My sense is that both situations are occurring. Relocating the IAT sensor in such a way that actual inlet air temps are not being accurately measured would be counterproductive. Relocating to where it does not get heat soaked and thus improve sensor accuracy would be beneficial.

Likewise, insulating the IAT sensor from the radiator hose might help, but right underneath the hose is a big radiator filled with hot coolant. Hard to keep that heat source from affecting inlet air temps.

That's what the CAI is designed to do, keep the inlet air as cool as possible. A Z06 style hood scoop might be the ticket. I haven't seen any threads about how effective it is --- don't get over to the Z06 forum much.

 

Foil backed insulation tape will help keep the radiant heat away from the sensor.



And add a little fresh air to the air inlet with the help of a hole saw...

 

The tape looks good. The holes look "cheesey".

It would be nice if someone could do a before and after comparison to measure the difference.

San

 

The airbridge is in physical contact with the radiator assembly and therefore a simple touch of it with your hand will let you know how its heating the air inside. Insulating from the heat is a good thought but actually lowering the heat is better.

Once again....scan the car with these fixes in place to see what the car's sensors are doing. Too many are making assumptions that are false and fixes that have been tried and do little to nothing. I'vee seen all this before and it does nothing. All I've seen it do is delay the lowering of the IAT because its insulating the heat into the air cleaner assembly. The foil itself holds heat. The heat is conducted in not radiated. Its in physical contacxt with the engine itself at the TB and at the radiator. Put your hand on it and see if its ambient, or a lot higher.

 

Part of the tune from all tuners is to exhaust that variable and shift the IAT vs timing table but you have to understand that there is the possibility that the air will actually one day BE higher and the IAT table has to be able to run less timing as the ambient temps in fact increase.

I would love to see the facial expression of the nay-sayers with all the theory as they watch the laptop while someone simply drives light to light on a 90-100 degree day with a H/C car. Maybe seeing 135+ IAT's will change their minds. What are you going to do, set all the fields to zero? The car shouldnt run the same timing on a 90 degree day as a 70 degree day but how do you not pull timing too aggressively and still have a car that can pull timing when it has to.

As a clarification, the airbridge IS heating the air up so its not just a matter of telling it to not pull timing when the air is not due to heat soak but rather also having the air not be heated up because its on top of a stove cooking the air 20 degrees hotter than it is. A hot air cleaner assembly is heating the air so having the airbridge 20 degrees cooler ACTUALLY cools the air inside it. The rate at which it heats the air is about 1 degree per second at a light and it doesnt cool down for a full 5 or 6 munutes after you get moving.

I dont understand what makes a person qualified to talk about these things with no evidence to support the position they take. A scan is the first prereq in this discussion. Seeing what the IAT's and coolant do in a performance drive is the basis for why you have to get the air cooler and eliminate artificial heat soak.....or you can ignore what I say which is based on that very evidence and keep quoting high school physics in the incomplete model for an argument(discussion).

Driving a car on the hiway at a steady cruise and seeing 178 on the engine coolant temps is not hurting an engine. The engine is not producing any real power and when you get on it, it will rise to the temps you see with any stat since modded cars produce more heat. What is so hard to deal with? Get past the OCD and let the cruise speed coolant temps stop dictating the decsin to runa stat that gets things under control in perofrmance situations. If you say you can get a performance car to run 200 degrees in Arizona while driving aggressively then prove it with evidence. Quoting tuning things you would do with fans is great and all but the fans dont come on under 192. Next theory?

 

OK, I get it.....must buy 160* t-stat.

Who makes the best quality piece?

 

They are almost all made by just a few suppliers. I got a Lingenfelter unit on EBay, just a few bucks cheaper than some others. Zip sells them right here on the Corvette store, I think.

 

...Like swiss cheese? Good thing they can't be seen, but they do meet the requirements; allow air inlet to see ambient air...

It would be nice if I could scan it to see what was effective and what wasn't, but the tape can't hurt much. The foil only serves to fend off some of the radiant heat anyway... If it's actually touching (conducting) the heat, I'll have to take a look at that next time I pop the hood. Perhaps I can make a cheap stand off.

And I will also be running a lower temp thermostat one of these days... I know why they work, and how well.

 

If you can't see them (the "cheese" holes), I'd do the same thing. I'm almost tempted to buy a Fluke infrared thermometer, but the scans would show a more accurate IAT.

San

 

That's an interesting observation and really helps explain the intake heating situation.

 

I had a LS2 twin turbo (APS) GTO with stock compression running the stock thermostat at 9 psi on 91 octane. Mid 10's on skinny rear tires at 133 mph at 12 psi (mixing race fuel). No issues, no superheating on track runs. Fans set to work with the stock thermostat more aggressively. Is that what you mean by modded? There is a way..

 

"There IS a way". But a "better way" would have been the same combo with a cooler stat.

Still waiting for you to produce examples we asked for earlier in the thread.

 

Why would it be better? My twin turbo car operating in phx is all the example needed. And like I told hitman, we're in agreement on most of the issues here despite the egos. Hey, I know it's cool to be a smart *** around here, but c'mon man.

 

I see nothing "smart ***" in his comment.

Comparing a twin turbo GTO to an OEM C6 is apples & oranges. I am pretty sure the air intake on those twin turbos was very different than what the C6 has. I also didn't see you post any information about whether you tried a cooler thermostat, any data about your inlet air temperatures, whether you were running an intercooler, etc. However, if that is all the example you need, then that's your decision. But it is not a convincing argument for anyone else.

Based on your comments, we may indeed be in agreement on most of the issues, but I haven't seen you acknowledge which issues those are.

In earlier threads, you offered some opinions about the possible negative consequences of running a cooler thermostat. That's OK. But claiming those opinions to be fact without offering real-world examples is not very convincing.

In counterpoint to your opinions, several of us have offered actual data, such as coolant temps, oil temps, dyno numbers, track results, scanning tool measurements, etc. These data are very convincing to me personally, which is why I have run a cooler thermostat on my last 3 LSx engines.

I suggest we just agree to disagree, and leave it at that.

 

If a twin turbo stock compression LS2 operating in phx isn't experiencing problems then I'd say that's a pretty good example, it doesn't get much harsher than that. With a 4000+ race weight and trapping 133 mph (high 120's on 91 pump fuel) you don't have a better example. Stating it'd run better with a colder thermostat is nonsense, hence the "smart ***" comment. Spin said "No way you have a modded car to say that. That assumption is 100% wrong and is why your argument doesnt hold any credibility." Well, I figure the track is the ultimate dyno, scan tool, etc. YOu can say it's apples and oranges, but it isn't really.

The forums are great resource of info, but at the same time isn't exactly the best source either. I've shown the light on another possibility, you can dismiss it if you like, or you can look further. But, sure, we can agree to disagree and leave it at that.

 

I looks to me like we're getting off track with the differences between theory and practical application. In theory, the larger the delta between intake air and combustion temperature, the greater the air expansion, and therefore, the greater the potential for work to be performed. The big problem in a production automobile is getting that delta. Total isolation of intake heat from the operating temperature of the engine is impossible to achieve, so while doing all you can to cool the intake is fine, it's not the end all if more HP in a typical automobile is the goal. The cooler thermostat certainly causes some thermodynamic loss, but it is "less bad" in poluting the fresh air charge than the stock thermostat, and will cause a net increase in performance. Even if you lose 3% of your theoretical power due to a lower thermal efficiency, but gain 4% due to the cooler air intake, you are still ahead of the game by 1%. The trick is to get the 3% AND the 4%, but as we've seen, tough to do in a production based engine system.

 

You contradict yourself by using an intercooler. Going by your theory that higher temps increase efficiency and therefore HP, you should run no intercooler. You cited the work done by Smokey Yunick to support your theory as he used a turbo to recover heat/HP from the exhaust to increase efficiency/HP in his "adiabatic" engines...he used no intercooler. If you ran your GTO with no intercooler, then you would be able to say your argument is credible. But you ran an intercooler and took all credibility from your argument. A cooler thermostat would allow you to run more boost to make more HP the same way the intercooler allows you to run more boost to make more HP...it's the same thing. Yes, you made a lot of HP but you could have made more with a cooler thermostat and that's the point of this thread. You can make a lot of power at 250°F (no one questions the ability of an engine to make power at higher temps), but you can make more at 160°F. I also suspect your "agressive" fan operation had a lot to do with increasing the efficiency of the intercooler plus the fact that they are now doing double duty to remove heat from the intercooler and the radiator. Just another viewpoint.

 

I haven't seen anything but "devils advocating" rhetoric from AirBus.

Of course your Twin Turbo LS2 "ran good" in where ever. That proves nothing, however, as to what OPTIMAL temps would or could be. You never checked. You have posted no real DATA in this entire thread. Spin has. You should take a look at it.


Still waiting for you to produce those specific examples that we asked about...

Your statement that a drag strip is the "best scan tool" is a joke. Running your car at the strip, by itself, tells you nothing about what is going on in your engine.

 

Nice post. This gentleman "gets it".

 

I dont know if the strip is the "best scan tool" but it does tell you a lot about what is going on with your engine and tranny at WOT. Over 200 parameters worth if you wish. So its no joke. In fact, I never go down the strip anymore without my HP Tuner hooked up in Scan mode. btw-lots of folks (including me) who do not have access to a dyno, use the street, freeway and strip scanning/logging to do all their tuning...and got me into the 11 Second Club.