Relation between IAT's & AFR
 

Is there any relation? Will a rich burn be cooler or hotter? Just wondering.

IAT is your air intake temp and has noting to do with AFR. Richer is usually cooler to a point then it will start to get hotter. Lean will usually get hotter also. Its a wierd deal but that is just the way it is. This is only for gasoline power. Diesel power will only get hotter the richer it is and cooler the leaner it is.

I know what IAT's are, the point I was trying to get at was around what AFR, rich or lean will the EGT's on a gas engine get hotter?

I told ya too rich or too lean. They both can get hot. I know it doesnt make much sense to me either but Ive seen what too lean did to my piston. Lets just say it wasn't a dished piston anymore.

then the title of your thread should read "relation of EGT to AFR". Fix it or you will get the same answer


Richening will lower EGT to a point, I have seen around 10.6 the fuel mass is too great to burn fully in the chamber and the flame carries over into the port and header, thus raising EGT from that point and drastically so.

Leaning generally raises EGTquickly from 13.0-14.0, then it tapers off quite a bit. When you are going into lean burn for cruise and get over 16.5 it starts to cool alot

No I want to know about IAT's, EGT's are just part of the equation (from my point of view) rich AFR = EGT= high IAT but I wasnt sure if that was how it went on a gas engine. I'm seeing over 158* in the end half of 3rd gear (th400) but my tune was pig rich (10.0 to 10.3). I just wanted to know & hoping my rich condition was causing the IAT to creep up to 158 by the end of the run. I just needed the input from someone who knew for sure that could confirm that my assumption was correct.

So according to your post I guessed right and I'm in a sense "2 stepping it " down the track, lol. Thanks for the post & the info.

Ohhh I got what you are saying. Are you intercooled? How much boost? Sounds like you are spinning the turbo too fast and super heating the air.

Yeah I have a front mount setup with an air to air intercooler, I have the front license plate cover screened to allow more air flow & no fog lights to attempt to flow more air. I mounted the IAT sensor on the charge pipe 10" away from the outlet of the intercooler, under the front bumper away from all the engine heat so it wont get heat soaked. I run 12 to 15 psi, a freind of mine did mention a theory of the the turbo working so hard & spinning so fast it could heat the air like you are saying, the rich air/fuel theory was my guess. I put a fan on my engine between passes until the compressor housing is ambient temp to minimize the IAT but it still happens. I was able to get the engine cool enough once and it picked up 3 mph, I need to figure out how to get the IAT down :bang: I'm not looking at water/meth as an option, just not a big fan of that.

IAT and AFR are barely connected. the amount of heat transferred across the turbo is fairly constant and i would doubt a change in AFR would make more than 5* of a difference. Also you are only running 130mph traps, that turbo should still be pretty efficient at that point, depending on your weight of course. Odds are your IC is getting plugged, or there is a leak somewhere on the cold side that is raising your IAT.

I am very thorough about boost leak testing my setup pretty frequently, anytime I have to pull off a charge pipe I pressurize the system and spray everything with soapy water. The car picks up 3 MPH like I posted above when I can get the engine really cool and it doesn't pull timing. The car weigh's 3780#, FWIW. What do you mean by the IC being plugged?

just like anything else, getting dirt and shit in the front making it less efficient. also turbos will leak a little bit of oil as a part of their nature, and i take IC off yearly and wash it out with alcohol to get the oil film off it. That has been worth about 10* every time i do it.

My cars would always pick up 2-3mph with a good cooldown as well, but would pick up another 2-4mph with cool air in the evening. If you havent for awhile, or ever, rinse out the IC and pipes and see what happens

If you have an ebay cooler you need to get rid of it and get a nice quality intercooler. If all else fails water to air always wins lol.

158* is hottt! I see maybe just over 100 in a pull through 4th gear stock turbo and intercooler on my neon at 15 lbs of boost. Now this is in 60* weather though too.

I'll look into that, thanks for the advice. I did look at some street driving logs to compare the IAT's. On a 4 minute log the IAT got at its hottest 104*, it only seems to get really hot when the turbo is working hard.

I do have the cheapest intercooler money can buy (Ebay), I know its not the most efficient.

On your Neon, did you ever log the IAT going down the track? Mine stays below 100 street driving, it only gets really hot when I'm under a lot of boost for a long time.

If your IAT's are over 150* then you should be pulling timing at that temperature. Meth would be a good investment. I haven't done a pull down the track with the th400 I have now, but the 4l60e I had my temps were 140ish at the end of the run.

My IAT's were logged on a WOT run from 70 to 130 MPH on the HWY. About topped out 4th gear.


You either need to spend big money on an intercooler or get a meth kit. If you don't want meth you definitely need an intercooler.

Hey man, havent seen you on here in a while, work keeping you busy?

Probably gonna shell out some cash for a quality intercooler, I wonder if the AR of my turbo would have anything to do with it super heating the air like Grr posted?

I'm going to pick up a meth kit and I think you would like the benefits of lower IAT's and more power with it more than you would spending big bucks for a quality IC

So if you get the meth, will you run 100 meth?

Just saying because i heard 100 meth you cant see!