1998 Ford Ranger: 2WD, 2.5L 4-cylinder, 5-speed manual tranny.

Now that I've got the Scangauge II installed, I've noticed that my intake air temperature is up around 140 deg after the engine is good and warm. It's got a "cold air intake" style of filter; the air is sucked from right behind the passenger-side headlight. It could be getting some warmth from the radiator (radiated heat lol). but for the most part the air should be relatively cool. When driving down the highway the intake temp is right at ambient.

I've noticed that when the intake air temp is high, the ignition advance is low. I've also heard that you should get cold air and warm fuel. I recently noticed that after driving around town and getting the intake air nice and hot, it takes a little while for my instant MPG to get all the way up. As the intake air temp drops, the instant mileage improves.

Would it be beneficial to insulate my intake tube from the engine heat? I was thinking about simply wrapping it with wrap-style house insulation (made for piping). I'd duct-tape the seams so it'd stay together pretty tight and would be pretty well insulated.

I've modified my air box for a much freer-flowing intake (and it sounds better lol) and stuck the "snorkel" as far forward as I could get it without running into the headlight. I could get another airbox from the junk yard and modify it so it draws light from inside of the passenger fender well using some dryer venting.

I'll get some pics up on my current airbox modifications so I can see if anyone can think of any improvements to it.

 

Here's the pics of my modified airbox. The original's intake snorkel only had a 1.5" inside diameter. This one is from a 4" dryer vent. The very last pic is from right above the passenger headlight. Most if not all of the air should be coming from in front of the radiator and the grille area.

 

I just insulated my intake duct and the IAT dropped by about 50°F!! Before, it was running in the ~130°F/140°F range. Now it's right around the outside temp of 80°F!! Ignition advance is staying closer to the 30° mark for a lot longer than before, too. Instant mileage readings seem to have gone up. Here's some pics of my rigged-up insulation. :P

 

Interesting. A 50* drop in intake air temp is pretty significant. Keep us posted on the affects.

 

Absolutely!!!!! Simple, simple mod with big effect. Definitely keep us up on what you find. Good tinkering Pinhead, it's the kind of thing everybody here likes.

Fred

 

So far according to my Scangauge I've gained 2mpg in town, from 23 to 25 mpg. This is with "normal" driving. Highway mileage is unaffected, at 30 mpg.

Using some driving tricks that I've learned by watching the Scangauge, I was able to get a 30mpg trip to Wal Mart and back. This was in Kansas City, but it was late enough that I didn't have to worry about traffic; I made it through 99% of the lights without having to stop.

 

Yes, and as you stated earlier, you noticed that your IAT at highway speeds was at ambient. It's the in town mileage that's the breakthrough. Looks like ford should insulate the air tube. Great insight Pinhead. You should have been an engineer.

thanx
Fred