Sounds like we need a kit for measuring EMP!

[chapelhill]

From what I am reading we need to take measurements of EMP, then we will really understand the limitations of the hot side of our Turbo's. If a vendor starts selling a kit to go from a plate on the egr port, I will buy one otherwise we will end up spending hours getting the right bits. I have the TDI turbo pressure gauge with separate MAP sensor.
We only need to monitor this whilst we set up the turbo, so we can probably get away with measuring either MAP or EMP.

I have a wastegate turbo and would like to see EMP to try and make a judgement if a hybrid would give a definative improvement or exacerbate and EMP problem. (Wastegate route is somewhat convoluted and limited on size on my k14.)

Anyone else interested?
Regards
Chapelhill.

 

[devonutopia]

I'm aware of this too, but I believe that as long as the pre-engine side of the turbo is doing fine (and I have a gauge to keep an eye on that) generally EMPs follow suit. I think having a good downpipe and exhaust system helps to keep EMPs down, but I might be wrong on that. I put my faith in a well designed hybrid turbo and a tuner with years and years of diesel tuning experience.

 

[Street Toys]

You are correct Chapelhill, I made one that was fairly inexpesive . If you look at the photo on Kermatdi.com "s home page you can see it there. I'm sure that it would not be to difficult for most people to fabricate however if you contact them I would be happy to make you one

 

[joevat]

yes i want 1 too.

 

[weedeater]

ElectroMagnetic Pulse measurements? hmmmm.....

 

[n1das]

ElectroMagnetic Pulse measurements? hmmmm.....

Exactly my first thought too since I'm an EMI/EMC Engineer.

Anything to help lower lower backpressure in the exhaust system like a mufflerectomy and/or larger pipe diameter is probably not a bad thing to do to help lower EMPs and keep turbo temps down.

 

[ecodean]

Does anyone know what the pressure range for the EMP would be?

 

[Passenger Performance]

Does anyone know what the pressure range for the EMP would be?

Get a gauge that reads 0-60 for these turbos and engines, if its anything over that you have issues. Generally you want to strive for a 1:1 drive ratio. Meaning if you have 28 psi of boost in your intake manifold, you want 28 psi of pressure in your exhaust manifold, less is better but is difficult to achieve without better manifolds and exhaust wheels. That said its not uncommon (yet still undesirable) to see a ratio of 2:1, (56psi n the exhaust side, 28psi in the intake).

 

[hatemi]

With VNT turbos its normal that the inital spike will be much higher than the boost at that time. After the vanes open the EMP will dorp significantly. With my hybrid the initial spike was to ~2.5bar and when the vanes openned it dropped to ~0.7bar. Then it started to rise from that and it was 1.9bar with 1.9bar boost @5k. That sounds pretty good to me.

Making one could not be any easier. You need an EGR block of plate but you can make one yourself from a piece of metal. You need a drill bit and maeby even a tools to make threads to it. Or you can just weld a short piece of metal tube to it. I have used copper and silver brazing and it has held so far. After the short metal piece you can use rubber hose to your gauge.

 

[shadowmaker]

I'm aware of this too, but I believe that as long as the pre-engine side of the turbo is doing fine (and I have a gauge to keep an eye on that) generally EMPs follow suit. I think having a good downpipe and exhaust system helps to keep EMPs down, but I might be wrong on that. I put my faith in a well designed hybrid turbo and a tuner with years and years of diesel tuning experience.

WRONG!

With VNT things are more complicated than can be expected by just reading boost gauge. You need to know EMP vs. boost to understand what's going on in the engine. With heavy modified engine this is crucial.

I use EMP gauge only while remapping, otherwise it is IMO useless.

 

[hatemi]

Remapping and fine tunign the turbo are the most common situations you need one. EGT alone is way too slow and inacurate way measuring whats realy happening in there. The gauges look pretty but I havent found them usefull at all. Boost and EMP is all you need. EGT is secondary.

 

[hgeittmann]

EMP will buzz much worse than Boost too, so get a nice gauge for it. I just had the EMP pressure line on my dash, plugged and not hooked up to a gauge, and it buzzed/snapped and jumped all over the place. I removed it once I was satisfied with the measurements because it was simply annoying. EMP/Boost ratio stayed pretty constant depending on the applied load.

 

[Fix_Until_Broke]

I just got the parts together for mine - will try to play around with it this weekend. I think I've got a 60 psi glycerin filled gauge to play around with which should work fine.

 

[LNXGUY]

With VNT things are more complicated than can be expected by just reading boost gauge. You need to know EMP vs. boost to understand what's going on in the engine. With heavy modified engine this is crucial.

You mean EMP with IMP correct? Measuring boost from a IC tube isn't the same as actually taking the reading from the intake manifold....

 

[LurkerMike]

Please make a dash pod that surrounds the OEM Jetta driver's cluster "hump".

I'm thinking this location would not be in the way of the airbags like the A-pillar "Instruments of Death" pods will do when the bags fire.

Give me maybe three round holes to the left and 3 round holes to the right with a rectangle slot top and center for a Scangauge.

Make mine, EGT, EMP, Boost Pressure, Boost Air Temp, Oil Pressure and something or another that escapes me at the moment.

 

[Fix_Until_Broke]

I think ideally we'd look at the differential between Exhaust and Compresor pressures. I brought this up a while ago and it was not thought to be very useful. It seemed like it in my simple mind, but the thoughts of those in that thread were to look at the efficiency maps. I think the efficiency maps are great, but we still don't know where we are at on the map unless we take some of these measurements.

Mabye there are some different thoughts now?

I can get a differential pressure gauge that will read both positive and negative so we don't have to try and subtract two gauges from each other.

 

[LNXGUY]

Doing math while flying down the road

 

[shadowmaker]

You mean EMP with IMP correct? Measuring boost from a IC tube isn't the same as actually taking the reading from the intake manifold....

Yep. That's the way to do it. Actual boost pressure is always taken from the IM.

 

[LNXGUY]

Yep. That's the way to do it. Actual boost pressure is always taken from the IM.

I've been doing some reading as of late and the standard acceptable range is 2:1 for EMP/IMP. So If I am boosting 25psi, it's acceptable to have 50psi at the turbine? (Is it that simple?) I also found some interesting facts about IMP being higher then EMP, go figure the mid 80's F1 cars were making 1000hp out of 90 cubic inches

 

[hgeittmann]

That sounds like Corkey Bell...

 

[Stealth TDI]

Funny thing is I thought of measuring EMP at my EGR port as well. And, until now, I thought I was being clever! What I'm not grasping is how you'd connect the gauge. Wouldn't the manifold be too hot to allow the use of regular gauge fittings? It would seem any hose with rubber would simply melt. Thoughts?

 

[Street Toys]

Funny thing is I thought of measuring EMP at my EGR port as well. And, until now, I thought I was being clever! What I'm not grasping is how you'd connect the gauge. Wouldn't the manifold be too hot to allow the use of regular gauge fittings? It would seem any hose with rubber would simply melt. Thoughts?

Thats why I use over 36 inches of copper tubing secured at both ends to eliviate any chances of the tubing to crack because of viberations. Rolling it in a coil acts as a "cooler" for the gasses and allows fitment for the tube to the guage. This installation however is not meant to be a permanent fixture as the time you only need this is during installation and tuning. once you've achieved correct ballance then the guage is not really usefull to monitor on a constant basis as per oil pressure or boost. However, some folks like to have more guages and switches and lights on thier dash, if your one of these guys then you can leave it in.
I hope I didn't offend the truck drivers on this forum
If you want to monitor the real pressure on a stock 15 or a 17 or 17hybrid then I would suggest that you get a guage that reads 80lbs ! I think that you will really be amazed at the results!

 

[hatemi]

20cm of 6mm or 1/4 inch copper tube is more than enough for the exhaust manifold end. The rubber hose wont heat that much after that short metal pipe if the hose isnt leaking somewhere. If you use thinner tube like some 1/8 capillary or smaler then then you can use unbuffered gauges and it wont rattle and jump that much.

I would instruct keeping the boost and EMP as close as 1:1 as possible. The initial spike at the beginning is common for VNT turbos but after the vanes open the EMPs should be the same or bellow the IMP. That cant be achieved with commonly fitted turbos but if you want to achieve real power and engine that will stand the abuse then you need to sacrifice some of the low RPM responsiveness and use something larger than VNT20

 

[LNXGUY]

That sounds like Corky Bell...

You got it. Hopefully it doesn't sound like I am trying to pass off his thoughts as my own, but man he has all kinds of answers to even the stupidest questions (Which works REALLY good for me, lol)

 

[hgeittmann]

If you use thinner tube like some 1/8 capillary or smaler then then you can use unbuffered gauges and it wont rattle and jump that much.

I used 4mm tubing and it was like listening to a bowl of rice crispies.

I've got a question now that might actually add something to this discussion... I logged EMP/MAP for 3rd gear WOT runs w/ oem and tune, both had very similar profiles and at full boost both tunes showed EMP/MAP of 1.6 (never greater than 2 and never less than 1, but my turbo is the ordinary PD130 variety). OEM peak boost was 15psi, tuned peak boost is 24psi. I collected the data and then thought 'oh, well that's interesting.' but still don't really understand the implications of it.

Since everyone has mentioned that EMP is useful mainly when developing the tune, what aspects of the tuning affect EMP/MAP? Would this indicate that the tune could be improved, or does it depend on the rest of the exhaust system too? How does one go about using the information to improve performance?

 

[Fix_Until_Broke]

Results of my setup here - see post #76

 

[LurkerMike]

However, some folks like to have more guages and switches and lights on thier dash, if your one of these guys then you can leave it in.
I hope I didn't offend the truck drivers on this forum

My dream car's instrument panel...

 

[Street Toys]

My dream car's instrument panel...

Whaaat? You really can't be serious now, come on...I've been looking at that dash and NOWHERE can I find the windshield washer fluid temp guage!

 

[chapelhill]

My supposition of the measurements to the meaning is this:
The ratio of EMP/MAP gives an indication of efficiency of the Turbo and as you approach max power rpm an indication if the turbine is reaching its flow limits.
eg: hgeittmann with 1.6:1 on a PD130 turbo. and fix until broke with 1:1 on a 17/22 hybrid. (We also need to bear in mind fix until broke has a very free flowing exhaust.) What we are particularly interested in is how the ration varies approaching the max power rpm, which is the maximum flow condition.

We need more comparitive information (Sketch of the graph of EMP, MAP and rpm) alongside better interpretation from people who know these turbos which I don't have incl max power for the vehicle.

With the limited information I see here I would say that the PD130 with its exhaust is already showing signs of being at the bottleneck point with just the OEM tune (Would neeed to see the EMP against rpm to comment on efficiency) and that 17/22 would appear to have quite a bit of flow capacity left at that power level (?) and be an effecient turbo.

Just my very limited theoretical opinion to stir up some discussion!

 

[Rub87]

Repost of my measurements.. maybe some input..

Measured my emp with the vnt20..

Boost is greater than egt from 1900 till 3600rpm..

At 4000rpm emp is around 2.1 bar, it peaks at 2.3bar at 4200 and then it falls again..

When flooring in 5th at low rpm it surges at 1700rpm, then emp is around 1.6-1.7 bar and boost around 1.5bar..

I also noticed that in the lower grears, 1,2 and 3rd emp's peak pretty high.. is this normal?

Can I conclude that the turbo is choking aboude 3600-3800rpm when askin 1.7-1.75 var of boost?