Rediculous IAT temperatures....

[5][Spyder]

Using a Acron 9145 Scanner, which does PID data, live engine data,

Driving around town I see, passing 2 banks I see their digital signs reading exactly 99deg, the ambient reading on the A/C system shows 100, and my scanner shows high a few deg about 103 for the variable 'Outside temperature' however the IAT sensor shows pretty much the same 103-103.5deg on startup, warms up and takes off dramatically. Within 5 minutes it goes up fast to like 110-115 whenever idleing at stop lights it will hit 120 easy, whenever stopping at a drive thru(3-5minutes) the IAT temperature will read up to 30deg over outside temperature, even 32-35deg over if u get stuck in traffic for 7, 8 minutes, then you speed up to 60 and hold there, it will take 2-3 minutes to get the IAT sensor reading to match outside temperature again.....these underhood temperatures are crazy, I came from a NA Camaro, and I never say IAT over 10deg over outside temp.

All this is expected though, with turbo's underhood temp is extreme for sure. Point of all this is, I'm really starting to feel the need for the CP-E CAI over the Cobb SRI. Dynos mean nothing compared to street numbers, on the street you sit at stoplights, stuck in traffic, and then when u get going you may have to drive to 5 minutes to get that IAT temperature back down, forget getting stuck in the pit at the track, here in Oklahoma you can get stuck in the pit wating on a track cleaning etc, even if you turn your s*** off as much as possible that heatsoak adds up fast. So its hard to believe those Cobb dyno numbers vs. sitting at the light with heatsoak out the ass.....

Can anyone else verify these numbers?

 

[JCurry]

Cant say ive monitored the iat's but ive seen sri kits on other cars have the same effect, which is the reason i try to stick with a good cai

 

[nytmar3]

My cobb intake doesn't heat up while idling. I monitor this with a dash hawk.

 

[MS3077]

I've been getting awesome performance out of my Cobb SRI.

 

[5][Spyder]

what IAT numbers are you getting exactly....? please post if you have them...

 

[5][Spyder]

My cobb intake doesn't heat up while idling. I monitor this with a dash hawk.

http://www.mazdas247.com/forum/showthread.php?t=123696367&highlight=IAT

in post#8 'Nypst' verfies what I'm seeing with the stock airbox with the COBB SRI.....the posts 45 & 46 user bova80 claims a 20-40deg increase over ambient with a COBB intake and when he had a CAI he saw only 7deg.

MS3 is serioulsy hot engine comparment. So I wonder what the difference in HP is on the street, a few butt dyno runs in good conditions(not hot, not heat soaked engine are one thing, when ppl do mods they usually test the first few butt dynos in ideal conditions) vs. stock its hard to know. All the 'dynos' ppl have done to compare aren't really accounting for heat soak are they?!??!?. You could debate that a dyno run will be hotter than a street run(as air is not running through the TMIC like crazy) but the dyno from cold is another....but its all in how its done, ppl using fans, ice on the TIMC, etc. Also ppl usually cool off between dyno runs, and the first dyno(coolest) is usually the highest numbers, I can't even image a dyno done after a 2 minute stop in traffic(i.e. actual street race conditions). Although because its a turbo car the IAT matters less and less, compared to an NA car where the IAT is pretty much exactly the temp of the air going into the Intake Manifold, here its going through the turbo/TMIC.....heated up like crazy then into the engine, either way those IAT numbers are sickening, I'm going to go with CP-E CAI, I would take actual street gains over 'more noise' any day. No offense to any COBB owners directed.

 

[nytmar3]

what IAT numbers are you getting exactly....? please post if you have them...

My Cobb consistently shows no more than 5 degress higher IAT than my current AT at that time.

 

[Vord]

Using a Acron 9145 Scanner, which does PID data, live engine data,

Driving around town I see, passing 2 banks I see their digital signs reading exactly 99deg, the ambient reading on the A/C system shows 100, and my scanner shows high a few deg about 103 for the variable 'Outside temperature' however the IAT sensor shows pretty much the same 103-103.5deg on startup, warms up and takes off dramatically. Within 5 minutes it goes up fast to like 110-115 whenever idleing at stop lights it will hit 120 easy, whenever stopping at a drive thru(3-5minutes) the IAT temperature will read up to 30deg over outside temperature, even 32-35deg over if u get stuck in traffic for 7, 8 minutes, then you speed up to 60 and hold there, it will take 2-3 minutes to get the IAT sensor reading to match outside temperature again.....these underhood temperatures are crazy, I came from a NA Camaro, and I never say IAT over 10deg over outside temp.

All this is expected though, with turbo's underhood temp is extreme for sure. Point of all this is, I'm really starting to feel the need for the CP-E CAI over the Cobb SRI. Dynos mean nothing compared to street numbers, on the street you sit at stoplights, stuck in traffic, and then when u get going you may have to drive to 5 minutes to get that IAT temperature back down, forget getting stuck in the pit at the track, here in Oklahoma you can get stuck in the pit wating on a track cleaning etc, even if you turn your s*** off as much as possible that heatsoak adds up fast. So its hard to believe those Cobb dyno numbers vs. sitting at the light with heatsoak out the ass.....

Can anyone else verify these numbers?

Cobb will be coming out with a pretty effective heatshield from what I have been hearing.

Specifically, people more excited about this than they would be otherwise, because the cover for the cobb worked really well with the STi

 

[5][Spyder]

My Cobb consistently shows no more than 5 degress higher IAT than my current AT at that time.

I just don't see how thats possible, its hot as hell in the engine comparment at idle, seriously hot. Are you talking about only 5deg while cruising? If so that sounds perfectly reasonable, my Stock airbox will get down to 1deg hotter than ambient once I've been at 60-70mph for 5+ mins or so. But if you talking about at idle for 1 min at a stop light only 5deg difference, theres something wrong, fauly IAT sensor or something.....

Cobb will be coming out with a pretty effective heatshield from what I have been hearing.

Specifically, people more excited about this than they would be otherwise, because the cover for the cobb worked really well with the STi

That sounds promising, so I guess cobb does see the heat soak problem, otherwise they would not be developing this heatshield.....I wonder exactly what it looks like, u think it will look similar to an STi solution? So prob check out pics of a COBB SRI for STi for an idea...?

 

[dread]

I don't think the IAT matters as much with a turbo engine because it is going to get heated up by the turbo anyway and cooled the intercooler. I would say your boost temps are more important.

 

[nhluhr]

I don't think the IAT matters as much with a turbo engine because it is going to get heated up by the turbo anyway and cooled the intercooler. I would say your boost temps are more important.

This is just wrong. A turbo doesn't heat the air to some pre-set temperature, nor does an intercooler cool whatever it gets to exactly ambient. If you feed the turbo ambient air, it will get hot when compressed. If you feed the turbo hot air, it will get REALLY HOT when compressed. Likewise, an intercooler won't be able to cool the charge air all the way back down to ambient temp so the hotter air you feed it, the hotter air you get out of it.

Anyway, with that said, WRX/STI also have problems with really hot engine bays since there are two catalytic converters in the engine bay as well as the exhaust manifold being way longer so it releases a lot more heat into the engine bay. Beyond the obvious loss of charge density from increased temperatures, the ECU also is programmed to pull timing as the intake heats up to prevent detonation. Here is a stock table from the Subaru ECU that shows how much timing gets pulled for a given IAT:

As you can see, going from 120 to 140 you lose 6 degrees of timing. That is a LOT. A lot of people incorrectly think the sluggish response from their Subarus on hot days in stop-n-go traffic is due to the intercooler getting heatsoaked but it is MOSTLY due to the timing issue. This makes a bigger difference. (Note: Subarus do not have a temperature sensor after the intercooler... only in the MAF prior to the Turbo)

And here is how well Cobb's box for the Subarus works:

Highway Driving:

COBB Intake no box: Max 124 degrees F, Avg. 91.6 degrees F
COBB Intake with box: Max 108 degrees F, Avg. 74.9 degrees F
Difference of: Max ~16 degrees F, Avg. ~16.7 degees F

City Driving:

COBB Intake no box: Max 149 degrees F, Avg. 117.4 degrees F
COBB Intake with box: Max 111 degrees F, Avg. 87.5 degrees F
Difference of: Max ~38 degrees F, Avg. ~29.9 degrees F

Idle (~5 mins):

COBB Intake no box: Max 149 degrees F, Avg. 133.5 degrees F
COBB Intake with box: Max 113 degrees F, Avg. 99.2 degrees F
Difference of: Max ~36 degrees F, Avg. ~34.3 degrees F

Personally, I think the box will be well worth it not only for improved charge density but also for the ECU aspect.

 

[whitey4311]

Haha, I love it. All the cheerleaders for the SRI=fail. LOL

Common sense will tell you that sucking hot engine bay air makes no sense but open the hood and blow a big ass fan over it then you can show dynos that prove the SRI is as good as a CAI. DUMB!

Real life driving is what matters and a SRI makes no sense at all and I have never seen a slight edge over it vs a real CAI. Cry all you want but it is a stupid idea to save a few bucks and to make it work will require that cool box which will set the price comparable to a good CAI.

 

[Betelgeuse]

Once moving the air temp in the engine bay will fall rapidly. This whole iat temp thing is being blown way out of proportion. It's not like the ambient temp around the SRI filter will stagnate while all the air around it moves.

Anyway I'm right here in Kendall/Miami. I'd love to race anyone with a cai from a dead stop. I'll demonstrate that the driver mod is 100X more important that any iat temp reading. PM me and we can do it any Sunday. Just 0 to 60, nothing crazy.

 

[Betelgeuse]

Anyway, with that said, WRX/STI also have problems with really hot engine bays since there are two catalytic converters in the engine bay as well as the exhaust manifold being way longer so it releases a lot more heat into the engine bay. Beyond the obvious loss of charge density from increased temperatures, the ECU also is programmed to pull timing as the intake heats up to prevent detonation. Here is a stock table from the Subaru ECU that shows how much timing gets pulled for a given IAT:

As you can see, going from 120 to 140 you lose 6 degrees of timing. That is a LOT. A lot of people incorrectly think the sluggish response from their Subarus on hot days in stop-n-go traffic is due to the intercooler getting heatsoaked but it is MOSTLY due to the timing issue. This makes a bigger difference. (Note: Subarus do not have a temperature sensor after the intercooler... only in the MAF prior to the Turbo)

And here is how well Cobb's box for the Subarus works:
Personally, I think the box will be well worth it not only for improved charge density but also for the ECU aspect.

The ms3 has a different engine, different technology (direct injection) and a different ECU. What applies to the WRX/STI isn't going to automatically apply to us. But you make a good argument for the box (on an STI/WRX).

 

[nhluhr]

The ms3 has a different engine, different technology (direct injection) and a different ECU. What applies to the WRX/STI isn't going to automatically apply to us. But you make a good argument for the box (on an STI/WRX).

I suppose you missed the point. These types of calibrations are present in all vehicles. I just happened to have the IAT compensation table for a 2006 STI handy.

 

[Betelgeuse]

I suppose you missed the point. These types of calibrations are present in all vehicles. I just happened to have the IAT compensation table for a 2006 STI handy.

Not really missed the point. I know we have calibrations/tables too, but the extent of timing pull and the temp our engines reach at X time at idle won't be the same. Do you have the table for the ms3?

 

[shane02pro5]

My IAT is right at the throttle body for my Haltech and with the CAI I don't get over 116.

 

[MS3077]

Once moving the air temp in the engine bay will fall rapidly. This whole iat temp thing is being blown way out of proportion. It's not like the ambient temp around the SRI filter will stagnate while all the air around it moves.

Anyway I'm right here in Kendall/Miami. I'd love to race anyone with a cai from a dead stop. I'll demonstrate that the driver mod is 100X more important that any iat temp reading. PM me and we can do it any Sunday. Just 0 to 60, nothing crazy.

Same here I would love to race some MS3's with CAI. Well I already have and beat all 3-4 of them no problem so this idea of a CAI in the MS3 being superior to a SRI is just dumb period.

 

[nhluhr]

Not really missed the point. I know we have calibrations/tables too, but the extent of timing pull and the temp our engines reach at X time at idle won't be the same. Do you have the table for the ms3?

Not handy as I don't have direct access to them.

However, don't take what I've said to say that a "CAI" will outperform a Cobb SRI because of cold air. Most of the cold air designs on the market have their own drawbacks, such as long tubes, bends, or poor inlet design that allow the Cobb to make up for any loss it might see from temperature.

However, Cobb realizes this and so should everybody else: If you can feed your SRI cold air, it will be even better. That's why this box is being released.

 

[Vord]

I just don't see how thats possible, its hot as hell in the engine comparment at idle, seriously hot. Are you talking about only 5deg while cruising? If so that sounds perfectly reasonable, my Stock airbox will get down to 1deg hotter than ambient once I've been at 60-70mph for 5+ mins or so. But if you talking about at idle for 1 min at a stop light only 5deg difference, theres something wrong, fauly IAT sensor or something.....



That sounds promising, so I guess cobb does see the heat soak problem, otherwise they would not be developing this heatshield.....I wonder exactly what it looks like, u think it will look similar to an STi solution? So prob check out pics of a COBB SRI for STi for an idea...?

Yea, its pretty much this black box that covers all the sides but the front of the head. Its a nifty lookin thing. look for some STi's with cobb, probably there is a picture at the cobb site.