Intercooler

[FB-GTI]

Are we going to argue pressure drop? I have 5 PSI drop with my ARM FMIC according to mygolfmk7.com, wastegate duty had enough left over for me to crank up to 20PSI on my IS12. Can't see how a higher flowing turbo would fare any worse.

Or are we talking EGT turbo side because of pressure drop that we don't have a sensor to measure?

Not picking sides, just curious what the logic is here.

Assuming the 5 psi drop is correct, you cranked the boost up to 25 psi, not 20 psi.

Here is one of my logs from my JB4. This is on Map 3 with a 6psi max increase. Am I losing boost somewhere? I'm hitting all my target boost.

https://datazap.me/u/exgokin/log-1602305606?log=0&data=1-2-3-4-6-11-14-18

Having a pressure drop doesn't mean the ECU fails to hit the target boost pressure. It causes an increase in the pressure required at the turbo. That isn't being measured so your log won't show what it is. If the boost level at the intake manifold is 16 psi, and the NS IC causes 5 psi of pressure drop (just guessing with the 5 psi StorableComa referenced) then your turbo needs to boost to 21 psi.

The higher the pressure gets, the greater the air temperature. So it's generating more heat that the IC has to get rid of. Higher pressure also requires the turbocharger to spin faster. That's why people look at the wastegate duty cycle to see if it rises.

The final result on how your car drives may not change much, it's just a matter of it operating less efficiently than it could with a different IC. If the tune is pushing the turbo near its limit, which is unknown since there aren't maps for the IS20 and IS38, perhaps that's 25 psi, and if you have 5 psi of pressure drop then you're really operating at 30 psi, and if that's fast enough to reduce the life of the turbo, well, you're reducing the life of the turbo.

 

[StorableComa]

At 25 PSI my IS12 should pop. That's way over the intended speed. It might as well be an IS20 at that point. They spin at 10 PSI stock and stage 1 only bumps them to 15-16 PSI.

I think people put way too much stock into partial calculations too. Pressure drop is a bigger concern at altitude as well. Relative pressure has to be considered. Anyhow, again. If an IS12 can cope with it, higher flowing turbos more than likely won't bat an eye at their flow rates.

 

[ShagginGSW]

That's why people look at the wastegate duty cycle to see if it rises.

So this, like @StorableComa said, seems to show the opposite of what you are saying about the pressure drop, or maybe testing the way mygolfmk7 does introduces pressure drop. I don't know but if @StorableComa saw his WGDC looking good enough to turn it up then the pressure drop must not have been an issue, if I am understanding correctly.

 

[FB-GTI]

At 25 PSI my IS12 should pop. That's way over the intended speed. It might as well be an IS20 at that point. They spin at 10 PSI stock and stage 1 only bumps them to 15-16 PSI.

I think people put way too much stock into partial calculations too. Pressure drop is a bigger concern at altitude as well. Relative pressure has to be considered. Anyhow, again. If an IS12 can cope with it, higher flowing turbos more than likely won't bat an eye at their flow rates.

I checked on the ARM number and it was reported to be 4 psi.

Stock setups are usually selected to operate through the center of a compressor map, where efficiency is maxed. How you are operating may or may not be exceeding the maximum, but even if it is past the maximum, that doesn't mean it's going to instantly fail.

I'm not following the reference to partial calculations. I agree that as elevation increases the speed that the turbo operates at becomes greater.

So this, like @StorableComa said, seems to show the opposite of what you are saying about the pressure drop, or maybe testing the way mygolfmk7 does introduces pressure drop. I don't know but if @StorableComa saw his WGDC looking good enough to turn it up then the pressure drop must not have been an issue, if I am understanding correctly.

He said there was still room to increase the wgdc further, that doesn't contradict what I'm saying. I'm pointing out that an indication of increased pressure drop is a higher wgdc. If he went a replaced the ARM FMIC with something like the Wagner or do88 the wgdc would decrease some amount.

 

[ShagginGSW]

He said there was still room to increase the wgdc further, that doesn't contradict what I'm saying. I'm pointing out that an indication of increased pressure drop is a higher wgdc. If he went a replaced the ARM FMIC with something like the Wagner or do88 the wgdc would decrease some amount.

I must be confused as usual. The way I read it was that he installed the ARM FMIC, which is said to have a 5PSI pressure drop, and yet his WGDC showed he could turn up the boost. Which is why I said it seemed to contradict what you were saying about the pressure drop increasing the WGDC.

 

[ShagginGSW]

At 25 PSI my IS12 should pop. That's way over the intended speed. It might as well be an IS20 at that point. They spin at 10 PSI stock and stage 1 only bumps them to 15-16 PSI.

I think people put way too much stock into partial calculations too. Pressure drop is a bigger concern at altitude as well. Relative pressure has to be considered. Anyhow, again. If an IS12 can cope with it, higher flowing turbos more than likely won't bat an eye at their flow rates.

Do you have charge air temps to show that the ARM didn't raise them, which would indicate your turbo spinning to the moon.

 

[StorableComa]

Do you have charge air temps to show that the ARM didn't raise them, which would indicate your turbo spinning to the moon.

EGTs are a modeled number on mk7s. We don't have an EGT sensor near the upstream o2. The only accurate number we have is IATs. I've got plenty of logs that show IATs drop quicker and longer than stock, resists heat soak longer than stock.

No, an overspun turbo isn't going to instantly pop, but at 20 PSI an IS12 is already at the far end of its efficiency range.

Again you've got to take elevation into account as well. Relative pressure will have a bigger effect on how much the turbo struggles. Its easier at sea level to make up a 5PSI loss than say in Denver.

I haven't paid too much attention to his charts outside size comparison and some of his ARM FMIC post. I know when he tried to use the ARM as a bicooler it didn't work.

Didn't he do H2O flow rate, or was it air resistance?

Anyhow, his street data with the charge air temps.
http://mygolfmk7.com/2020/10/arm-fmic-street-data/

 

[StorableComa]

I checked on the ARM number and it was reported to be 4 psi.

Stock setups are usually selected to operate through the center of a compressor map, where efficiency is maxed. How you are operating may or may not be exceeding the maximum, but even if it is past the maximum, that doesn't mean it's going to instantly fail.

I'm not following the reference to partial calculations. I agree that as elevation increases the speed that the turbo operates at becomes greater.


He said there was still room to increase the wgdc further, that doesn't contradict what I'm saying. I'm pointing out that an indication of increased pressure drop is a higher wgdc. If he went a replaced the ARM FMIC with something like the Wagner or do88 the wgdc would decrease some amount.

He reported 5 in the comparison to the vibrant core. 4 must be based on his flow charts from another post.

Charge air pressure on a IS38 with his street data.
http://mygolfmk7.com/2020/10/arm-fmic-street-data/

http://mygolfmk7.com/2020/09/arm-motorsports-fmic-flow-test/

http://mygolfmk7.com/2020/12/arm-fmic-bicooled/

http://mygolfmk7.com/mk7-gti-intercooler-test/

 

[mrmatto]

The only accurate number we have is IATs.

About that... https://mygolfmk7.com/2020/07/iat-sensor-lies/

 

[StorableComa]

About that... https://mygolfmk7.com/2020/07/iat-sensor-lies/

Eh, I think he is stringing things out a bit here. Temps being higher while cruising is normal. You're not in boost and moving no air through the charge pipes or IC. It's stagnant almost. You'll only see temp changes once you're moving air at about 7PSI plus through the system regardless of how much airflow is passing through the cooling stack.

 

[mrmatto]

Eh, I think he is stringing things out a bit here. Temps being higher while cruising is normal. You're not in boost and moving no air through the charge pipes or IC. It's stagnant almost. You'll only see temp changes once you're moving air at about 7PSI plus through the system regardless of how much airflow is passing through the cooling stack.

I think you're completely missing the point. Temps are NOT actually higher when you're not in boost. It's very clear from the IC_OUT data that the intercooler is ALWAYS cooling the air, even when you're out of boost and just cruising. So the issue is people judge intercooler performance by how much IATs drop when they go WOT. As we can see, that "drop" is almost entirely due to faulty IAT readings. And even after a long pull, the IAT reading sometimes still has only just barely reached the IC_OUT temp. That's not to say the IAT readings are unusable, but they're far from perfect and shouldn't be relied on as the only data point.

 

[Subliminal]

What’s the best intercooler for a mk7 gti? Looking to go stage 2.

G-Plus bicooler.

why? because it's what's on my car. /thread

 

[mrmatto]

G-Plus bicooler.

why? because it's what's on my car. /thread

I mean, that's basically it, because almost every aftermarket cooler dramatically outperforms the stock one.

 

[StorableComa]

I think you're completely missing the point. Temps are NOT actually higher when you're not in boost. It's very clear from the IC_OUT data that the intercooler is ALWAYS cooling the air, even when you're out of boost and just cruising. So the issue is people judge intercooler performance by how much IATs drop when they go WOT. As we can see, that "drop" is almost entirely due to faulty IAT readings. And even after a long pull, the IAT reading sometimes still has only just barely reached the IC_OUT temp. That's not to say the IAT readings are unusable, but they're far from perfect and shouldn't be relied on as the only data point.

To me this seems easily explainable by thermal principals. You're pushing no compressed air, and the hot side pipe is just that.. hot and tucked against the engine. Cold side isn't, and I'd like more info on his probe and placement.

It's a metal body probe in the middle of the cooling stack airflow from his picture.

I never said they were the only data point. But when compared to EGTs, IAT is not a modeled number, it's a direct reading.

For pressure drop EGTs is what you want to worry about. How hard the turbo is spinning and how much heat it's throwing out, not IATs anyhow.

 

[Daks]

I think you're completely missing the point. Temps are NOT actually higher when you're not in boost. It's very clear from the IC_OUT data that the intercooler is ALWAYS cooling the air, even when you're out of boost and just cruising. So the issue is people judge intercooler performance by how much IATs drop when they go WOT. As we can see, that "drop" is almost entirely due to faulty IAT readings. And even after a long pull, the IAT reading sometimes still has only just barely reached the IC_OUT temp. That's not to say the IAT readings are unusable, but they're far from perfect and shouldn't be relied on as the only data point.