Vx d15 questions (VX vs DX trans)
 

I am wondering what the fuel economy difference is between the taller 5th gear VX transmission compared to the 5 speed from a DX? I found a Civic with a D15z1 in it, but I'm pretty sure it is still the DX transmission, and wondering how much it is leaving on the table, fuel economy wise.

Is there anything else to consider about a swapped Z1, I'm guessing the ecu has to be from the z1, anything else?

Thanks in advance.

Also, could you guys confirm that this is a D15Z1? I have always told them apart by the oil cap on the top corner, the spark plug location, and the valve cover. So to me this seems to fit, but I want to be sure, and I have asked the seller about engine code, but waiting to here back.

... And yes I would probably switch the header to a manifold if I were to buy this.

Edit: maybe I should add the pic,
http://i282.photobucket.com/albums/k...G_00000176.jpg

I would say your going to loose 4 to 5 mpg in 5th gear at 55mph.
Also the D15z1 had egr with a control box but I would not bother with it unless you need it for emissions.

Oh wow that much?! Do you think it could pass emissions without the egr control box? How much of a hassle (and money) is it? Would not having egr hurt its fuel economy?

He said that it is a "d15 mini-me" swap. I am totally new to hondas, and im searching but having a tough time understanding this mini me swap. So it is not a d15z1? It is the engine pictured above.

Edit: it appears this is probably a d16y8 head....

That looks like the intake manifold for the vtec and vtec-e engines in the VX, HX, and EX trim levels. On the transmission, I am not sure how much you would lose or gain. But at least a couple at steady cruise seems certain. It's a mod I would want, and do want, and I have been shopping for a VX/CX transmission. On the EGR, my understanding is that the purpose is partly to reduce pumping losses, which would be good for FE. As for "mini me" ... "It's when you take a D series non V-tec block, and bolt on a D series V-tec head. Doing so, you gain HP, a bit of higher compression, and V-tec" (says this guy who did it). That does not sound good for FE. The DX block would not have EGR, so if this engine does not have a spot for EGR, I guess you are looking at a DX block with VX (vtec-e) parts added on. Avoid?

Well this to me sounds like I'm going to pass on it... I will keep searching and waiting for a decent vx to pop up. Someday I will find one..

My stock VX would do 30 MPH at 1000 RPM in 5th gear, same as 90 MPH at 3k RPM in 5th.

regards
Mech

Wow that is a seriously deep gear. That to me says to avoid this car as well, too many things I want to change, work on, improve, etc.

Mini me is a 6z head on a d15 block. It's a speedy setup, not terribly efficient. That car would only get 32-35 mpg mixed.

Okay thanks a lot, I appreciate the input. 35 mpg would be a step down for me... That's not happening! This is exactly why you read BEFORE you buy! I am now better at spotting VX's and d15z1's (Po7 cylinder head).

That's a V-Tec setup, same as the one in my '94 Si. Like Hondaguy72 says, it's kinda neat but not a real FE setup. Keep your eyes peeled for a real VX or HF, the gearing and the lean burn will be where it's at.

A bit of history:

People used to take the B18 engine from the Integra LS (a 1.8 liter non-VTEC making ~130 HP) and put the VTEC head from a B16 or B18C on it. This was a less expensive way to make a 1.8 liter motor with VTEC which made quite a bit of power, and was easier to come by than a B18C or a US-spec B16 motor. It was dubbed an "LS-VTEC swap".

Someone then realized that you could take a D-series bottom end (in the 88-91 CRX world I was interested in, it was usually a D16A6 "Si" motor) and put a D16Z6 or D16Y8 head on it. That would give you a bit more compression on your 1.6 liter D-series motor, and VTEC. This was after the Austin Powers movies were out, and it got called the "Mini-Me LS-VTEC swap".

I don't know which head is on there, but it appears to be either the Z6 or Y8 one due to the position of the spark plugs. Someone would have to read the engine code (on a boss in the front of the motor near where the trans bolts up) to see if it was a 1.5 ("D15") or a 1.6 ("D16") liter motor.

-soD

Thanks a lot! I have been reading about VX's,but am still very new to hondas in general.