Air Charge Temperatures

[V8TV]

Has anyone datalogged their Air Charge Temperature vaules? I've got an EFI coversion car ('62 Galaxie w/351 windsor) and I'm curious to know what a factory ACT is on a Camaro, Mustang, Corvette, etc. Obviously, the cooler the better. I've logged 190 degree Engine Coolant Temps and the Air Charge is hovering around 132 degrees over a 10 mile cruise at around 70 degree ambient. That's with a cone filter on a factory FOX Mustang style air intake tube with no airbox. I am going to fab up a cold air box and log that data to compare, but I am curious to see what the intake air temps are on factory installations.

THanks!

- KO

[camcojb]

Originally Posted by V8TV

Has anyone datalogged their Air Charge Temperature vaules? I've got an EFI coversion car ('62 Galaxie w/351 windsor) and I'm curious to know what a factory ACT is on a Camaro, Mustang, Corvette, etc. Obviously, the cooler the better. I've logged 190 degree Engine Coolant Temps and the Air Charge is hovering around 132 degrees over a 10 mile cruise at around 70 degree ambient. That's with a cone filter on a factory FOX Mustang style air intake tube with no airbox. I am going to fab up a cold air box and log that data to compare, but I am curious to see what the intake air temps are on factory installations.

THanks!

- KO

Kevin,

I've done a lot of logging with the Camaro, Lightning, and now the new GTO. 132 cruising down the road in 70 degrees ambient is bad. But it's typical of an open element under the hood. The other thing I noticed with the open element on the Lightning was after idling at a light in traffic and the temps rising quite a bit it took a long time to get the temps back to where they were when moving. When I went to an enclosed box filter drawing cool air the temps dropped very fast once moving, and usually settled within 10 degrees of ambient when cruising or even lower.

My GTO when stock was plaqued with high IAT's even though it's in an enclosed box. It doesn't get fresh air, still draws underhood air and the temps are stupid. I now have converted it to twin turbo with the filters located out of the engine compartment. I see some heat soak if idling sitting still, but it immediately drops to about 8-10 degrees above ambient. With the intercooler and wot it will drop another 5 degrees through a run.

Air temps are a large reason cars get lazy, especially the later efi cars. The computer pulls a TON of timing as the temps go up. I remember on the Lightning it was pulling 15-20 degrees at a step.

Here's a thread I started on this subject when I had the Lightning:

I had the Swanson $300. open air filter setup with nice billet aluminum MAF adapter and anodized aluminum brackets and air diverter. Very nice quality. I always wondered about the IAT though. So I did some datalogging yesterday and since I thought I knew what was going to happen I had ordered an Airaid system to replace it.

It was 83 degrees yesterday and today when I tested. I drove the exact same 40 mile round trip with a mix of in-town and rural 55-65 mph open roads.

Yesterday I had the Swanson 4" by 9" open K&N filter and their brackets and panels which supposedly block and divert hot fan air from the filter on the truck. Once going and up to temp the IAT1 temps (at the MAF) were at least 17-18 degrees above ambient. The IAT2 temps (after the intercooler) were between 25 and 30 degrees above that. So for a cruise on an 83 degree day the IAT1 temps were at about 100 degrees with the IAT2 temps between 125-130 degrees. This was the best case while at a steady cruise of at least 55 mph and no stop lights. Swanson told me they stay within 10 degrees of ambient.

When you got into traffic the temps rose quickly. Averaged 30-40 degrees above ambient with the below 45 mph heavy traffic and occasional red lights. Saw a high of 130 degrees (47 degrees above ambient!) sitting at a couple of lights. The IAT's stayed about 25-30 above this which put them over 150 degrees at points, and we're not under any boost yet. What surprised me the most was that the IAT1 temps took so long to drop even when moving in traffic. I mean literally miles to get 4-6 degrees of drop. I had to run at 55 mph without stopping for about 10 miles to get them back to 17 to 20 degrees above ambient again.

Today I installed the Airaid. I've heard good and bad, but figured it had the exact same filter as the Swanson and was basically enclosed, drawing air through the (probably) too small factory hole in the fenderwell. I am planning on adding a fresh air hose to the box for additional cool air, but decided to go ahead and try it just to see if there was a difference.

Same exact route and same temp today so it was a very even comparison. On the open road section my IAT1 temps were within 3-4 degrees of ambient for an improvement of 13-14 degrees. The IAT2 temps were the same 25-30 degrees higher, but of course were lower than the open filter due to the IAT1 temps being so much lower.

In town traffic and stop lights saw the same temp rise as before, but never exceeded 22 degrees over ambient, versus up to 47 degrees over with the open filter. Most of the time they remained 12-15 degrees over ambient. But the biggest difference was in how fast the temps dropped when you pulled away from the light. Before it took miles (literally) to see a 6 degree drop in temps at the IAT1. With the enclosed unit they dropped 10 degrees within a 1/4 mile tops, and dropped the rest of the way to 3-4 above ambient within 1/2 to 3/4 of a mile. HUGE difference as the IAT2 temps are so much improved due to the lowered IAT1 temps.

It's basically like jumping on your truck on a 65 degree day versus jumping on it on a 85-90 degree day. There's (on my truck) a 20-25 degree reduction on the in-town slower speed stuff and 14-15 degree reduction out on the open road.

Jody

[V8TV]

Jody -

Thanks for taking the time to post all the great info! Hopefully I can get this airbox completed later this week and I'll log and post the difference.

Thanks again,

- Kevin Oeste

[camcojb]

Originally Posted by V8TV

Jody -

Thanks for taking the time to post all the great info! Hopefully I can get this airbox completed later this week and I'll log and post the difference.

Thanks again,

- Kevin Oeste

You're welcome Kevin. The plastic boxes don't seem to transfer heat as bad as the metal ones, but metal is usually easier to work with. Insulating the box with something will help. Any type of heat shield on the exhaust is also beneficial. Some of the aftermarket enclosures use fresh air and underhood air, but the most effective seem to isolate the box from underhood air and draw only fresh air. Just make sure the inlet and air path is large enough and unrestricted to support your airflow and horsepower.

Good luck and post up your results.

Jody

[V8TV]

Jody,

Do you have an opinion on how much an intake manifold will color the findings of an air charge temp sensor? My ACT sesor lives in my Edelbrock aluminum intake, and it seems that the intake would warm the sensor. I assume this is the reason why later systems seem to have the ACT sensor upstream in the plastic / rubber air intake tube.

I've seen some people who simply move the ACT forward and out of the intake, but I believe the ECM should know the temp as close to the combustion chamber as possible to correctly maintiain the right tune.

My procedure will be to install the cold air systme but leave the ACT in the manifold and log some data to see what happens.

[camcojb]

Originally Posted by V8TV

Jody,

Do you have an opinion on how much an intake manifold will color the findings of an air charge temp sensor? My ACT sesor lives in my Edelbrock aluminum intake, and it seems that the intake would warm the sensor. I assume this is the reason why later systems seem to have the ACT sensor upstream in the plastic / rubber air intake tube.

I've seen some people who simply move the ACT forward and out of the intake, but I believe the ECM should know the temp as close to the combustion chamber as possible to correctly maintiain the right tune.

My procedure will be to install the cold air systme but leave the ACT in the manifold and log some data to see what happens.

You are correct in that the temp closest to the cylinder is the most accurate. Extending the IAT harness and getting the IAT into cooler air will pick up some power as the computer won't be pulling as much timing. Most people notice their late-model car feels stronger before it's fully warmed, and this is one of the major reasons.

In the intake will be slightly off, mostly in a heat soak like idle and right after a re-start. But I think it would stabilize pretty quickly with the airflow coming over it. I've run there before with no issues, and the air temps didn't look much different than when I had it in the filter assembly.

Jody

[Speedster]

Hey Jody -
On your cars (or your opinion) is it better to get the air from the base of the windshield or from behind the grille or fender area ? The car is a 68 Firebird and I was going to grab air from the cowl area. Thoughts ? Opinion ?
Thanks !!

[camcojb]

Originally Posted by Speedster

Hey Jody -
On your cars (or your opinion) is it better to get the air from the base of the windshield or from behind the grille or fender area ? The car is a 68 Firebird and I was going to grab air from the cowl area. Thoughts ? Opinion ?
Thanks !!

That's ideal as it's a high pressure area, plus a bit higher off the ground. But either works very well, anywhere but inside the engine compartment.

Jody

[Speedster]

Thanks Jody. You've definately 'been there, done that.

[V8TV]

Jody,

I have the option of pulling from behind the grille or in a fenderwell. The OEMs seem to like pulling air from the well... I'm assuming it's also for NVH reasons. Do you have any thoughts?

Thanks again,

- Kevin Oeste