Intercooler performance

[billbadass]

Drive high pressure is a major strain on internals and after a certain point becomes a major restriction on flow on the hot and cold side.

Think of a engine like a simple pump. If the outlet is clogged efficiency goes out the window.

“Drive Pressure” is the opposite of Boost. It’s the pressure between the valves and the turbine disk (hot side of the turbo). In a perfect turbo application boost is equal to drive pressure (1:1 ratio).

Hybrid turbos are probably more like 1:4 at 550whp

Take a step back and look at what I’m pointing out. Boost onset starts a downward trend in IAT. In a balanced set up (properly sized turbo and Intercooler) after onset the IAT value should continue to drop until a certain point and level off. If the trend switches directions and IAT climbs its because the heat exchanger has been overwhelmed and is becoming heat soaked.

None of these replies are aimed at anything other than my explanation based of experience. Please, nobody take my dry way of spelling things out as an attack of any kind lol

Regardless if we’re talking about a heat exchanger on an aircraft or a mk7 climbing numbers aren’t “good”

ok got it, so you're just saying that these engines and the hybrid turbos are each inherently inefficient in many ways, and we know the heads on them flow like shite so once we start stuffing >600 crank horsepower worth of air through them, using these inefficient hybrid turbos, that we start having backpressure and and drive pressure and all sorts of issues. That makes sense also in that the guys who get professional port jobs on MQB heads see some pretty serious gains.


seems like the best bandaid is probably to just run E85 so the motor is less sensitive to IATs and to keep combustion temps down as much as we can.

I wonder if the 500+hp MK7 setups should also be running even colder spark plugs than we all do anyway. I've seen some of the nitrous street cars daily drive on very cold plugs without issues

I personally have seen the fuel distribution issues between cylinders with my own eyes on methanol and don't like that option, especially when considering the other issues you can have with the kits themselves.

 

[billbadass]

I’m saying even one of the largest and the best flowing direct replacement is having trouble with high horsepower hybrids

https://mygolfmk7.com/2020/03/do88-intercooler-flow-test/

http://mygolfmk7.com/mk7-gti-r-intercooler-comparison/

What I’m saying is I don’t believe IE going bigger is going to make a significant difference.

GTI _Jake - I'm curious given what you've seen, that if you had to choose an OEM location intercooler which one you'd choose?

 

[oddspyke]

Boost pressure is what produces more mass flow.

You missed the whole point of the post and that was literally the next sentence after the one you bolded. Removing downstream restrictions (i.e. the heads) increases mass flow without increasing pressure. At power levels over 400+ HP, I think that's the better answer than continuing to push the turbo harder, generate too much heat, and try to compensate with a larger intercooler.

 

[Diggs24]

Not Jake, but I'd pick any of the 3 in the middle (Uni, APR, Mishi).

http://mygolfmk7.com/2020/04/mishimoto-intercooler-flow-test/

Unitronic (when on sale) is the best deal. Would also pick AMS but those are $$$$. I also have no qualms with my IE but some do so I dunno. It should be cheaper than it is.

 

[billbadass]

Not Jake, but I'd pick any of the 3 in the middle (Uni, APR, Mishi).

http://mygolfmk7.com/2020/04/mishimoto-intercooler-flow-test/

Unitronic (when on sale) is the best deal. Would also pick AMS but those are $$$$. I also have no qualms with my IE but some do so I dunno. It should be cheaper than it is.

Thanks, I placed an order for APR (2 week backorder)

but then the Do88 one looks really interesting also since has much less pressure drop but then it looks like their strategy is to make up for the IAT negative of less dense core with a larger core itself. tempted to cancel my APR and try the Do88 one

 

[Diggs24]

I wouldn't.

 

[aaronc7]

At around the 350 400 hp level, a 20 degree increase in IAT has a bigger negative impact on charge air density vs 1 psi loss. And we're only talking about a fraction of a psi difference between best and worst intercoolers that were tested. Physics ftw.

 

[Diggs24]

1. You have no idea how it fits. APR fits like a glove.
2. Does it cool well? Sure it flows well but can it cool? I've seen one of those knockoff ebay ones (don't recall which one as there are quite a few now) that did a piss poor job of an IS20 on JB4. Piss poor. Wasn't much better than stock. I bet it flowed well though. Do you really think do88 found magic? I don't. If I'm getting direct fit and I have to decide flow vs cooling I pick cooling. Front mount? I lean towards flow.

Unfortunately there is only flow data here so no way to say how these things cool. We know that these in the middle perform well in such that we have track data to show it. I mean if pacdawg can get his Tomioka Uni IC car to run 10.8@128 it must be doing just fine. Pretty sure the 9 second APR car runs an APR IC. The Puerto Rican 9 second R guy runs an AMS. Go with what is known.

 

[billbadass]

1. You have no idea how it fits. APR fits like a glove.
2. Does it cool well? Sure it flows well but can it cool? I've seen one of those knockoff ebay ones (don't recall which one as there are quite a few now) that did a piss poor job of an IS20 on JB4. Piss poor. Wasn't much better than stock. I bet it flowed well though. Do you really think do88 found magic? I don't. If I'm getting direct fit and I have to decide flow vs cooling I pick cooling. Front mount? I lean towards flow.

Unfortunately there is only flow data here so no way to say how these things cool. We know that these in the middle perform well in such that we have track data to show it. I mean if pacdawg can get his Tomioka Uni IC car to run 10.8@128 it must be doing just fine. Pretty sure the 9 second APR car runs an APR IC. The Puerto Rican 9 second R guy runs an AMS. Go with what is known.

good points, I don't like reinventing the wheel anyway. I'm not running a big hybrid and probably never will either.

Do88 website has both pressure drop., and IAT data from a 0-210km/h run comparing theirs vs Wagner but that's not a real high bar on the IAT side since Wagner does not cool that well from what I've seen anyway

https://www.do88.se/en/artiklar/audi-seat-skoda-vw-18-20-tsi-mqb-intercooler.html

 

[drrck]

I can tell you I track my car (HPDE) and the IE unit was great for IS20 and remains great for my IS38 fitment was easy too. Like Diggs said, most of the proven ones are just that, more or less proven because enough people are running them. The eBay ones could be great one shipment and terrible the next, but you don't know what you're going to get.

 

[GTI_Owner]

You missed the whole point of the post and that was literally the next sentence after the one you bolded. Removing downstream restrictions (i.e. the heads) increases mass flow without increasing pressure. At power levels over 400+ HP, I think that's the better answer than continuing to push the turbo harder, generate too much heat, and try to compensate with a larger intercooler.

Ok. I'm onboard with improving airflow by whatever means there are.

At around the 350 400 hp level, a 20 degree increase in IAT has a bigger negative impact on charge air density vs 1 psi loss. And we're only talking about a fraction of a psi difference between best and worst intercoolers that were tested. Physics ftw.

The chart of flow testing shows most of them flowing "around" 200-220 CFM, is that how much the engine needs to make 350-400hp?

 

[aaronc7]

Ok. I'm onboard with improving airflow by whatever means there are.



The chart of flow testing shows most of them flowing "around" 200-220 CFM, is that how much the engine needs to make 350-400hp?

CFM and intercoolers get weird because the air is compressed so CFM naturally goes down for a given mass flow of air....so it greatly depends on air density. The test is done at atmospheric conditions so if we measured airflow in the air intake, 350hp is probably like 450 CFM, ballpark value

 

[GTI Jake]

TIP - Turbine Inlet Pressure. Similar to what you are calling drive pressure.

How is TIP aka drive pressure causing the IAT to rise? That was what you said when you said the high drive pressure and high EGT is adding up to high IAT. I'm not following how the condition in the exhaust would be driving up the temperature in the intake.



Boost pressure is what produces more mass flow.

The ratio being so far from 1:1 literally has an effect on everything including IAT. I’m not an engineer as I assume you are, so I can’t fall back on the math or vocabulary words for this one, but based on my practical experience in Aviation, diesel, and gas forced induction performance high drive pressure is a big deal in a negative way because high drive pressure is the RESULT of an inefficient turbo not the cause of it.

and basically what you are saying is that a hybrid turbo on MK7 is just not efficient enough and is making tons of hot air that no air/air intercooler can overcome?

the intercooler volume of these OEM location setups are easily as large as what other 550-650+ setups use on other platforms so on paper it should be more than enough intercooler

The problem is the direct replacements are horribly inefficient. That’s why on a sub 400hp mk7 my FMIC performs equal to or better than direct replacement at just over half the size. Fighting indirect airflow and radiant heat from two other heat exchangers will do that. The companies who say “dIrEcT RePlaCmEntS aRe BeTtEr” are selling direct replacements...looking out for sales bottom dollar, not what performs best.

An equally sized FMIC compared to a direct replacement would be no comparison

GTI _Jake - I'm curious given what you've seen, that if you had to choose an OEM location intercooler which one you'd choose?

I wouldn’t, that’s why I don’t have one.

If my car made over 400whp I’d have a larger FMIC.

 

[anotero]

Just to chime in here my Baun Performance FMIC keeps my IATs within 9* of ambient while moving 27psi.

How's your wastegate actuator duty doing with Baun Performance FMIC?

 

[mk7_bk]

The ratio being so far from 1:1 literally has an effect on everything including IAT. I’m not an engineer as I assume you are, so I can’t fall back on the math or vocabulary words for this one, but based on my practical experience in Aviation, diesel, and gas forced induction performance high drive pressure is a big deal in a negative way because high drive pressure is the RESULT of an inefficient turbo not the cause of it.



The problem is the direct replacements are horribly inefficient. That’s why on a sub 400hp mk7 my FMIC performs equal to or better than direct replacement at just over half the size. Fighting indirect airflow and radiant heat from two other heat exchangers will do that. The companies who say “dIrEcT RePlaCmEntS aRe BeTtEr” are selling direct replacements...looking out for sales bottom dollar, not what performs best.

An equally sized FMIC compared to a direct replacement would be no comparison



I wouldn’t, that’s why I don’t have one.

If my car made over 400whp I’d have a larger FMIC.

So what is the Baun Performance kit good for hp wise? 4-500? 550?