Fuel Efficiency Swap For 6th Gen Civic Hb?

[Jas68]

Hello. First post, so here goes.

I've been trying to find a 5th gen VX, with little luck, so I'm considering another model and might do a swap for a VTEC-E engine. I'm pretty positive now that I can get a 92-95 CX and put a D15Z1 in that, no problems (same tranny, too).

Question is, is there any possibility for a 6th-gen model? I just saw a nice '96 DX for a good price, so I'm wondering. I guess the question is Can a D15Z1 go in a 6th gen Civic HB?

Also, JDMExchange is selling a JDM D15B with VTEC-E stamped on the valve cover. What engine is this? The seller claims it's the same as a VX engine, just JDM (ie, approx 90hp, VTEC-E).

Thanks.

[Siege911]

look for a civic hx... they're the lean burn fuel efficient 6th gen model

[jtw156]

ummm i believe you will be fuel efficiant enough in any stock civic model. Is this a joke? Save ur money for gas not a pointless swap.

[Jas68]

<div class='quotetop'>QUOTE(jtw156 @ Apr 20 2006, 01:23 AM) [snapback]101055[/snapback]</div>

ummm i believe you will be fuel efficiant enough in any stock civic model. Is this a joke? Save ur money for gas not a pointless swap.
[/b]

Money isn't always the point. If I score a car with relatively high mileage, I could put in a much lower mileage engine, plus it seems the VTEC-E should give better performance (compared with a stock Civic CX engine). A DX gets much worse mileage from what I've read (upper 20s to mid-30s, compared with combined mid-to-upper 30s or even low-to-mid 40s).

As for the HX, thanks for the suggestion, but I just don't like coupes. I want a HB.

Finally, I have to say it's a laugh for someone to suggest this question's a joke, and that it's a pointless swap, considering that the millions of people out there who are evidently obsessed with swapping in less fuel efficient engines and all sorts of other junk, all of which could be called pointless. There seems to be a lot of pent up frustration on these Honda swap sites, when someone responds to a simple question with a derisive comment. Notice that I did post in the Newbie section, too.

[tonyroll]

It's gonna be hard to find a vx high mileage or not at a decent price, everyone is scooping up all the fifth gen hatches and modifying them, trust me i've had about 3 of them. You can find an automatic fairly cheap but lately it seems like even those are fetching a premium. I was able to consistantly pull high 30 mpg out of my cx, and i don't think you're gonna see that much of an increase in power in the vx. You must also understand that most of these honda forums are dedicated to increasing the performance of these gas efficent cars, typical advise from someone on one of these sites will usually be "keep your stock motor if you want great gas mileage". I'm sure no one meant to offend you, it's just not something we hear every day around here.

[Jas68]

<div class='quotetop'>QUOTE(tonyroll @ Apr 20 2006, 02:39 PM) [snapback]101060[/snapback]</div>

It's gonna be hard to find a vx high mileage or not at a decent price, everyone is scooping up all the fifth gen hatches and modifying them, trust me i've had about 3 of them. You can find an automatic fairly cheap but lately it seems like even those are fetching a premium. I was able to consistantly pull high 30 mpg out of my cx, and i don't think you're gonna see that much of an increase in power in the vx. You must also understand that most of these honda forums are dedicated to increasing the performance of these gas efficent cars, typical advise from someone on one of these sites will usually be "keep your stock motor if you want great gas mileage". I'm sure no one meant to offend you, it's just not something we hear every day around here.
[/b]

Thanks for the kinder reply. I know how hard it is to find a VX, and that's why I'm looking at CXs (it's even easier to find DXs, but they get worse mileage stock, and they don't have the same tranny has the CX and VX, at least 5th gen). I'm looking at some 5th gen CXs, and the mileage isn't so bad, but I'm trying to think ahead. I'd like to keep the car for a while, and if a VX engine swap is a possibility, that's nice to know.

Originally I was asking whether any 6th gen swaps of this kind are possible, but I think at this point I'm looking at sticking with 5th gen, since the stock CX does get pretty good mileage, as is, and I'm pretty sure a future VX engine swap is in the realm of possibility.

I also asked what a JDM D15B with VTEC-E on the valve cover was, and didn't hear a response. I've looked around, and it seems a mystery. There were D15B VTEC-Es in Japan, but from what I've seen they didn't say VTEC-E on the valve cover. All these model numbers get very confusing after a while.

Oh, and I understand that you guys are about performance, not fuel economy. I'm not knocking that, just saying it's as purposeless as trying to stretch miles-per-gallon. Anyway, you're the only people out there who know so much about Civics!

[tonyroll]

AS for your questions i'm sure you could put a vtec e motor out of a 5th gen in a sixth gen, might not be legal though, general rule is you put a motor that is from the year of your car or newer in. You would also go from obd2 to obd1 in a sixth gen so it would be a major problem come inspection time. As for the D15B i found this site

http://www.leecao.com/honda/vtec/3stagevtec.html

Still trying to find out what years they were produced.

"All the work Honda has done on the VTEC mechanism are combined to make the 3-Stage VTEC system. It is not a rumor, the engine exists: D15B. The engine is used in Honda Civics in Europe and Japan. In short, it combines VTEC-E and SOHC VTEC to get both extraordinarily good RPM fuel economy, and excellent high RPM power. The D15B is a 1.5L engine that is capable of about 54mpg and is rated for about 128HP. There is no other engine that can boast such combination of good fuel economy and power output."

"VTEC-E is a twist on the regular VTEC mechanism. Whereas VTEC's purpose can be more or less summarized as: extracting high RPM performance while maintaining smooth low RPM operation, VTEC-E can be summarized as: allow extremely lean fuel-air mixture at low RPMs in order to increase fuel economy. In other words, VTEC technology is used to optimize different ends of the RPM range in the two different implementations

First, some background information. Fuel is mixed with air and then combusted in cylinders to make torque. How much torque is generated is affected directly by how much and how well the fuel and air are mixed together. Less fuel and more air is called a "lean" mixture, the opposite is called a "rich" mixture. For low RPMs, a normal engine's intake charge velocity is low enough that the fuel and air are not mixed together very well. To make up for the sub-optimal mixing effect, a slightly rich fuel/air mixture (more fuel) is needed to maintain smooth operation. VTEC-E artificially increases the intake charge velocity, which creates a swirling effect inside the cylinder. This promotes a very good mixture of the fuel and air, thus allowing a lean fuel/air mixture to be used. The result of this is great fuel economy when running at low RPMs. Indeed, the current Civic HX, a 2400lb coupe, is capable of 37cty/44hwy fuel economy from a 115hp 1.6L VTEC-E engine. Now lets see how VTEC-E works in detail.

Unlike regular VTEC mechanisms, there aren't any extra cam lobes in a VTEC-E engine. So each pair of valves works off of exactly two cam lobes. Since VTEC-E merely increases the low RPM intake charge velocity, it is a mechanism that only affects the operation of the intake valves. VTEC-E is found only in SOHC engines due to its economical intentions. All this means that we only have to look at the two intake cam lobes and the associated rocker arms and valves in order to gain a full understanding of VTEC-E.

A non-VTEC-E engine normally has one single cam profile for the intake valves. A VTEC-E engine has two different intake cam profiles. At low RPMs, each intake valve works from its own intake cam profile. One of the intake cam profiles is very normal looking. The other one, however, is almost perfectly round, with just enough profile to it so that it pushes the valve open just enough to avoid pooling of fuel above the valve lip. Therefore at low RPM, only one intake valve is opening and closing. Most of the intake fuel and air are squeezed through this one valve, resulting in a good swirling effect in the cylinder. The swirling effect optimizes the fuel/air mixture, thus allowing a very lean mixture to be used.

As the RPMs increase, the demand for more fuel/air rises as well. Once a certain RPM is reached (approximately 2500RPM for the Civic HX), the one-intake-valve configuration starts to become a significant intake restriction. At this time, a solid pin is pushed through the two intake valve rocker arms, thus binding the two rocker arms into a single unit. This causes both intake valves to open and close according to the normal cam profile, while the almost-round cam profile is no longer used.

VTEC-E is some times confused to be just another high-RPM optimizing mechanism like other VTEC variants. And there is some truth to this: since only one intake valve is used at low RPMs, the one normal cam lobe is made to open that one valve slightly taller and for longer duration than if both intake valves are used. At higher RPMs, both valves follow this same cam lobe so they are both opened slightly taller and for longer duration. This results in a slight improvement in high RPM breathing compared to non-VTEC-E engines and thus slightly more power. This is evident by comparing the Civic DX and Civic HX engine. The two engines are essentially the same except for the VTEC-E in the Civic HX. But the Civic HX's VTEC-E mechanism results in 115hp, versus 106hp from the Civic DX. So the Civic HX has more power in addition to better fuel economy. But make no mistake, VTEC-E is designed with economy as the primary goal, not power output."



Here is a link to the chasis codes and available motors, looks like it was available in the 6th gen models

http://www.d-series.org/forums/printthread.php?t=3289

[Jas68]

<div class='quotetop'>QUOTE(tonyroll @ Apr 20 2006, 03:38 PM) [snapback]101062[/snapback]</div>

AS for your questions i'm sure you could put a vtec e motor out of a 5th gen in a sixth gen, might not be legal though, general rule is you put a motor that is from the year of your car or newer in. [/b]

Thanks for all the info, tonyroll.

I've actually read this and seen your links.

Thing is, I've confused the issue a little.

The engine I've seen, the D15B, claims to be 5th gen, not 6th, and to put out 90 hp, or the same as the D15Z1 USDM in the VX (see here). But I'm suspicious, because I can't confirm it. The good part is it's available locally for a reasonable price with 40-60K miles on it. D15Z1s are available from Nippon Motors, but they're all the way across the country.

If I got a 6th gen hatch, I guess I could try to get one of those D15B 3-stage motors (or even a used HX motor), but I'm less sure about the match. Still seems like a 5th gen CX and 5th gen VX motor's the best match, if I really do this (and I've read I'd need another ECU and VTEC controls, etc, but I think the tranny would be able to stay, just fine).

Also, I'm not ignoring previous comments. If I can find a lower mileage CX, I'll grab it and may well just leave it stock, particularly if I can get decent mileage out of it. I've read some basic tips for improving mileage if it seems abnormally low, and of course I won't know how well the car does til I drive it for a while.

Thanks for your help, everyone.

[Siege911]

well, you have a good idea swapping in a more fuel efficient engine, and if you can squeeze 50mpg like that article said then I'd think it'd be a worthwhile swap... the question is how much would one of those 3-stage vtec-e engines run? and to have someone install it for you? (I'm sure the wiring will be killer... ecu's gonna be different probably, etc). But that would be cool, 128hp and 54mpg? damn, that's amazing... another reason why I love honda's

I get b/w 37 and 40mpg in my 98 ex, and 127hp... it's good enough for me, 40mpg is a lot compared to the average of today.

[tonyroll]

that swap would be just as easy as any other swap probably easier, as i see it you would just add the wires for vtec and swap the ecu. you could do that swap in an afternoon easily with the right tools. Correct me if i'm wrong put didn't some cx's come prewired for vtec like the 92's maybe, i know it's either the dx or cx in a particular year.