but if you have one of my actuator set-ups on a VNT you won't have any problems with setting up or spiking.

Jim or Adam probably, can you also do variable inlet guide vane (VIGV) as well? I would certainly be very interested in this for a twin-turbo prv lump.

[Sparkie]

Do you know what killed them?

i had my suspicions. good oil pressure when hot, yet it still messed up. might be due to stalling of compressor wheel whilst driving normally on part throttle.

major problem for me was the fact that the turbo ran out of puff at 5.5k, didnt like a revvy cam at all, no like a t28/t25 at all.

[James5]

Jim or Adam probably, can you also do variable inlet guide vane (VIGV) as well? I would certainly be very interested in this for a twin-turbo prv lump.

It would appear from Phils pics that the jims vnt is using a boost operated actuator to control the vanes but it looks like jim has taped the base of the boost actuator so it is being used like a vacum actuator but in the correct way for the gtt. So the vanes are being pulled closed instead to limit boost were if you just used a normal boost actuator you would be pushing the vanes open and have to use the actuator arm as the limiter / restrictor for the flow of vanes opening this woukd cause spiking.
Be interesting to see phils up and running as not seen this setup in action yet.

Personally out of choice I would choose a vnt over a conventional turbo anyday even though the inital setup of getting the vnt to boost early or late in the rpm range you want then getting the actuator to hold the boost you want is hassle and time consuming but I say well worth it. Never had a vnt run out of puff though in fact my engine didn't rev high enough for the vnt and we saw 7880 rpm (msm cam to which I believe is a piper 285 but timed up slighlty different 110 degrees rings a bell also on a high comp engine 8.1.1) on the track n road rollers and the vnt was still pulling hard.

[Big Jim]

Just reread my post, looks like I'm having ago, sorry didn't mean it to sound that way.

I'd like to know how your actuator setup works compared to the standard actuator they come with and if it would sort the stable boost upto 4000rpm wher it goes nuts, going past 25psi without any sign of slowing


It's ok, didn't think you were having a go:) just been watching Fawlty towers.

It's not just a std T3 actuator. I s'pose I can spill the beans cos' it isn't really rocket science.

It uses a soft spring with a manifold side pressure signal on the spring side of the diaphragm. That way you get vacuum to open the vanes on part throttle and lower the back pressure/ give the turbo an easier life. When you open the throttle the vacuum disappears, the vanes shut and the turbo spins up. Then you get boost pressure, or at least a part of it, adding to the soft spring to give you the boost level you want. The soft spring means you get a much flatter (if not flat) boost curve as opposed to the characteristic you describe.

Hope that makes sense, but if it doesn't I'll sell you the bits for £150...

[markey b]

mine has always spiked off the boost gauge on big boost.... a little spike is fun :laugh: