DOB Install

[crownaviation]

You have the old style metal housing IAT sensor or the new plastic one? I was spinning my ported m122 up to 20k rpm and did get the IAT to 150's but that was on a 90*+ day on the street. You are spinning yours around 16k rpm?

I did have a good cooling system in place tho (AFCO Pro/fans, meziere pump and big IC tank in the trunk.

 

[o2sys]

I monitor mine everytime via Plx. It turns on automatically.

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[Department Of Boost]

It might depend on what you call low. I'm seeing about 40-50 over ambient on a route that heated the whipple up to 20-30. That's a mixed driving loop. So far the highway has been about 30-40 but I haven't done a lot of highway driving to get a real good average.

They still aren't out of control but having 120 on a day in the low 70's is more than I'd like to see. I monitor the iat all the time, it's programmed to come up on my plx gauge at startup. I wonder how many people monitor the iat on a constant basis like I do. It's part of my normal driving routine to scan gauges.

One thing I haven't done much of is to compare iat to water temp at start up. Every other setup I've had they are very close with a cold motor startup. Maybe the sensor itself is off? I'll pay more attention at start up tomorrow.

Wow, that sounds pretty high to me. Everything we have around here has IAT's reading out all the time so I get to see what stuff is running in real time in a few different cars.

-In mixed driving I am used to seeing 20-25 over ambient.

-On the freeway "cold soaking" (that's my dorky name for it) I am used to seeing 5-15deg over.

-Buried in traffic with it 100deg ambient temp and a HE with no fan I've seen a max of 40 over. That's pretty dramatic though.

-I've done a 60mph-175mph WOT (that's a pretty long run) run with a 90deg ambient temp and only seen 145deg when I shut it down. And the IAT's came right back as soon as I got out of the gas.

Questions:

-Are you running the PCV system as closed loop? Were you on your Whipple?

-What thermostat are you running (engine cooling).

-Is the "airbox" sealed as well as the Whipple was?

You have the old style metal housing IAT sensor or the new plastic one? I was spinning my ported m122 up to 20k rpm and did get the IAT to 150's but that was on a 90*+ day on the street. You are spinning yours around 16k rpm?

I did have a good cooling system in place tho (AFCO Pro/fans, meziere pump and big IC tank in the trunk.

If he is spinning the motor to 6,500rpm the blower is only spinning 14K. Which is slower than a stock GT500 (15,625rpm).

 

[o2sys]

Can you post actual iat temps? Not over ambiant so I can compare it to mine? I don't have an ambient gauge so can't compare it like that.

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[Department Of Boost]

Can you post actual iat temps? Not over ambiant so I can compare it to mine? I don't have an ambient gauge so can't compare it like that.

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Your smart phone doesn't get the weather?

"Over ambient" is the only thing that matters anyway. If I tell you I have a 100deg IAT and it's 30deg ambient that is a whole lot different than if I have a 100deg IAT and it's 90deg ambient. IAT's always have to be judged against ambient.

 

[o2sys]

Your smart phone doesn't get the weather?

"Over ambient" is the only thing that matters anyway. If I tell you I have a 100deg IAT and it's 30deg ambient that is a whole lot different than if I have a 100deg IAT and it's 90deg ambient. IAT's always have to be judged against ambient.

I was think of the some sensor that read engine bay's ambient.

If mine is running on at startup its always at ambient, but normal street driving its always 50-60 over ambient. And in traffic it will go up to 70 over ambient and get heat soaked and will only come down to 10-15 degrees if it start moving again.

"Cold Soaking" its the most 40 over ambient never less than that...

 

[Department Of Boost]

I was think of the some sensor that read engine bay's ambient.

A true IAT1 from the air intake would be best, most people don't have that data though.

If mine is running on at startup its always at ambient, but normal street driving its always 50-60 over ambient. And in traffic it will go up to 70 over ambient and get heat soaked and will only come down to 10-15 degrees if it start moving again.

"Cold Soaking" its the most 40 over ambient never less than that...

DOB GT450 setup?

 

[o2sys]

Yes DOB setup. This is using all GT500 components and M122 blower, 2.875" pulley IIRC

 

[Dubstep Shep]

I have a 2.65 pulley on my GT450 and cold soaking is about 30-40 over ambient. Third gear pulls are another 30-40 over that.

I need a better heat exchanger though. I know that lol

 

[Department Of Boost]

Yes DOB setup. This is using all GT500 components and M122 blower, 2.875" pulley IIRC

I have a 2.65 pulley on my GT450 and cold soaking is about 30-40 over ambient. Third gear pulls are another 30-40 over that.

I need a better heat exchanger though. I know that lol

Are you guys running stock thermostats?

 

[Dubstep Shep]

At the moment, yes. I have a 175 thermostat, I just haven't gotten around to pulling the blower to put it in lol.

My IATs were a lot lower when I had the 3" pulley. This is with Jim's ported M122.

 

[Department Of Boost]

At the moment, yes. I have a 175 thermostat, I just haven't gotten around to pulling the blower to put it in lol.

My IATs were a lot lower when I had the 3" pulley. This is with Jim's ported M122.

Last year we figured out that running the colder T-stats reduce IAT's more than you would think.

That new blower combo you have shouldn't be making any more heat when you are not making boost.

 

[o2sys]

I just put in a 170* T-stat last night...i'll see how it improves.

 

[Dubstep Shep]

Last year we figured out that running the colder T-stats reduce IAT's more than you would think.



That new blower combo you have shouldn't be making any more heat when you are not making boost.

Just driving it really doesn't. I'm at about 120-130 when it's 90 out. That's about how it was with the 3" pulley.

On pulls it gets a but warmer though. I need to upgrade my radiator and heat exchanger as well

 

[Department Of Boost]

I just put in a 170* T-stat last night...i'll see how it improves.

Yeah, LMK. We never did a true A/B comparison. It was more along the lines of "now that these cars are running cooler the IAT's seem to be lower".

Just driving it really doesn't. I'm at about 120-130 when it's 90 out. That's about how it was with the 3" pulley.

On pulls it gets a but warmer though. I need to upgrade my radiator and heat exchanger as well

No such thing as too much heat exchanger!

 

[BruceH]

First about the iats. The main difference besides the blowers would be the thermostat. Whipple includes a 160 with their kit. I used a stock 178? with this set up. The reason being that the whipple motor was too damn cold imo. It didn't get over 160 coolant temp most of the time. Changing out the thermostat would be an easy fix.

Did some datalogging today. A few interesting things were observed.

A wot pull from 6k rpm to 7k rpm saw an a/f of around 12.7 and a spark source of 2 which means it's being controlled by the borderline knock table. This means spark wasn't being pulled. Spark was fairly low though at 15.25 degrees. IAT started at 122 and ended at 126 for this short pull.

Another pull from 4k to 6k saw the same a/f, iat of 126-128, and spark source 2 again.

I'll have to say that it's a good thing I listened to lito and commanded .76 labda which is about 11.17 a/f and lower spark just in case. I normally command more of both in my base tunes but this motor with the high compression and 92 octane gas needs caution.

I've ran supercharged motors at 12-12.5 a/f at wot on purpose before and never had an issue. It looks like this combo isn't going to be very fragile.

For now I'll adjust the maf xfer so the a/f will be where it's commanded to be and then probably shoot for 11.5-11.7 in the base fuel table. It's good to see that I'll be able to run pump gas without issue. I really wish we had a blender pump nearby. I'd really like to see what e30 or e50 would do.

 

[BruceH]

It's plastic.

You have the old style metal housing IAT sensor or the new plastic one? I was spinning my ported m122 up to 20k rpm and did get the IAT to 150's but that was on a 90*+ day on the street. You are spinning yours around 16k rpm?

I did have a good cooling system in place tho (AFCO Pro/fans, meziere pump and big IC tank in the trunk.

 

[lito]

I want to add something regarding the IAT discussion many people tend to misinterpret, the readings we are seeing are very far away from instantaneous temperature, the thermistor used here is VERY slow, latency is quite big, when reading logs, more than particular reads at points, the ramp behaviors have to be analyzed. Accurate reads will only happen when temp is steady for a few seconds, when you see it ramping in a direction is because actual temp is higher or lower depending on direction, the bigger the delta, the steeper the ramp.

Heatsoaking ACT is normal on any car, PD blowers tend to have some higher temperature but is mostly because they are the only situations when usually a downstream sensor is used, you will have similar temps on idling/traffic NA, centri or turbo, the thing is that you rarely measure it, I've had cars with turbos and centris with ACTs as high as any PD blower (without any bypass recirculation that would affect the actual temps).

Cams will affect these temps due to lower momentum and reversion, the bigger the cam, the bigger the heatsoak.

 

[Department Of Boost]

First about the iats. The main difference besides the blowers would be the thermostat. Whipple includes a 160 with their kit. I used a stock 178? with this set up.

The stock T-stat is 192deg. The Whipple coming with a 160 explains why you were seeing IAT's so low.

I run a 170deg T-stat. On the cool side, but I'm not very upset about it. I'll take the low IAT's.

 

[GreenTerror]

Just to add my data to the pile I have the stock 192 T-stat and on most summer days with 80-90 degree ambient temperature I'm running between 120-130 IAT according to my aeroforce gauge, that's just average temps. In the city with lots of stops and a hot day I've seen up over 130, typically cruising down the highway I'm at 110-120.