[Jason18ZL1LE]

My system has the Prospeed Intercooler and the Prospeed fender tank. I have a 10% lower pulley, ARH Long Tubes, Cam and E85. I can tell you that I monitor IAT2 constatly and when the car is moving it’s NEVER more than 15F above ambient temp. When I do WOT pulls the IATs will actually cool down to approximately 10 above ambient and for prolonged driving like uphill mountain road, my IATs stay between 15-20 above ambient. I’ve seen IAT2 as low as 55F when on freeway in 50F weather.

I know this isn’t a log but I can tell you mine never wavers from this formula. The stock LT4 heat exchanger is laughably small. It’s woeth the upgrade

[BMWM.D.]

Originally Posted by 17txcamaross

BMW, I was hoping to get some new data and a little more input from multiple members. Logs would be great, but just a nice sample of IAT data would also help. I want to make certain I know what temps I am shooting for and talking with ADM and Weapon X makes it seem that temps will not be close to ambient temps during colder weather. I still feel that 120-130 in 65-70* weather is not ideal, but according to some sources these blowers rarely run under 100* due to that being their normal operating temps and from heat transfer from the engine and radiator.

If you wouldn't mind I would love to get some data now that temps are lower in your area. I will grab a log of mine tomorrow morning to show temps at idle, at cruise, and at idle following cruise.

Thanks everyone for your input and I hope to gather as many IAT logs or information as possible.

I get it. I’m out of town for a few days for work, but I’ll take the car out this weekend for sure. You may be right about there being a larger delta in cool weather, but we have a very mild climate here on the coast. It’ll probably be in the 60’s this weekend when I drive it.

I have IAT2 displayed a lot of the time on my P3 gauge, so I’m pretty in tune with how it’s running. I’ve always been impressed with how cool it runs. But I’ll get some more data when I can.

[17txcamaross]

Originally Posted by Jason18ZL1LE

My system has the Prospeed Intercooler and the Prospeed fender tank. I have a 10% lower pulley, ARH Long Tubes, Cam and E85. I can tell you that I monitor IAT2 constatly and when the car is moving it’s NEVER more than 15F above ambient temp. When I do WOT pulls the IATs will actually cool down to approximately 10 above ambient and for prolonged driving like uphill mountain road, my IATs stay between 15-20 above ambient. I’ve seen IAT2 as low as 55F when on freeway in 50F weather.

I know this isn’t a log but I can tell you mine never wavers from this formula. The stock LT4 heat exchanger is laughably small. It’s woeth the upgrade

Thanks for the information. I have the Weapon X heat exchanger in the center with the reservoir tank replacing the factory vacuum fill system. Yesterday on the way home it was 72 degrees out and I saw 110-120* IAT2 temps at a steady cruise with minor traffic doing 50-60 MPH. I constantly have my IAT showing on my P3 gauge unless going WOT where I track my AFR.

[BMWM.D.]

Originally Posted by 17txcamaross

Thanks for the information. I have the Weapon X heat exchanger in the center with the reservoir tank replacing the factory vacuum fill system. Yesterday on the way home it was 72 degrees out and I saw 110-120* IAT2 temps at a steady cruise with minor traffic doing 50-60 MPH. I constantly have my IAT showing on my P3 gauge unless going WOT where I track my AFR.

Just for reference, mine stabilized at 102 degrees on a 91 degree day. That was freak weather here, and much higher IAT2 than normal. I’ve never seen higher than that during a steady cruise. I bet this weekend, IAT2 will be in the 75-80 degree range. I’ll post what I find.

[17txcamaross]

Ok, thanks BMW. I just want to figure this out. I'm pretty sure I have my sensor calibrated correctly in HP Tuners and the harness is plugged in correctly.

I have checked temp with an infrared and it reads the same as the P3 gauge.

I am at a loss! I just want to see these wonderful temps everyone talks about. I am starting to wonder if it is something in the tune, something with the higher compression of the LT1, or just my s**t luck haha.

[Jason18ZL1LE]

So Matt with Lethal Garage dealt with the same issue and it’s just an LT1 issue. IAT2 is calculated and not actual like the LT4. But if your thermal laser is confirming the temps then thats odd.

I can tell you when we built my LT4 we had a similar high temp issue and one of my factory cooling bricks in the SC itself somehow became clogged. Might be worth a check.

[grampa_ss]

Originally Posted by Jason18ZL1LE

So Matt with Lethal Garage dealt with the same issue and it’s just an LT1 issue. IAT2 is calculated and not actual like the LT4. But if your thermal laser is confirming the temps then thats odd.

I can tell you when we built my LT4 we had a similar high temp issue and one of my factory cooling bricks in the SC itself somehow became clogged. Might be worth a check.

That's what my tuner told me...The SS does not have IAT2. They had to bust the IAT sensor out of the MAF and move it manifold so it's reading after the Meth. Which it what matters most.

[BMWM.D.]

Okay, so I took the car out for a few drives today. I didn’t pay much attention earlier, but tonight I watched everything took note of temps and driving conditions.

I started out in my garage after parking the car 5 or 6 hours earlier. IAT2 was at 81 degrees, with the temp in my garage showing as 67.

I then drove 7 miles to my parents house. It was about 56 degrees on my drive, and as long as I was moving, the IAT2s continued to drop. They eventually seemed to settle at 68 degrees. This was driving on the freeway at 70+ mph.

After a few miles at low speed with some stop lights and such, the IAT2 was up to 72. I then parked it for an hour and a half.

When I got back into the car, it had obviously heat soaked and was up to 92 degrees. I took the same route back home, and again, it dropped back down to 68 or so. I got into boost a couple times, and the IAT2 actually dropped. The lowest I saw was 63. The outside temp was 54 at this time.

The only time I saw temps climb (other than sitting with the engine off), was if I was idling with no movement or airflow. When I got home, I let it idle for 10 minutes. It got up to about 110 degrees. I’m guessing it would have kept climbing, as the engine temp was a lot higher (about 175).

After that, I took a 15 minute cruise down by the beach. This was 30-50 mph driving with the occasional stop light or stop sign. Again, it didn’t take long for the temps to come back down to 68 degrees. Outside temp was still about 54 degrees.

So my conclusion is about the same as before, despite an almost 40 degree difference in ambient temperature. 12-14 degrees above ambient is about average for normal driving. It can be even lower if the engine is sucking in a lot of air. Heat soak (parking with engine off) or long idle periods are the only way my car will get over 100 degrees. And even then, it recovers quickly with any airflow over the heat exchangers.

For reference, the car is stock cooling wise, other than a 160 thermostat. It has a 2.30” blower pulley as well.

[17txcamaross]

Originally Posted by Jason18ZL1LE

So Matt with Lethal Garage dealt with the same issue and it’s just an LT1 issue. IAT2 is calculated and not actual like the LT4. But if your thermal laser is confirming the temps then thats odd.

I can tell you when we built my LT4 we had a similar high temp issue and one of my factory cooling bricks in the SC itself somehow became clogged. Might be worth a check.

You are correct here. My TMAP sensor has been broken out to read as IAT1. I am logging IAT1 and temps just seem high. Maybe I will call and speak with Matt at Lethal Garage.

[17txcamaross]

Sorry for the late response here, but for those who have responded or even those with experience on the LT4 swapped motor, what are possible causes of the increased blower temps?

I have ADMs reservoir installed so there shouldn't be any air in the system. Also, have the WeaponX intercooler.

Since this is an LT1 the Baro sensor is not wired up...not sure this would have any effect.

Again due to being an LT1 the bypass valve is not electronically controlled.

I also have the base of the blower case plugged off with nipple removed.

I am truely baffled on why my temps are so much higher than everyone else. This weekend for example the P3 gauge showed temps from 110-120* under normal city driving and freeway cruise with outside temps at 74*.

[17txcamaross]

So, just for current readings. Just took the Camaro out to grab lunch. Has been parked for 5 hours and started at 100*. Dropped to 98* during high idle warmup then quickly rose back to 100-102* as RPMs fell. Cruise on freeway was 110*. Parked the car for a total of 5 minutes...temp up to 132* when I started again. Lowest the temps got on the trip back which included a short 1 mile freeway cruise and stop/go traffic around 30-35 mph was 129*.

Outside temp 74*

There must be something causing the high temps...what could cause this?

This is a complete nuisance when I want to be able to take the car for trips longer than 10-15 miles from home, but don't want to have such high temps.

[g26er]

Not sure if it's helpful but, on the SS, the IAT2 temps are a mix of IAT1 vs ECT. Lower airflow leans more towards ECT's than higher airflow.

IAT2 can be changed to bias more towards IAT1 in HPTuners, Engine > Airflow >General and it will be in the Cylinder Charge Temperature section. I'm 98% sure when I messed with this before, I could change my IAT2 temps to read more inline w/ IAT1 actual temps.

[17txcamaross]

Originally Posted by g26er

Not sure if it's helpful but, on the SS, the IAT2 temps are a mix of IAT1 vs ECT. Lower airflow leans more towards ECT's than higher airflow.

IAT2 can be changed to bias more towards IAT1 in HPTuners, Engine > Airflow >General and it will be in the Cylinder Charge Temperature section. I'm 98% sure when I messed with this before, I could change my IAT2 temps to read more inline w/ IAT1 actual temps.

Thanks, but I should say that what I am reading is the IAT1 for the SS which translate directly to IAT2 for ZL1 via the sensor breakout wire which replaces IAT1 in the MAF with IAT2 from the TMAP. Although I did not confirm these temps today...I have been able to confirm IAT1 temps match to an infrared reading on the outter blower case near the rear of the intake manifolds.

I swear I will figure this out, but for now any insight will prove helpful.

[g26er]

Originally Posted by 17txcamaross

Thanks, but I should say that what I am reading is the IAT1 for the SS which translate directly to IAT2 for ZL1 via the sensor breakout wire which replaces IAT1 in the MAF with IAT2 from the TMAP. Although I did not confirm these temps today...I have been able to confirm IAT1 temps match to an infrared reading on the outter blower case near the rear of the intake manifolds.

I swear I will figure this out, but for now any insight will prove helpful.

Here's a screenshot of the table I'm referring to. You'd probably want to lower these numbers so it's biased more towards actual IAT temps. I haven't tried but, I'd assume zeroing this table out would not involve ECT temps at all in the charge temp calculations though I didn't try when messing with it.

There's also a Filter table that controls how fast the bias (IAT vs. ECT) changes when airflow changes.

Good luck.