Best MPG for RT-4wd, d15z1, d16y5, d15b6??

vtecn8ivevtecn8ive Senior Wagonist
in Engine & Drivetrain
Not quite sure where to put this. I'm just curious if anyone has swapped the head (with intake mani/exhaust mani) or complete long block (both manis again) with a d15b6 (88-91 Crx HF), d15z1 (92-95 Civic Vx), d16y5 (96-00 Civic Hx).

I am in the process of lining up a possible purchase of a RT-4wd for $500, but i'm pretty sure its going to need some minor engine work. As long as its not the rings or anything on the lower end I was planning to swap a d15z1 head on it.

I'm well aware what is involved for this type of swap and all of the wiring involved with it (i've done lots of swaps in crx/civics and I do all the wiring myself dpfi-mpfi-vtec-obd1-etc.).

I'm thinking the d16y5 would be the best bet since its made for a heavier car, but i have a z1 head lined up too, so I'd rather do it that way.

Well let me know if you have done this and what your MPG is at please. This is just for the RT-4wd since it has the drive train.

Thanks,
Shane

Comments

  • noahrexionnoahrexion Wagonist
    I cannot recall ANY posts I've come across where people have swapped D15 heads onto the D16A6 block. Furthermore, if anyone has, I bet there is such little (good), or none at all, comparative information that could be used for mpg. Its all about your tune (ECU), driving habits and motor/injector size. I am sure someone babying around in there mini-me would get very similar results to someone babying around in there stock A6. Regardless of weight concerns, the D15B6 is probably the best bet to achieve gas mileage figures consistently over 30.

    FWIW, my 190k mile A6 is always a 25-30mpg sipper in town; I've little to no road trip comparisons for highway results. Wagons are heavier than a HF CRX (my 89 used to get 45 all the time), RT4WDs even more so. Put on a nice Z6 head and enjoy the benefits of that over the couple mpg's you may get otherwise. Or make sure you even need a "head" before you buy one because the money you'd not spend on gas with a uber-fuel efficient D15 head on your A6, could be saved 10 times over if you don't even need a head to begin with.
  • vtecn8ivevtecn8ive Senior Wagonist
    The d15z1 has the EGR valve so its recycling unspent fuel. the ecu would be swapped out for a z1 ecu (p07?) and the oxygen sensor isn't just a single wire. it has 5 wires I believe its compared to a wide-band o2 sensor (well the 49 state one).

    I will have a spare d15b6 head laying around too.. maybe even an entire engine that COULD be installed. This also has the egr, but other then that smaller intake smaller FI.

    I will probably go with the z1 head since its 16 valve and gets a bit more HP which will be better for the heavier car. i also read the z1 head tends to do better at slightly higher rpms (2k-3k) then a d15b6 head does, the d15b6 head is better at lower rpms (i'm talking 1-2.5k), but I guess that would really depend on the gearing of the tranny on the RT4wd.

    I'm well aware of driving styles playing the major factor in it. I generally drive pretty economical.

    I'm fairly confident the head, ecu, o2 sensor would play a decent role in getting better gas mileage.

    thanks for the input though. I was really hoping to have someone with experience give some info.

    I currently drive a 90 Crx HF (stock motor) with 320,000 miles on it that still gets 40-49mpg.
Sign In or Register to comment.

© Vanilla Keystone Theme 2025