Hi, I would like to know what MPG will a 20b get in turbo, street port condition?

 

Injector sizes? Psi?

 

um................................10


neil

 

As with any rotary, porting the engine to the point it's adding overlap will kill the fuel economy. I think it could get really good mileage with the right combination of tuning and gearing.

Example: Look at the v8's in the Camaro's and Vetts. Those cars get 28-29 mpg on the highway. Why? The engines have soo much low end torque GM can engineer the 6th gear to be very tall keeping the rpm's low at highway speeds. I think at 70mph the rpm's are like at 2k? At that low an rpm, the engine is barely sipping any fuel(even though 8 injectors are pulsing). In hindsight, think about how much worse these same v8's fuel economy would be if the highway cruising rpms was at 3k? The mileage would drop like a rock.

In my fd, if I cruise at 75mph my rpm's are at 3k. I get about 26mpg in this range. Imagine if I had a 20b in place of my 13b and still had the same gearing? The mileage wouldn't be nearly as good even with a great tune. Since the 20b has more low end torque, you could use a taller final gear to take advantage of it and put the rpm's lower just like what GM does for it's v8's. This is the number one reason I want a tall 6th gear for my 20b conversion.

Bottom line, there is no reason a 20b can't get good mileage (especially on the highway).

 

Damn what the hell! Might as well add one more example.

In the Rx8 crusing at 75mph the rpm's are at 3,750. All because of gearing. And they wonder why they have such crappy fuel economy. That same rpm is also the staging point for the secondary injectors. The 6th gear in the 8 is pointless IMO.

 

I am averaging 16mpg, and POUND THE HELL out of my every day I drive it, and then cruise at 2500-3000 rpms on the freeway, which is 65-85 in 5th. A 6 speed would be nice!! Ls-1 guys are super hung up on gas milege.

 

My JC Cosmo gets around 14lt/100km HWY cycle

Unsure what that is in 19th century MPG

 

I think that is 16.79 MPG if I did the conversion right, but I probably screwed it up, haha.

 

even though i did not start the post thanks for the info

 

14 to 17mpg is typical.
I don't build these things to save gas...


-Ted

 

I wish the microtech had a closed loop o2 system, that was as awesome as the GM computers, lean that puppy out to 16:1 afr for crusing. I bet you could get some milege out of that.

 

Un tuned? 8-10mpg

 

6 Litres a min

 

My 616 20B gets around 17mpg on the highway with basically little porting.Also
my car probably a little lighter than a stock Cosmo.

 

whats a 616?


neil

 

my 20b fc got 19.9 highway, tuned to 14.5ish afrs, stock engine/turbos

in mixed driving it was more like 14-16, put your foot down and you could almost watch the gas guage move