VNT and rpm

[rodpaslow]

I have a very quick question.  I read recently; can't remember which post, but someone had a vnt that started spooling right off 1000 rpm. I think it was about 5 lbs of boost.  I am going to be starting to install mine shortly (vnt 15) - with the vanes closed at this rpm is it safe?  Can you bend a rod spooling right off idle?

[nathan_b]

I don't think an idi injection pump can put out enough fuel at 1,000rpms to create enough boost to bend a rod. Personally, I think if you made that much boost without rpms increasing, (theoretical) the motor would stall before it made enough power to bend a rod.

but theres only one way to find out. put a boost gauge on it and report back.

My k14 can make 5 psi in neutral, so 5psi in a loaded 1000rpms is not that impressive imo.

[R.O.R-2.0]

if you make 5 psi at 1000 rpms, you are going to be making around 40 by 3500 rpms.. ask me how i know? ask me what happens?

seriously tho, you can boost the head right off a VW diesel with a VNT..

ive done it before 

[nathan_b]

So... don't run the vanes closed/ problem avoided.

As long as you ave acceptable egts and boost numbers

[R.O.R-2.0]

no dude, dont run them closed.. you will (possibly damage your engine) make 40 psi, and NO power.. run the vanes as open as you can get them if you arent gonna hook them up cable operated..

that stop with the adjustable set screw, thats the closed position.. you want the lever to point up, not towards the firewall..

[ibizz]

R.O.R-2.0

what vw engine you send head to space ?

how manny boost to that hapen ?

im trying to use vnt 15 too , but i was thinking just change the can by 1 of pression and kind take it easy to pedal in low rpms..

but since im a fast and nervous guy in trafic ...  probably not good ideia just relay in heavy food..

in actuactor arm , you can take pression away ?  going forward , or backwards?

[R.O.R-2.0]

im going to make the assumption that pression means pressure?

and the head never actually left the block, it was just very close..

it was a 1.5D that i turbocharged the crap out of..

my timing was stupidly retarded, and it would make 40 psi boost, apparently enough to vaporize a head gasket..

if you dont have the ability to hook up your vanes of the turbo to the inj pump throttle arm like many on here have done, then just open them all the way up..

the little arm on the turbo is pointing up when the vanes are open, and the lever should be away from the adjustable stop,not against it. when the lever is against the stop, the vanes are closed, and you will overboost the hell out of your engine..

i drive my car like i stole it every day. it has no way to control max boost besides the fuel quantity going into the engine.. if i want more or less boost, i use my max fuel screw on the pump to adjust it.. thats basically the only way to adjust the max boost of the turbo, since it has no wastegate..

[rodpaslow]

I'm am planning to hook up some sort of cable control to control the vanes, but I'd like to hit between 20-25 lbs of boost.  I've seen some posts here with cable and full mechanical control and from the sounds of it, from posts, seems to work pretty good.  I don't drive my car too hard, most days; but I definitely want to improve the off idle to 3500 rpm speed.  I have a t3 at the moment with all the goodies (& water to air intercooler) and I don't see any speed till about 2500+ rpm, and then woosh I off.  I want to improve that too maybe 1500 with a steady pull till max boost & 35 to 4000 rpm.

It sounds like it will definitely improve bottom end, was just concerned about over-doing it down low.

Thanks!

[nathan_b]

sounds to me like you need a k14, not a vnt.

[ktownboostn]

Im going to be running a VNT onmy 1.6td pretty soon .I plan on modifying a 1.8t wastegate actuator in place of the factory VNT actuator. That should give me proper operation of the viens while using a manual boost controller

[fatmobile]

I have the vanes locked closed on my 1.5 Rabbit,
 with the VNT-15.

I watch the boost gauge more closely than the speedometer when accelerating.

I have boosted past 30psi,... last number on the gauge.
Yeah for head studs.

I'm going to set mine up so it can be adjusted with a knob on the dash, like the cold start handle,
 and still be effected by boost.

[MJF]

30psi with vanes closed makes no power, it just chokes engine breathing. EMP will tell what is going in vnt.

[R.O.R-2.0]

Im going to be running a VNT onmy 1.6td pretty soon .I plan on modifying a 1.8t wastegate actuator in place of the factory VNT actuator. That should give me proper operation of the viens while using a manual boost controller

no, it wont, its going to give you a turbo that is super restrictive off boost..

unless you know something about a 1.8T wastegate that we dont..

wastegate cans are a BAD IDEA when it comes to VNT operation..

[R.O.R-2.0]

I have the vanes locked closed on my 1.5 Rabbit,
 with the VNT-15.

I watch the boost gauge more closely than the speedometer when accelerating.

I have boosted past 30psi,... last number on the gauge.
Yeah for head studs.

I'm going to set mine up so it can be adjusted with a knob on the dash, like the cold start handle,
 and still be effected by boost.

were your vanes on the stop, or away from the stop?

like closed down to where the turbo will overspeed very easily and make boost at idle basically?

mine are wide open, and it works best this way, from my experiences..

[fatmobile]

Right, against the stop, will make boost without being under load but not at idle.
Your's is a VNT-17, right? There is a big difference. I wouldn't run my VNT-15 with the vanes tied open.

 I agree 30 psi doesn't give me more power, actually feels like less power.
I'll be pulling the turbo, freeing up the vanes and working on a vane controller that can be manually adjusted like the cold start timing advance knob.
My last controller held the lever tight against the turbo,..
it's on a small arc,
it needs to pull away from the turbo to come off open or closed.
 The next controller won't push it against the turbo, might even pull it away some,.. then the boost does some more controlling like my current setup would if the boost line was connected.