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Old 12-06-2019, 07:10 PM   #1
jimh3063
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Default Intake temps too hot

I have 2004 STi. It's have a GT30 kit on it and a FMIC. I am getting 190 intake temps. I can't do a cold air intake as the place to put it in the fender is being taken by the FMIC plumbing.

Does anyone have a similar config and have rigged up some type of cold air intake?
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Old 12-06-2019, 10:46 PM   #2
A.S.N.F.
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Let me guess, your cold side piping to your throttle body is on the right hand side. Also could you post a pic of your set up or give more info?
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Old 12-07-2019, 08:10 AM   #3
jimh3063
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Default Fmic

A.S.N.F.
You are correct on the cold side piping routing


Any constructive thoughts would be appreciated.

Thanks
Jimmy
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Old 12-07-2019, 08:32 AM   #4
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you mean 190 steady state? Like running at speed decent throttle, not after sitting or something?

If so yeah that blows, that's majorly sapping power.
I mean you have intercooling piping snaking up to a front mount right? So you obviously know how to lay out good flowing curves. You must know there's one solution, re-do your intake piping and duct it to a better spot. Even if you have a long length exposed to under hood temps it will still be an improvement when running at steady state, there won't be much heat transfer to a substantial flow and you could even insulate it if you wanted to make it better.

I get space is not in abundance but there's no other way.
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Old 12-07-2019, 09:41 AM   #5
A.S.N.F.
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Actually there is something you could do. The problem with these set ups is the air is being cooled down and then re-heated after it leaves the inter-cooler by the header/down-pipe, tubro and coolant tank. I would take out that side of the piping and get some heat isolation on the inter cooler pipe in that area.
You could also start playing with the idea of redoing the piping to your turbo and to your throttle body to effectively reverse them, as in the cold side of the piping is on the left hand side. Cobb specifically makes their kits to be reversed like this to avoid this type of thing.
Not to be mean, but right now my GrimmSpeed top mount is able to keep things cooler even before I used heat reflecting tap and wrapped my turbo. Not saying that to be mean, just saying as how bad it is heating up.

Also, just to be safe, inspect your intercooler and make sure it is not clogged up with crap. I have seen intercoolers and radiators clogged up by cotton (some areas have cotton every year from cotton trees).

Last edited by A.S.N.F.; 12-07-2019 at 09:49 AM.
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Old 12-07-2019, 08:42 PM   #6
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First of all, testing and data acquisition is important to plan your next steps so your not just throwing money and guessing based on what the internet said.

That said......

Some of this is reiterated and expounded on a bit.

I get that the intake is positioned this way more so out of necessity, but where is your IAT sensor located? Have you measured the intake temps at the filter and if so, are these temps satisfactory? If they are, leave the intake alone. If not, as you and a few others have kindly pointed out, you'll need to relocate the inlet and/or isolate the filter element. Where it's sitting may very well have nice, fresh cold air hitting the area from the front of the hood, so it may end up being a gigantic waste of time and money to use/design a new intake but you'll need data to determine whether or not you are satisfied with where it is.

Second, your piping runs back over a few radiating heat sources (i.e.: the turbo). You practically might as well just remove the intercooler as all that is practically undoing the IC's job. Your cheapest option would be to insulate. Better option would be to relocate. The best option is to do both.

I would personally be curious to know temps at every step of the way. Ideally in five locations: intake filter, just after the compressor outlet, IC inlet, IC outlet, at the throttlebody. This data would give you a decent picture of how the air is being affected as it moves through the intake and would help give you a better understanding on what needs to happen.

Also, your IC, even though it's a reputable name brand, may not be as efficient as we are lead to believe, however testing would be required to determine if this is the case.

All of this is assuming that you're serious about horsepower. If all you want is to see improvements, skip all that and proceed to spending money where you may not need to.
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Old 12-07-2019, 09:00 PM   #7
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Quote:
Originally Posted by A.S.N.F. View Post
...
Not to be mean, but right now my GrimmSpeed top mount is able to keep things cooler even before I used heat reflecting tap and wrapped my turbo. Not saying that to be mean, just saying as how bad it is heating up.
what is the R value of this magical tape???
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Old 12-07-2019, 10:59 PM   #8
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Quote:
Originally Posted by turboblew View Post
what is the R value of this magical tape???
Just the standard DEI heat tape that everyone else uses. Heck of a lot cheaper that it was 16 years ago when I was getting whatever I could for my Supra. Their is more expensive and better stuff, but that goes up an enormous amount per square foot.
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Old 12-07-2019, 11:56 PM   #9
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Quote:
Originally Posted by A.S.N.F. View Post
Just the standard DEI heat tape that everyone else uses. Heck of a lot cheaper that it was 16 years ago when I was getting whatever I could for my Supra. Their is more expensive and better stuff, but that goes up an enormous amount per square foot.

afaik there has always been a high R value foil insulation available at home depot... R30 as a single layer or double if you 2 layer it. I dont believe the DEI stuff does anything and would be suprised if its higher than an R1 value.

Also there have been sleeve materials available for well over 20 yrs... they are pretty effective in engine compartments with not much real estate.
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Old 09-29-2020, 04:27 PM   #10
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Searching for some input from STI owners. I just got my STI and am curious if my high intake air temps are okay or signs of an issue.

Mods that matter to this equation:
Cobb SF w/box and OEM snorkel
IAG stage 2 shortblock with 2k miles
Heat-wrapped Cobb downpipe
Heat-wrapped Tomei UEL headers

Mods that probably don't play into this:
Koyorad radiator
Process West TMIC
Perrin turbo inlet
Stock turbo
Stock fuel delivery

Ambient temp 63*F, sunny day
Observed intake temps when driving slowly between a couple stores with some time spent at stand-still: 160*F, or +97*F over ambient.

I see people say "45*F over ambient is normal". OK....well what about 100*F over ambient?

I popped the hood when I got to my destination when it was reading 160*F for intake temps and it was like a sauna of heat coming out of there. This was after I was at the bank, stopped for about 2 minutes in the shade, another minute of crossing a parking lot at maybe 20mph, no hard acceleration or anything.

I would love to have a reading of the air temp post-intercooler, but I don't.

Driving at 35mph in the same 63*F weather, intake temps settled around 90*F.
On the highway doing 75mph, I was seeing mid 80's I believe, or +20*F over ambient.

Just curious if this is normal or something to be concerned about.
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Old 09-29-2020, 04:40 PM   #11
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There's no easy way around this, you'd need to make some significant changes to make anything beyond small marginal fixes here. Your filter is sucking air that passes through a screaming hot radiator (that may or may not have an A/C condenser in front of it as well), plus you have a FMIC adding even more heat load. Change the setup or figure out a way to get the filter to an arear that has access to fresh clean air.

Another option is to get speed density tuned since you really don't know what post I/C temps are at this point. They might be great, they might not.
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Old 09-29-2020, 04:51 PM   #12
snake2332
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Yeah, I can tell the Cobb box is heat-soaking pretty badly. It sure seems like a CAI pulling from somewhere else would be much cooler. I don't like going into the fender area since that gets dangerously close to water, slush, de-icer, etc. from the road, but it would probably be safe enough. Based on what I'm seeing today, in the summer when it's 100*F outside, my intake air is going to be damn near 200*F pre-IC.

So I shouldn't be alarmed at my nearly +100*F over ambient with this setup? I have yet to read a post from anyone with anywhere near this level.
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Old 09-29-2020, 05:03 PM   #13
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For anyone running short-ram intakes:

Track proven with actual data (top speed and IAT) that they're worse than stock, he also gives a good reason why they dyno higher than stock: because most people dyno with the hood open and a fan blowing which isn't a great simulation of running conditions.

He also mentions that running a hot air intake + intercooler runs into the same problem OP is having, it can negate each other.
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Old 09-29-2020, 05:35 PM   #14
snake2332
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Good info, thanks guys. I wanted the GrimmSpeed short-ram on my 2015 WRX but it was not in stock at the time. I could tell how it sealed off the area a lot better than Cobb's. I went with the K&N Typhoon, then sold the car 3 days later and got a 2011 STI because I wanted better sounds and stronger components. I'm going to do some more research on insulating the Cobb airbox better, sealing it up better so it only pulls from the snorkel, or if it's worth it to try and extend it into the fender. I really don't think 160*F inlet temps are acceptable when it's only 63*F outside. I would put the stock airbox back on this car if they seller included it, haha!
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Old 09-29-2020, 07:57 PM   #15
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this is why i didn't go with perrin fmic on my 2011 wrx, went with cobb. this is what i did to my fmic and cobb sf box. my IAT are still some what high in the summer down here in GA but right now they are around 10* or so above ambient temp

https://drive.google.com/file/d/1w_t...ew?usp=sharing
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Old 09-30-2020, 09:16 AM   #16
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People are so afraid of sucking up water for no reason. Unless the filter is submerged in water it will not suck up enough water to damage your eng. I use a APS 70mm CAI with FMIC piping in the passengers side fender and drove in big rain storms and its all good. Even had the wheel lining come of and still didn't suck up any water.

Last edited by BlackFighter; 09-30-2020 at 10:00 AM.
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Old 09-30-2020, 09:40 AM   #17
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Quote:
Originally Posted by snake2332 View Post
I don't like going into the fender area since that gets dangerously close to water, slush, de-icer, etc. from the road, but it would probably be safe enough.
If that makes you uneasy, then stay clear of water-meth injection kits.
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Old 09-30-2020, 12:19 PM   #18
snake2332
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I'll definitely go into the fender if I can't get better temps with the current airbox. I am not that worried about water getting up in there since it looks fairly protected. Plus the filter is oiled.

My airbox does have gold foil on it, but not that great of coverage. I'm going to insulate the box and close up the gaps. I also like the idea of installing a ~100CFM fan to actively pump air from the fender into the box as a cheap solution. I could probably sell this Cobb setup and afford a CAI, so that's my plan B.
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Old 09-30-2020, 02:55 PM   #19
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Quote:
Originally Posted by BlackFighter View Post
People are so afraid of sucking up water for no reason. Unless the filter is submerged in water it will not suck up enough water to damage your eng. I use a APS 70mm CAI with FMIC piping in the passengers side fender and drove in big rain storms and its all good. Even had the wheel lining come of and still didn't suck up any water.
^this
No clue why so many people have that fear. If you drive into enough water to fully intake water via the fender area your car is going to be the least of your worries. If I was in that much water I'd be unbuckling my seatbelt and planning how to ditch the car and keep my life.

Quote:
Originally Posted by snake2332 View Post
I also like the idea of installing a ~100CFM fan to actively pump air from the fender into the box as a cheap solution. I could probably sell this Cobb setup and afford a CAI, so that's my plan B.
no clue what the fan idea is going to achieve. If you let the car pull air from the fender area you will get 10 over ambient when actually driving. If you are in parking lots like you described before don't even look at the intake temp as it is a meaningless number. No car can manage intake temps with little to no movement, plus it doesn't matter anyway at no throttle.
The stock air box works great in this car. People mod them into hot air intakes and make them worse.
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Old 09-30-2020, 03:04 PM   #20
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Quote:
Originally Posted by snake2332 View Post
I'll definitely go into the fender if I can't get better temps with the current airbox. I am not that worried about water getting up in there since it looks fairly protected. Plus the filter is oiled.

My airbox does have gold foil on it, but not that great of coverage. I'm going to insulate the box and close up the gaps. I also like the idea of installing a ~100CFM fan to actively pump air from the fender into the box as a cheap solution. I could probably sell this Cobb setup and afford a CAI, so that's my plan B.
FYI, most of the heat soak that you see in stop and go is coming off the exhaust manifold. Routing more air through the fender makes the situation worse.
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Old 09-30-2020, 03:22 PM   #21
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The two main reasons you having high intake temp is because of the weird ass short ram you have, looks like something is missing, and 2 that the FMIC intake pipe is designed wrong. All that cold air from the FMIC goes right over the turbo before entering the eng, one of the hottest part in your car. So your FMIC is useless. What are the brand names of the short ram and fmic?
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Old 09-30-2020, 03:56 PM   #22
snake2332
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I don't care about hearing the turbo noises really, so I might go back to stock. I could probably trade this Cobb SF for a stock unit + cash and make money on the deal, haha!

Sure, IAT doesn't really matter when putting around town, but when I want to pull into traffic or get on the interstate and IATs are still at 150*F, I guess the ECU will tell it to reduce boost target by 4% - that isn't much at all. I guess that harkens back to my original question of "is 100*F over ambient something to be worried about?", and the answer is apparently "not really, but the stock airbox would reduce it".

My car was e-tuned for the Cobb SF and I want to keep it for now, so I'll just insulate the box and snorkus better and stop worrying about IATs. The values just seemed really high to me and I'm technically still in the break-in period on this motor so I am being overly careful (except that 3rd gear pull to 6400 rpms on the way home ). It's killing me to let it run on this break-in oil of unknown specs from a Subaru dealership until it hits 3k miles so I can put in some Motul, but hey, this is what IAG says to do.

Thanks for the input fellas!
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Old 10-02-2020, 03:41 PM   #23
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Just for fun, I spent $15 at Lowe's and used a server fan (~150CFM Delta 5" 12V) I salvaged years ago. I plugged the fan into the DRL plug since it was hanging there and in a convenient location, which means the fan is running at over 14V - not sure if that is going to make it catch on fire or anything Tested the fan operation by blocking the tires and running the car with and without e-brake on - it works. I ran the vent hose down to the fog light cover (my STI is not a Limited, so no fog lights), with the cover taken off. The fan isn't perfectly sealed in the 5" to 4" reducer currently, but still pulls in plenty of air, which I can feel when I put my hand up to the hose at the bumper.

I let the car run in the driveway with Cobb airbox "sealed" back up. I left the snorkus off so I can view the fan, which is a couple inches below the air filter. 59*F ambient temp, sitting in the sun, hood closed. Car got up to 131*F intake air temp after 15 minutes or so with the e-brake on (thus fan not running). I disengaged the e-brake and in about 1 minute, IATs dropped 20*F to 111*F. Not bad! Can't even hear the fan noise over the car. I realize this improvement might not really matter to the actual performance of the car, but it might help my Cobb AP (anxiety port) symptoms.

It's just a ghetto test-setup for now, but here are a few pics.






I'm going to turn the fake vent into a real vent on the fog light cover, or get a fog light bezel which has a pretty perfect hole for my 4" vent hose. I might throw a screen into the vent hose to avoid making the air filter get dirtier/wetter than usual. I think I'll leave the fan plugged into the DRL plug. Then, when it's -10*F outside and I (remote) start my car at work, the server fan won't be trying to run at such a low temp. It will get up to a normal temp by the time I disengage the e-brake.

Definitely a cheap setup. Now I need to bolt the 5" to 4" reducer to the body of the car and seal up the fan, and a few other tweaks to make it less ghetto.
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Old 10-02-2020, 04:54 PM   #24
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Whatever fan you have will never blow more then normal air flow at high speeds. It will only help when the car is not moving, or city light to light driving. Which at the kind of driving it doesn't matter if your intake temp is a little high. If anything that fan will obstruct airflow on high speeds. The fog light duct system is a good idea, was going to suggest it but was not sure if 2011 had foglight covers. Leave the ducts without the fan.
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Old 10-02-2020, 05:08 PM   #25
snake2332
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Ya, it's more like when I am done running errands, IAT is at 160*F, then I need to pull out into 45mph or 70mph traffic. I know it's only a 4% reduction of boost when IAT > 140*F, so it's more of a placebo effect with small actual improvement.

Not sure how this would reduce any airflow. I'm still going to use the snorkus, I just have it off at the moment while I finish this setup.

When driving at speed, I'm concerned about the air flow forced into the vent hose causing the fan to run too fast and wrecking it, but I don't really care since it was free and I could replace it for under $20 if I feel like. Maybe I'll point the vent hose down or sideways so it doesn't get air forced into it at speed, but rather just pulls the air from near the fog light cover.

Next, I'll be insulating the bottom of the snorkus and the Cobb airbox better (it already has that gold foil crap that doesn't really seem to do much) to help avoid some of the heat-soak. That'll be a whole $35 I spent on this, so I don't care if others don't think it's necessary or even worthwhile.
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