vnt 15 mechanical controlling

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0767cummins

I remember my first hx35!
Joined
Aug 16, 2010
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Long story short I acquired a vnt 15 for my 1.6 idi Jetta. Looking for a simple way to control the little thing. I have made a few mechanical set ups for the he351ve on my 12 valve and also ran a standalone controller from fleece for a Garrett off a 6.0 ford on my truck. So im familiar with vnt/vgts. My first idea was to use a wastegate actuator to control it. Already bench tested it with an air pressure regulator and it seems to work well. Just wondering if there is a better/more simple way to control it.
 
Actually It won't choke it out. I put a one way check valve in it that holds air pressure between the check valve itself and the wastegate actuator. That trapped air will bleed off and allow the wg actuator to retract slowly (which closes the vanes slowly on deceleration) works great. I can actually adjust the speed the vanes close at. So lets say if you are at WOT then suddenly let off the pedal, the vanes will close slowly instead of just closing instantly.
 
0767cummins said:
Actually It won't choke it out.
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That is false information.

I put a one way check valve in it that holds air pressure between the check valve itself and the wastegate actuator. That trapped air will bleed off and allow the wg actuator to retract slowly (which closes the vanes slowly on deceleration) works great.
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Sorry, no. That doesn't affect how it works, it only slows down the time it takes to choke off the exhaust. In normal driving, such as highway cruising, it will bleed down and choke the exhaust exactly the same trying to bring boost back up to the wastegates cracking pressure.
 
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I get what you are saying now. I should clarify that I have not road tested this yet. Only bench tested. I will give it a go sometime soon to see how it acts
 
Basically you are stating at highway speeds it would be running with the vanes closed which wouldn't be good at all. I wonder if I found a w g actuator that cracks around 5 psi and create a stop for the w g arm that won't allow it to close fully .... Im making this a little complicated but it's fun to toy with it.
 
0767cummins said:
Basically you are stating at highway speeds it would be running with the vanes closed which wouldn't be good at all.
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Correct.
Also, when engine speed or load changes (such as when the transmission shifts up a gear) the vanes will not be able to close to make up for the lower exhaust volume/velocity. That will leave you with a loss of boost and poor throttle response.

Also #2, check valves by nature do not bleed down so you will need an orifice to release pressure from the wastegate actuator. Its lose-lose. Either the orifice is too small and transient response is crap or its too big and the turbo chokes exhaust flow at low loads.

I wonder if I found a w g actuator that cracks around 5 psi
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No, it will not have enough spring power to close the vanes against the exhaust pressure.

Anything involving using a wastegate actuator will not work. You'll end up either choking the exhaust at low loads or you will only control how fast the turbo spools up (not boost pressure). The VW groups made the second one popular despite how poorly it works.

The only two ways to control a VGT correctly are to limit boost pressure based on engine load (throttle position) or electronically.
You must use an actively controllable actuator. Vacuum, air pressure, hydraulic or electric.

If you want to use a simple wastegate actuator you must set the vanes significantly open, but at that point you end up with an overcomplicated version of a traditional wastegated turbo.
 
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Its been done many times. I have friend that runs a vnt15 on his 1.6l idi and it works great. Use a boost actuator instead of the vacuum actuator that they come with.
 
Neither is putting a VNT turbo on an engine not designed for one, whats your point troll?
 
The boost actuator my friend used is a Garrett part. I talked to him last evening and he said he didn't have the part number anywhere in his notes or I'd have it to share. I asked him a bit more about how he has it tuned and he said there was nothing to it! He just put a simple wastegate control valve in the boost hose and adjusted the rod slightly open at idle. He's got it set at 20 psi max but said boost will creep to 22 psi on long pulls.

Tormentor, whoever you are, you need to chill. There are alot of members here who have VNT/VGT chargers on truck, engines, motors, cars, etc and have had great success tuning them with mechanical boost actuators. Just because you may have tried and failed does not mean that others have not succeeded. Try some boost with your breakfast tea, you might like it! ;)
 
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LReiff said:
The boost actuator my friend used is a Garrett part.
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Doesn't matter one red cent. A Genuine Garrett or $3 Chinese junk will function exactly the same.

He's got it set at 20 psi max but said boost will creep to 22 psi on long pulls.
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So? That does absolutely nothing to alter the fact it chokes the crap out of his engine at part load.

There are alot of members here who have VNT/VGT chargers on truck, engines, motors, cars,
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Where? Clearly you're not one of them so you don't have any experience or knowledge of the subject to talk. Come back when you have actually tried something yourself, anecdotes are not facts.
 
I never said it wasn't possible, I said it was a moronic way to control a modern turbo.
 
Tormentor said:
I never said it wasn't possible, I said it was a moronic way to control a modern turbo.
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So these 64+ mm turbos that come on mack trucks with 11+ liter engines are moronically designed due to the fact that they indeed do use a pressure actuator that looks near identical to the average wastegate actuator found on many internal gates. Good thing those engineers have their jobs still and thousands of those trucks are still on the road with a "moronic" design under the hood. if I had seen otherwise, I would know for sure they suck. But since the failure rate is low and they are still around, I would imagine someone did it right, without spending more than was necessary on fancy electronic gizmo s that have reliability issues.

And I wouldn't call lreiff a troll. I am sure he has way more experience than you...
 
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My actuator idea with my homemade check valve worked fine enough for me on an he351ve on my 5sp 12valve.... Each time I grabbed a gear it never barked or choked it out and it was fun to drive so im saying it will work fine for me on my jetta if I find a smaller actuator. Once i finish it I'll get some pics and a video up of it. My IP shaft bushing took a crap and shredded my timing belt so it will be a bit before it's back on the road again.
 
LOL I don't think tormentor knows the kind of people that frequent CompD. Everyone here just uses stock parts. We don't know the meaning of the word modify.
 
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