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Question for those that have modified warm air intakes.
Is there a target temp or temperature range that seams to be best?

I used Scangauge today to check my fIA, I was surprised just how cold it was. Outside temp of 5f, fIA reading 10f, cut ICE at a stop and fIA rose to 15f.
I thought it would have been warmer. I remember my VW Bug had a diverter that took intake air right off the cylinder walls when it was cold out.

I can't pin down a number for you, but my thinking is that the ideal temperature would be about as warm as you can get it before the ECU starts to back off ignition timing. An overly hot intake charge tends to cause knocking (the old plague of the turbocharger) which will screw things up. If you want to experiment, try watching the ignition advance with different levels of intake air heating. I, among others, would be interested in what you see.

I have ran IAT's as high as 120°. I generally try to keep it no more than 100°. The Insight and HCHII did not have any knocking associated. 80° to 90° seems to be a good temp range.

3" aluminum dryer flex duct makes an excellent material for an extended intake air duct. You can bend it and flatten it and still not cause an intake air restriction.

Great info, thanks guys.

I like to keep mine below 100F. Above that and it gets sluggish. That seems to be good for higher-speed driving like highway trips, but terrible for my normal slower in-town driving.

I have very little data for this, though. (yet. I'm not letting it slip away that easily. ;))

Back in the early '70s I recall reading somewhere that the thermostatic intake on my Chevy 250 c.i.d. L6 (in a big 4WD Blazer) was set to mix underhood air with hot air from the exhaust manifold shroud to maintain an approximate temperature of 130F. The reasoning was to quickly warm the intake air, then maintain a constant air temperature for constant air density so they could set the mixture close to the ideal and it wouldn't change with weather conditions. This was before oxygen sensors and ECU control. Since 130F is about as hot as it ever gets anywhere in the continental US (Death Valley), that's a logical temperature to choose for that purpose. Probably didn't get any hotter than that under the hood during normal driving conditions, either.

In the last week I have discovered that my intake temp is almost always right at the exterior temp.

Something I am going to have to fix.

Highway mine runs 10*F above ambient after 20 minutes to cool the plastic airbox and tubing. Sitting at a stoplight all bets are off.