Intercooler performance

[GTI_Owner]

So I know it effects it because I’ve experienced it but you need me to prove it.

The easy answer would be to tell you to google it, as several others have explained the “why” you’re seeking.

Excessive drive pressure defeats the scavenging effects of valve overlap this hurting the engines efficiency, which requires more boost to accomplish the same power and thus higher EGT.

Hopefully that makes sense, and I’m once again able to pick engineers out of a crowd retaining my 100% accuracy rating on that.

A decent explanation will suffice, you don't need to prove it, but a little more than saying "believe me" is helpful.

To the point you make here, I don't disagree except with the logic in saying "which requires more boost to accomplish the same power." The exhaust pressure increase isn't causing IAT to increase, it's causing a drop in VE, that leads to a power drop, and then a decision is made to increase boost pressure to try and regain the lost power. The exhaust pressure isn't causing the IAT to rise.

 

[GTI Jake]

A decent explanation will suffice, you don't need to prove it, but a little more than saying "believe me" is helpful.

To the point you make here, I don't disagree except with the logic in saying "which requires more boost to accomplish the same power." The exhaust pressure increase isn't causing IAT to increase, it's causing a drop in VE, that leads to a power drop, and then a decision is made to increase boost pressure to try and regain the lost power. The exhaust pressure isn't causing the IAT to rise.

The tune isn’t written to seek a set boost pressure, it’s after a calculated torque so there’s no decision made.

If you tune at sea level on a dyno that isn’t loaded properly you could see 500whp at 30psi. Take a drive and make 32 psi on the street, then at higher elevation make 34psi and still fall short of what the ECU is tuned to make

 

[GTI_Owner]

Right, there's a target torque value and the ECU programming (multiple decision trees) manipulates boost, timing, and AFR to reach that target.

In your example of the car going to higher elevation, what is causing the boost pressure to rise? It's not increasing simply by going up in elevation, the ECU controls the turbo to spin faster. That's what I'm calling a decision, there's not a natural cause and effect happening.

 

[anotero]

I saw roughly a 3-5% gain in WG duty after install of the IC on my IS20. It’s insignificant enough that it could be chalked up to ambient temperature difference.

My WG duty while running the hybrid has been fine.

Gain as in the wastegate closes 3-5% less?

 

[Navi]

 

[PowerDemon]

Gain as in the wastegate closes 3-5% less?

It’s more closed, not less.

 

[anotero]

It’s more closed, not less.

I thought the more it's closed, the more the turbo is trained, needing all that exhaust to spin the compressor wheel to build boost.

 

[PowerDemon]

I thought the more it's closed, the more the turbo is trained, needing all that exhaust to spin the compressor wheel to build boost.

That’s exactly what it means.

 

[anotero]

That’s exactly what it means.

I was getting hung up on the assumption that ICs should lower wastegate duty. I understand what you said before now.

 

[shortyb]

I was getting hung up on the assumption that ICs should lower wastegate duty. I understand what you said before now.

I am a super green newb when it comes to knowledge of this subject, but if you base that on flow of a cooler at a standardized measurement, then yeah. Stands to reason that a freer flowing IC will lower the need for a turbine to close the WG more to produce a seen pressure. However, there are lots more variables in the voodoo-science of intercooled turbo cars than that obviously. According to Jeff's chart, the Vibrant flows a bit less than an OE GTI cooler (168 vs. 195 cfm @ 28 inches of water), but will throw stones at the GTI one in terms of overall performance, especially in the area of heat shedding abilities. Thats where you need to find the balance and what works on your car. Tough to do in reality.

Want a head scratcher? I'm using a Neuspeed IS38 IC, admittedly one of the shittiest flowing ones out there. But I'm pushing 28 psi on an IS20, while achieving 10 + ambient WOT with only a mid-high 70s turbine actual final. Can you say WTF??

 

[Diggs24]

Never hurts to look things over....

https://www.golfmk7.com/forums/inde...ive-custom-etune.350616/page-152#post-7436501

 

[PowerDemon]

Never hurts to look things over....

https://www.golfmk7.com/forums/inde...ive-custom-etune.350616/page-152#post-7436501

Been meaning to do that too but I realllyyyyy don't wanna pull the bumper off again...

 

[anotero]

I am a super green newb when it comes to knowledge of this subject, but if you base that on flow of a cooler at a standardized measurement, then yeah. Stands to reason that a freer flowing IC will lower the need for a turbine to close the WG more to produce a seen pressure. However, there are lots more variables in the voodoo-science of intercooled turbo cars than that obviously. According to Jeff's chart, the Vibrant flows a bit less than an OE GTI cooler (168 vs. 195 cfm @ 28 inches of water), but will throw stones at the GTI one in terms of overall performance, especially in the area of heat shedding abilities. Thats where you need to find the balance and what works on your car. Tough to do in reality.

Want a head scratcher? I'm using a Neuspeed IS38 IC, admittedly one of the shittiest flowing ones out there. But I'm pushing 28 psi on an IS20, while achieving 10 + ambient WOT with only a mid-high 70s turbine actual final. Can you say WTF??

Lol at the last part.

 

[anotero]

Been meaning to do that too but I realllyyyyy don't wanna pull the bumper off again...

It's one of the easiest manipulations on this car. Imho, of course.

 

[mk7_bk]

hmm, kinda hard to crack the metal piping on jakes kit... tehehe