Lean and Mean - 1998 Honda Civic HX Project Log

[cbaber]

The DX and HX of the 6th gen Civic share the same part # flywheel, which is about 20 lbs.

The VX flywheel, I noticed, is about double the price of a regular flywheel (from Honda). If you search parts places like AutoZone or AdvanceAuto, they don't have a direct replacement for the VX. Instead they give you the same flywheel all the other Civics use.

I keep finding more disadvantages to lighter flywheels than I do advantages. Check out this thread (was searching for stock flywheel weight): Flywheel weight? - D-series.org

It seems the 7lbs region is very extreme, and shouldn't be used for street cars. Most of these "racers" prefer around 10lbs. If the VX is around 16lbs, that should be nice balance between the stock 20lbs and the more performance oriented weight. Again, we can only assume at this point if the decreased weight was for fuel economy, or because the VX motor had less power than standard Civic motors.

And I don't buy the claim that lightened flywheels increase HP by that much. They might free up some power because the motor doesn't have to build up speed in a heavier flywheel, but once you are at a steady speed the effects are minimal. Going back to California98Civic's point, a mildly light flywheel (12-16 lbs) could actually benefit P&G driving without effecting driving.

[cbaber]

Update to EGR Situation

I just filled up and this tank was 44.21 MPG. It appears my theory was correct, the ScanGauge was reading wrong with the EGR system connected. It was previously calibrated with the EGR system disconnected and not working. Even though 44 MPG is lower than my earlier 47 MPG tank, I blame it on about 100 miles of faster highway driving (65-70 mph) due to me being in a hurry. So I'm convinced everything is normal.

The only issue is that my aftermarket O2 sensor is not performing well. The EGR system is a crucial part of the lean burn system on the HX motor. With it disconnected the car won't try to engage lean burn. With it connected again, it tries to enter lean burn. My low quality aftermarket O2 sensor cannot handle lean burn A/F ratio's, so the car stalls out and stumbles every time lean burn engages. I have to keep the EGR disconnected until I get a new OEM O2 sensor.

Bye bye $360

[02ws6]

What o2 is in there now?

Rockauto has an ntk brand sensor (from the makers of ngk) for $240. The bosch is $360. Honestly never liked them for plugs or sensors.

[cbaber]

It was the cheapest sensor RockAuto had, I think I paid $170. I get CELs for the front O2 sensor "slow response" and "poor performance". No doubt the car does not like the sensor when its time for lean burn.

But at this point its not a top priority. I can achieve 46 mpg tanks without lean burn, and I hope that increases with my planned projects.

[cbaber]

Finally, finally, FINALLY found a decent set of OEM HX wheels for my car. I've been looking off and on for years, trying to find a set with a decent price and no damage. Luckily a guy responded to a wanted ad with these:



I'm not a fan of the black, but they look to be in good condition. I plan to paint them the original silver color, and get new tires since the ones on there are shot. He's asking $150 which is a decent deal.

Because im cheap, and it wouldn't make economical sense to get rid of my current good tires (that wont fit the HX rims due to being 15 in and not 14 in) I'm going to wait to install them until I need new tires. I've got another 50,000 miles left! With my driving that is about a year. Another long term project added to the list.

[Stoked]

Nice find on the wheels! I've been keeping my eyes open for a set as well, but only if I can find them in that price range. I'm due for new tires soon and one of my factory steel wheels has a bent lip, but seems to be holding air.

[California98Civic]

Originally Posted by cbaber

Another long term project added to the list.

My car develops in glacial time too.

Nice wheels.

[cbaber]

A little update...

I've got the VX transmission ready to install in the car. I opened up the transmission and resealed the casings together with RTV. I could tell that it was leaking fluid from how dirty and oily it was in a certain area. I also installed new axle seals, and cleaned up the transmission a lot.

I've also been underestimating my fuel economy in the logs, by a pretty large amount. I've got tires that are about 1 inch larger diameter than the stock configuration. This setup made my speedometer read dead on, GPS verified. I know most cars actually read slower anyway from the factory, so I figured the larger diameter tires corrected that. Well tonight I measured out my 50 mile commute home, accounting for elevation changes. It came out to 49.9 miles. My ODO read 47.5 miles. 2.4 miles difference is 5%! If you look at my current highest tank of about 46 MPG and apply the correct miles traveled, it brings it up past 48 MPG!!!

I'm going to calibrate the ScanGauge with the correction, and use SG data for calculations from now on. I've got a GPS unit I could try too, just another way to make sure my calculations are accurate.

[user removed]

Go back and correct your log for the different tire diameter, if you haven't already. I did on my Ranger, now I multiply the recorded mileage by 1.026 to reflect the larger diameter tires and I corrected it back to the point when I had the tires installed.

regards
Mech

[California98Civic]

Originally Posted by cbaber

tonight I measured out my 50 mile commute home, accounting for elevation changes. It came out to 49.9 miles. My ODO read 47.5 miles. 2.4 miles difference is 5%! If you look at my current highest tank of about 46 MPG and apply the correct miles traveled, it brings it up past 48 MPG!!

You might go back and correct your earlier entries like Old Mech says. I did not, because I only became aware of the under count my tires were producing after I swapped the transmission. But ever since the swap I have applied a 1.055 multiplier to the stock odometer reading. That's 5.5%, which I confirmed repeatedly using a GPS and ridewithgps.com ... when I get new tires this fall and switch my front wheels to my 13" VX wheels (like the back ones currently are) I will re-calibrate.