Need opinios d15b7 vs d15z1 vs d16z6 swap battle

[metalslug]

So I blew my z6 in my 93 hatch. I had done some weight reduction mods and just had one seat in it. I got about 44-46 avg MPG with the z6 and 47 MPG the highest, and it was an automatic. I plan to keep it auto btw. Now, I was thinking of swapping in a d15z1 automatic lean burn, but they range from 700-900 bucks. I can find used CL b7's for very little, but import b7's are about the same as the z1 maybe a little cheaper. And lastly I have my blown z6 which I loved. Now I also have currently a b7 in my civic sedan which I get 40 MPG with no mods which makes me think how that engine would perform in my hatch. And the z1 can be a little more demanding as a swap. So do I rebuild the z6 which will cost way more than a swap but it will be at zero miles, or swap in a b7 or z1? What do you guys see as the better option? I would love to read any opinions to kinda help me make up my mind. Thanks in advance.

[cbaber]

The Z1 is going to deliver the best gas mileage, no doubt, but the problem is no stock ECU will properly run an automatic D15Z1 setup. All USDM Civic VX's were manual. It would run, but no other ECU will be able to control lean burn which is the only reason to get this engine.

So between the B7 and Z6 it's a matter of power. The Z6 has more power, but the B7 was meant to be more economical. What is interesting is that you got 46 MPG from your automatic Z6, so it seems to me you could use another Z6 and get more power and good fuel economy. If you were able to get great gas mileage before, why switch to a less powerful motor?

If it were me I would buy whatever I could find the cheapest, in the best condition. Used motors are sketchy sometimes, especially off craigslist.

[metalslug]

Originally Posted by cbaber

The Z1 is going to deliver the best gas mileage, no doubt, but the problem is no stock ECU will properly run an automatic D15Z1 setup. All USDM Civic VX's were manual. It would run, but no other ECU will be able to control lean burn which is the only reason to get this engine.

So between the B7 and Z6 it's a matter of power. The Z6 has more power, but the B7 was meant to be more economical. What is interesting is that you got 46 MPG from your automatic Z6, so it seems to me you could use another Z6 and get more power and good fuel economy. If you were able to get great gas mileage before, why switch to a less powerful motor?

If it were me I would buy whatever I could find the cheapest, in the best condition. Used motors are sketchy sometimes, especially off craigslist.

Makes sense, I forgot to mention I d have the auto ECU for a JDM VX automatic. Maybe a z6 slight rebuild, rings, valves and such?

[slownugly]

i got 46mpg in a 95 sedan with a y8 in it.

the problem with running an auto with a z1 is the gear ratios might not be in the optimal range since the vx trans is geared for very low rpm. the rpm ranges you would be in might not even be optimal for lean burn. what was the cruising rpm at say 70mph? i guess it depends on the jdm ecu parameters as well. if the jdm auto transmissions gear ratio is different than yours i would shy away from that.

[roosterk0031]

You loved the z6, so give it a rebuild and love it for a long time. Keep all your receipts from the rebuild just incase it outlast the car so you can increase it's value.

I've swap engines in the past, but I won't buy a car with a swapped engine.

[metalslug]

Originally Posted by roosterk0031

You loved the z6, so give it a rebuild and love it for a long time. Keep all your receipts from the rebuild just incase it outlast the car so you can increase it's value.

I've swap engines in the past, but I won't buy a car with a swapped engine.

I am leaning that way, but I should also mention I drive about 680 miles a week. So I am looking for the MOST economical solution that I can find.

[metalslug]

Originally Posted by slownugly

i got 46mpg in a 95 sedan with a y8 in it.

the problem with running an auto with a z1 is the gear ratios might not be in the optimal range since the vx trans is geared for very low rpm. the rpm ranges you would be in might not even be optimal for lean burn. what was the cruising rpm at say 70mph? i guess it depends on the jdm ecu parameters as well. if the jdm auto transmissions gear ratio is different than yours i would shy away from that.

The transmission for the auto set up is a S4PA, which is different code than the z6 auto and b7 auto so I am thinking its geared for fuel economy.

[cbaber]

Originally Posted by metalslug

Makes sense, I forgot to mention I d have the auto ECU for a JDM VX automatic. Maybe a z6 slight rebuild, rings, valves and such?

The JDM didn't receive the D15Z1 motor, so there is no automatic ECU that can control the D15Z1 and automatic transmission. Their lean-burn engine was the D15B 3-stage VTEC, which is a different design than the D15Z1. So it looks like if you want to go auto, you can't go with the Z1.

I don't see a reason to downgrade to a B7 if you already get good numbers with the Z6. It was only more technically economical because the M/T gear ratios for B7 motors were taller than Z6 models. SOHC VTEC combines good fuel economy and torque down low, and more power in the top end.

[metalslug]

Originally Posted by cbaber

The JDM didn't receive the D15Z1 motor, so there is no automatic ECU that can control the D15Z1 and automatic transmission. Their lean-burn engine was the D15B 3-stage VTEC, which is a different design than the D15Z1. So it looks like if you want to go auto, you can't go with the Z1.

I don't see a reason to downgrade to a B7 if you already get good numbers with the Z6. It was only more technically economical because the M/T gear ratios for B7 motors were taller than Z6 models. SOHC VTEC combines good fuel economy and torque down low, and more power in the top end.

Thats an obd1 JDM d15b, which is a d15z1. The ECU is a p84-901 or the p07-900.

This is a 3 stage which was only obd2 I think?

[cbaber]

Hmmm I didn't think the JDM offered a VTEC-E for the EG generation but I guess they do. It was offered in the Civic ETi. 95+ D15B's are 3-stage VTEC OBD2.

The top motors have 2 o2 sensors, meaning they are OBD2, unless JDM is different than USDM with o2 sensors? Bottom one is a 3 stage, you can tell by the 2 VTEC solenoids.