Which motor will get better MPG'S? (VX TRANNY) D15Z1 -VS- D15B DUAL VTEC?

[vrmouseyd15b]

My daily driver is the Minion (96 Civic lx 4-door manual VX trans w/ LSD block & D15B dual vtec motor 37820-p2j-j62 (CVT)ecu)

I also have a D15Z1 motor ( I was intially thinking mini-me and turbo - forgive me! )

As I understand it, the D15Z1 motor has more torque, and less power in my normal highway rpm range ( 65-70 mph, 2500 max rpm ), and I should be able to do better for mileage with this motor versus the dual vtec D15B, correct?



Next question - hell, I already know, but I'll ask anyway.. I bought a second VX tranny from fellow ecomodder turbovr41991 (one left, I think info here: http://ecomodder.com/forum/showthrea...ale-28931.html), and I'm rebuilding it. Would I get better mileage with an open differential or a limited slip differential?

Thanks in advance,
Victor

[Superfuelgero]

D15z1 will do better due to the smaller ports and less friction. Also most D15b's I've seen lack egr (most were early ones though).

2500 is on the edge of the efficiency window. Larger tires to bring this closer to 2K would help (or slow down).

A turbo won't necessarily hurt mpg, as long as you stay out of boost. The increase in backpressure will aid the egr system actually.

Open diff is more efficient.

[vrmouseyd15b]

Thank you, but I don't run an egr on the d15b motor. The ecu is happy - no check engine light (I did get one before for knock sensor, so I'm sure it works).

The d15z1 motor does have an egr setup. I'm going to have to read around to see what other ecu's support lean burn without the egr (something makes me want to take it off)

That makes me wonder if I could run the d15z1 with this same ecu, and Lie to it about the second vtec solenoid so it won't throw a code just like how I lie to it about the three wire idle air control valve

[Superfuelgero]

egr is helpful, it reduces throttling losses and is better for low speed lb.

[vrmouseyd15b]

Damn. I need to read! Ok, does this motor use an evap canister with 3 wires on it as well? I think I read that, but I'll pick your brain while it's available . if you're pushing 60 mpgs, your word is the freaking gospel to me!

[vrmouseyd15b]

I'm at about 2350 at 70 mph on the highway with my vx tranny I'm going a little over 70 in the shot, but you get it:



True about the slow down - my new world record 46.2 mpg's was wiith a max speed of 65mph!!

[Superfuelgero]

Don't believe any one person btw. You'll Know just as much if not more than me if you keep actively trying to learn.

I suspect the euro ecu's are low egr, but haven't investigated it much (despite running one currently).

For your setup and rpm, a d15z3 setup may be better (p1g ecu).

[vrmouseyd15b]

THANK YOU, xntrx! now I guess I'll have to read up on that egr "control box" as well! Just shows how much I have to learn yet...

Happy 4th!!

If I still have all my fingers tonight, I'll have to start clicking thru my FSM for the VX!!!

[Superfuelgero]

Use crxmpg for some good overviews
Happy 4th

[vrmouseyd15b]

Sweet! Thanks!

Here's my 65mph shot: