VTEC vs VTEC-E Is it all about the ECU?

[byoung]

Here's a question. Can you make a normal 99 Civic EX with the VTEC motor behave like the HX VTEC-E with just a change of the ECU?

I assume you would also have to swap the transmission to get the better HX gearing, but would this work?

Brad

[brick]

The HX is a lean burn motor, which also requires a 5-wire O2 sensor as well. Couldn't tell you if there is anything mechanically different about the engine. But you would have to be careful if you have state emissions inspections in MO because it probably wouldn't pass anymore.

[-mr. bill]

No. Just a quick peek at the parts lists, it's not just the ECU. The heads are the same, but the valvetrain (camshafts, rocker arms) is different, plus some supporting parts.

For the transmission, you should just be able to swap the final drive, rather than the whole transmission. That might be the bang for the buck mod.

You can order a 1996-2000 factory service manual from helminc to scope out in detail the differences.

For free, you can do the tedious method of going through the parts list side by side. Open two browsers, go to hondapartsdeals, and click and compare your way to scope out the swap you are talking about.

-mr. bill

[byoung]

Thanks Tim and Bill. I was afraid that the conversion wouldn't be as simple as I would like.

Brad

[xcel]

Hi Mr. Bill:

___Do you know ~ how many hours it would take for a final drive swap in a 96 Civic as Andrew would probably be interested in that mod for sure!

___Good Luck

___Wayne

[phatalbert]

I'm interested on more info on this as well. I've got a 99 ex and do 90% freeway driving, so an easier way to better mileage than selling my car or trying to swap the entire tranny is very enticing... where would I purchase just a "final drive."

Also is this statement (from a civic forum) true? I had always though the HX's were geared even higher than other models. If the following statement is true, should I then expect only DX mileage from an EX with an HX tranny?
OK well there are 2 different manual trannies for the 96-00 Civics - the one that comes in the Civic EX or the one that comes with the Civic LX/DX/CX. The EX tranny has lower gear ratios which is great for aggressive acceleration. To get better gas mileage using the EX tranny you can swap in the final drive from a LX/DX/CX tranny or swap in the entire tranny. If you already have a LX/DX/CX you're already getting the best mileage possible from that tranny.

[byoung]

Originally Posted by brick

The HX is a lean burn motor, which also requires a 5-wire O2 sensor as well. Couldn't tell you if there is anything mechanically different about the engine. But you would have to be careful if you have state emissions inspections in MO because it probably wouldn't pass anymore.

Good Point, Yes we have Emissions inspections on all cars 96 and newer.

Brad

[warthog1984]

Originally Posted by phatalbert

where would I purchase just a "final drive."[/i]

I would assume either a NAPA type parts store or J.C Whitney. Maybe a tuner store like Summit Racing? Worst case, hit up your local junkyard for a compatible gear.

[Daox]

I'd check the salvage yard first. The price of a new differential would be through the roof.

I always start here: www.car-part.com

[some_other_dave]

Originally Posted by phatalbert

...where would I purchase just a "final drive."

You understand what a "final drive" is, yes? It's the ring and pinion inside the transmission. Those act as a multiplier "downstream" of all of the regular gears inside the transmission, so two cars that have identical 1st/2nd/3rd/4th/5th gears could still be turning different RPMs at the same speed in the same gear if the ring and pinion ratio (the "final drive") is different.

You can get a similar effect, at a potentially-significant cost in weight, by going to larger wheels and/or taller tires.

Swapping the ring and pinion is major transmission surgery. It may require some very fine and very specific measuring tools to make sure it doesn't shred itself in its new home; I do not remember if Honda transmissions need those or not, but old Porsche ones sure as heck do!

Another possible option might be to see if anyone makes a taller 5th gear for your transmission.

-soD