What engine/tranny for best GPM potential?

[ob1coby]

Hello all. my 95 civic HB is on it's last leg and after reading this GREAT site for a few weeks, I've decided to swap out everything in my SI in favor of a high efficiency powerplant. What combo will have the best potential?

I have somewhat gathered that the D15B8 will be the best choice while converting the gear ratio in the tranny to that of the HF. Does this sound correct, or should I go with the Z1 or B6? I just want to have it all figured out before I go buying parts. Should I also start looking for a VTEC-E ecu? Any help would be greatly appriciated! Thanks.

[Sludgy]

Originally Posted by ob1coby

Hello all. my 95 civic HB is on it's last leg and after reading this GREAT site for a few weeks, I've decided to swap out everything in my SI in favor of a high efficiency powerplant. What combo will have the best potential?

I have somewhat gathered that the D15B8 will be the best choice while converting the gear ratio in the tranny to that of the HF. Does this sound correct, or should I go with the Z1 or B6? I just want to have it all figured out before I go buying parts. Should I also start looking for a VTEC-E ecu? Any help would be greatly appriciated! Thanks.

The good way to get high gas mileage would be to swap a small motorcycle engine into the car. A single cylinder 250 - 400 cc motor would give a lightweight car 60 mpg. How about a Suzuki GZ250? It gets 82 mpg as a motorcycle.

[GasSavers_Ryland]

the B6 is going to have the OBD-0 where both the B8 and the Z1 are going to have OBD-1, the Z1 is also going to have the v-tec bits, along with the JDM D15B engine, of course if you can find a JDM D15B engine that has the 3 stage v-tec (you can either hack it for the 3rd stage, or keep the engine under 5,500rpm), but I would vote for for the D15Z1 or the D15B as they would both be able to take advantage of the v-tec wiring that is already in your SI, and as for a tranny, you have a hydrolic clutch, so sticking with a 1992 and newer tranny is going to be your easiest, and it's going to bolt in, for that the vx/cx tranny is most likely going to be your best bet.

[SVOboy]

Get a d15z1 and cx/vx tranny, that'll be the best combination.

[ob1coby]

So the D15B6 was only used up to 1991? That?s good info because in my state I have to keep the powerplants and auto series the same, (ie. OBD-1 for OBD-1).

When you say JDM d15B engine, does that include the JDM D15B8? If so, that narrows me down to the D15Z1 or D15B8. I am a very conservative driver anyway and I rarely reach 5K rpm so would the JDM D15B8 with the 3-stage v-tec have the most potential for efficiency? Or will the 16 valves of the Z1 (SVOboys choice) enable me to use a higher gear ratio resulting in higher MPG? I want to break the 50-MPG mark so if I need to sacrifice power and torque so beit.

I'm sure some of my questions are very amateur, but then again I am an amateur so... Thanks for all the help so far.

[ob1coby]

Originally Posted by Ryland

the B6 is going to have the OBD-0 where both the B8 and the Z1 are going to have OBD-1, the Z1 is also going to have the v-tec bits, along with the JDM D15B engine, of course if you can find a JDM D15B engine that has the 3 stage v-tec (you can either hack it for the 3rd stage, or keep the engine under 5,500rpm), but I would vote for for the D15Z1 or the D15B as they would both be able to take advantage of the v-tec wiring that is already in your SI, and as for a tranny, you have a hydrolic clutch, so sticking with a 1992 and newer tranny is going to be your easiest, and it's going to bolt in, for that the vx/cx tranny is most likely going to be your best bet.

Sorry I think I replied in the wrong place. ob1coby.

[brelandt]

good comments so far!

A couple of things I would like to do.

1st an underbelly pan is out of the question for this truck. Would never be smooth enough So I will need to build a HUGE air damn instead. Would not do much for my coasting however!

2nd is to find a taller rear axle. The gears are something like 5.61:1!!!!!!! That's horrible! They must make a gear set taller than this somewhere?

[ob1coby]

Originally Posted by brelandt

good comments so far!

A couple of things I would like to do.

1st an underbelly pan is out of the question for this truck. Would never be smooth enough So I will need to build a HUGE air damn instead. Would not do much for my coasting however!

2nd is to find a taller rear axle. The gears are something like 5.61:1!!!!!!! That's horrible! They must make a gear set taller than this somewhere?

Did you mean to reply to this thread? Not that it matters, but you might get better help in a different topic.

[GasSavers_Ryland]

has a whole page on the D-series of engines, including HP and toruqe, and years that it was used, and what type of OBD it has.
the JDM D15B appears to be differnt then the D15B8, just to avoid confusesion, of course the other advantage of the Z1, is that it uses commen, and avalible off the shelf parts, and if you keep things simple, and all in one family, then if you need to fix something, or go to sell the car, it's going to be much simpler.

[ob1coby]

Originally Posted by Ryland

has a whole page on the D-series of engines, including HP and toruqe, and years that it was used, and what type of OBD it has.
the JDM D15B appears to be differnt then the D15B8, just to avoid confusesion, of course the other advantage of the Z1, is that it uses commen, and avalible off the shelf parts, and if you keep things simple, and all in one family, then if you need to fix something, or go to sell the car, it's going to be much simpler.

Well I just looked at the JDM D15B specs and it has a lot more power and torque than the other two. I thought the Best efficiency will come from the engine with the least amount of horse power and torque. That leaves me with the D15B8 unless there are other factors involved that I'm just not getting (Not unlikely). I like your suggestion of eveything being bolt on and having easy access parts, but I would seriously consider any engine that has the most potential for efficiency even if that means buying JDM and doing some part chasing. I am feeling the pressure to go with the D15Z1 though. It is the most suggested. Is it the only one that will be direct bolt on? My only problem with it is that it has 8 more valves and 12 more horses over the B8. I hope my questions aren't getting cumbersome. Thanks again for the help.