considering a street port -- how much gas?
 

well it appears that ive lsot a coolant seal in my s5. Im sending the engine to rx7 specialties in Calgary for a rebuild, and am considering a mild street port while its apart.

How much will fuel consumption go up with a mild street port? Just ball park.. say if it gave me a 10 or 15% HP increase.

That's like asking when is it going to rain next?

Technically, your fuel consumption is supposed to go DOWN...
Engine VE is increased, thus engine efficiency is increased.
Increase in engine efficiency means less fuel is used.

We can't tell you your gas mileage is going to go up 13.2453567457246%; that's just plain ludicrous.


-Ted

Since RX-7 Specialties street ports aren't any bigger then stock, you shouldn't have any increase in fuel consumption. :)

Seriously, you might want to search their name in the Canadian Forum, since many people have not had a good experience. I personally have bought parts from them, and have been happy with their service.

I was recomended to them by a fellow here whos had his past 5 engines rebuilt there, he was very satisfied, so im giving thema try!

:werd: Ted speaks!!!

Its not the porting that cuts your fuel mileage..... its your right foot!!!!!!!!!

Just like a free flow exhaust CAN give you better fuel mileage, it also frees up some horspowah, and horsepowah need fuel. So whatever gains you get in fuel mileage are DESTROYED everytime you beat on the car!!!! ESPECIALLY on a turbo car!!

i have noted that a ported motor like to run slightly richer at idle than a stock motor though...

Most "power mods" will, in fact, improve fuel economy, IF THE ENGINE IS KEPT TO IT'S PREVIOUS OUTPUT. Freer flowing intake/exhaust, higher compression ratio, etc - those will all improve fuel economy, but if you use them to make more power frequently, you'll counter any gains by the increased fuel demands for higher power.

I'm betting a 400+WHP rotary car could, if tuned and driven right, put out close to 30mpg. Just not while making frequent use of those 400WHP.

-=Russ=-

That's an interesting concept, good logical reasoning for building a 400hp ;)

I agree ;)

Yo dood unless ur friend is like 200 years old its not a good sign that he has needed 5 engines rebuilt from teh same place. So do teh engine rebuilds from that shop only last a month or what?

it was for 5 different cars :P

thanks for the answers guys

A Related topick, those "rotary diesel" 2-cycle engines, what compression do they run I wonder? I'm curious if a 13B can be converted for improved fuel economy.

pwn3d

Good luck with the engine. I am having the same dilemma...I want a pretty aggressive port but I'm not sure if I'll be able to pussyfoot the gas and not take advantage of the new power.

i seriously doubt a 13B could handle a diesel conversion, it just isn't made to handle the forces.

i just found out we have a local shop that experiments and produces them, you could try calling them and see if they can offer some input.

http://www.freedom-motors.com/

take a look at the skycar while you are there, interesting concept they have, trying to revolutionize the way we commute. i would love to see a rotary powered hovercar in the future. :)

30 mpg? that's like 12.7543105 Km/L

i still having trouble to keep mine up more than 10 Km/L... where everything is still untouched (eg. cold intake, exhaust, and bunch of others)

Fuel consumption did not go up in my case with the first iterations of my street port. However, the more overlap it gets (earlier opening intake, later closing exhaust) the more it likes fuel. A mild port that will give you 15% more power shouldn't use more gas when cruising. Put on a free flowing intake exhaust and your total fuel economy could actually get better.