How to hypermile Civic HX??

[brucepick]

These days my intake air is between about 25-40 degrees F. ('97 Civic HX) It would be nice to have intake temps between about 70-90 deg. F. I'm curious to see a pic of PaleMelanesian's heated intake setup.

[palemelanesian]

Sorry - no camera pic, but here's a quick doodle.

I pulled out the stock air tube and routed the new one as shown in red. It seems to work on cold days, like below 40F, and with short drives. More than 10 miles and it gets a little warm and sluggish.
Attachment 1561
I'm considering cutting a hole in the air box and putting in a shorter tube - see the yellow drawing.

Used a 2" carburetor heater hose like this:
Attachment 1562

The weather warmed up last week, so I took it off. Didn't gather enough data to say if it really helped. Will try again soon.

[brucepick]

Aha. Is that your air filter back near the windshield?

If your air filter is in front, near the anti-freeze reservoir, does that mean that your pre-heated air is not filtered before it goes to the engine?

My filter is down in front, where you have a black plastic box just rear of the anti-freeze reservoir. I've investigated running a tube like your yellow doodle. But there are obstructions and difficulties, it's definitely a job for warm weather when there's time to resolve the various issues.

The main issue is that due to filter position within the box, the yellow tube must enter the box at the bottom where the original has a snake type intake that ultimately leads to the right front wheel well area. Cramped quarters to work in but I think it could be done.

[palemelanesian]

Bummer! My air filter is in the back.

[R.I.D.E.]

On the earlier (AF in front) models, reverse the intake snorkel, trim some off the end and stick the heater tube in the stock snorkel and run it down next to the catalytic converter.

I did this with my VX and also noticed the loss in power mentioned by Pale.

regards
gary

[brucepick]

Originally Posted by R.I.D.E.

On the earlier (AF in front) models, reverse the intake snorkel, trim some off the end and stick the heater tube in the stock snorkel and run it down next to the catalytic converter.

I did this with my VX and also noticed the loss in power mentioned by Pale.

regards
gary

If I do this, I want to have a mix of heated and raw air. That should solve the "overheated air" problem. Or a way to close off the hot air during warm season. A hole in the heater tube with duct tape over it would do the job. My '89 Volvo has a thermostatically controlled air damper for that purpose but it's not very transplantable to another vehicle.

[R.I.D.E.]

Just pull the heater tube out of the snorkel in warmer weather, which will pull the intake air from the area near the top radiator hose. If it gets real hot put the snorkel back in its stock position.

regards
gary

[R.I.D.E.]

I beleive you can determine the intake air temp with a scan guage since the HX is OBD2, not possible with the VX.

regards
gary

[brucepick]

Originally Posted by R.I.D.E.

I beleive you can determine the intake air temp with a scan guage since the HX is OBD2, not possible with the VX.

regards
gary

Correct. The readout is labeled "FIA" for Fahrenheit Intake Air. It's "CIA" if you set the output to metric or if you're a spy.

ScanGauge temp readout will be a good tool for optimizing the heated intake.

[theholycow]

If a ScanGauge is unavailable, a cooking/barbecue thermometer with a remote probe is often suggested as a good way to measure IAT.