26 lbs boost, head gasket...poof

[theman53]

I think the 1.6IDI vs the 1.9 TDI is a tough call. The TDI is more efficient then the IDI so less heat is wasted out the ex. BUT you loose .3L of displacement. Plus with the higher revs of a 1.6 you might be better with one of malone's 1852v than either of the 15, 17, or 17/22. For either engine. This is just a GUESS. We need someone who has unlimited ammount of resources to test all of our theories.
Robbed this off of our very own Malone's site:

The biggest advantages the GT1852v turbo has over the popular bolt-on VNT-17 and VNT-17/22 (aka GT1752v) turbos are lower EGT and EMP. The VNT-17/22 tends to struggle with EGT and EMP at 170+ whp and it tends to struggle with boost creep at 180+ whp with the manufacturer’s recommended 26 PSI (1.8 BAR) boost limit. The GT1852v can handle these power figures with ease. The rotationally fired exhaust manifold design allows the GT18v and larger turbos to build boost relatively quickly.

[R.O.R-2.0]

I think the 1.6IDI vs the 1.9 TDI is a tough call. The TDI is more efficient then the IDI so less heat is wasted out the ex. BUT you loose .3L of displacement. Plus with the higher revs of a 1.6 you might be better with one of malone's 1852v than either of the 15, 17, or 17/22. For either engine. This is just a GUESS. We need someone who has unlimited ammount of resources to test all of our theories.
Robbed this off of our very own Malone's site:

The biggest advantages the GT1852v turbo has over the popular bolt-on VNT-17 and VNT-17/22 (aka GT1752v) turbos are lower EGT and EMP. The VNT-17/22 tends to struggle with EGT and EMP at 170+ whp and it tends to struggle with boost creep at 180+ whp with the manufacturer’s recommended 26 PSI (1.8 BAR) boost limit. The GT1852v can handle these power figures with ease. The rotationally fired exhaust manifold design allows the GT18v and larger turbos to build boost relatively quickly.

finally, someone paid attention to drive pressure!!

drive pressure is a big problem on smaller VNTs at high boost levels.. a vnt15 will make enough drive pressure to blow a head almost off a block..

[theman53]

Yes he did. Also I think that the drive pressure is a cause of the boost creep. Even when the vanes are fully open there might be enough drive pressure to continue to spool the turbo. If he is buying a turbo then I would look into one of these. If he already had one then I would say run it. This is something I am making educated guesses on, but I am reading a lot of what guys have written about on this. Also, reading Malone's site is helping me get my head around it.

Maybe even a call to Malone would help. Most all of his setup's are for TDI's, but I am sure he is more learned on this subject than I.

[Toby]

finally, someone paid attention to drive pressure!!

drive pressure is a big problem on smaller VNTs at high boost levels.. a vnt15 will make enough drive pressure to blow a head almost off a block..

IF so called "drive pressure" is actually EMP (exhaust manifold pressure) then this can't be true. EMP is in the 10s of psi. Cylinder pressure (BMEP) is in the 1000s of psi in a typical diesel engine, so EMP is not significant. I do not know what wasted your motor, but it wasn't too much pressure in the exhaust manifold. High EMP is self limiting. Just like any other plugged exhaust. If we also experience a boost runaway that is also unlikely to cause the problems that you have had because BMEP is limited by the amount of fuel available. (AEBE)

[rodpaslow]

The 1852V sounds awesome, although I don't know if I need 26 to 30 psi of boost as I'm sure I'm not anywhere close to 170+ bhp.  I think it's comparable, maybe a bit higher than my 16V jetta so I might be 135-140 max.  I have sent Malone an email to see if he offers it yet and $$.  If it's comparably priced it seems like it will offer more if I ever decide to go to higher bhp or a 1.9 td.

[theman53]

Understood. I was just thinking if you were going the 17/22 route then you were looking for power. I think power is limited to our turbos to a point. I think the stock pump is capable of a lot. If you have a Giles pump then it is more. But I think you can attain close to 190 with a stock pump and a big old turbo. The reason you maybe less than that now is the turbo can't push enough cold air to clear the heat if you turned up the pump.

[rodpaslow]

I think I have a motor capable of more, ARP fastners on all the important bits - rods, mains & head and a Giles pump, and probably less than 20 k miles on a fresh rebuild (pistons, rings, and all that).  I do want some reliability (don't want to have to replace a turbo every so often, why I'm want new)- but if I can push 150-170 bhp, I wouldn't mind that either.  Within reason anyway.  I drive it pretty hard when accelerating, but otherwise cruising I think is relatively soft on it.  I prefer it to be my DD - but I have an old golf n/a as backup I'm driving now....

trying not to beat around the bush, I guess I want to be able to handle a turbo that somewhat can handle more boost (bit better hp/torque) and not break the bank. 

[BlueMule]

I think I have a motor capable of more, ARP fastners on all the important bits - rods, mains & head and a Giles pump, and probably less than 20 k miles on a fresh rebuild (pistons, rings, and all that).  I do want some reliability (don't want to have to replace a turbo every so often, why I'm want new)- but if I can push 150-170 bhp, I wouldn't mind that either.  Within reason anyway.  I drive it pretty hard when accelerating, but otherwise cruising I think is relatively soft on it.  I prefer it to be my DD - but I have an old golf n/a as backup I'm driving now....

trying not to beat around the bush, I guess I want to be able to handle a turbo that somewhat can handle more boost (bit better hp/torque) and not break the bank. 

Rod, if I may respectfully inquire, why a VNT? Why not a new Garrett that has a known Map that you can match scientifically to your engines needs? If you have spent the money on a Giles Pump, it would seem worth knowing exactly where your tubo will work and have a simple and reliable control system for it.


BlueMule

[R.O.R-2.0]

finally, someone paid attention to drive pressure!!

drive pressure is a big problem on smaller VNTs at high boost levels.. a vnt15 will make enough drive pressure to blow a head almost off a block..

IF so called "drive pressure" is actually EMP (exhaust manifold pressure) then this can't be true. EMP is in the 10s of psi. Cylinder pressure (BMEP) is in the 1000s of psi in a typical diesel engine, so EMP is not significant. I do not know what wasted your motor, but it wasn't too much pressure in the exhaust manifold. High EMP is self limiting. Just like any other plugged exhaust. If we also experience a boost runaway that is also unlikely to cause the problems that you have had because BMEP is limited by the amount of fuel available. (AEBE)

high drive pressure = REALLY HIGH cylinder pressure..

the drive pressure never stays in check because like a restriction, there is a fixed (so to speak) supply of air to it, but with a turbo, the more the restriction, the harder the boost is pushing to get thru it.. drive pressure is not a fixed restriction like you say, its a variable restriction that goes up as boost goes up. DRIVE PRESSURE DOES KILL ENGINES.

drive pressure is the pressure between the exhaust valve, and turbine inlet.. drive pressure is what makes the turbo work.

if you dont believe me about drive pressure, look up people modifying 6.4L ford powerjokes.. they would often have 50psi boost, and 80-90psi drive pressure. that right there would keep the cylinder pressures higher than safe, and pop head gaskets on those engines also.

drive pressure is no secret, its been working on every turbo engine ever produced.. DRIVE PRESSURE blew the head off my 1.5D block.. you know why? cause high drive pressure means higher peak cylinder pressures (less exhaust evacuated) and higher pressure everywhere between the face of the intake valve, and the outlet of the turbine.. drive pressure makes all other pressures exponentially greater..

And BlueMule:

he wants a vnt because VNTs are SWEET. you know of a conventional turbo that will boost at low revs, and flow well at upper rpms? no, because you get one, or the other, not both..

a VNT is like having a variable sized turbo.. starts out small, like K03 sized, then as the vanes open, the turbo grows, and spools later and flows better..

[rodpaslow]

ROR - You hit it perfectly.  I love the fact even with the VNT 15, I can get boost starting at 1600-1800 rpm depending on how hard I step on it from stopped.  And as RPM increases the vane control backs off and still provides good boost all the way up to 4000 and past.

In my opinion I think it's hard to beat.  I haven't used new other turbos of sorts, but why would OEM manufacturers be moving to VNT if they weren't as good as others?  I think they are the best of both worlds; plus the fact I've changed my exhaust over to fit the VNT, why would I change back.  If the 1852V is better, I think it's worth the time to investigate.

I'm still waiting to receive my Hylomar Blue.  I've cleaned both the block and cylinder head and checked the flatness, they are virtually perfect with a Mitutoyo stainless ruler.  Once I get the Hylomar (next week) I can start putting the head back on and make a choice on what turbo to get.  I'm taking a chance and putting a new MLS 1.9 head gasket back on....

[BlueMule]

Toby, This mysterious "drive pressure" is all the rage with the Pickumup modifiers. They even have gauges to read this ethereal pressure. Pros basically call it "Hey dummy, your choke point has been reached". Drive pressure is an indication that the turbos limit has been reached, with all of the wonderful symptoms of "barking", etc.

If you know, the following.
Engine size
RPM
Boost
Which will give you your Mass Flow Rate

Then you couple this with your pressure ratio, plot it on your Map, and you never have to worry about "drivepressure" because you have claculated were you "choke ".  Science, don't leave home without it.


BlueMule

[R.O.R-2.0]

Toby, This mysterious "drive pressure" is all the rage with the Pickumup modifiers. They even have gauges to read this ethereal pressure. Pros basically call it "Hey dummy, your choke point has been reached". Drive pressure is an indication that the turbos limit has been reached, with all of the wonderful symptoms of "barking", etc.

If you know, the following.
Engine size
RPM
Boost
Which will give you your Mass Flow Rate

Then you couple this with your pressure ratio, plot it on your Map, and you never have to worry about "drivepressure" because you have claculated were you "choke ".  Science, don't leave home without it.


BlueMule

thank you for confirming what i was saying 

[rodpaslow]

I received an email from Malone - Mark, he says the 1852V is no longer available and is out of production.  I was under the impression that he sold them, but he doesn't.  The tuning side is his forte?

So where does a VNT 15 choke?  Is 17 any better for choke and drive pressure issues?  I'm going to be looking for this info - I see faq doesn't have any VNT maps.  Any help is appreciated.

[rodpaslow]

I've read a VNT 20 off a V6 (not sure of what car, likely passat or audi??) is producing over 300 ft.lbs on a m4 TDI.  totally different setup than manifold combined like the VNT.

If I were to use our engine with say 5000 rpm max what is the max flow rate if I can find a useful map?  Roughly 280 cfm @ 100% VE.  At 5000 if I'm wanting a max of say 25 psi boost, what's my mass flow rate? 

[Swartzvw]

I received an email from Malone - Mark, he says the 1852V is no longer available and is out of production.  I was under the impression that he sold them, but he doesn't.  The tuning side is his forte?

So where does a VNT 15 choke?  Is 17 any better for choke and drive pressure issues?  I'm going to be looking for this info - I see faq doesn't have any VNT maps.  Any help is appreciated.

AFAIK the vnt15 and vnt17 have the same size turbine, the 17 just has a slightly larger compressor so I would imagine the 17 wouldnt be any better for drive pressure.