MrEvanchi

2 minutes ago, seanyb505 said:

Any string theory test before? I suppose you can do it now either way. 

Nope, but I will have to give it a shot. I don't have any good way to film it besides from inside the windshield, but it's fairly visible from there. 

It is FMIC now. It is on my list to block it off, just haven't decided how I'm going to yet without destroying the scoop.
It's a carbon fiber Cyber R scoop. It's a fairly small opening on the inside, easy to cap.  I only keep the scoop for the aesthetics, otherwise I've contemplated using a 2.5i hood instead.
When I block the scoop, I was also thinking about adding more louvers directly behind the scoop, but I haven't worked out exactly how much room there is yet, as the plastic wiper cowling and firewall are a good 3-5" inside from the edge of the hood. I also don't know for a fact if it's possible to go "too far" up the hood, as I'm sure the closer to the back, the higher and higher the pressure you will be fighting to move air through. But perhaps directly behind the scoop is plenty low pressure anyways. (Especially with how large the Cyber R is compared to stock.)

I want to say on average cruising on the highway, there is probably approximately a 10-15* delta on IAT's from ambient. I'll be watching as I commute from now on to compare. I'm most curious about extreme hot days, which are not far away here in the Dallas/FW area. 
I have a Cobb SF, I realize I forgot to include. It has no heat shielding of any kind. Very much at the mercy of the under bay temps. 

Please ignore my ugly multi-colored car.

I've wanted to attempt to make some hood louvers for this thing for awhile now, so here it finally is. 

I should have done more testing beforehand to get a baseline on IAT's to substantiate their affect, but oh well. 

By nature of their design, the louvers are individually hand bendable, and also adjustable. I'm sure I'll be playing with the attack angles, as the first 1-2 need to be especially steep as to generate an optimal low pressure zone behind them to increase the flow rate of the rest. 

In any case, there's a tremendous amount of heat flowing them them just sitting idling with the radiator fans going. 

They're made of  18G(0.050" stainless, and fastened with M6 flanged button socket screws. The raw stainless will fair well in the elements, so I haven't decided if I would prefer it painted or not. 

Let me know what you think! 

(I can turn around and sell these to anyone interested, but I'll wait for feedback.) 

Had something similar, ended up being the center differential carrier bearings. Of course that'd be wheel speed dependent like yours. The whole tail-section of the transmission pops off which is where the countershaft, center differential, and all their bearings live. Not too difficult, it's just glued on with RTV which is tough to pop off. (There was a good writeup on the forum I referenced long ago when I did mine, including all part numbers.)
(

Alternatively, those aren't the only bearings it could be. There's a solid chance your front differential bearings are the cause too, which would make much more sense if your mechanic very confidently narrowed it down the front, and not the rear of the transmission.
Mine manifested much like a whirring/whining noise, and only got worse and louder as I continued to drive it. 

31 minutes ago, xt2005bonbon said:

yeah, when the coolant temp goes above a certain threshold, the ECU commands a richer mixture, probably to help cool down the combustion chamber.

I haven't come across any AFR compensations in my 07 LGT's stock ROM, but it does at least pull timing with extreme coolant and IAT temps.
-2.11* @ 212F, -3.87* @ 230F Coolant

And -2.11* @104F-158F,  -5.98* @176F+  IAT

Just realized there was even a thread here devoted to gaining Flex Fuel support. Boy what an emotional roller coaster of a read this has been. I'm stoked! Been dying to have flex fuel on my 07 LGT since forever. I'm getting giddy at the thought of it finally becoming reality! Emailed Cobb about my interest, and asked for any new ETA's.

I've certainly got cash quarantined for this.