I'm going to start by saying I don't know very much about swapped Honda....
I picked up this 96 hatch in pretty bad shape and the motor blew on me in the first couple hundred miles.

I was going to daily it for awhile so I threw in a B20B and actually kept the stock head on. I had to pick up a different intake manifold since it was a GSR engine in it before.

It has a S4 tranny in it (99-00 Civic Si) and doing 70 on the highway I'm doing about 4K RPMs. I think the stock redline is 6.3K. It has a chrome ECU that is flashed with a stock b20 map.

I'm averaging 25mpg. Should it be higher, or with that tranny and low revving engine on the highway does that seem about right.

I have a set of type r heads that we're on it and now need to be re-machined... but I don't think that would help out MPGs.
It's times like this that I miss my under-powered single cam....

 

if u wanna improve ur mpg u need a ls transmission there's no way around it. u either want speed or more mpg and longer gearing.

 

does your ecu have closed loop enabled?

 

Yeah, I know an LS tranny would do better, but 25mpg on a bone stock b20??

As far as the closed loop ECU piece, I'll have to check?? Not really sure what that means.
We flashed my chrome with a stock b20map.

 

its your trans bringing down you MPG, could always do a custom b16 ls trans if you want to spend alittle cash. also your putting some wear on an engine that wasnt ment to be reved that high for long periods of time.

 

If it helps, I've got an ITR head that I could throw on?
I just need to take it to a machine shop first.

For some reason I thought the stock b20 would be better on mpg... Kinda forgot about the low revs. Don.

 

Any ideas on this? Would a higher revving vtec head help gas mileage?
I thought 2000 civic si's would get about 30mpgs.

 

they do but you have a 2.0 liter and the si has a 1.6 liter and vtec hence the 30mpg or better

You could get the b20 tuned for better mpg. vtec head on the b20 may get better mpg's but thats up to the tune as well.

 

my turbo ls with si transmission was getting 33ish on the highway. it's mostly in the tune.