I currently have a bone stock 95 Civic LX 5-speed with 214k which averages around 37 mpg highway. My commute is 150 miles per day which consists mostly of 65-75 mph interstate driving and I'm looking for more mpg. I have located a VX transmission for a good price. Would there be a noticeable mpg difference with the higher geared VX transmission? And if so, is the swap as simple as swapping transmissions? Are the axles, flywheel-clutch, etc. the same between the two transmissions? Thanks in advance for any input.

 

Yep, you will find that your mpg will improve with the CX/VX transmission. Ideally, a full VX D15Z1 swap would be what you should be doing to get 55+mpg. JDMfanbois will basically give you one away in order for them to install their gagillion-hp engine, but I digress. The axles will be the same, flywheel too, IIRC.

 

The flywheels are interchangeable, but the VX (and USDM CX) are supposed to be lighter. They have a different part number, 22100-PLD-005 for the CX/VX vs 22100-PEL-005 for all other '92 - '95 Civics.

 

So everything will bolt up and interchange with no issues...great news!

What is your best guesstimate as far as fuel mileage goes? Am I looking at 1-2 mpg more? 5-10 mpg? I'm just trying to determine if the swap is worth the cost/trouble.

 

Anyone?

 

you will get better mpg but its really hard to say im sure someone out there has done it already for the same reason but ive never read up on anything like this. also hard to say because vx is of course lighter than the lx sedan. do you plan on doing other things to it to increase the mpg? i always found this kinda thing interesting

 

Can you drive your LX at 1200rpm? the gearing is so high in the vx I go from 1000rpm to 2000. At 60 I'm at 2000rpm. I just dont know if you have any power in the city for stop and go with the LX engine.

 

Perhaps this will help your calculations? Dunno. http://www.fatboyraceworks.com/gears/

 

My car currently at 60 mph turns 2200 rpm. I would think the VX with it's significantly higher final drive ration would be a lot lower than 2000 rpm at 60 mph. According to the following chart the final drive for the VX is 3.25 whereas my car is 4.05.

http://www.knology.net/~jediklc/gearratiosdseries.htm

And as hp and torque go, it looks to me like the LX stock has more hp and torque than the VX according to the following information obtained from Wikipedia:

D15Z1
• VTEC-E
• Found in:
• 1992-1995 Honda Civic VX
• 1992-1995 Honda Civic VEi (European Market)
• Displacement : 1,493 cc (91.1 cu in)
• Bore and Stroke :75 mm × 84.5 mm (3.0 in × 3.3 in)
• Rod Length : 137 mm
• Rod/Stroke : 1.62
• Compression : 9.3:1
• Power : 90 hp (67.1 kW, 91.3 ps) @ 5600 rpm (92 hp @ 5500 rpm USDM)
• Torque : 98 ft•lb (13.5 kg/m, 133 Nm) @ 4800 rpm (97 ft•lb @ 3000 rpm USDM)
• Valvetrain : SOHC VTEC-E (USDM- Lean Burn Federal Emissions 49 State)
(3-4 valves per cylinder depending on RPM)
• VTEC Switchover : 2500 rpm
• ECU Code : P07
• Fuel Control : OBD-1 MPFI



D15B7
• Found in:
• 1992-1995 Honda Civic CX (Canadian model)
• 1992-1995 Honda Civic DX/LX
• 1993-1995 Honda Civic del Sol S
• 1992-1995 Honda Civic LSi Coupe (European Market)
• Displacement : 1,493 cc (91.1 cu in)
• Bore and Stroke : 75 mm × 84.5 mm (3.0 in × 3.3 in)
• Compression : 9.2:1
• Power : 112 hp (76.1 kW, 109 ps) @ 5900 rpm (102 hp @ 5900 rpm in U.S.)
• Torque : 98 ft•lbf (13.5 kg/m, 133 Nm) @ 5000 rpm
• Valvetrain : SOHC (4 valves per cylinder)
• Cam Gear: 38 Tooth
• Piston Code : PM3
• Fuel Control : OBD-1 MPFI
• ECU Code: P06

 

As others have said its really hard to say just how much you'll gain for mileage. The tall geared tranny was just one of several ways the VX got better mileage than other civics. It also had the following going for it:

-D15Z1 engine (had leanburn and vtec-e)
-lighter chassis
-manual steering
-lightweight 13" alloy wheels
-smaller gas tank
-rear diffuser
-front lip
-lighter flywheel
-less sound deadening (especially when compared to any sedan)
-no power windows, locks, mirrors, cruise control

 

I put a VX transmission in my DX thinking it was an SI. The first thing I noticed was 3rd, 4th, and 5th speeds. I had to rev higher to get into those gears with any usable power. 1st and 2nd seemed the same although the final drive ratios work out much higher. As for gas mileage... I have kept careful records for 3 years since the swap and 4 years before. I found essentially no difference. The best I got was 44 mpg and I average 36~37; maybe 2~3 mpg better. Most people would probably hate the higher ratio as there is less power, it seems. I like driving around at lower rpm. My vote for you is keep your current tranny but if you want better mileage get a 1995 VX car with the wimpier, but gas sipping motor.

 

The vx trans has some rediculously tall gearing for a 4 cylinder. I have a vx and the stock gearing around town was pretty obnoxious, even though i have the z1 which makes alot more lowend then most of the other d-deries motors do to v-tec-e. The final drive isn't even that bad its just that on top of it 2nd 3rd and 4th are extra tall still. I ended up putting the final drive, countershaft and 5th gear in a del sol si trans when i pulled it do to a bad isb. Made it much more driveable.

 

Thanks! This is the information that I'm looking for. Having heard this, it looks as if I may hang onto the tranny as a spare if I acquire a VX later.