Fuel Economy, Hypermiling, EcoModding News and Forum - EcoModder.com - View Single Post - Thinking of Civic DX to HX Conversion (lean burn engine)

vskid3 · 02-27-2011, 03:09 AM

I have a 1997 Civic DX sedan that will get around 40MPG at 70MPH with the only modification being 44PSI in the tires. I really wanted to get an HX, but there weren't any available when I was buying a car. I've been thinking of swapping an HX engine into my car, but I would really like to get my current engine over 300k miles (it has 227k now).
Today I found out that the only real difference between the DX engine (D16Y7) and HX engine (D16Y5) is the head, computer, and a wideband O2 sensor. This would allow me to keep most of the original engine and lower costs and time. What I want to do is confirm that all I need is the head and ECU and that there shouldn't any snags that I'll run into. I don't plan on doing the actual conversion for a while, but it will give me a chance to keep my eyes open for parts or a parts car.
How much of a cruising mileage increase should I expect to see? Lean burn will throw off the mileage that my Ultragauge reports, correct? Should I be able to at least tell when it's in lean burn?

02-27-2011, 03:09 AM	#1 (permalink)
vskid3 Master EcoModder Join Date: Jun 2008 Location: Utah Posts: 975 Civic DX (sold) - '97 Honda Civic DX 90 day: 34.15 mpg (US) GTO (sold) - '04 Pontiac GTO 90 day: 22.62 mpg (US) Green Brick (sold) - '06 Ford Escape Hybrid 90 day: 31.93 mpg (US) Thanks: 193 Thanked 312 Times in 221 Posts	Thinking of Civic DX to HX Conversion (lean burn engine) I have a 1997 Civic DX sedan that will get around 40MPG at 70MPH with the only modification being 44PSI in the tires. I really wanted to get an HX, but there weren't any available when I was buying a car. I've been thinking of swapping an HX engine into my car, but I would really like to get my current engine over 300k miles (it has 227k now). Today I found out that the only real difference between the DX engine (D16Y7) and HX engine (D16Y5) is the head, computer, and a wideband O2 sensor. This would allow me to keep most of the original engine and lower costs and time. What I want to do is confirm that all I need is the head and ECU and that there shouldn't any snags that I'll run into. I don't plan on doing the actual conversion for a while, but it will give me a chance to keep my eyes open for parts or a parts car. How much of a cruising mileage increase should I expect to see? Lean burn will throw off the mileage that my Ultragauge reports, correct? Should I be able to at least tell when it's in lean burn?