Wifes car,almost completed L67 build/swap -56k run away.

[Playtoy_18]

His IAT readings are taken BEFORE the supercharger not after. In this particular car, heat from the exhaust crossover pipe can radiate up into the rubber elbow that houses the IAT sensor causing the sensor to heat up and read high. However, even though the elbow and sensor are hot, it doesn't mean that the air flowing through is as hot.

That's it right thurr.
it is getting heatsoaked and not reading true temps,i'll post a pic up.
In the future I will likely swap to the TBI charge sensor which is brass and mount in the lower intake.

I have been meaning to put a ktype in it and making sure of temp readings.
I'm honestly not sure what the heck it is doing,I suspect it is reading wayy off though.

[pmkls1]

Just remember that if you install a MAT sensor, the readings will be higher because you will be seeing the boosted air temps. The readings will be true to what the temps are, but the algorithm in the PCM is expecting to see the incoming air temps which will naturally be lower. I would assume that the readings may affect both MAF sensor calibration and ignition timing.

[Six_Shooter]

That's it right thurr.
it is getting heatsoaked and not reading true temps,i'll post a pic up.
In the future I will likely swap to the TBI charge sensor which is brass and mount in the lower intake.

I have been meaning to put a ktype in it and making sure of temp readings.
I'm honestly not sure what the heck it is doing,I suspect it is reading wayy off though.

Why would you go to a closed element style, those sensors DO get heat soaked and not show true air temp. Unless you just mean the MAT sensor that uses a brass thread. There were more than just TBI applications that used them.

I don't care if you believe me or not, but the open element type does NOT get heat soaked, at least not to the same extent that the closed element style does. If you're reading 140* from the open element sensor, that is your true air temp. The piping that the air is passing through is heat soaked which then transfers the heat to the passing air. I have the same thing in my car, where the intake manifold is mounted above the exhaust manifold, so the intake manifold itself gets heat soaked, this heats up the air passing through it. Opening the throttle to a large degree brings in cooler air.

[Playtoy_18]

I haven't a clue honestly,I know i'm getting hot air because of the intake tube on it and the fact that the filter is in the engine bay.

my thoughts on the IAT come from threads i've been finding like this
http://www.grandprixforums.net/your-...here-2707.html
(I haven't fully read all of them ,just perused thru)
I haven't a clue what is actually happening,i've just seen enough conjecture that I was curious so figured I would rig up and test for myself.

I will admit that I was going to relocate before testing however.
But now I will likely do some testing before I actually relocate the sensor to see the sensitivity and get actual temp data from the intake tube inner/outer as well as a probe in the lower manifold and also ambient.
I should have enough tools around to check all at once as well,though not on the same log.

Any suggestions on testing structure?
I've got the factory sensors to use,as well as a multimeter with a thermocouple attachment,and infared temp gun as well as a couple spare pcms/scantools/sensors I can hook up quick enough to use for temp sensor pids for testing only.

Car is in my insulated shop so that is as controlled of an environment as I can get.


Also,on the lower intake sensor install,it is not something I plan to do for sure.
I planned to do some more readin' and figurin' and based on my testing decide if I should go to the trouble on her car.
Even then wait until I take the blower off for some reason before I do it.

I appreciate the advice guy's,between all of us we'll get r'figured.

*Here in a few when i'm on computer I will post a log,nice to have info from it as well i'm sure.
This is the first and last log of last 30m drive.

[Playtoy_18]

Old setup.


New and improved-ish. (still need to make a top for it,and looking for suitable material to trash the elbow.)
The wall/barrier goes all the way to the bottom and is cut to the front contour as well. The weatherstrip at top just barely doesn't touch the hood. Should be getting plenty of fresh air.


Here is a quick log with this setup,it still steadily rose till I had to get back home.
Pulled up to shop and left key on,popped hood and pulled out sensor from elbow. (118*)
Blew on it hard for a few seconds and checked and it only went down a couple degrees,did it twice more for a little longer/harder and rechecked and it got down as far as 108*.
Left hood up,about to take another drive and see how high it will go this time.
Key on temp at beginning of log shows 75* ambient which seems about right.

Infared temps were high on the components as well,starting about 180* and going down as I move along the tube. IAT body was 160* but elbow started around 140 and cooled to about 120* where it enters the "barrier".
Barrier itself was about 111* as well as the tube also around 108*.
My multimeter with thermocouple has crapped on me so no secondary reading inside the intake tube itself yet.
Gonna try to get some more data,need to look over the log as well since I think I saw some high trims that looked odd.

Might need to have a buddy help listen to it and see if mayne I have an exhaust leak.
Might explain trims that I thought were in line now and the excessive heat from both IAT's and coolant temp (running a 180 stat with fans programmed as well,shouldn't be steady at 208).
if I have a crossover leak it would hit almost directly on the ECT and IAT both.
I can't hear well enough for those small ticks like that sometimes.

[pmkls1]

The coolant temps staying around 208 is a little bit concerning, but does kind of make sense. You are running nearly a point higher on compression than a standard L67. Then, there is the fact that the engine is supercharged. You also most likely have elevated inlet air temps. Couple that with the fact that you are running a radiator that is really just barely adequate for a N/A 3800 (I'm assuming) and chances are that the cooling system is maxed out.

[Playtoy_18]

That brings up an excellent point I haven't thought of actually.
Checking the part numbers for radiators they are listed as the same (chain store) as well as the other cooling system components. (Radiator is fairly new and has been flushed several times).

However,the heads/intake are thermally coated internally to keep heat in and externally to promote transfer.
So besides the higher compression,due to the external coatings (and a possible exhaust leak) the underhood temps are higher and the internal coatings keep the heat in the engine.

Right now it is parked while I finish installing motor in my little sister's car.
When it's done my plans are to install the headers and figure out a way to let heat escape from underhood.
Stock manifolds are killing power output i'm positive,as well as contributing to the underhood heat.
I planned to use some TGP louvers,but she doesn't want any hood scoops or anything so I will need to get creative.
Also be thinking on the radiators heat load and how to tweak that.

Idea's welcome.

[EagleMark]

Ceramic coated headers will keep the heat going out exhaust and not underhood.

[Playtoy_18]

The headers are the only part that have not been coated yet.
They are halfway thru sandblasting,just sent someone to pick up my new unloader valve for compressor.
Just need to finish the Geo then I have two sets of headers to coat,one for me and one for a buddy.

So they will be coated inside and out when they get installed and that should help quite a bit.

[EagleMark]

First time I used a set of Headman Elite ceramic coated headers and knew the vehicle before and after? I was amazed at how much heat they keep out of engine bay. Long tube headers would stay closed loop idle even in winter with one wire O2 sensor, didn't do that before...

[Playtoy_18]

You should see what happens with coated headers and turbines on turbocharged stuff.
Keeps the heat in the pipe for increased expansion which means more exhaust velocity.
Lowers lag times,spools faster etc..
Controlled mileage testing on the big semi's showed a big increase in MPG as well which is no small feat.

I think on boosted applications the number for power is 10% over uncoated with turbo.
Nothing but good things about header coatings.
Some have mentioned pipes rusting from inside out,but that is because you want a coating on the inside as well or the excess retained heat just kills the metal.
I use one product on the inside and one on the outside. The I.D. Coating is the same stuff that is on the exhaust runners in the cylinder head.

So it's pretty,gains power and lowers underhood heat.
I should just post a signup list. :)

[pmkls1]

From what I can tell the N/A and supercharged applications do use the same radiator. But, the radiator is really pretty dinky even for a N/A L36. The core thickness is something like 5/8". That's pretty sorry if you ask me. But, I haven't heard much about radiator upgrades for W-bodys though.

Headers that are coated on the outside only won't last long. The heat does affect the metal and there's nothing to protect the metal from moisture and the acids in the exhaust. A lot of people don't realize that water is a byproduct of the combustion process and that is why you see steam coming out of the exhaust on cooler days. That's also why you will see water dripping out of the exhaust on vehicles that have not been running very long. Most stock mufflers actually have little drain holes near the bottom to allow any condensed water to drain out in order to slow down the corrosion process. After a cold start you will often see a little puddle under the muffler from all of the water draining out. In my opinion, it is a must to coat the inside of the headers as well as the outside. Not only are you protecting them from rotting from the inside out, but you are keeping the heat in the pipes and out of the metal. I know for sure that cerakote makes a specific coating for inside headers and exhaust pipes and I think that techline does too. Normal coatings work fine on the inside, but the coatings designed for inside pipes actually have better insulating qualities. With those coatings, they actually retain more heat than the coating for the external surfaces. Keeping the heat in the exhaust maintains velocity which is good on all exhaust systems, but it is critical on turbo applications. There are also specific coatings designed for turbo housings too.

As for helping the engine temps in the Impala, I have a couple ideas to help. I would make an additional shield to go between the exhaust crossover pipe and the intake pipe. That would go a long way to insulate the intake charge from excess heat. You could also consider a thermal coating on the intake pipe. I know it sounds gimmicky, but you can also add a coolant additive like water wetter. There are several companies that make additives like that and they do help by lowering the surface tension of the water allowing it to make better contact with the metal in the engine and radiator thus enhancing it's thermal transfer properties. It doesn't make a huge difference, but the average cost is around $15 so the cost is inline with the improvement.

Gotta go for now. I'm in the process of a tranny rebuild on the mother-in-law's 2004 Impala. I just got the tranny out last night and I am about to make a bracket to allow the tranny to be bolted to an engine stand for repairs/overhaul.

[RobertISaar]

not sure if 2nd/3rd gen W-bodies can use them, but the LQ1 radiators are something like 1.125" thick. they're pretty beefy. i imagine the 3rd gen V8 models got something similarly hefty that could probably be used on a 2nd gen.

[pmkls1]

I just did some looking and found some interesting information. I did some searching on autozone's website for different radiators and looked at specs and part numbers as well as pictures. The first and most important discovery was that I looked up Radiators for Grand Prix, Regals, Impalas, and Monte Carlos in the 2000-2004 year range. The catalog listed a 5/8" radiator for L36 engines and a 1" radiator for L67 engines in the Grand Prix and Regals, but only listed a 5/8" radiator for all of the Impalas and Monte Carlos. The only supercharged Impalas and Monte Carlos were in the 2003-2006 year range IIRC. Now, regardless of whether this is a typo or not it still indicates that the supercharged engines do require a larger radiator which makes perfect sense to me. One odd thing that I did notice with all of the larger radiators was that they had a specific note saying that they would not fit to replace the 5/8" thick core radiators. Now, I do not see how it would be that big of a difference and can't see any major differences in the pictures. I am guessing that there may be some minor modifications needed for either the fans and/or the condenser, but I can't see much more than that being necessary. Another oddity was that all 3 different brands had different part numbers for the radiators. The Buicks and Pontiacs look the same, but the radiator hoses show to be different sizes. The Chevys look the same as the other two and share the same hose size as the Pontiacs but they carry a different part number. All of the radiators that I looked at showed the same hose size except for the Buicks.

I also looked up the radiators for the 3rd gen V8 models and the old LQ1 models. The v8 models are beefier, but they are quite a bit different and would take a bit of work to fit. The radiator hoses are in different locations as well as the trans cooler lines and I think the fans are different. They could be made to fit with enough work, but I don't see it being worth the effort. The LQ1 radiators are a different story, though. They look nearly identical to the Grand Prix 3800 radiators judging by the pics and specs with 1 minor difference that I could tell. The lower radiator hose connection on the passenger side on the Grand Prix 3800 radiators sticks straight out. The same connection on the LQ1 radiator is angled towards the drivers side pretty sharply. Other than that small difference it looks like the LQ1 radiator would drop right in. The only other differences would maybe be the fans and mounting for the condenser. Interesting stuff though.......

[Playtoy_18]

Thanks for the info guys,definately save me some time.
I work part time at AZ and know the guy's at both NAPA/Oreilly's here in town as well (I work on their cars alot :) )
So I shouldn't have an issue comparing the different W-body radiators more closely or side by side.
If I need to update then I will definately,and i'm with you guys and thinking it's a no-brainer and I need to.

I did plug the SC/TB coolant ports in the manifold,but I opened up behind the crossover plate as well so there should be plenty of flow.

I have spare sheetmetal as well as plenty of header wrap to wrap it all up if I decide to go that far.
The heat shields are a given though once I get the headers in.

Finally got all the parts/gaskets in tonight for my little sisters geo so hopefully be done with it by tomorrow and get started back on the impala this weekend.