I recently bought a VX D15Z1 that I am going to swap into my 1989 HB to build a gas miser. But the D15Z1 that I bought came with a DX manifold rather than a VX manifold. And there is a grave mismatch between the manifold runner and the intake port.



The brownish area around the port represents the difference between the two manifolds. I am sure this is no good for flow OR fuel economy. So I need to get a more proper manifold. The problem is that VX parts are rare in the junkyards. But CXs are MUCH more common. Although I have not looked closely at a CX manifold, I know they are similarly small. But do they have the accommodation for the EGR valve? Someone told me that the CX manifold has a blind hole fo the passage and untapped holes for the bolts, and that it is not hard to modify it. Is this true? Could the CX manifold be substituted?

 

i have a vx manifold in my garage, if you don't get an answer let me know and i'll take some photos for you.

my question is why are you going with the vx, the hf motor available in an ef get similar (and in my case) better gas mileage then the vx.

good luck either way.

 

I went with the VX for a couple of reasons. Car for car, the HF might get better mileage than the VX. But, with VTEC-E, lean burn, AND OBDI electronics (which even makes motors like B-series get better fuel economy vs OBD0), I think the D15Z1 is a more efficient motor than the D15B6. I think the HF wins out only because of the lighter weight and better aero of the CRX HF body itself. So in a given shell, the D15Z1 is probably going to do quite a bit better (a few people on gassavers.org have swapped their HF CRXs to D15Z1s). Also, the D15Z1 was 30 more HP. And although this car is not really made for HP (I always have the ITR CRX), 30 more HP is certainly welcme.


Modified by StorminMatt at 7:17 PM 1/2/2008

 

Storminmatt....
Give me a call Im sure I have a Manifold in stock. As far as the Cx and Vx being the same Im sure they are the same. I would have to look at a Cx real quick to determine the interchangability between the 2. It should be the same.
A friend of mine is building an MPG monster. Its an 85 CRX HF with the VX swap. Should be a nice lil commuter when its done. Im thinking of doing the same thing. I have a VX swap from my 92 Hatch just sitting. One day.....too many projects right now....
Well Storminmatt good luck w/ the build and if you need the mani give me a call Im local.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by HAPRECYCLING &raquo;</TD></TR><TR><TD CLASS="quote">A friend of mine is building an MPG monster. Its an 85 CRX HF with the VX swap. Should be a nice lil commuter when its done. Im thinking of doing the same thing. I have a VX swap from my 92 Hatch just sitting. One day.....too many projects right now....</TD></TR></TABLE>

What kind of transmission is he going to use? As far as I know, the only transmission available for this swap would be a 1986-1989 Integra. And that transmission has some REALLY short gears. Not too good if you are going for mileage - especially with a motor designed for tall gearing. And I don't know that you can swap gears from other D-series transmissions with this one, as it is an oddball of sorts. Regardless, it would be nice to see how it goes. If he STILL gets good mileage, then that would be nice to know. I myself would CERTAINLY like to use something with better gear spacing than the HF transmission (which is HORRIBLE in the lower gears) if I could get away with it.

 

I'm not certain about the size on the ports but VX and CX mannys are completely different.

 

Its a complete VX swap. He using The VX tranny as well. VX Cluster too.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by HAPRECYCLING &raquo;</TD></TR><TR><TD CLASS="quote">Its a complete VX swap. He using The VX tranny as well. VX Cluster too.</TD></TR></TABLE>

In other words, it is a completely custom, cut and weld swap.

 

Does the CX have an EGR valve????

 

In response to your "why you got the VX thread."

My friend got a CX for awhile, he swapped an H22A in it but while he was still dicking around - getting parts together and such - it had the stock B8 in it - to which he replaced the headgasket (he had to keep it reliable and the gasket was leaking quite nicely), cleaned it up, did some basic maintenance on it, and it ran quite nicely.

Now I gotta say, that's a mega-light chassis, I LOVED that car. Sure, it couldn't get out of its own way, but I was able to beat on that thing like there was no tomorrow going up hills - high RPM, etc. etc. - and gas mileage was still GREAT. I know damn well if I did what I did in that car (everything you're not supposed to do to get good gas mileage) in my car, I'd be staring at a good high teens gas mpg - but nope.

8v = win when it comes to fuel economy.

That's why the Jettas kick so much ***.

8v SOHC with a gear box which is about as short as a B16 (just by feel, I don't know the actual ratios).

By this they accomplish 36mpg CC on the highway that rivals my EX perfectly @ 77mph, nice torque due to the trans amplification, not exactly raw "drag" horsepower - but you can keep it in 5th for a hell of a long time (which is rare in my area, and impossible for any Honda Civic).

8v SOHC + short trans seems to = win when it comes to economy - it makes the best of the power you have while still maintaining gas mileage.

As far as the intake manifolds go - I wanna say they're exactly the same, but I simply don't know for sure (maybe =70% sure?) - so Good luck with that, bro.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by kaiba &raquo;</TD></TR><TR><TD CLASS="quote">Does the CX have an EGR valve????</TD></TR></TABLE>
Yes it does

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Syndacate &raquo;</TD></TR><TR><TD CLASS="quote">8v SOHC with a gear box which is about as short as a B16 (just by feel, I don't know the actual ratios).

By this they accomplish 36mpg CC on the highway that rivals my EX perfectly @ 77mph, nice torque due to the trans amplification, not exactly raw "drag" horsepower - but you can keep it in 5th for a hell of a long time (which is rare in my area, and impossible for any Honda Civic).

8v SOHC + short trans seems to = win when it comes to economy - it makes the best of the power you have while still maintaining gas mileage.</TD></TR></TABLE>

The shortest D-series transmission is actually nowhere near as short as a B16A transmission. But regardless, I don't think the transmission in this CX is stock. The CX and VX transmissions are actually the same. And both are VERY tall. It sounds to me like someone swapped in an SI transmission.

As for 36MPG, this is okay but not great. After all, I already get low 30s with my ITR CRX. True, that is in a CRX and not a HB. But I would hardly consider a CX swap to be worthwhile if all I am getting for giving up all that HP is a few MPG.

 

Honestly the custom fab work is very minimal. I should take some pics of the motor mount set ups. Very Simple. Before the motor went out in the 85 Hf w/ 236k it was still getting 40-42mpg!! Then it popped a gasket. Do qoute me but I believe the 85 Hf made like 60-something Hp. The VX is about 90 -something. Thats about a 25-30hp jump. Not bad when your talking Fuel Economy. Im thinking that lil Crx may yield 50-55 mpg? out the gate.

 

Actually, HP is 58HP on the 1G HF, and 92HP on the VX. What is noteworthy about this is that the VX actually produces exactly 1 more HP and 4 more ft-lb torque vs a stock 1G SI. However, if you use the VX transmission, you will be slower than a 1G SI due to the less performance-oriented gearing. On the other hand, the 1G HF DOES weigh about 200 pounds less than the 1G SI. So the penalty due to the transmission will be less than you might think. Speaking of transmissions, have you looked into swapping gears? You would actually have one hell of a car if you could get tigher ratios 1-4 for the street, with a really tall fifth for freeway cruising. This might even improve mileage around town, since the gears would be more usable.

Speaking of transmissions, I am curious as to why you chose to use the VX transmission. I woud think a cable transmission from a 1988-1991 Civic/CRX would be an easier choice.

 

That just the way he wanted to go. The Vx is 125hp according to Hollander. and 58hp to the Hf. Also its getting harder to find a low mileage cable tranny.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by StorminMatt &raquo;</TD></TR><TR><TD CLASS="quote">

The shortest D-series transmission is actually nowhere near as short as a B16A transmission. But regardless, I don't think the transmission in this CX is stock. The CX and VX transmissions are actually the same. And both are VERY tall. It sounds to me like someone swapped in an SI transmission.

As for 36MPG, this is okay but not great. After all, I already get low 30s with my ITR CRX. True, that is in a CRX and not a HB. But I would hardly consider a CX swap to be worthwhile if all I am getting for giving up all that HP is a few MPG. </TD></TR></TABLE>

And if you bothered to read the other half of which you didn't quote you'll see that I wasn't talking about a D series transmission at all when I compared it to the B16A

Reading officially &gt; you.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Syndacate &raquo;</TD></TR><TR><TD CLASS="quote">That's why the Jettas kick so much ***.

8v SOHC with a gear box which is about as short as a B16 (just by feel, I don't know the actual ratios).</TD></TR></TABLE>

The shortest Honda Civic D series transmission, the '92-'95 Ex/Si transmission (the Z6), has comparable ratios (almost exactly the same) to the LS Integra's transmission, which people refer to as "extremely long" - which it simply isn't - more rather that the GSR/B16/ITR are very short.

The Jetta's gear box is comparable to a B16A's transmission, easy.

Sorry for the mis-understanding there, chief.

EDIT:
PS: 36MPG aint great?

Consider this:
Jetta: 2.0L motor, ~3400lbs, approx 36mpg highway
Civic EX Coupe: 1.6L motor, ~2300lbs, approx 36mpg highway

So it's got .4L more than the Honda, with about 1,000 more pounds, and it gets about the same highway gas mileage, plus with the Jetta having the shorter gear box, it gets better gas mileage around town since you don't have to wind it out as far for each shift without bogging the engine down. Your ITR CRX is vaguely comparable - if I remember correctly the HF CRX was like 1600lbs. Your typical Honda Civic EX/DX will net about 36mpg on the highway, a Jetta will do the same.

at you, man.

I do realize this is a Honda site, and civic's are god, etc. etc. - all that happy horse ****. Though please, just admit it - another company has made other cars that get good gas mileage as well, and if you consider the weight and the fact you can keep it in 5th all day long - it's excellent.



Modified by Syndacate at 12:01 PM 1/4/2008

 

I don't think he meant to attack you. He's thinking out loud about it not being worth it to him to go through all this trouble to only get 36mpg.