I'm building motors for both my DelSols right now and stepping way up to AEM Infinity ECUs for all the bells programability. So, I got to look into my factory OBD1 box to see how it had been chipped all this time and it's bone stock P75? Which should be like a 1.8LS ECU, amiright?
It's got 100kmi on this set up, gets 37 MPG and runs out decent until about 110; then if you stay in it a tad it'l go 125.

Learn me some P75 ECU.

 

Because the B18B and the B20B are "close enough", the P75 can run the B20B.

 

I thought it could be that simple.
thanx

 

Yep. It's not optimal, but it's functional. 5MT CRV ECUs are really hard to find.

 

Yeah, the P75 runs the B20 pretty well for a stock ECU. But, there is LOTS left on the table compared to a good tune. Expect the power to carry much better past 5000 rpms with a good tune, as well as a good bump in the down low area.

 

I wonder if you could make adjustments of the low load fuel maps even yield better gas mileage. I know NOX would go up but for places with no emissions, Is there any "extra room" in the mpg department?
No b20 tuning experience here.

 

Sure you can. There are a few threads on here about tuning for fuel economy

 

Take this for what it is from a guy who currently has 2 of his 3 civics running b20s

It seems to run great because its really lean id bet between 13.5-14.0:1 wide open especially from 4500-5500 rpm. It will be much safer with some fuel in there. Also cold starts can sometimes be lean. The timing map is close enough if anything ive found the b20s to like 2 or 3 degrees less timing but no big differences

 

As mentioned above, the B18B and B20 engines are basically identical except bore size, so they "like" similar timing/fuel maps. The only main variance is that the B20B will need more fuel volume throughout in order to run its best. You will be running a little lean since you are running an ECU that is setup for the 1.8 displacement. When we setup basemaps and/or begin tuning a stock B20 engine swap, we start with a tuned stock engine P75 map and simply add about 10% more fuel to the maps and find the engine runs almost perfect with no additional changes needed.

If you aren't into tuning/chipping this setup, you can get away with simply increasing fuel pressure and it will run very well. Not "perfect", but good.

 

If running a stock P75 ecu, what would you recommend increasing the fuel pressure to?

 

changing fuel pressure is not a valid method to compensate for displacement. for most applications you should always maintain stock fuel pressure.
add 10% to the fuel trim for a basemap.
you're still missing out on a ton of power without a tune though.