1998 Civic LX to HX D16y5 conversion has begun!

[firehawk618]

Originally Posted by Chrysler kid

Get a few more tanks of gas under your belt and some pictures of all this work you're doing would be great too, I enjoy documenting and seeing pictures of builds.

Id like to find a Dyno sheet showing a stock y5 curve in 12v operation it is probably a more torque than a b series

To agree and contradict you; I would lose mileage switching back to a long geared trans just because I spend most of my longer sections of commute at 50-55mph. Sometimes the extra throttle to stay in lean burn would hurt my tank average.

One thing I am absolutely TERRIBLE at is documenting this kind of stuff.

Tomorrow or Thursday the VX trans is getting pulled back out, opened up and new bearings installed. I can shoot some pics if you guys like.

I hear ya on the extra throttle vs gearing but it looks to me like on flat ground the extra tallness is far superior than LB is. I have yet to go fast enough to get LB in 5th.

The thing with the ratio is, if you feel 5th is too tall for a given situation and you feel like 5th in the HX / DX trans would have yielded greater mileage all you have to do is down shift to 4th. 4th is ~ what 5th was with my DX trans.....

I can say that so far it's VERY hard to get the MPG reading to drop below 35MPG on the highway in 5th under any reasonable throttle percentage. I'm not talking about flooring it but am talking about slowly accelerating and again, no LB.

It really boils down to wider spacing 1 through 4th and 5th is just a bonus over the DX ratio.

The only tank I have logged was all DX trans.

I have ~80 miles so far on the VX tank and will definitely be comparing and sharing.

I5 where I live is 60mph from here south and 70mph from here north. I go south daily for work and occasionally north to visit a friend. That's the one I'm really curious about because before it was extremely hard to get a 40MPG average at those speeds with the DX gearing.

Either direction from here is rolling hills. Heck, everywhere you go around here is hills.


http://www.zealautowerks.com/transcalc.php


I have been using this calculator, it's right on the money and I have confirmed their ratios ARE in fact correct because I have had the Si, DX, and EX transmissions all apart and counted each gear ratio.

I'm sure their VX/CX listing is correct just by their rpm / gear / speed calculations.

My tires are 185/60/14's.

[iveyjh]

That calculator has only one final drive ratio for the HF(3.25).That is the California, I think the 49 state HF trans has a final drive of 2.954. Maybe I missed it in my scan.

[Chrysler kid]

Originally Posted by firehawk618

One thing I am absolutely TERRIBLE at is documenting this kind of stuff.

Tomorrow or Thursday the VX trans is getting pulled back out, opened up and new bearings installed. I can shoot some pics if you guys like.

I hear ya on the extra throttle vs gearing but it looks to me like on flat ground the extra tallness is far superior than LB is. I have yet to go fast enough to get LB in 5th.

The thing with the ratio is, if you feel 5th is too tall for a given situation and you feel like 5th in the HX / DX trans would have yielded greater mileage all you have to do is down shift to 4th. 4th is ~ what 5th was with my DX trans.....

I can say that so far it's VERY hard to get the MPG reading to drop below 35MPG on the highway in 5th under any reasonable throttle percentage. I'm not talking about flooring it but am talking about slowly accelerating and again, no LB.

It really boils down to wider spacing 1 through 4th and 5th is just a bonus over the DX ratio.

The only tank I have logged was all DX trans.

I have ~80 miles so far on the VX tank and will definitely be comparing and sharing.

I5 where I live is 60mph from here south and 70mph from here north. I go south daily for work and occasionally north to visit a friend. That's the one I'm really curious about because before it was extremely hard to get a 40MPG average at those speeds with the DX gearing.

Either direction from here is rolling hills. Heck, everywhere you go around here is hills.


Honda Transmission Calculator by ZealAutowerks


I have been using this calculator, it's right on the money and I have confirmed their ratios ARE in fact correct because I have had the Si, DX, and EX transmissions all apart and counted each gear ratio.

I'm sure their VX/CX listing is correct just by their rpm / gear / speed calculations.

My tires are 185/60/14's.

You should see a drastic improvement in gas mileage with your commute being over 60mph. You will also need to make an upper grille block and lower grille block to increase your aero. The rear bumper on these civics is a huge parachute so you will want to create a rear belly pan. With the proper technique and aero you should start easily getting 50mpg tanks. I spend the majority of my time in 4th gear until I'm over 45mph

At over 60mph my car feels like its dragging a parachute because of lean burn and that drag created by the rear bumper. You should also see if you can increase your aerodynamics by following a safe distance behind an 18 wheeler. They often accelerate down hills and decelerate going up hill and traffic will pass you as you save gas

[California98Civic]

Originally Posted by iveyjh

That calculator has only one final drive ratio for the HF(3.25).That is the California, I think the 49 state HF trans has a final drive of 2.954. Maybe I missed it in my scan.

Yeah, that's what I show in the table of ratios I collected together for this site:
http://ecomodder.com/forum/showthrea...tml#post378478 (and this means that my tale is better tan the calculator! lol)

I included OEM tire sizes and VSS data where I could get it. The stock HF and the stock VX tire/wheel combo was almost a quarter inch shorter in diameter than the 185/60-14s you are running. So your effective gearing is notably taller than he 3.25 VX/CX.

As for lean burn, I'm not sure the gearing is the reason LB is not working at speed. But you could test it, maybe, this way.... the HX transmission was a 3.722 final drive and the same 0.702 fifth as the VX/CX. So your VX/CX fourth (0.853) will be close to the HX fifth when you factor in your tire/weel combo. Your car should be able to go into lean burn at freeway speeds in 4th, because the HX ecu will be reading the data as roughly the same as OEM HX fifth.

EDIT: The problem with LB might be about throttling. Aero improvements would reduce throttle position, seems to me, and allow lean burn, even in fifth on your VX/CX trans at 60 mph and roughly 2000 rpms, as long as everything else is woking well for LB.

Good luck!

james

[MPGomatic]

Originally Posted by Chrysler kid

You should see a drastic improvement in gas mileage with your commute being over 60mph. You will also need to make an upper grille block and lower grille block to increase your aero. The rear bumper on these civics is a huge parachute so you will want to create a rear belly pan. With the proper technique and aero you should start easily getting 50mpg tanks. I spend the majority of my time in 4th gear until I'm over 45mph

At over 60mph my car feels like its dragging a parachute because of lean burn and that drag created by the rear bumper. You should also see if you can increase your aerodynamics by following a safe distance behind an 18 wheeler. They often accelerate down hills and decelerate going up hill and traffic will pass you as you save gas

The driver side rear gap looks like it might be relatively easy to cover with a belly panel. The passenger side, not so much, because of the muffler. One of my dreams is to solve this and produce an affordable bolt-on part. For off-road use only.

The "Sergeant" rear diffuser looks interesting, but at $399 it's way too pricey and trapped heat might be an issue.

Sergeant Rear Diffuser EK9 - RHDJapan

For 96 00 Honda Civic EK9 Sergeant 3DR Hatchback Rear Bumper Diffuser Spoiler | eBay

[firehawk618]

Originally Posted by Xist

VX engine and SI transmission? How was that a good combination?

I never claimed it was. I'm just stating what the guy had.

[firehawk618]

Originally Posted by iveyjh

That calculator has only one final drive ratio for the HF(3.25).That is the California, I think the 49 state HF trans has a final drive of 2.954. Maybe I missed it in my scan.

That's true. Of all the ratios listed on line this is the only one that has been accurate for me and the transmission I have verified.


Here's my new thread on fixing a civic 5-speed trans.

http://ecomodder.com/forum/showthrea...tml#post475620

[firehawk618]

Originally Posted by California98Civic

Yeah, that's what I show in the table of ratios I collected together for this site:
http://ecomodder.com/forum/showthrea...tml#post378478 (and this means that my tale is better tan the calculator! lol)

I included OEM tire sizes and VSS data where I could get it. The stock HF and the stock VX tire/wheel combo was almost a quarter inch shorter in diameter than the 185/60-14s you are running. So your effective gearing is notably taller than he 3.25 VX/CX.

As for lean burn, I'm not sure the gearing is the reason LB is not working at speed. But you could test it, maybe, this way.... the HX transmission was a 3.722 final drive and the same 0.702 fifth as the VX/CX. So your VX/CX fourth (0.853) will be close to the HX fifth when you factor in your tire/weel combo. Your car should be able to go into lean burn at freeway speeds in 4th, because the HX ecu will be reading the data as roughly the same as OEM HX fifth.

EDIT: The problem with LB might be about throttling. Aero improvements would reduce throttle position, seems to me, and allow lean burn, even in fifth on your VX/CX trans at 60 mph and roughly 2000 rpms, as long as everything else is woking well for LB.

Good luck!

james

Your theories are right about LB. 5th is on the very low end of lb's rpm requirements and the engine load is too high. 4th gear at the same speed I can get it on demand.

So far the 3 days I drove the car with this trans, when the situation comes up to stay in 5th with no LB or downshift to 4th and get lb it's always been beneficial to stay in 5th according to the mpguino.

Lower RPM > LB in all instances so far.

[California98Civic]

Cool! So, if you reduce engine load significantly at freeway speeds in fifth gear, you may be able to stay in LB in 5th. The best way would be aeromods (undertray, airdam, grill block, and maybe side and wheel skirts). You might also reduce weight significantly (like 100 or 200 lbs). And you might reduce tire/wheel diameter and rotational mass while raising RPMs just slightly with some VX wheels and 175/70-13 tires. Somewhere in there you might cross the magic line and be able to stay in LB in fifth at freeway speeds.

Originally Posted by firehawk618

That's true. Of all the ratios listed on line this is the only one that has been accurate for me and the transmission I have verified.

I invite you to find errors in my list, linked a couple posts up. I checked, corrected, and added to online listings with data published by Honda. That 2.95 FD for te HF is on my list. And everything is cited. If there are still errors, I'd like to know.

[Xist]

Originally Posted by firehawk618

I never claimed it was. I'm just stating what the guy had.

I just thought it was a strange choice. Maybe they told themselves they would eventually swap in an Si engine... or a V8, whatever...