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Old 01-23-2021, 01:31 PM   #1
linuxman51
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Default Impromptu dyno intercooler testing.


This may belong in showroom, but it's definitely got a performance aspect to it. I kinda teased it out a little on the facebook group (mostly because I posted in between meetings and work, partly to draw interest and discussion along the way), so anyone over there already knows how this went down. I'll do the TL;DR up front this time, and show other things as the post develops, as well as provide more information here than FB (most of it can be inferred, but the nature of social media is a quick splash and move on, whereas you can get a little more verbose in a forum setting-which I prefer, personally)

Sam brought his chumpcar/champcar/whatever over weds to do tuning with a new turbo setup and shake down the new clutch setup prior to an upcoming race. the new turbo did well (As was expected, it's not huge, mostly an upgrade on the turbine side, not looking for huge power here), although some overzealous porting on the wastegate led it tappering boost as rpms went up rather than holding. at some point that will be addressed via a new turbine housing, but for the purposes of this, it only bears mention as an artifact of the setup and not so much a direct contributor to the data. boost was set to wastegate pressure (no shens, from the compressor cover to the actuator), roughly 9.5-10psi on the hit, tapering 1-2psi by redline, or so it was with the factory late 940 intercooler fitted on the car.

Once he got done tuning, he wanted to test out the stereotypical ebay intercooler, the old tried and supposedly true 24x12x3 unit that everyone runs because they're awesome and cheap. I will preface everything here and say that I and Sam both had expectations of a roughly 10ish hp increase, maybe a little more. To say that we were surprised by the results is a little bit of an understatement.

We went on to test the garret core intercooler from the gold car (because why not, and readily available), and I'll break that down with the image here in a second:


Pink run: Stock intercooler avg of 3 pulls back to back (little bit of a spread, iirc ~2hp up/down, I can light up the dyno computer later and get all 3)
Dark blue: Ebay intercooler avg of 3 pulls back to back
Orange run: Garret intercooler. That's the high value of 3 pulls back to back, the other two pulls were 193.4 hp, I figured yall wouldn't mind the extra .2hp. I think torque fluctuated a couple ft/lbs across them.

to be fair to the stock intercooler, it did have the roughest time of all three, as it was stuck in where it belongs, and the other two were sitting on top of the core support, like so:




The datalog data bore out some interesting things as well, namely that there was a consistently lower pressure start to finish with the ebay intercooler, indicating a healthy restriction pretty much from start to finish (as can be seen in the overall shape of the graphs, where it starts lower and ends lower. This created a minor controversy on the internets, I'll explain that towards the bottom, but it has to do with the dyno setup)
ebay intercooler:


garret intercooler:

you can see the taper still exists on the garret setup, but it's not quite as bad as the ebay intercooler.

As this was kind of a spur of the moment test, not much thought was given to gathering additional data (eg pressure differential across the various cores, pre and post air temps, etc.). Of course, we didn't expect the results to be what they turned out to be either.

So, the setup:
Car is a b230f with a custom turbo.. I think it's like a gt2871 or 75 or something compressor wheel and a stage3 turbine wheel, .63 a/r back housing, 3 inch exhaust. Microsquirt, manual transmission, RSI Stage3 cam. Pretty basic, not unlike the normal tbricks "turbo intercooler chips exhaust" kind of thing. No magic, no tricks, no excessive cool downs to benefit one over the other (I mean, we expected different results hah)

the dyno was setup with a fixed load amount (I don't recall if it was 5 or 10%, sam can speak to that, but it didn't change), and had a 3 second hold-to-start value, which basically gives you 3 seconds to build boost before the run starts.. so all of the runs benefitted from that, and one of the things it did create was a gap from the beginning as boost was already building. Without having the datalogs in front of me I can't say what the ecu was seeing for boost at the beginning of the runs, only that it started in boost.
This is why the runs don't all start at the same point and diverge from there.. on a more 'normal' run where you hit the go button and mash the gas, you would expect and see that the instant output at the beginning would be more or less the same for all 3.

One thing I noticed across the stock pulls was the early 'bump' in torque from the stock intercooler, and I'd like to see the datalogs but I suspect it spikes a little and drops right away before settling down to a gradual falling boost curve, and it's possible that at that pressure level the stock intercooler is starting to choke a little, but without the pre-intercooler pressures to go along with the manifold pressure it's speculation on my part and certainly not proven fact.


So what's the takeaway here? Do all ebay intercoolers suck? Can I get a second opinion? Why are you cheating the data and fudging the results?

-For the moment, I would say the takeaway is you get what you pay for to a certain extent. Not all ebay intercoolers are the same, not all are bar and plate. If you can get your hands on one to look at before you buy, I would look for one that has larger passages through it rather than smaller, and I would probably look at a tube-and-fin over a bar and plate. You can also go bigger (if it's available), a thicker and taller core will give you more of a chance of not choking.
This is what you're looking at in the average ebay bar/plate (and has been the case for at least 15 years or so):

vs the garret core:


a more direct comparison. the solid bars are where the air flows through the cores


-there are probably better ebay intercoolers floating around, but some of the more name-brand budget options get pretty close and you can buy a known product at that point. Treadstone cores are pretty good, I have one in the blue 242 as well as one in the v8 car, they seem to fight a bit above their weight class. Precision makes cores now (or did..), and garret as well.. garret last time I checked was kind of the gold standard, and certainly on the higher end of the price range.

-you can get as many as you want if you want to do the leg work ;)
We did this experiment quite a while ago (-04 or 05, I forget when exactly) on a buddy's turbo honda.. he had the same ebay intercooler and was turning the wick up and noticed that he just wasn't making nearly the power that was expected for the boost level, and got talked into an intercooler upgrade. The specific numbers are probably lost to time now, but the car went from roughly 450-480hp to like 600 or 620hp, ran out of fuel and fuel injector at the same time. He ended up turning the boost down quite a bit to get the car to a more moderate 500 or 550hp.

-no data changing or results fudging. I'm not in the business of selling intercoolers, I don't plan to get into that business, and honestly we expected a different result. If data were being fudged, we would've turned the boost up and lied about it or something I guess. I may do some more tests with the black wagon, as it has the early style oem intercooler and is otherwise virtually stock except for the boost controller. I guess I'll turn off learning on LH so I can get consistent results from the ecu, that's easy enough though.


Reviewed the runs again while I was in the shop yesterday and realized I'd sandbagged a little (or.. something. whatever). I put up all three runs for each intercooler individually, and then put everything on one graph. The trends are still very clear. The ebay intercooler had an average of 170.5ish, and the stock intercooler had an average of roughly 179 to 180.

All 9 runs for ALL THE GLORY:


Of course I managed to do a real bangup job getting the numbers in the shot :-/ Top three are stock, middle three are ebay, bottom three are garret. If you work right to left you can see the three distinct trends.

stock intercooler runs:

numbers are 180.2, 180.6, 178.9

ebay intercooler runs:


garret intercooler runs:


You can see on one of those runs sam was either a little early getting on the go button, or late getting on the gas after hitting the go button because the torque at the start of sampling was 25-30ft/lbs lower than the other two runs.

That's actually something interesting to talk about as well, because that's the basis of argument for one of the tools on facebook "the runs didn't start from the same spot".. it is almost impossible to start at exactly the same spot, human error and all that, and at the end of the day unless you just skip half of the powerband, it doesn't really change much.
On that run (the green line), it essentially got a slow start, but this only delayed peak boost by what looks like about 100 rpms over the orange line that started higher than the other two, and around 50 from the pink one that started at a lower rpm (And thus a lower boost amount). They all look to have hit peak boost around the 3500-3600 rpm mark, and after that point all of the runs were about as close to identical as you can realistically hope to get.. normally if I'm doing checks to see if a tune is going to back itself up (i.e. I've done a decent job with it) you wanna see a tight grouping, but normally the spread is still a bit more than that.. more along the lines of 1-2hp or so at that power level (it doesn't really get to be much larger of a gap at higher hp levels either, but on something north of 500 hp that's turbocharged, I'd like to see 3 runs back to back that are more or less within 5hp of each other). Turbo cars generally have a little more variability in them than NA cars or blower cars (which behave essentially like big NA cars). Anyway, I'm off track. enjoy the datas, there will likely be more to come.
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Last edited by linuxman51; 01-24-2021 at 11:39 AM.. Reason: wrong ebay pic lol
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Old 01-23-2021, 02:21 PM   #2
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Where is the wastegate port terminated? Im assuming pre ic core?
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Old 01-23-2021, 07:19 PM   #3
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"like"

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Old 01-23-2021, 08:04 PM   #4
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Too bad you don't have a NPR to test with also.
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Old 01-24-2021, 11:14 AM   #5
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Originally Posted by Jerd View Post
Where is the wastegate port terminated? Im assuming pre ic core?
compressor housing as is with the stock turbos.


I have a confession to make, I sandbagged the ebay intercooler a little, it had a peak number of 171. I'll upload all three runs for each here in a few
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Old 01-24-2021, 11:29 AM   #6
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So, correct me if I'm wrong: what I'm seeing here is that in reality, the stock IC is better at this power level than the ebay core?

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Old 01-24-2021, 01:20 PM   #7
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that's what it looks like
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Old 01-24-2021, 01:52 PM   #8
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Too bad you don't have a NPR to test with also.
yeah, this isn't the end of it. still have a stock intercooled volvo here, the ebay intercooler is still here, and my 940 is an early one to boot, so may get to test the old style, the ebay, an npr, etc.
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Old 01-24-2021, 03:12 PM   #9
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Thanks for sharing!
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Old 01-24-2021, 04:00 PM   #10
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This all certainly makes me think about changing my generic cheap eBay bar and plate 25X12X3. I'm trying to blow about 550-ish hp worth of air through it. And I don't think that extra inch of width is going to help much.

PS: This one: https://www.ebay.com/itm/25084361482...E:L:OC:US:1120
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Old 01-24-2021, 05:05 PM   #11
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I love the scientific method.

This is also further proof that just because you did something doesn't mean it improved anything.

I wonder how many guys that ebay intercooler kept out of the 300 club.
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Old 01-24-2021, 06:24 PM   #12
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compressor housing as is with the stock turbos.
Well, that explains why each core ran at a different manifold pressure. While this gives us a good indication of pressure loss across the core it doesn't really tell us how much power one core makes vs the other.

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Old 01-24-2021, 08:38 PM   #13
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you're not really saying anything. If it's restrictive at ~10psi and 200ish hp worth of airflow, it's not like it's suddenly going to *not* be restrictive at 300 or 400hp and 20+psi, that's not really how that works.

further, the numbers are right there-and directly related to the pressure loss across the core.
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Old 01-24-2021, 10:10 PM   #14
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you're not really saying anything. If it's restrictive at ~10psi and 200ish hp worth of airflow, it's not like it's suddenly going to *not* be restrictive at 300 or 400hp and 20+psi, that's not really how that works.

further, the numbers are right there-and directly related to the pressure loss across the core.
I didn't mean any disrespect, I was just pointing something out. Sorry you didnt get what i was saying. Would you agree that your test intention wasn't to find pre and post core temperatures or pressures? It seems as if you where only interested in power output. I was just pointing out that you failed to eliminate a major variable and that lead to misleading test results.

I thought the resistance in the charge air plumbing only really has an impact on power because the charger itself then becomes more resistant, waste gate would need to stay closed longer, load on the compressor wheel and turbine wheel becomes greater, etc. If one cooler has more resistance than another than the pre core pressure will need to be higher to maintain a similar manifold pressure.

I would argue that if you have a 1.5psi drop across the core at 10psi of manifold pressure and a 3psi drop across the core at 20psi of manifold pressure, than you have increased your manifold pressure by 10psi and your pre intercooler core pressure by 11.5psi. Im just not seeing how that could create a drastic difference in power output.

I dont know, im no expert. Just thought it would be interesting to see the test with the same boost pressure in the manifold.
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Old 01-25-2021, 02:55 AM   #15
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So, correct me if I'm wrong: what I'm seeing here is that in reality, the stock IC is better at this power level than the ebay core?
But without real world wind speed across the cores, aren't all of them operating more as heat sinks than radiators? So doesn't the comparison show that the stock intercooler is a better heat sink than the eBay core?
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Old 01-25-2021, 09:58 AM   #16
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I think you guys are missing that Kenny has made a strong effort to offer an "All things being equal..." scenario, in which this particular ebay intercooler is the clear loser. This is like a back to back dyno test where you run the car, then run the car again with an intake restrictor. Which will make more power? Yeah, you can do all kinds of stuff to get your power back, or you can just remove the restrictor (unless the rules require it).
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Old 01-25-2021, 11:09 AM   #17
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Originally Posted by Jerd View Post
I didn't mean any disrespect, I was just pointing something out. Sorry you didnt get what i was saying. Would you agree that your test intention wasn't to find pre and post core temperatures or pressures? It seems as if you where only interested in power output. I was just pointing out that you failed to eliminate a major variable and that lead to misleading test results.

I thought the resistance in the charge air plumbing only really has an impact on power because the charger itself then becomes more resistant, waste gate would need to stay closed longer, load on the compressor wheel and turbine wheel becomes greater, etc. If one cooler has more resistance than another than the pre core pressure will need to be higher to maintain a similar manifold pressure.

I would argue that if you have a 1.5psi drop across the core at 10psi of manifold pressure and a 3psi drop across the core at 20psi of manifold pressure, than you have increased your manifold pressure by 10psi and your pre intercooler core pressure by 11.5psi. Im just not seeing how that could create a drastic difference in power output.

I dont know, im no expert. Just thought it would be interesting to see the test with the same boost pressure in the manifold.
So I think you're in the weeds here, and I'm not mad or upset about any of the comments, working through the process lends to better understanding. The intent of the test was to see and/or "Verify" whether or not the cheap commonly used intercoolers are in fact an upgrade, and that was the expected outcome as I said above. It was not reality. We did it all the same night, on the same car, with the same dyno settings, over a fairly short period of time, with the same configuration on the vehicle each time. no tuning changes were done to benefit or hurt any of them,

To that end, as many variables were fixed as possible, and while we did not bother getting pre-intercooler data, it doesn't take much to gauge what's going on based on the post-intercooler data we do have. Maybe if it was something planned out, we could've figured out a way to hook a second ms up for datalogging purposes, but really at the end of the day it's not really necessary as enough information was already procured to reach the conclusion we reached: that that type of intercooler is not really an upgrade, rather it's going to hold you back. And listen, this is not ground breaking or earth shattering news either, this has been a known thing for a while.

There are several things to try and keep in mind with all of this, probably the minimum things really. for brevity I'll list them rather than go into great detail-
- the object here is to make more power, right? that's essentially the stated goal of collaboration in the realm of turbobricks-increasing the hp on our turbo volvos. To that end, the best system test we have available is a dyno (be it engine, or more frequently, chassis)

- not all boost is equal, or we wouldn't ever upgrade beyond stock turbos, and pressures tend to vary with rpms (sharp taper, for instance, which can indicate choking... this was somewhat evident with nick's 940 a couple of weeks ago)

- intercoolers are somewhat of a necessary evil, as one component of compressing air is introducing heat into the compressed air.. on your shop air compressor for instance, the discharge tube into the tank has a tendency to get pretty hot, same concept. As higher IAT's tend to lead to unstable ignition (and reduction in air density), we trade some of the maximum potential flow of the turbo for cooler more dense and thus a higher power potential air charge

- engine hp (generally) correlates fairly closely to the amount of airflow through the system, the volume thereof (g/s, lb/min, however you wish to express it). the key thing to remember there is just like with compressor maps, the units are measured in volume over time. This is fairly simplistic, but the idea is what we're going for, not the 10th decimal place

- in dynamic systems, restrictions tend to also be dynamic. If your air filter is already choking the engine at 3000 rpms, at the very least you can expect the rate of choke to remain constant (This is generally not true, either, but bear with me), thus doubling the amount/volume of air being deprived of. Again, overly simplistic, but we're going for concepts. In situations such as this, the increase tends to be more of an exponential one rather than a simple linear increase, or fixed amount as you referred to above (with your 1.5psi difference at 20).

So what am I getting at exactly..
Well for starters, one should keep in mind that equalizing the intake pressure across the tests does not equalize the test-if you have to make say 12psi pre-intercooler to achieve the same 10.2 as the garret one did, you are introducing more heat in the compressed charge, as well as generating more back pressure in the turbine housing. Ordinarily, I'd say at this power level you probably wouldn't be talking about much, but it's already starting out down.

I imagine if we'd put a map sensor on the same line as the wastegate actuator what we would've seen was something along the lines of a peak value of around 10.5, dropping down to 8.5 or 9 or there abouts by virtue of how that'd been behaving all night. What this allowed us to do is indirectly measure how restrictive the intercoolers are without putting a specific number on it... since the turbo doesn't know or really care what's down stream as long as it's enough for it to generate pressure, any differences in pressure would point directly at whatever was last changed.. in this case, the intercooler. I'm not totally sure the overall scope is clear here: you have a ~13% difference in power with no other changes.. you didn't turn the boost up, you didn't swap cams, nothing. That's essentially free horsepower (not in terms of dollars obviously, but do you want an ~8% increase over stock, or a 5% decrease over stock for the money you're spending).

At the end of the day here we're talking about a pretty significant restriction if it's enough to consistently drop 10whp over the stock intercooler at only ~10psi. I mentioned before that this not new information, some time ago, probably... 15 years now.. a buddy with a turbo civic was running a similar intercooler, with a big (to us at the time) 67mm turbo. When he started leaning on it, it rapidly became apparent he had some kind of problem making power. At 20psi (as measured at the manifold) he was only making around 450hp, and after tweaking and tuning and banging and poking I think he got it up to like 470 or 480. So we'll say 480. While that sounds like a lot of power in the volvo world, in the turbo honda world something was wrong.. similar setups were easily making mid 500's, and after going back and forth with the guys on honda-tech, someone talked him into an intercooler upgrade. Similar core to the one I'm using on my gold car, same fairly basic endtanks as the ebay intercooler. bolted it on, strapped it down, and first pull it made over 600hp and was out of fuel system and injector. Now you're talking about roughly 25% more power.

Andy's v8 turbo was seeing extremely high intake air temps with his at around 500 to 550hp (pro-tip: 550 is an easy number to hit on a v8 turbo without running a lot of boost. mine will do 550 wheel all day long at like 8 or 10 psi with air temps barely higher than ambient, and it does not have nearly as nice an intercooler as the gold car), I think he was seeing over 220 degrees.

I will say in both of those examples we're talking about higher powered cars, so it stood to reason that the cheap intercooler may be an issue up there. Like I said at the beginning, we expected different results, but all it did was cement the fact that probably nobody should be running that particular type of ebay intercooler. There are others that I'm sure do more along the lines of what we expected to see, this is a case of either knowing what to get, or having enough information about what you're buying matters. I would venture a guess that a budget tube-fin intercooler would do better in the sub 400 category. May test that one day.



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But without real world wind speed across the cores, aren't all of them operating more as heat sinks than radiators? So doesn't the comparison show that the stock intercooler is a better heat sink than the eBay core?

IAT's weren't really an issue with any of them given the low pressure ratios as well as the fairly low ambient air temperature that evening. for the relatively short duration of the pulls, "air at speed" is not a necessary thing. There are fans blowing across them. Further, IAT's alone don't explain the power differences, as the ebay core was most definitely cooler on the outlet side, based on the scientific "hand on the pipe test" (and probably this is born out in the logs as well, but...I don't have the logs in front of me to put numbers with assertions).

Think about it: from a heat-sink-ability, is a thin aluminum radiator with plastic end tanks going to be able to sink more heat, or a 10lb all aluminum, 3x as thick radiator going to sink more? there's a lot more to heat up on the ebay core.
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Old 01-25-2021, 11:33 AM   #18
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IAT's would be an interesting one to log if you can pull that from the MS logs. I remember way back, first round with MS on my wagon, watching the IAT's actually drop in boost vs. not in boost, while running the NPR IC. 18psi, 100* ambient, 130* while cruising, 120* under full tilt. I'll be going back to MS soon on that car, curious how the do88 does, hopefully similar.

That would be interesting as well, if you have the opportunity...how do the do88 an NPR IC's stack up?

Thanks for putting this together Kenny. I've got a long-term plan for boost on the 140, looks like that ebay core won't be going on there now...
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Old 01-25-2021, 12:04 PM   #19
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After getting curious about this earlier on, I started looking around. And one of the things I noticed was on Treadstone's intercoolers, they have similarly sized coolers, regular and 'R-rated'. Apparently, the R rated just means that it's not designed to be stacked in front of a radiator, like we're generally doing on Volvos. They're intended to be in their own airstream. Off to the side, down below, wherever. Just not in front of a radiator. This is because when they design one for sitting in front of a radiator, they have to allow a LOT of air through in that direction, it becomes an important design consideration vs. just getting engine air through it the other way. So on the R rated ones, no consideration for enough air getting through to a radiator, they make the engine air bars taller, and the 'cooling air' bars shorter. And thus rebalance (for the given space) airflow giving more priority to engine airflow.

With that in mind I looked at pics of the 'generic bar-and-plate' intercooler I have in mine. And their shot of the core through one of the inlets made it clear - this was certainly designed to favor radiator air flow. Look at that wall of metal air going in the inlet sees:

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Old 01-25-2021, 12:32 PM   #20
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Thanks for doing the testing, I really enjoy comparisons and im always working to better understand cause and effect. I appreciate you taking the time to further explain your testing method. One of the things I like most about this group of people is their willingness to contribute and discuss.
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Old 01-25-2021, 12:44 PM   #21
vwbusman66
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Originally Posted by linuxman51 View Post
you're not really saying anything. If it's restrictive at ~10psi and 200ish hp worth of airflow, it's not like it's suddenly going to *not* be restrictive at 300 or 400hp and 20+psi, that's not really how that works.

further, the numbers are right there-and directly related to the pressure loss across the core.
I believe as airflow/pressure/temperature increases, it's an exponential loss.
Though someone who did better than a C in fluid dynamics should probably chime in on that statement.
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Old 01-25-2021, 12:56 PM   #22
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Originally Posted by vwbusman66 View Post
I believe as airflow/pressure/temperature increases, it's an exponential loss.
Though someone who did better than a C in fluid dynamics should probably chime in on that statement.
better than the grade I have in it (I didn't take it ;) )
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Old 01-25-2021, 01:11 PM   #23
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Has anyone here tried the mishimoto stuff? Prices seem resonoable and specs are given in terms of airflow and pressure drop
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Old 01-25-2021, 02:35 PM   #24
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Hi, interesting results.

However, I have some difficulties in explaining this from a physical point of view.

Let's assume power output is proportional to mass flow trough the engine.
And, that mass flow is (among displacement and rpm) a function of 1:volumetric efficiency, 2:manifold pressure, and 3:manifold temperature.

For the sake of argument, let us assume 1 and 2 remain unchanged (in practice boost will differ if intercooler restriction differs and the WG is plumbed directly from the compressor housing).

A decrease in power of 13% (ebay vs garrett) roughly corresponds to a inlet temperature increase of 40 degrees celsius (ideal gas law).
I have been doing quite some data logging with the ebay IC, and although I have not been running huge amounts of boost, I have not seen higher than 20 degrees above ambient at max.

Also, when swapping the 940 cooler for the ebay cooler (12x24) my boost increased by 0.2-0.3 bar. Yet when direct swapping a stock one for a ebay cooler, you lose power?

How did you control boost? Manifold pressure the same for all runs?
Edit: Ok, some more careful reading, so you see less boost with the ebay core vs the garret. Is this also the case for the stock 940 one? Because my results have shown the opposite. Maybe it's a different cooler, although it looks the same.

Last edited by Sjeng; 01-25-2021 at 02:49 PM..
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Old 01-25-2021, 02:47 PM   #25
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Very interesting write up. Thanks for posting!

I will say this however, I upgraded my standard Volvo intercooler (car is a 244T) to a Do88 and was VERY surprised at the difference it made. No Dyno testing, just driving, but there is a very noticeable increase in power. Maybe that's because the Volvo unit was old and tired, not sure...
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