EMP as related to the VNT 17/22

[vwdsmguy]

I been reading about Exhaust Manifold Pressure and how a small turbine side can raise EMP well up there. Anyone measure the VNT17/22's EMP?
TDIfreak relates to this, I think.
Join Date: Sep 2001
Location: Finland
Re: GT17/20 non-vnt hybrid?
There are no 'better' or 'worse' flow, but there are IMO three (and only three) variables that count:
boost
intake air temperature
exhaust manifold pressure
They tell you relatively how many oxygen molecules you get into the engine for burning the fuel dose. They are all linked together and both IAT and EMP (relative to boost) tell when you have correctly spec'd turbo.
If you can make the boost with the small turbo, you are only going to achieve anything by lowering IAT and lowering EMP with bigger or better sized turbo.
High IAT you can make a lot lower with good intercooler, so that the temp difference produced by different size turbos becomes very small. It's always there and in some cases it's meaningful and in others, not.
High EMP is said to kill turbos and raise exhaust and engine temp. High EMP is partly due to the inefficiency of the turbo and with vnt-turbos it tells you when the turbo is too small; boost creep is high EMP's best buddy.

 

[KROUT]

I haven't checked mine. But I have thought about making a plate with the fitting so I can see the emp.

 

[CarlUman]

Question... wouldn't high EMP also cause high EGTs? If presure is high then there is too much restriction for the amount of exhaust but that also means the heat can't get away so high EGTs will be there as well. So my question asked a little different... would high EGTs always be present with high EMP? Now the reverse... if you have EGTs (which is a problem anyhow) would you be certian to have high EMP also? If so then couldn't EGTs be used as a ruff guage for EMP?

Seems to me if you have EGTs in a good range, say under 1400, then EMP shouldn't be much of a problem. If you are hitting 1600+ then you are not getting the flow you need or you need a better tune.

Just thinking out loud

I hope to be getting a turbo in the next month so I'm interested in this topic.

Thanks

 

[Scott_DeWitt]

Exhaust Pressure is the primary force acting on the turbine. Higher exhaust pressure means a more responsive turbo, however high EMP = high EGT.

The turbine section of a turbo (vnt or otherwise) is essentially a restriction in the exhaust that extracts pressure and heat from the exhaust and puts it to work. If EGT's are high, installing a larger restriction (turbine) exducer will decrease egt's allowing more fuel and air to be burned which increases egts, which needs a larger turbine, which decreases egts, which allows more air/fuel to be burned... and so on.

If your maxing out EGT's on a VNT17VB, then a vnt17/22 with added fueling will make things worse.

 

[Passenger Performance]

Exhaust Pressure is the primary force acting on the turbine. Higher exhaust pressure means a more responsive turbo, however high EMP = high EGT.

The turbine section of a turbo (vnt or otherwise) is essentially a restriction in the exhaust that extracts pressure and heat from the exhaust and puts it to work. If EGT's are high, installing a larger restriction (turbine) exducer will decrease egt's allowing more fuel and air to be burned which increases egts, which needs a larger turbine, which decreases egts, which allows more air/fuel to be burned... and so on.

If your maxing out EGT's on a VNT17VB, then a vnt17/22 with added fueling will make things worse.

Higher exhaust pressure does not mean more response, quite the opposite is true, higher pressure on the exhaust side results in poor turbo and engine response.
Higher EMP's often does in fact equal higher egt's.

I think you meant to say "if a LESSER restriction..."

 

[Scott_DeWitt]

Higher exhaust pressure does not mean more response, quite the opposite is true, higher pressure on the exhaust side results in poor turbo and engine response.
Higher EMP's often does in fact equal higher egt's.

I think you meant to say "if a LESSER restriction..."

My goof up, you got it, Larger Turbine = Lesser Restriction....

 

[CarlUman]

If your maxing out EGT's on a VNT17VB, then a vnt17/22 with added fueling will make things worse.

If this true then what is the purpose of the 17/22 hybrid? Not a flame... just wondering what I'm missing

I thought the intent of the hybrids was to drop EGTs and allow more fuel. This is what I've been told by people that have them anyhow. The 1852 from Kerma was one I was thinking about getting.

 

[KROUT]

The vnt 17/22 is way better than just a regular vnt 17. Yes egt's can be a problem when running wot alot. But how often and how long do you use wot. I could peg my egt guage in the summer time with my old vnt17. Not really a big deal because I didn't hold it there long. I had my old vnt17 hit 1700 more than once for a few seconds did not hurt anything. It was still working great with over 100,000 hard miles on it running 24psi.

I cant hold wot for more than 10 to 15 seconds because of being well into triple digit speeds.

If your building a track car that will be runing wot for long periods this turbo is still a good option just dial back the fuel if you have egt problems. Or get a better turbo for racing. Like a vnt20.

 

[Mark@MaloneTuning]

If this true then what is the purpose of the 17/22 hybrid? Not a flame... just wondering what I'm missing

I thought the intent of the hybrids was to drop EGTs and allow more fuel. This is what I've been told by people that have them anyhow. The 1852 from Kerma was one I was thinking about getting.

You can put together a VNT-15/20 or VNT-15/22 hybrid and it still won't drop EMP/EGT significantly compared to a stock VNT-15. While the VNT-17 exhaust side is simlar to stock VNT-15, the SS1852's exhaust exducer is comparable to or larger than a VNT-20's.. the difference is enormous.

The purposes of this VNT-17/22 hybrid might be:

1. A bolt-on solution. This particular seller has not developed a bolt-on VNT-18 or VNT-20 kit yet. Kerma already has various kits available.
2. Easy to tune - remap contains same boost control as VNT-15. Some popular tuners had problems making tunes for larger turbos such VNT-20 or similar hybrids.

The VNT-17/22 is basically at the end of the VNT-15 or 17 spectrum, squeezing the last few drops of performance regardless of effciency.

IMO I'd choose a straight OEM VNT-17(VB) or, if I want more bolt-on power without EMP/EGT going through the roof after adding fuel, I'd choose a VNT-20 style bolt-on hybrid. The EMP/EGT with VNT-20+ are so nice - a fresh breath of air . It's possible to beat on it all day, including towing heavy loads up a hill (see Vanagon Syncro/4x4 TDI-R VNT-20 project in B.C.). All VNT15 and 17 turbos in stock and hybrid forms already reach EGT limit too quickly.

 

[Passenger Performance]

I gotta say, I just installed a ss1852v yesterday. Thought it was interesting. Never seen a performance turbo with the wheels and housings misaligned.

Compressor, the green fin has .023" clearance, which is normal. 180 degrees from there, there is only.010" clearance... Too tight, and misaligned.
Usually on compressor wheels to housings you machine the profiles for .020".

Heres the exhaust side:
The green fin has .041" of clearance, which isn't too bad, Usually you machine the profiles on the exhaust side for .037"-.045" depending on the application.
Now the problem once again is that about 270 degrees clockwise from the green fin there is only .027", way too tight. And crooked.

I didn't pull apart the turbo to check the complete profiles, but judging from the alignment Its likely safe to say the profiles don't match too well either.

So what does all this mean? Higher chances of turbo failure than necessary.

 

[KROUT]

That might be the reason for several turbos blowing. I'll keep my 17/22 that was set up perfect by people that have been doing turbos for a long time. I may have high emp's but it runs real, real good.

But it sure is purty. What kind of warranty do they come with.

 

[Passenger Performance]

That might be the reason for several turbos blowing. I'll keep my 17/22 that was set up perfect by people that have been doing turbos for a long time. I may have high emp's but it runs real, real good.

But it sure is purty. What kind of warranty do they come with.

Yeah within 30 minutes of posting those specs I got a couple pm's with people saying "so thats why mine blew up".

 

[KROUT]

I have talked to several people that blew turbos that were new. I just wonder if they get new ones free or if they have to buy a new one again.
I cant wait to see this thread in a few days. lol

 

[KERMA]

As the installer, if you thought there was something wrong with the turbo, you should have flagged it and got it fixed before you installed it. That would be the responsible thing to do.

just for S&G, I pulled a brand new in the garrett box vnt-17 off the shelf, hmmm will you look at this...

I gotta say, I just installed a ss1852v yesterday. Thought it was interesting. Never seen a performance turbo with the wheels and housings misaligned.

Compressor, the green fin has .023" clearance, which is normal. 180 degrees from there, there is only.010" clearance... Too tight, and misaligned.
Usually on compressor wheels to housings you machine the profiles for .020".

Heres the exhaust side:
The green fin has .041" of clearance, which isn't too bad, Usually you machine the profiles on the exhaust side for .037"-.045" depending on the application.
Now the problem once again is that about 270 degrees clockwise from the green fin there is only .027", way too tight. And crooked.

I didn't pull apart the turbo to check the complete profiles, but judging from the alignment Its likely safe to say the profiles don't match too well either.

So what does all this mean? Higher chances of turbo failure than necessary.

 

[LNXGUY]

Doesn't the shaft have a bit of wiggle room until the turbo has some decent oil pressure?

 

[Passenger Performance]

Customer was informed, he needed his car back asap. I said plan on coming back for a re&re, he understands.

That picture doesn't mean much without measurements.
For reference the pictures I posted have the shaft side to side tolerance maxed for the minimum for each measurement.

 

[Passenger Performance]

Doesn't the shaft have a bit of wiggle room until the turbo has some decent oil pressure?

Absolutely. I took up the tolerance for my measurements.

 

[Street Toys]

I gotta say, I just installed a ss1852v yesterday. Thought it was interesting. Never seen a performance turbo with the wheels and housings misaligned.

Compressor, the green fin has .023" clearance, which is normal. 180 degrees from there, there is only.010" clearance... Too tight, and misaligned.
Usually on compressor wheels to housings you machine the profiles for .020".

Heres the exhaust side:
The green fin has .041" of clearance, which isn't too bad, Usually you machine the profiles on the exhaust side for .037"-.045" depending on the application.
Now the problem once again is that about 270 degrees clockwise from the green fin there is only .027", way too tight. And crooked.

I didn't pull apart the turbo to check the complete profiles, but judging from the alignment Its likely safe to say the profiles don't match too well either.

So what does all this mean? Higher chances of turbo failure than necessary.

This CRAP has gone on too far! If there was a problem with that turbo, then why did you install it? This is another smoke and mirror trick again! Just like your magical calipers that you photografed last year. Dave take your fricking fingers off the wheel on the other side of the turbo when you are taking a picture! It is totaly impossable for a turbo to be alined in the fashion that you are trying to trick people into thinking! I've been ignoring you for months but you have crossed the line on this one buddy! I will contact the customer personaly and pay to have that turbo removed by a real mechanic and rephotografed! And if there is a defect I will also ship him one out on my dime and pay for installation or I will personaly fly out and do it myself.

Then when we see the real pictures this forum will see exactly what you are about!


And as for you Krout, where are you getting this information about blowed up turbos anyway? Do people call you up and tell you when they have a problem or what?

I am proud that the return pecentage of turbo's out of my shop is less that 2% ! There are not many turbo shops in this country that can say
that!

I invite any TDIclub member to stop by and see how turbos are manufatured out of my shop and then feel free to coment on this forum after you see the process for yourselves. Even when the larger turbo shops in the area need special tooling who do you think they contact do make it for them?

There is not a single shop in this country that warrantees a turbo like myself or KERMA does! including GARRETT.

Another question that I have for you Dave is: By your own photos that you posted of the compressor wheel, What are those marks at the six oclock position? That is/was a brand NEW wheel when it left here! It looks like to me that you struck it with a screwdriver of somthing to knock it out of ballance! How are you going to explain that one to your customer! This picture was taken before you installed it I would asssume?

 

[Passenger Performance]

This CRAP has gone on too far! If there was a problem with that turbo, then why did you install it? This is another smoke and mirror trick again! Just like your magical calipers that you photografed last year. Dave take your fricking fingers off the wheel on the other side of the turbo when you are taking a picture! It is totaly impossable for a turbo to be alined in the fashion that you are trying to trick people into thinking! I've been ignoring you for months but you have crossed the line on this one buddy! I will contact the customer personaly and pay to have that turbo removed by a real mechanic and rephotografed! And if there is a defect I will also ship him one out on my dime and pay for installation or I will personaly fly out and do it myself.

Then when we see the real pictures this forum will see exactly what you are about!


And as for you Krout, where are you getting this information about blowed up turbos anyway? Do people call you up and tell you when they have a problem or what?

I am proud that the return pecentage of turbo's out of my shop is less that 2% ! There are not many turbo shops in this country that can say
that!

I invite any TDIclub member to stop by and see how turbos are manufatured out of my shop and then feel free to coment on this forum after you see the process for yourselves. Even when the larger turbo shops in the area need special tooling who do you think they contact do make it for them?

There is not a single shop in this country that warrantees a turbo like myself or KERMA does! including GARRETT.

Another question that I have for you Dave is: By your own photos that you posted of the compressor wheel, What are those marks at the six oclock position? That is/was a brand NEW wheel when it left here! It looks like to me that you struck it with a screwdriver of somthing to knock it out of ballance! How are you going to explain that one to your customer! This picture was taken before you installed it I would asssume?

Easy pumpkin, it'll be ok.

No I did not have my finger on the other side of the wheel or any of that stuf man. I've worked in a turbo shop before, my room mate works for one of the biggest turbo manufacturers out here. We know how these things go together.
This isn't the first time I have heard of issues with these turbos with profile clearance. The turbo will run for a while, how long I am not sure.
By the way the pictures I posted really doesn't mean a whole hell of a lot, I'll be the first to admit that. Its hard to see thousandths of an inch especially with crappy cameras and stuff. I don't think my pictures really show the problem anyways. Heck the stock turbo Kerma posted looks way worse than one I posted, photos really aren't a great reference here.

It is plenty possible for the wheels to sit as they do, I've machined housings before, drilled fresh chra's etc. The only part of custom turbo machining I haven't done is wheel profiling, my friend does that for me.

The marks on the compressor wheel were there when the turbo showed up at my shop, the customer will confirm this as he mentioned to me that it came that way out of the box. It looks to me whoever balanced the wheel hit it with the die grinder by accident, it happens, a new wheel should have been put on though IMO.

Thats great you warranty your turbo's. Its your responsibility as a manufacturer. A fellow who Pm'd me a few hours back mentioned after his first 1852 went he got another, but its making the same noise his last one made before it blew.

As for showing other people turbo manufacturing processes, to the average person its all gonna look impressive, and they won't be able to tell the difference between a good way to do things or a bad way to do things.

I've installed hundreds of turbo's and plenty on race vehicles exceeding the value of 10 mk4 tdi jettas. Its NOT rocket science. Neither is machining or building them, its just takes more skill and equipment and knowledge.

Anyways take it easy man, it'll all work out, tomorrow is another day.

 

[Street Toys]

Easy pumpkin, it'll be ok.



The marks on the compressor wheel were there when the turbo showed up at my shop, the customer will confirm this as he mentioned to me that it came that way out of the box. It looks to me whoever balanced the wheel hit it with the die grinder by accident, it happens, a new wheel should have been put on though IMO.


As for showing other people turbo manufacturing processes, to the average person its all gonna look impressive, and they won't be able to tell the difference between a good way to do things or a bad way to do things.

I've installed hundreds of turbo's and plenty on race vehicles exceeding the value of 10 mk4 tdi jettas. Its NOT rocket science. Neither is machining or building them, its just takes more skill and equipment and knowledge.

Anyways take it easy man, it'll all work out, tomorrow is another day.

First of all No die grinder hit that wheel! I do not use a die grinder to remove material! And NO wheel ever left my shop looking like that! Everyone here knows that you have a problem with KERMA, that is not a secret. However malicously causing damage to a part that cost over a thousand dollars to make KERMA look bad and you think this might make you look good is not a good idea! I'll bet you are going to get a lot of people knocking your door down to ask you to install thier turbo,huh?

So, the average person might be impressed when they see how a turbo is built? Because no one is as smart as you to know the corect way to do this? Well, Maybe you might like to come out and take the tour? Utah is beautiful this time of year. People drive hundreds of miles to come see the leaves change colors.

 

[Passenger Performance]

First of all No die grinder hit that wheel! I do not use a die grinder to remove material! And NO wheel ever left my shop looking like that! Everyone here knows that you have a problem with KERMA, that is not a secret. However malicously causing damage to a part that cost over a thousand dollars to make KERMA look bad and you think this might make you look good is not a good idea! I'll bet you are going to get a lot of people knocking your door down to ask you to install thier turbo,huh?

So, the average person might be impressed when they see how a turbo is built? Because no one is as smart as you to know the corect way to do this? Well, Maybe you might like to come out and take the tour? Utah is beautiful this time of year. People drive hundreds of miles to come see the leaves change colors.

Ok well I don't know what it was, the customer will confirm that the wheel looked like that before it came to my shop. I would never sabotage someones work. So please get the facts straight it was like this before I ever saw it, before it came to my shop, before I knew I was installing it.

You have me all wrong man, I don't why you keep saying I think I'm the only person that knows how to do this stuff, pretty much all my friends are involved in auto performance manufacturing one way or another.

I actually would like a tour, I love machinery and manufacturing machines and processes. I've been meaning to go snowboard in Utah for a while if I ever do I'll give you a shout.

 

[DbLog]

My first VNT20 had a problem when I was trying the Aligator tune and Charlie sent me a new one. When I was tracking in Virginia (with the second vnt20) there was white smoke and the car lost a litre of oil. I thought I blew my turbo. Charlie was going to give me $150 for the core. The problem was actually high EGT's and my faulty return line. Yeah I know it's my fault I made it but it looks better than the one that came with the kit. Right now the turbo is boosting 35psi+. I haven't had a chance (or the nutz) to pull it apart and clean the vanes. It's gonna be my first time and would really like someone to give me a hand. So is my VNT20t under warrenty? It's maybe 6 months old. Or are only Aligator tunes under warrenty?

There is not a single shop in this country that warrantees a turbo like myself or KERMA does! including GARRETT.

 

[oldpoopie]

By the way the pictures I posted really doesn't mean a whole hell of a lot, I'll be the first to admit that. Its hard to see thousandths of an inch especially with crappy cameras and stuff. I don't think my pictures really show the problem anyways. Heck the stock turbo Kerma posted looks way worse than one I posted, photos really aren't a great reference here.

Dave, then why post them????
As for people blowing multiple turbos, I find that usually, when the same parts are failing repeatedly in short order, its usually caused by something else....
In this case, I'd bet the mystery person has a bad oil feed or return, bad air filtration (FOD), didnt ensure clean intercooler and piping (again FOD) or a tuning or boost controll issue..... That, and abuse......

 

[Passenger Performance]

By the way the pictures I posted really doesn't mean a whole hell of a lot, I'll be the first to admit that. Its hard to see thousandths of an inch especially with crappy cameras and stuff. I don't think my pictures really show the problem anyways. Heck the stock turbo Kerma posted looks way worse than one I posted, photos really aren't a great reference here. [\quote]

Dave, then why post them????
As for people blowing multiple turbos, I find that usually, when the same parts are failing repeatedly in short order, its usually caused by something else....
In this case, I'd bet the mystery person has a bad oil feed or return, bad air filtration (FOD), didnt ensure clean intercooler and piping (again FOD) or a tuning or boost controll issue..... That, and abuse......

If I didn't post pics, I would have been harassed about not posting pics.
I agree about the short term failure issues like oil lines etc. The people that contacted me with failures were after about 5-10k though.

 

[oldpoopie]

Easy pumpkin, it'll be ok.

And you cant call someone out and then poo poo them when they react.

Still, if they had problems, they need to make themselves heard, not you...

My parents always crushed my childhood arguments whenevery I talked about They and Them.

2nd hand They and thems are just inflamatory and dont carry any real weight. Its propaganda.

If there are real problems, then those people need to come forward so that the issues can be resolved. Not secretly wispered about

They and Them need to translate into real people to carry any weight.

 

[Rub87]

If I look at the compressor I must say I've never seen a new garrett turbo out of the box with that much clearance between the wheel and housing..

Here's a bad pic of my vnt20, but the difference is clearly noticeable..

 

[Scott_DeWitt]

And you cant call someone out and then poo poo them when they react.

Still, if they had problems, they need to make themselves heard, not you...

My parents always crushed my childhood arguments whenevery I talked about They and Them.

2nd hand They and thems are just inflamatory and dont carry any real weight. Its propaganda.

If there are real problems, then those people need to come forward so that the issues can be resolved. Not secretly wispered about

They and Them need to translate into real people to carry any weight.

Excellent point! How about someone start a new thread to discuss turbo failures. There have already been a few documented within these forums.
PP- those people that pm'd you mind asking them to post?

 

[KROUT]

And as for you Krout, where are you getting this information about blowed up turbos anyway? Do people call you up and tell you when they have a problem or what?

I am not looking to get into a pissing match with anyone. Yes I have gotten a few pm's about new turbos blowing the rest I read about in the forums. I could give names but wont. I could care less what hapens to your turbos as I do not use them. Stuff happens, especialy in high performance aplications.

 

[jsrmonster]

I could name a dozen folks who blew-up new (ummm aftermarket reman) turbos and got replacements shipped back. Why would they come here and complain, it would be like biteing the hand that feeds them. 2% return rate, I wouldn't even go there. Keep up the good customer service and all will be happy, regardless. It is always blamed on the careless installer, or the tune, so that's that!

 

[Passenger Performance]

Sorry Oldpoopie and Scott, I will try and have better manners next time.
We'll see if the people who pm'd me post up, one mentioned hes a bit fearful of saying something as he think he may have a harder time getting another replacement when his current one blows.