Thread: Why Cold Air Intakes Matter

All right, multi-quote for all the cool kids, and I'll add some additional thoughts/hopefully to clarify the original post.

Originally Posted by Hardgainer

Very informative and well written. I think you could benefit by keeping the IAT located in a cooler spot. I read an article just earlier today where a guy had wizaired and routed his IAT through the heat resistant box into the intake. Im in at loss for what the exact word is for it.

It's not so much "a cooler spot" than it is "a more accurate spot". Knowing the IAT right after it passes the air filter is completely useless in determining the actual intake temperature when it enters the engine.... because in a supercharged application there's this Eaton blower making heat in between the IAT sensor and the engine... While there is almost certainly a correlation between the two, it's not an exact science (at least not as exact as placing an IAT sensor in the LIM would be).

Originally Posted by DanPrixGTP

Someone I've seen on the facebook groups, have actually relocated their IAT sensor by the intake runners in the LIM. You may want to get a hold of that person, and hear his .02 cents on the idea.

Originally Posted by Russosaur

Bill has it in his thread on modding a LIM iirc

Originally Posted by 231FUN

Fairly easy to relocate the IAT by drilling and tapping the LIM if you so desire.
There are threads on here about it, including which GM IAT you need to get the job done.

It's definitely a squirrel worth chasing, although it would be most effective if you combined it with a tune that automatically modified timing based on IAT, and allow you to eke out a few more ponies for as long as possible.

Originally Posted by 91parkave

If its like anything else GM on older stuff like 3800 platforms and earlier LS stuff uses IAT sensor and other values to calcuate whats called MAT (manifold air temperature) and use that accordingly for fueling adjustments. There is no need to need to relocate the IAT, however if you want it for your data then thats your bag. On newer GM supercharged v8 vehicles 2 physical IAT sensors are used to give the PCM realtime information of pre and post blower temps.

Originally Posted by matt5112

I was under the impression the 741 didn't do that, and it wasn't until the LS2 era that the temp calculations appeared.

This sounds like what GM should have done with the L67 setup, but cheaped out (because L67's were produced in far greater numbers than their new SC'd V8s ever will be).

Originally Posted by matt5112

How do you know you're heatsoaking your intercooler? Are you monitoring your intercooler fluid temps as well?

That's what Brian told me was the result of doing a 3rd gear pull on the dyno - it only started showing KR after a good fifteen seconds at WOT, and said "it was the blower outrunning the intercooler", I only had KR at ~5600 in 3rd (a speed that I honestly rarely reach).

Originally Posted by 98GrandPrixIraqVet

I don't mean to start a pissing match here but both the OP's dyno and Dsmuts dyno beg the question why are you not running E85?
Solid numbers from both cars but this all seems to be in the same category as running your car down the strip on ****ty street tires....... Why not use every advantage available for example drag radials and E85!???

I can't speak for Dan or what he's doing but I'm probably going E85 this winter/spring, basically as soon as I can scrounge up another $600 for 80# injectors, fuel pump, and the inevitable retune. Ported heads and roller rockers are also coming in 2015. Don't worry, I'll be stretching chains before long.

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To clarify what I'm getting at in my original post, because I was really attempting to chase two squirrels at once:

1) The IAT's positioning is awful for a supercharged application. It's impossible to extrapolate exactly what the "true" IAT is after the blower, apart from "definitely a hell of a lot higher than before." That means from a tuning standpoint you're basically shooting in the dark and hoping you dial in the tune correctly. Moreover, it's impossible to accurately create an "adaptive" file that corrects for higher or lower IAT's - resulting in either (a) a chunked piston, or (b) a conservative tune that doesn't get the maximum number of ponies. The presence of an intercooler further complicates the IAT issue - we don't know how much exactly the air is being cooled, and moreover, a tune can't account for when the intercooler heat soaks and IAT's at the engine rise dramatically (even if they aren't per the IAT located near the air filter).

2) Irrespective of this terrible positioning, a CAI will lower IAT's, even post-blower, even if we don't know by how much. That should, in theory, permit more timing to be thrown at it, and thus add more power. I called out the "Dyno Science" thread because the car had the exact same tune for all pulls. He didn't retune for the CAI, however insigificant it may have been.

Originally Posted by hensleya1

Irrespective of this terrible positioning, a CAI will lower IAT's, even post-blower, even if we don't know by how much. That should, in theory, permit more timing to be thrown at it, and thus add more power. I called out the "Dyno Science" thread because the car had the exact same tune for all pulls. He didn't retune for the CAI, however insigificant it may have been.

See I'm still not convinced that colder air does anything tune or not. Someone please correct me if I'm wrong but you first have to think of the heat from the blower itself is going to hundred some degrees possibly from being bolted to the motor which already isn't helping keep that "cooler air" stay cool. Then factor in once you start spinning the m90 its not very efficient (as I've read) as you would expect with compressing air. So in theory whatever cold air you had is now hotter and it shouldn't make a difference. So if you had pre blower temps of like 60* and post blower temps of say 130* (these are just random numbers) i can't see that 60* air staying cooler than say maybe 90* air as its just going to heat it up roughly the same temp because the blower would be spinning at however fast it spins depending on pulley size. Again this is all theory here. Sure ita possible it may lower temps a little but not enough to be benifical to say let you add timing or reduce knock.

This is why intercoolers exist i would think, or if you used a more efficient blowe like when snowflake did that TVS swap and gained what like 50whp or something without changing anything about the car.

Shouldn't any significantly cooler air no matter tuned for it or not show an increase in power on a dyno?

Would be nice to actually see someone test this theory.

Im not doubting anything about IAT placement about what you said above but just what I've quoted above.

Again this is what I'm thinking, if I'm wrong i want someone to correct me for learning purposes.






Sent from BFE