I have to drive a whole lot for work and I want to start trying to keep all these miles off my ZC sedan, so I bought a 91 Civic STD. I am trying to find some data on this engine and find out what I could do to squeeze as much gas mileage out of it as I can. I figured a MPFI swap might be in order, I can probably get a HF MPFI setup from my friends old HF motor, anybody heard of this being done? Any other ideas? Maybe a SI MPFI and a DX cam, or do you think that would use more gas than the stock setup? I figure this should help as long as I kept my foot out of it and then I would at least have the extra power there in case it was needed to get out of the way.

 

HFs are already MPFI. That's your best and easiest option for better gas mileage. i have also heard of people getting 50+ MPG by installing a HF trans on a DX motor and using "hypermilling" driving techniques. Google it or PM "DaX" on here for more info.

 

I also have a 91 hatch STD...I was all ready getting pretty great MPG. With a bit of city and 80% highway I was getting low 40's.

Switched to MPFI a week ago and I'm getting high 30's. It may be due to the fact that I'm driving more aggressive now that I have a little more power.

For better gas mileage I'd stick with DPFI.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by DenzComp &raquo;</TD></TR><TR><TD CLASS="quote">I also have a 91 hatch STD...I was all ready getting pretty great MPG. With a bit of city and 80% highway I was getting low 40's.

Switched to MPFI a week ago and I'm getting high 30's. It may be due to the fact that I'm driving more aggressive now that I have a little more power.

For better gas mileage I'd stick with DPFI.</TD></TR></TABLE>
MPFI definitely has more potential for better gas mileage. DPFI is really pretty inefficient, hence the HF being MPFI. However I kinda think that I am going to have to retune with the MPFI to really see an increase cause when you swap to the pm6 computer it is expecting a more sporty 1.6 w/ the SI a6 cam and thus giving it more gas than needed. Has anybody else watched their gas mileage closely before and after doing a MPFI swap on a b1?

 

I've only refueled once so I don't know for sure. I have an old 89 PM6 so I can't really tune mine I don't think. I wish it was better gas mileage, but so far...it isn't.

 

After my MPFI swap, getting low 40's mpg. A littlle better than my mileage with DPFI, maybe more effecient, or it could be that I changed plugs, wires, fuel and air filters, and timed it properly at the same time. 36-40 mpg before.

 

My poor MPG is most likely due to the fact I just threw the dizzy on. I'll have to get it timed.

I'm an idiot when it comes to timing...would it be better to retard it or advance for better MPG?

 

id say your best bet for good gas mileage would be to swap the hf mpfi manifold as you said. replace your 4 speed with the hf 5 speed and run the hf ecu pm8 i believe it is. not to mention change your driving style for better mpg.

just for the record, in my stock 88 crx dx (dpfi) i regularly got 40-42 mpg when driving a mix of city and highway. the worst i ever got was 37 mpg. the best was 48 pmg all highway. so dpfi can net you good mileage.

 

depends on how far you wanna take it.. toss the hf tranny in, v-tec head, obd1 wiring and run the VX Lean burn... i know people get 58-60 hahaha.. but again.. how far do you wanna go.. if you raise the compression by doing the v-tec head, you could in theory run propane off that.. again.. how far you wanna go with this?... i found my biggest fuel millage gain was a short ram air..

 

Check out the link in my sig.

Great site with lots of MPG related info. I've learned a lot on that site.

 

id say your best bet for good gas mileage would be to swap the hf mpfi manifold as you said. replace your 4 speed with the hf 5 speed and run the hf ecu pm8 i believe it is. not to mention change your driving style for better mpg.

just for the record, in my stock 88 crx dx (dpfi) i regularly got 40-42 mpg when driving a mix of city and highway. the worst i ever got was 37 mpg. the best was 48 pmg all highway. so dpfi can net you good mileage.