Fuel Economy, Hypermiling, EcoModding News and Forum - EcoModder.com - View Single Post - 1997 Civic CX to HX engine/VX trans swap! 63 MPG @ 62 MPH

turbovr41991 · 09-14-2012, 09:21 AM

***Update***
The donor car is just about back together and 100 miles have been put on the CX with the HX engine. Low end power and torque are MUCH better than the CX engine. I am able to accelerate at a lower RPM and use higher gears relative to the speeds than before.
I am still calibrating the ScanGaugeii . I am about 150 miles into the tank. I find myself doing more tests with lean burn than I am EOC /DFCO so fuel efficiency will suffer a bit. After programming a X-Gauge feature on the ScanGaugeii to display when I am in lean burn, I found I was not going into lean burn easily. On a 35 mile stretch I will only enter lean burn 1 or two times for a short period of time. When put in under the ideal conditions (warm temp, on highway, and 15% TPS) to engage lean burn the check engine light has occasionally come on with the code P1164 (front O2 sensor.) I suspect this is the main reason it is struggling to get into lean burn. So I ordered an OEM sensor (This is one expensive O2!) and will see if this solves the issue.

Also, if anyone is planning to do this swap, it was 100% plug and play. Get an HX dropout, 5 wire (fed spec) manual trans harness and a Manual trans ECU.

Only a few slight differences:
1) Throttle cable is completely different. You could make the CX/DX/LX work , but I would recomend getting the stock cable as well as the mounting braket that bolts to the strut tower.
2) Fuel line return. Probably not large enough of a difference to NEED swapping, but they are slighly different in lenth. Also swap the bracket that holds it to the intake manifold. (Depending on your needs, Power steering also shares the same braket and can be separated by drilling out a spot weld on the bracket.)
3) Brake booster hose. Is formed completely different. Will need a new one.

09-14-2012, 09:21 AM	#12 (permalink)
turbovr41991 Master EcoModder Join Date: Nov 2008 Location: Cincinnati Posts: 323 Civic CX/HX - '97 Honda Civic CX/HX Team Honda 90 day: 63.77 mpg (US) Thanks: 12 Thanked 50 Times in 36 Posts	*Update* The donor car is just about back together and 100 miles have been put on the CX with the HX engine. Low end power and torque are MUCH better than the CX engine. I am able to accelerate at a lower RPM and use higher gears relative to the speeds than before. I am still calibrating the ScanGaugeii . I am about 150 miles into the tank. I find myself doing more tests with lean burn than I am EOC /DFCO so fuel efficiency will suffer a bit. After programming a X-Gauge feature on the ScanGaugeii to display when I am in lean burn, I found I was not going into lean burn easily. On a 35 mile stretch I will only enter lean burn 1 or two times for a short period of time. When put in under the ideal conditions (warm temp, on highway, and 15% TPS) to engage lean burn the check engine light has occasionally come on with the code P1164 (front O2 sensor.) I suspect this is the main reason it is struggling to get into lean burn. So I ordered an OEM sensor (This is one expensive O2!) and will see if this solves the issue. Also, if anyone is planning to do this swap, it was 100% plug and play. Get an HX dropout, 5 wire (fed spec) manual trans harness and a Manual trans ECU. Only a few slight differences: 1) Throttle cable is completely different. You could make the CX/DX/LX work , but I would recomend getting the stock cable as well as the mounting braket that bolts to the strut tower. 2) Fuel line return. Probably not large enough of a difference to NEED swapping, but they are slighly different in lenth. Also swap the bracket that holds it to the intake manifold. (Depending on your needs, Power steering also shares the same braket and can be separated by drilling out a spot weld on the bracket.) 3) Brake booster hose. Is formed completely different. Will need a new one. __________________ Last edited by turbovr41991; 09-14-2012 at 11:49 AM..