Highway cruising IAT's on a NA AP1
03-11-2015, 08:06 AM
#1
Highway cruising IAT's on a NA AP1
I had a misfire earlier this week. So tried the basics map whacked, cleaned my iac, burned off any stale gas, new plugs, I think I got that cracked. I hooked up my obd2 scanner and figured I'd watch the live values to see if anything pops out as out of the ordinary. Now, truthfully, I've never had a single problem with my s2 so I've never logged it. I have no idea what the stock ranges are etc etc.
BUT what I did notice was that my IAT's LOVE to climb. Its 45F degrees in my neck of the woods atm, and I was logging 120 degree iats crusing at 70 mph on the highway. With a STOCK na motor! Traffic got it up to 160, if i was boosted, this would be insane. Now I realize that the stock ap1 iat is located in the back of the intake mani, just above a coolant line, and I get that many people have had success moving it to the front of the motor.
But before I start relocating more stuff on my car, I wanted to see if anyone has run straight water injection on an NA motor. Imo, I think it might be quite effective at combating this ridiculous NA heatsoaking issue. I dont think we'd need to run it all the time, just on the grid to get the initial iat's down, I'd hope from that point the incoming air keeps it closer to ambient, especially if we're on the track at WOT all day.
I've had great success with alcohol kits in the past, though they can get messy. Gets everywhere on a turbo car. With this one, I'm only looking for the cooling purpose of the kit and plan to only run distilled water. Can anyone shed some light on the topic? Pros, cons etc.
BUT what I did notice was that my IAT's LOVE to climb. Its 45F degrees in my neck of the woods atm, and I was logging 120 degree iats crusing at 70 mph on the highway. With a STOCK na motor! Traffic got it up to 160, if i was boosted, this would be insane. Now I realize that the stock ap1 iat is located in the back of the intake mani, just above a coolant line, and I get that many people have had success moving it to the front of the motor.
But before I start relocating more stuff on my car, I wanted to see if anyone has run straight water injection on an NA motor. Imo, I think it might be quite effective at combating this ridiculous NA heatsoaking issue. I dont think we'd need to run it all the time, just on the grid to get the initial iat's down, I'd hope from that point the incoming air keeps it closer to ambient, especially if we're on the track at WOT all day.
I've had great success with alcohol kits in the past, though they can get messy. Gets everywhere on a turbo car. With this one, I'm only looking for the cooling purpose of the kit and plan to only run distilled water. Can anyone shed some light on the topic? Pros, cons etc.
03-11-2015, 08:21 AM
#2
I can't speak to an AP1 specifically, but in general I would always expect IAT to be within a few degrees 10 to 20 degrees of ambient during steady state highway cruising. Maybe 20 degrees higher at max?
You're seeing an increase of 75 degrees over ambient. That's a lot.
What modifications, if any, have you made to the car? Different intake, maybe a cooling plate, etc?
I'd be tempted to try a different IAT sensor first, as the #'s it's giving seem almost unbelievable to me. My s/c IAT's are similar to what you're seeing.
You're seeing an increase of 75 degrees over ambient. That's a lot.
What modifications, if any, have you made to the car? Different intake, maybe a cooling plate, etc?
I'd be tempted to try a different IAT sensor first, as the #'s it's giving seem almost unbelievable to me. My s/c IAT's are similar to what you're seeing.
03-11-2015, 08:26 AM
#3
I don't disagree with ^ per say, but I always log at least several degrees over ambient temp. If I remember correctly, when ti was about 32F out, I would see ~70F at idle and maybe 55F while cruising, highway speeds. I may be wrong, but I definitely remember them being a good bit higher than ambient temps.
03-11-2015, 08:50 AM
#4
I don't disagree with ^ per say, but I always log at least several degrees over ambient temp. If I remember correctly, when ti was about 32F out, I would see ~70F at idle and maybe 55F while cruising, highway speeds. I may be wrong, but I definitely remember them being a good bit higher than ambient temps.
03-12-2015, 05:16 AM
#5
Your temp readings don't sound abnormal, if I recall readings I've taken in the past. Here is some info. I have to share.
The temps your are seeing are basically the temperatures inside the intake manifold, based on the location of the sensor on ap1's. With coolant flowing through the manifold and with the head touching the manifold you are going to get some high temps in most conditions. Temps will be much higher than ambient even cruising on the highway. The temps you are seeing will be impacted mostly by throttle opening/throttle position. At cruising speeds the throttle isn't open very much and the intake manifold stays hot, run it on the highway at WOT and you will see temps drop quickly as the manifold is cooled by incoming air. The only drawback is that you can't run WOT for miles at a time, lol, so the temps eventually climb back up as throttle position returns to lower settings when you return to cruise conditions. With coolant temps being around 190+ degrees and head temps being much higher than 200 degrees it is not surprising to see the temps that you are reporting. The manifold is a heat sink.
I used to log my intake temps quite a bit and I was always surprised how much higher than ambient they were, in stock form it is hard to dissipate all of the heat that is held within the intake manifold. I've always wondered if the ap1 temp sensor setup is more representative of the air that is entering the intake ports of the head, and the ap2 temp sensor is more representative of the temperature of the air that is entering the intake box/arm. For fuel metering perhaps the ap1 setup is more accurate ?.
I've always been skeptical about the location of the mouth of the oem intake box, as it sits right in front of the radiator location. With the hot underhood temps of these cars the intake manifold heats up considerably and the incoming air isn't cold enough to cool the manifold. I also think the insulation on the underside of the oem hood traps heat in the engine bay and around the intake manifold. You need to get a cold air source to feed the intake box which will help to cool off the intake manifold, and you also need to vent the engine bay of heat if you really want to see intake temps stabilize to a reasonable level.
My intake temps have dropped dramatically by installing a J's Racing intake snorkel, and a J's racing vented hood. I'm not advocating the J's parts, you can get the same results with cheaper parts if you want. I am using a stock air box and filter, with just a snorkel and a vented hood. In bumper to bumper traffic conditions it will still heat up but as soon as I get on an open road and increase speeds the temps will drop quickly. The longer I drive on the highway the cooler my intake temps get, as the manifold loses heat in those conditions. It would never do that before with the stock intake and hood setup. My intake manifold is now lukewarm after a drive on the highway, and my intake system is really cool.
Lastly don't compare your intake temp readings to someone that has similar info. from an ap2, the readings will be totally different as they take readings from different locations. Hope this helps.
The temps your are seeing are basically the temperatures inside the intake manifold, based on the location of the sensor on ap1's. With coolant flowing through the manifold and with the head touching the manifold you are going to get some high temps in most conditions. Temps will be much higher than ambient even cruising on the highway. The temps you are seeing will be impacted mostly by throttle opening/throttle position. At cruising speeds the throttle isn't open very much and the intake manifold stays hot, run it on the highway at WOT and you will see temps drop quickly as the manifold is cooled by incoming air. The only drawback is that you can't run WOT for miles at a time, lol, so the temps eventually climb back up as throttle position returns to lower settings when you return to cruise conditions. With coolant temps being around 190+ degrees and head temps being much higher than 200 degrees it is not surprising to see the temps that you are reporting. The manifold is a heat sink.
I used to log my intake temps quite a bit and I was always surprised how much higher than ambient they were, in stock form it is hard to dissipate all of the heat that is held within the intake manifold. I've always wondered if the ap1 temp sensor setup is more representative of the air that is entering the intake ports of the head, and the ap2 temp sensor is more representative of the temperature of the air that is entering the intake box/arm. For fuel metering perhaps the ap1 setup is more accurate ?.
I've always been skeptical about the location of the mouth of the oem intake box, as it sits right in front of the radiator location. With the hot underhood temps of these cars the intake manifold heats up considerably and the incoming air isn't cold enough to cool the manifold. I also think the insulation on the underside of the oem hood traps heat in the engine bay and around the intake manifold. You need to get a cold air source to feed the intake box which will help to cool off the intake manifold, and you also need to vent the engine bay of heat if you really want to see intake temps stabilize to a reasonable level.
My intake temps have dropped dramatically by installing a J's Racing intake snorkel, and a J's racing vented hood. I'm not advocating the J's parts, you can get the same results with cheaper parts if you want. I am using a stock air box and filter, with just a snorkel and a vented hood. In bumper to bumper traffic conditions it will still heat up but as soon as I get on an open road and increase speeds the temps will drop quickly. The longer I drive on the highway the cooler my intake temps get, as the manifold loses heat in those conditions. It would never do that before with the stock intake and hood setup. My intake manifold is now lukewarm after a drive on the highway, and my intake system is really cool.
Lastly don't compare your intake temp readings to someone that has similar info. from an ap2, the readings will be totally different as they take readings from different locations. Hope this helps.
03-12-2015, 06:49 AM
#6
I wonder how much heat the air actually picks up off the manifold? Perhaps we could use phenolic spacers like they sell for other cars. That plus bypassing the coolant out of the manifold should make it IATs much cooler.
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