Porting the engine allows more air flow. More air means that you need to add more fuel or it will run lean. Same holds true for turning up the boost, if you are pushing more air you need to add more fuel.

Anyone can get decent fuel economy if they are tuned lean, do not go WOT, and not exceding 3500rpm so that the secondaries never come on. You will also not make any power. If this is how you plan on driving the car then there is no need for any porting, it will actually hurt performance as the power band will be moved higher in the RPM range. If you want to just putter around then leave the engine ports stock so that you do not hurt the low end torque.

 

I'm the guy who posted the 188 hp without fuel management. My 88 NA runs 20+ mpg all day long, unless I really stand on it for long periods of time. Best I've gotten so far is 25.2 mpg. That was on a nice freeway drive of 100 miles round trip @ 75-80 mph. I do have an aftermarket air filter on it and also HKS 2-1/2" exhaust with a header. No emissions.

 

There you have it, I would consider that pretty good MPG for highway. Stop and go, around town and high RPM driving will guzzle considerably more fuel. In our 13b-re single turbo vert, we see 22-26 MPG on the highway and 8-10 MPG when having fun....basically any time the secondary injectors come on line the gas gauge drops noticeably

 

well with my car being a daily driver keeping it below 3500 is no problem going to work and back... i mainly want the port for weekend fun.

lots of good information

 

13bt fresh rebuilt
550/720
rev 2 full exhaust
rtek 1.7
cone filter
13cty 19hwy

 

https://www.rx7club.com/naturally-aspirated-performance-forum-220/my-bridgeport-project-754841/
e's making 30+ highway with a Bridgie, Itb's n Megasquirt

 

Can it b done yes. is it cheap not always

 

Not sure what you mean by this. Pretty much the only limit is the side seal has to be supported. This only limits port opening. The highest I've heard is ~225whp with a 38mm choked carb. The only options for EP intakes are 38mm choked carbs or modded stock manifolds. Plenty more can be had with an unlimited intake.

 

Pumping mean effective pressure (pmep) should reduce giving greater Brake mean effect pressure (bmep) so in theroy should make the engine more efficient, but larger ports will have greater thermal losses therefore reducing efficiency. Swings and Roundabouts.
To conclude the ECU is putting the same AFR into the engine but the larger port allows more charge in but only if you demand it. Personnally I dont think a Street port would change they mpg if driven in the same manor, But under WOT the ported engine will use more fuel than a un ported engine.

 

with my street port and a okay tune I can get as much as 25 mpg

 

13b n/a
large street port
weber carb 48
mmm 10mpg daily driving

btw that's revving no higher than 3grand.