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GrimmSpeed 05-09 LGT Intake - Any Interest?


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The AEM intake uses a smaller diameter MAF housing, as they often do, which in stock form is a kind of way to get around making it a "tune required" intake. The smaller housing will make it so the calculated airflow is greater than the actual airflow, which will cause you to run rich.

 

 

This is interesting, my experience with the smaller diameter K&N Typhoon was different. It was still leaner then stock, by about one whole AFR point, I had to add 15% to MAF scales to get it back to where it should be.

 

I haven't played with AEM's, maybe they are not as bad? K&N Typhoon does use a flow stack, so maybe that's why it's leaner vs richer?

 

 

Also @CovertRussian: great post in the turbo section regarding drop in filters running lean, this is the exact same trend and data we've seen in our own testing. Not only in turbo cars, but on on N/A vehicles as well for the same reasons. More proof that the MAF curve is not only dictated by the MAF housing alone, which is an unfortunate common misconception. I didn't want to booger up your thread though.

 

Chase

Engineering

 

Oh it wouldn't be clutter at all, I appreciate feedback and other's experience (especially someone of your caliber :)).

 

I heard the MAF housing size myth all the time myself, for other MAF cars it might be true, but not for how Subaru calculates airflow. This is why I cut the MAF housing out of my airbox and built an intake with it... long story short it was very lean and required a retune.

05 LGT 16G 14psi 290whp/30mpg (SOLD)

12 OBP Stock 130whp/27mpg@87 Oct

00 G20t GT28r 10psi 250whp/36mpg

22 Ascent STOCK

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This is interesting, my experience with the smaller diameter K&N Typhoon was different. It was still leaner then stock, by about one whole AFR point, I had to add 15% to MAF scales to get it back to where it should be.

 

I haven't played with AEM's, maybe they are not as bad? K&N Typhoon does use a flow stack, so maybe that's why it's leaner vs richer?

 

I worded what I said very poorly. It's not that it'll make you run rich (richer than stock), but that it'll make you run richer than you would be if the MAF were the same size as stock. I did all my testing on a GR, but I would wager that the results are about the same as what you saw. This was years ago, and while I still have the logs of that intake with a tune, I can't find it with the stock tune.

 

 

Oh it wouldn't be clutter at all, I appreciate feedback and other's experience (especially someone of your caliber :)).

 

I heard the MAF housing size myth all the time myself, for other MAF cars it might be true, but not for how Subaru calculates airflow. This is why I cut the MAF housing out of my airbox and built an intake with it... long story short it was very lean and required a retune.

 

Ha, my caliber. The only difference between you and me here is that I do this every day for a living. Your value to this community greatly surpasses my own.

 

Chase

Engineering

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  • 10 months later...

Has anyone had success reigning in the heating of this intake?

 

ed24769792eb32bca328d237389851d5.jpg

9b1b133ffac30f3c8827ba3c63afab7c.heic

 

Put it back on with DEI reflective gold on the pipe, Lava Matt (a self adhesive basalt matt) on the box, AND a fog light removed. It’s still getting extremely hot, after sitting for any length of time IAT’s climb up to 140*F when the ambient is ~90*F. This is better than the 145F IAT in 65F weather I was seeing a year and a half ago, but still fairly rough.

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Even on stock intake I would see 150F but I would have to idle for a while (drive through or heavy traffic would do it). Stock intake would take a lot longer to lose heat compared to my CAI though.

 

Have you blocked off the fender well? I believe most of the heat is coming from the header, even the stock belly pan doesn't fully seal off the fenderwell from the header.

05 LGT 16G 14psi 290whp/30mpg (SOLD)

12 OBP Stock 130whp/27mpg@87 Oct

00 G20t GT28r 10psi 250whp/36mpg

22 Ascent STOCK

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  • 4 months later...

I'm currently running an up pipe, down pipe and custom exhaust w/ stock air intake.

I had a road tune done by MSPT back in long island, NY, and have since moved to atlanta, GA.

 

If I install this grimmspeed intake, do you guys think I can get away without having a tune again?

2005 LGT wagon 5eat.

 

Thanks in advance!

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I'm currently running an up pipe, down pipe and custom exhaust w/ stock air intake.

I had a road tune done by MSPT back in long island, NY, and have since moved to atlanta, GA.

 

If I install this grimmspeed intake, do you guys think I can get away without having a tune again?

2005 LGT wagon 5eat.

 

Thanks in advance!

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I'm currently running an up pipe, down pipe and custom exhaust w/ stock air intake.

I had a road tune done by MSPT back in long island, NY, and have since moved to atlanta, GA.

 

If I install this grimmspeed intake, do you guys think I can get away without having a tune again?

2005 LGT wagon 5eat.

 

Thanks in advance!

 

I wouldn't risk it. MAF needs to be rescaled. Been a while since I ran it on my OBXT but IIRC I needed to increase scaling b/n ~7%-15% over stock across the board to hit my AFR targets.

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NO! MAF Scaling is WAYYYY off from stock.

 

Also the stock intake has a pretty big pressure drop, so for the same WGDC you'll be making significantly more boost. Thus your turbo dynamics tables will need a lot of work.

 

There are numinous good tuning outfits in Atlanta that can take care of it. Please wait until the car is in their hands to install it.

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Nothing more for me to add that these two already have not said. The scale is going to be a bit off (7-15% is about what i've seen too), and the increase in boost is usually a little less than a PSI at peak boost, and then more than a PSI at the top end.

 

Thanks for the help as always folks!

 

Chase

Engineering

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Pardon me if I have missed it somewhere in the 23 pages of this thread, but are there any specs for the Grimmspeed air filters? Either the one that comes with the CAI kit or the dry flow filter that is optional?

 

Mostly seeking filtering efficiency data.

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Just read though this thread. Very interesting information -- thank you for providing it to this community. And honestly, for technically minded persons who want data to make decisions, it probably works better than most other types of marketing.

 

I might be picking one of these up when I go to a VF52 on the Spec.B.

 

Is there a fitment for a 2002 WRX? I'm thinking about improving the overall breathing on an EJ205 and this seems like a solid option.

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Pardon me if I have missed it somewhere in the 23 pages of this thread, but are there any specs for the Grimmspeed air filters? Either the one that comes with the CAI kit or the dry flow filter that is optional?

 

Mostly seeking filtering efficiency data.

 

I think I have the info you want. These are 96-99% effective at filtering particulate in the 10-20 micron range (these are regarded as the size responsible for most engine wear), and still effective down to 5 microns.

 

These are not that other major brand with the red mesh, but rather are manufactured by the same company that SPT (Subaru Performance Tuning) uses for their air filters. These are custom sized just for us and feature an integrated venturi in the base of the filter. Lots of companies and race teams use this brand of filter and truly believe it to have advantages over other manufacturers.

 

I use an AEM 21-203D-XK on mine. I think a longer (8” ish media) filter would also work based on measurements I took.

 

Unless you bought a new car, this intake won’t work on your 2.5i.

 

You do make a pretty good point about the 2.5 :p

 

Also, that length of filter might be pushing it depending on how you rotate the intake. I think at that size you might start resting the filter on the splash shield, which I advise against.

 

Just read though this thread. Very interesting information -- thank you for providing it to this community. And honestly, for technically minded persons who want data to make decisions, it probably works better than most other types of marketing.

 

I might be picking one of these up when I go to a VF52 on the Spec.B.

 

Is there a fitment for a 2002 WRX? I'm thinking about improving the overall breathing on an EJ205 and this seems like a solid option.

 

Thank you very much for the kind words, we certainly appreciate that. There has definitely been a shift in the last decade or so from the forums and finding your information that way, to social media and things being far more advertisement based than actually informational. There is a certainly struggle now to be informative now without being nearly as long winded and potentially "TL;DR" as most of the stuff I post. But just as you've mentioned, this is the type of information I find valuable when I'm doing research, so we will continue to do so.

 

You are in luck, we will be releasing that exact intake (02-07) very soon. It tunes and performs just as well as this intake here, and certainly adds a lot to the aesthetic of the GD engine bay (ie it covers up that ugly ass abs pump). I believe marketing is getting the final touches for it right now, and it should be out in the next few weeks.

 

Thanks again everyone, and please let me know if you have any more questions!

 

Chase

Engineering

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You are in luck, we will be releasing that exact intake (02-07) very soon. It tunes and performs just as well as this intake here...

 

Amazing, thank you. Honestly, I'm pleasantly surprised that there is still development for the EJ and GD/GG platform -- it's fairly dated by now. Things will get a little tougher when the STi moves off the EJ257, I'm sure.

 

Thank you!

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  • 3 weeks later...
Have you blocked off the fender well? I believe most of the heat is coming from the header, even the stock belly pan doesn't fully seal off the fenderwell from the header.

 

So I went and did as you suggested today:92f9e63367fcc465109b94290bbb28ff.jpg

 

There is now only a small gap in the front where the wires go through, and some air can leak below the headlight. I'm running without the passenger side fog light so air has a direct path into the fender.

 

It appears to be doing something (FLIR shot of plate through fog light hole):

3e8d334588933e9f016518430f13576d.jpg

 

But the city ITA's (text IAT, gauge one is post IC and the sensor heat soaks) still got up to 141°F on ~60°F night!

cad4eae8034b5ad2a47dd952df656990.jpg

 

With minimal movement temperatures would drop from to 25°F over ambient (85°F ish), but shoot back up as soon as the car is stopped for more then a few seconds. After a few minutes on the highway (where the greater flow efficiency of the intake can be easy seen by the thing boost creeping like crazy in 3rd gear or higher :spin:) the intake temp would cool down to ~5-7°F over ambient.

 

Looking around once stopped, I noticed even the filter is really hot:

83fbef5e89b88eaaf1e407dbd0b7480e.jpg

Flir shot of filter through the fog hole shows it at 149F!!!

 

This is only slightly cooler than the airbox it'self, which is quite hot:

423d8a42ab3d3dc1d8fe32b104c87da0.jpg

 

Even though it has a ton of heat shielding:

475d113cd41f8cf2a3a14cc581b7884f.jpg

Not shown here is a layer of foam inside the airbox in addition to the external basalt (lava/"titanium") matt on the outside.

 

So any other ideas on how to tame high city IAT's with the Grimmspeed intake? More shielding? Forced air cooling with a fan?

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That is freaking awesome, thank you so much for testing this!

 

Are you're headers wrapped or heat shielded? Reason I ask is, my intake is far less sophisticated and completely open to engine bay, but I am using stock cast iron headers.

 

Here is my city drive home from today, Ambient temps were at 70-72F. Exhaust Gas temperature is actually post intercooler IAT. Notice that my Intercooler was happy as a clam and around MAF IAT levels too.

attachment.php?attachmentid=270276&stc=1&d=1541043095

735618614_70F_15minCityDriving.thumb.PNG.b40204a157e7b6b17725958c0c8cd34b.PNG

05 LGT 16G 14psi 290whp/30mpg (SOLD)

12 OBP Stock 130whp/27mpg@87 Oct

00 G20t GT28r 10psi 250whp/36mpg

22 Ascent STOCK

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That is freaking awesome, thank you so much for testing this!

 

Are you're headers wrapped or heat shielded? Reason I ask is, my intake is far less sophisticated and completely open to engine bay, but I am using stock cast iron headers.

 

Yes they are wrapped. Depending on how i deal with the boostcreep issue I may add additional shielding to them at that time. Maybe a 4-channel EGT as well.

 

Sticking my hand in the fog light hole you can feel warm air when the fans kick on, but it feels more in the 90f than 120F range. So the gap may not have been the biggest heat source in the first place. The intake baking inside the engine bay may be.

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Have you thought about PM'ing Chase at GS with your findings. I'm sure he'd love to hear some real life data.

 

Anything you can tell him will be good knowledge for the future.

305,600miles 5/2012 ej257 short block, 8/2011 installed VF52 turbo, @20.8psi, 280whp, 300ftlbs. (SOLD).  CHECK your oil, these cars use it.

 

Engine Build - Click Here

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Well, I had written this post out with a very thorough explanation, but it got lost unfortunately. And since I've now lost an hour I'll have to be a bit more brief. Too bad, I thought it was a pretty good post too

 

The gist of it though is that I don't see anything here out of the ordinary, and it looks like you're starting to fight an impossible battle. That is trying to lower IATs at the inlet when not moving.

 

Have you thought about PM'ing Chase at GS with your findings. I'm sure he'd love to hear some real life data.

 

Anything you can tell him will be good knowledge for the future.

 

No need, I'm usually pretty close by ;)

 

So I went and did as you suggested today:92f9e63367fcc465109b94290bbb28ff.jpg

 

There is now only a small gap in the front where the wires go through, and some air can leak below the headlight. I'm running without the passenger side fog light so air has a direct path into the fender.

 

It appears to be doing something (FLIR shot of plate through fog light hole):

3e8d334588933e9f016518430f13576d.jpg

 

So it looks like what you're trying to accomplish is trying to black off the fenderwell area to keep the radiant heat of the exhaust manifold away, and possibly to block off the flow of hot air from the outlet of the radiator from getting to the fender area. In this instance it looks like the plate is helping with the radiant heat input and would probably benefit a small amount further from some of that gold tape you've been using as this is the exact application it is intended for (radiant heat). However, based on what you say later that when the fans are on you can feel hot radiator air moving in this area. So there is still a contribution from that unfortunately.

 

But the city ITA's (text IAT, gauge one is post IC and the sensor heat soaks) still got up to 141°F on ~60°F night!

cad4eae8034b5ad2a47dd952df656990.jpg

 

This is what I would expect to see from a hot car that is idling, completely normal. If there is little to no air movement there is no opportunity to decrease temperature. No reason for cool ambient air to flow into the fenderwell, and the mass of air going through the intake is very small. And there is no cool mass of air flowing over the intake pipe to cool it down either. Even though the MAFS itself is in the airbox it is still connected to the intake, so conduction is playing a part in heating up all of the intake components. And since the thermal mass of the intake itself is very large in comparison to the MAFS, it will take longer to react to temperature changes. This is why it makes a contribution to IAT.

 

With minimal movement temperatures would drop from to 25°F over ambient (85°F ish), but shoot back up as soon as the car is stopped for more then a few seconds. After a few minutes on the highway (where the greater flow efficiency of the intake can be easy seen by the thing boost creeping like crazy in 3rd gear or higher :spin:) the intake temp would cool down to ~5-7°F over ambient.

 

What you're seeing here is what I was trying to explain in the previous paragraph. So when you start moving suddenly we have some fresh air and some different heat transfer happening. There is now much more air moving through the pipe, and a substantially larger and cooler mass of air moving over the pipe. The area the intake is getting air from is now going to be cooler as a result of movement as well.

 

Now all the materials here have a certain value for heat transfer, and there are several heat transfer mechanisms at work here, but what I really want to stress is that when moving the mass of air is huge in comparison to when you're not moving. The way to visualize it would be if you've ever had a hot piece of metal that you cool off by putting under running water. Depending on the temperature and mass of the object you know that you need to run it under more and more of the same temperature water to decrease it's overall temperature. Larger thermal mass takes more water than a smaller one.

 

So the MAFS hotwire has a very small thermal mass and can react quickly, so you do see a relatively quick drop in temperature, but the rest of the system can't react as fast and is still providing some temperature input into the system. So if you only start moving for a little bit of time, or at low speed, you're not cooling the entire system. And that's fine, it's completely normal and to be expected.

 

I hope this makes sense, and I'm basically just saying that it is important to look at the temperature at the MAFS as a system rather than as a point.

 

Looking around once stopped, I noticed even the filter is really hot:

83fbef5e89b88eaaf1e407dbd0b7480e.jpg

Flir shot of filter through the fog hole shows it at 149F!!!

 

With everything I've said it should make sense why it is so hot. Now back to thinking about these things as a system: The air filter itself is the major source of restriction. So two things to consider here. One is friction, which is going to be a source of heat, and that the filter has a ton of surface area as well as a metal mesh. So it is going to heat up quick, but will cool down quick as well. However, if you don't have much air moving across the filter, it is going to retain that heat much longer. Again, its thermal mass is so low its not going to be a major contribution of heat, but this is why you're seeing a hot filter. The prefilter is also another contribution too.

 

So completely normal.

 

This is only slightly cooler than the airbox it'self, which is quite hot:

423d8a42ab3d3dc1d8fe32b104c87da0.jpg

 

This picture tells us a ton. It looks like the majority of the engine bay surface temperatures are the same as your coolant temperature, and the intake and heatshield are substantially cooler. Now, I know you said it was hot, which it is, but it's a lot cooler than its surroundings.

 

Even though it has a ton of heat shielding:

475d113cd41f8cf2a3a14cc581b7884f.jpg

Not shown here is a layer of foam inside the airbox in addition to the external basalt (lava/"titanium") matt on the outside.

 

Lets talk about all the heatwrap and foam you have on it for a second. I assume the foam is for sound deadening, but we also know it is acting as an insulator. Keeping the cooler air inside the fender from affecting or cooling down the heatshield. And on the outside the lavawrap is also acting as an insulator, trying to minimize the impact of the hot engine bay air from the heatshield. So now the heatshield is a super insulator, and you should expect this to be hot. It should take a long time to heat up and a long time to cool down. Completely normal for what you've done here.

 

Sticking my hand in the fog light hole you can feel warm air when the fans kick on, but it feels more in the 90f than 120F range. So the gap may not have been the biggest heat source in the first place. The intake baking inside the engine bay may be.

 

This is where it'll all come together I am hoping. We know from the FLIR pics that the surface of almost everything aft of the radiator is about the same as the temperature of the water. And we also know that even with this modification that there is still hot air from the radiator making its way to the intake inlet. We also know that this effect really only is happening when the car is not moving or at low speed, which points towards the hot radiator air. Those two driving conditions also just so happen to be during the only times when radiator fans are effective. IE when the mass of air going through the radiator and engine bay is so low it needs a fan to remain effective. So what is probably the largest major contribution to climbing AITs when not moving? Dirty radiator air. Not the radiant heat from the exhaust manifold as would be expected. And we also wouldn't expect convection from air moving across the exhaust manifold and flowing sideways into the fenderwell on a car that is moving forwards.

 

Obviously this isn't the only contribution to IATs, but it is major.

 

So any other ideas on how to tame high city IAT's with the Grimmspeed intake? More shielding? Forced air cooling with a fan?

 

The only way to do what you're trying to accomplish is keeping that dirty air away. Sure you could completely try and seal off the fenderwell, but that isn't going to work either. You could replace the black off plate that you've made with a fan blowing out back into the engine bay, with the goal being to force it to intake cooler air from the foglight hole and have that air flow out, preventing the dirty air from entering. But that's probably not going to work either, especially without enough CFM and proper ducting to make the air do what you actually want it to do.

 

The answer is that you're fighting an uphill battle, one that really doesn't exist. There is nothing at all wrong with these IATs. Nothing wrong with a high idle IAT, and even a cruising IAT. We care very little about the IATs unless we are at WOT. At idle we are at WOT never, and in stop and go traffic we certainly shouldn't be at WOT. Say, what if you're a stoplight hero, or a drag racer? It would be nice to have the coolest air possible, but it ends up being a very small contribution based on the fact that we know that at WOT the IATs drop very fast, as would be expected, and just the same with our intercoolers. Lowering the IATs reduces the burden initially on the charge air temps, but becomes a non issue almost immediately.

 

At the end of the day there are two very important things to remember. That while cooler air is more dense which would theoretically lead to more power, the decrease in restriction from the intake is offering a substantial benefit in the ability to increase boost. Our intakes have shown gains of 1.5-2.0psi in the top end of cars over the stock airbox, even with drop in filters. The other important thing to remember is what I said about IAT and WOT. What we have created here for an intake does a great job of doing what it is intended to do which is to decrease restriction, increase performance, look good, be easy to install, keep temperatures in check, and be a competitive price. You can certainly keep trying to achieve lower idle IATs, but just make sure to identify why you are doing it before you keep going.

 

Speaking of which, I've gotta get back to it myself. Let me know what you think!

 

Chase

Engineering

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One thing I'd wonder, Chase (and if you'd want to look at running the experiment, utc), is what happens if you idle at a higher RPM, i.e., race the engine so it's pulling more air in at a standstill. That will increase the mass airflow, and the increased vacuum may pull air from the path of least restriction (in this case, the foglight hole, I'd imagine?), cooling the mesh around the filter and potentially the IAT sensor. Purely an academic exercise, I understand, but something worth trying to understand the sensitivities of the entire system, IMO.
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One thing I'd wonder, Chase (and if you'd want to look at running the experiment, utc), is what happens if you idle at a higher RPM, i.e., race the engine so it's pulling more air in at a standstill. That will increase the mass airflow, and the increased vacuum may pull air from the path of least restriction (in this case, the foglight hole, I'd imagine?), cooling the mesh around the filter and potentially the IAT sensor. Purely an academic exercise, I understand, but something worth trying to understand the sensitivities of the entire system, IMO.

 

While it would technically help, the contribution would be so small in comparison to what we know we need to make a major temperature drop contribution as far as mass of air goes.

 

Im not sure off the top of my head how CFM we use at idle, but i know it is small. Rough calculation would be:

 

CFM = (In^3 x RPM x VE)/3456

 

Convert 2.5 liters to CI = 152.6

VE= volumetric efficiency

 

Since we're at idle VE is going to be very low, 10% is a safe assumption, so lets go nuts and say its 30%

 

And lets idle at 1000, why not

 

the 3456 is a conversion from cubic inches to cubic feet and a factor because we have an induction stroke every two rotations on a four stroke engine

 

so CFM =(152.6 x 1000 x .30)/3456

= 13.24 CFM

 

13 CFM sounds about right, but its nothing compared to fans in the 1000s of CFM. I mean, we're working with turbos that are sub 500 CFM, which should give you a good idea of what I'm talking about here.

 

So it simply is not enough I think. And the issue still stands of how badly we care about non WOT IATs in most situations.

 

Chase

Engineering

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Let me preface all of this: I am in no way attacking the Grimmspeed intake. I actually think it's a well though out design, hence why I bought it in the first place. It was very easy to tune, and picked up ~20g/sec of airflow.

 

The issues I'm seeing likely effect all finder fed intakes with metal piping in the engine bay.

 

So it looks like what you're trying to accomplish is trying to black off the fenderwell area to keep the radiant heat of the exhaust manifold away, and possibly to block off the flow of hot air from the outlet of the radiator from getting to the fender area.

 

Goal was to minimize airflow coming from the hot engine compartment into the finder. The undertray has an ~2" gap where hot air from the engine compartment was flowing in. Exhaust manafold radiant heat is more heating the frame rail and then conducting into the finder well and the box, but that's an experiment for later.

 

In this instance it looks like the plate is helping with the radiant heat input and would probably benefit a small amount further from some of that gold tape you've been using as this is the exact application it is intended for (radiant heat).

 

You'd think, but in testing I've found the gold foil to be more or less garbage compared to bare aluminum. I only used it on the intake tube because it was better than painted metal, and looked cool :lol:.

 

However, based on what you say later that when the fans are on you can feel hot radiator air moving in this area. So there is still a contribution from that unfortunately.

 

There is a small gap at the front of the plate for the wires pass through, and that's where the air was coming from. That will be sealed later.

 

Lets talk about all the heatwrap and foam you have on it for a second. I assume the foam is for sound deadening, but we also know it is acting as an insulator. Keeping the cooler air inside the fender from affecting or cooling down the heatshield. And on the outside the lavawrap is also acting as an insulator, trying to minimize the impact of the hot engine bay air from the heatshield. So now the heatshield is a super insulator, and you should expect this to be hot. It should take a long time to heat up and a long time to cool down. Completely normal for what you've done here.

 

Foam is because the Basalt stuff is also garbage :lol:. It does cut down on the amount of thermal transfer to the air though, so even though it looks hot on the flir camera I dont intuativly expect it to be having a major effect on the temperatures. Covertrussian suggested testing without the box to see how much of and effect it has, which I may try even though I expect it to be worse.

 

So the MAFS hotwire has a very small thermal mass and can react quickly, so you do see a relatively quick drop in temperature, but the rest of the system can't react as fast and is still providing some temperature input into the system. So if you only start moving for a little bit of time, or at low speed, you're not cooling the entire system. And that's fine, it's completely normal and to be expected.

 

I hope this makes sense, and I'm basically just saying that it is important to look at the temperature at the MAFS as a system rather than as a point.

 

The hot wire portion of the MAF responds quite quickly, I agree 100%. The idle MAF scaling is fairly stable even with the large temperature fluctuations. Part of this is the superior air straitener setup you all implement compared to most aftermerket intakes.

 

The big fat thermistor on the other hand is not so responsive. This is what gives the issues as that's what the ECU is using to determine how much timing to pull.

 

.... And there is no cool mass of air flowing over the intake pipe to cool it down either. Even though the MAFS itself is in the airbox it is still connected to the intake, so conduction is playing a part in heating up all of the intake components. And since the thermal mass of the intake itself is very large in comparison to the MAFS, it will take longer to react to temperature changes. This is why it makes a contribution to IAT.

 

......

 

Now all the materials here have a certain value for heat transfer, and there are several heat transfer mechanisms at work here, but what I really want to stress is that when moving the mass of air is huge in comparison to when you're not moving. The way to visualize it would be if you've ever had a hot piece of metal that you cool off by putting under running water. Depending on the temperature and mass of the object you know that you need to run it under more and more of the same temperature water to decrease it's overall temperature. Larger thermal mass takes more water than a smaller one.

 

....

 

With everything I've said it should make sense why it is so hot. Now back to thinking about these things as a system: The air filter itself is the major source of restriction. So two things to consider here. One is friction, which is going to be a source of heat, and that the filter has a ton of surface area as well as a metal mesh. So it is going to heat up quick, but will cool down quick as well. However, if you don't have much air moving across the filter, it is going to retain that heat much longer. Again, its thermal mass is so low its not going to be a major contribution of heat, but this is why you're seeing a hot filter. The prefilter is also another contribution too.

 

.....

 

This picture tells us a ton. It looks like the majority of the engine bay surface temperatures are the same as your coolant temperature, and the intake and heatshield are substantially cooler. Now, I know you said it was hot, which it is, but it's a lot cooler than its surroundings.

 

.....

 

This is where it'll all come together I am hoping. We know from the FLIR pics that the surface of almost everything aft of the radiator is about the same as the temperature of the water. And we also know that even with this modification that there is still hot air from the radiator making its way to the intake inlet. We also know that this effect really only is happening when the car is not moving or at low speed, which points towards the hot radiator air. Those two driving conditions also just so happen to be during the only times when radiator fans are effective. IE when the mass of air going through the radiator and engine bay is so low it needs a fan to remain effective. So what is probably the largest major contribution to climbing AITs when not moving? Dirty radiator air. Not the radiant heat from the exhaust manifold as would be expected. And we also wouldn't expect convection from air moving across the exhaust manifold and flowing sideways into the fenderwell on a car that is moving forwards.

 

Obviously this isn't the only contribution to IATs, but it is major.

 

And this is exactly what I theorize the issue actually is: Hot radiator air in the engine bay heating up the metal intake pipe. This pipe heats up the air in it, the MAF, and the filter. This isnt just an issue for the Grimmspeed intake, but ALL intakes made out of thermally conductive material. There isn't that much fresh air flowing through them to counter this external heating and to make things worse there is a turbo coolant return line draped across them.

 

The only "hole" in this hypothis that I currently see is the rubber part of the filter looked colder on the FLIR camera. This may be thermal emissary related though.

 

The only way to do what you're trying to accomplish is keeping that dirty air away. Sure you could completely try and seal off the fenderwell, but that isn't going to work either. You could replace the black off plate that you've made with a fan blowing out back into the engine bay, with the goal being to force it to intake cooler air from the foglight hole and have that air flow out, preventing the dirty air from entering. But that's probably not going to work either, especially without enough CFM and proper ducting to make the air do what you actually want it to do.

 

Hold my beer ;)

 

What I was thinking was some sort of blanket around the intake pipe outside of the box to knock down on radiator air heating. Following this finishing the finder air isolation, and then adding a small duct fed fan to blow cool air around the filter/MAF. As you said, the issue isn't at WOT airflows. It's where airflow is too low for the flow inside the intake to cool it more than the radiator exhaust air is heating it.

 

Again, this isn't something wrong with the Grimmspeed intake design, it's going to happen on ANY aftermarket metal intake.

 

The answer is that you're fighting an uphill battle, one that really doesn't exist. There is nothing at all wrong with these IATs. Nothing wrong with a high idle IAT, and even a cruising IAT. We care very little about the IATs unless we are at WOT. At idle we are at WOT never, and in stop and go traffic we certainly shouldn't be at WOT. Say, what if you're a stoplight hero, or a drag racer? It would be nice to have the coolest air possible, but it ends up being a very small contribution based on the fact that we know that at WOT the IATs drop very fast, as would be expected, and just the same with our intercoolers. Lowering the IATs reduces the burden initially on the charge air temps, but becomes a non issue almost immediately.

 

At the end of the day there are two very important things to remember. That while cooler air is more dense which would theoretically lead to more power, the decrease in restriction from the intake is offering a substantial benefit in the ability to increase boost. Our intakes have shown gains of 1.5-2.0psi in the top end of cars over the stock airbox, even with drop in filters. The other important thing to remember is what I said about IAT and WOT. What we have created here for an intake does a great job of doing what it is intended to do which is to decrease restriction, increase performance, look good, be easy to install, keep temperatures in check, and be a competitive price. You can certainly keep trying to achieve lower idle IATs, but just make sure to identify why you are doing it before you keep going.

 

.... <next post>

 

And the issue still stands of how badly we care about non WOT IATs in most situations.

 

And this is where we differ in opinion. I care about transient and mid throttle performance in traffic. The ECU adjust timing due to termistor IAT reading, and is pulling a ton in the city. Most times I drive the car it never goes over 40mph, and dosent get into boost for more than two seconds at a time.

 

The other issues is perfomance being on tap after restarting when it's been heat soaking in a parking lot for an hour. These are when most "social" performance opportunities arise, and your friends with fast german stuff showing you up until things cool down.

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And this is where we differ in opinion. I care about transient and mid throttle performance in traffic. The ECU adjust timing due to termistor IAT reading, and is pulling a ton in the city. Most times I drive the car it never goes over 40mph, and dosent get into boost for more than two seconds at a time.

 

The other issues is perfomance being on tap after restarting when it's been heat soaking in a parking lot for an hour. These are when most "social" performance opportunities arise, and your friends with fast german stuff showing you up until things cool down.

 

 

I agree with this regarding performance. But I do also agree with Chase that it's an uphill battle.

 

 

You could always tune for pulling less timing due to IAT, but naturally that's not a great idea. The best solution, IMO, would be to get a very small temperature sensor (i.e. miniscule thermal mass and very fast transient response), place it post-I/C and re-tune accordingly. Of course that's a much different game to play, but I think probably easier than trying to make the stock IAT sensor work the way you'd like. And I know you'd have no issue with the wiring and setup ;)

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Let me preface all of this: I am in no way attacking the Grimmspeed intake. I actually think it's a well though out design, hence why I bought it in the first place. It was very easy to tune, and picked up ~20g/sec of airflow.

 

Nope, I know that 100%, I just needed to make sure that you were just tinkering with your car and not looking for help. And then I decided to offer that help unsolicited :p Projects like yours and posts like these are things we save and use to help our customer service staff learn more about the ideology of our designs. These ideas and concerns etc are very helpful for training. I know there was no slight at all!

 

You'd think, but in testing I've found the gold foil to be more or less garbage compared to bare aluminum. I only used it on the intake tube because it was better than painted metal, and looked cool :lol:.

 

That's pretty much how I feel about a lot of tape jobs, radiant heat is what gold foil combats best, but is not usually the major heat source where people tend to put it. But that doesn't matter most of the time, because it looks cool! The only time I'm vocal against wrapping or coating is on hot side charge pipes, where you end up missing out on some on boost heat transfer.

 

Hold my beer ;)

 

What I was thinking was some sort of blanket around the intake pipe outside of the box to knock down on radiator air heating. Following this finishing the finder air isolation, and then adding a small duct fed fan to blow cool air around the filter/MAF. As you said, the issue isn't at WOT airflows. It's where airflow is too low for the flow inside the intake to cool it more than the radiator exhaust air is heating it.

 

I like it, there is nothing wrong with tinkering with your car to hit specific goals, I just wanted to make sure that that is what you were doing. I see things like the flame guard on the coolant hose that drapes over the intake, and that part only goes over silicone. It really seems like this combination is doing a decent job of minimizing conduction.

 

It might be worth trying to make a simple round heatshield that would be held by the hose clamp just in front of the intake, between the radiator. It would only be in contact with the silicone, which would be good, but I'm not entirely sure how effective it would be obviously.

 

If you were interested in trying a fan idea I still am pretty adamant about focusing on blowing the area OUT of that area instead of feeding in from outside. With a little better sealing like you've suggested, I think this would do double duty as making sure dirty radiator air stays away, and would force cool air to be fed in the area at the same time. You could probably set it to run whenever the radiator fans were running, as well as whenever the car was on. That might help you accomplish what you're trying to do.

 

I don't know if it'll work, but I want it to!

 

Chase

Engineering

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