High Compression Motor Mileage

[llxkevinxll]

I am currently building a 6 bolt with 10:1 Manley's. Any idea what kind of mileage I will be able to get?

-Car will not be driven hard when driving to work etc.
-Injectors will be stock to begin and will changed as needed, so assume 450cc.
-Car is an AWD 5 speed.
-Small 16g @ stock gate pressure.
-93 octane pump gas.
-Will be tuned using DSMLink

I know there are a lot of variables at play but I would like to see rough estimates.

Thanks,
Kevin

 

[Black-Out]

I am currently building a 6 bolt with 10:1 Manley's. Any idea what kind of mileage I will be able to get?

-Car will not be driven hard when driving to work etc.
-Injectors will be stock to begin and will changed as needed, so assume 450cc.
-Car is an AWD 5 speed.
-Small 16g @ stock gate pressure.
-93 octane pump gas.
-Will be tuned using DSMLink

I know there are a lot of variables at play but I would like to see rough estimates.

Thanks,
Kevin

Generally that's all in the tune, however higher compression under cruise conditions will generally lead to improved fuel economy because you won't need as much throttle to get the same amount of torque from a lower compression engine and then there's the fact the higher compression generally helps the combustion process become cleaner and more efficient, requiring less fuel to burn more completely.....But part throttle tuning and cruise maps will be what will determine if you can get 25mpg or 35......It's not impossible by any means for you to get close to or even break the 30mpg mark but you won't be making any power there without risking the well being of your engine....The leaner you run the hotter the
valves and piston crowns will become and ceramic coatings only stave off the damage temporarily.... make sure your tuner knows what they're doing or you will have great gas mileage until the engine melts a piston or burns a valve-

In short, your gas mileage should take a back seat to the engines well being and if you can get great mileage then great.....but if not, remember you built your engine for performance first and there weren't any 400+ horsepower cars getting 25+mpg in the mid 90's........

Will

 

[llxkevinxll]

Generally that's all in the tune, however higher compression under cruise conditions will generally lead to improved fuel economy because you won't need as much throttle to get the same amount of torque from a lower compression engine and then there's the fact the higher compression generally helps the combustion process become cleaner and more efficient, requiring less fuel to burn more completely.....But part throttle tuning and cruise maps will be what will determine if you can get 25mpg or 35......It's not impossible by any means for you to get close to or even break the 30mpg mark but you won't be making any power there without risking the well being of your engine....The leaner you run the hotter the
valves and piston crowns will become and ceramic coatings only stave off the damage temporarily.... make sure your tuner knows what they're doing or you will have great gas mileage until the engine melts a piston or burns a valve-

In short, your gas mileage should take a back seat to the engines well being and if you can get great mileage then great.....but if not, remember you built your engine for performance first and there weren't any 400+ horsepower cars getting 25+mpg in the mid 90's........

Will

I agree with the engine safety/performance being priority #1. What AFR would you consider safe to run under cruising conditions with these motors?

 

[Black-Out]

I agree with the engine safety/performance being priority #1. What AFR would you consider safe to run under cruising conditions with these motors?

This is where things can get a little funny because ultimately while you're tuning the engine will tell you what it wants to see- Modern engines can go as lean as 18,19, even 20:1 afr under different conditions....A steady 10-20% throttle cruise can go as lean as 14-16:1...... but ultimately your cylinder head combustion chamber design, compression, cam selection, airflow capability and turbo selection will determine cruise afr's and wot afr's...... A wide ban, and a dyno, along with a subsequent street tune will be your friends- and truthfully you can tune for weeks on the street after your initial tune has been done just to get the drive-ability down good.....The side effect of the drive-ability tune being spot on will be improved fuel economy under cruise conditions........


Will

 

[jayson427]

I'm not Turbo'd but I run 10.5 compression 24lb injectors and on a full tank (11-12 gallons) I get 200-250 all depends how I drive.

 

[Black-Out]

I'm not Turbo'd but I run 10.5 compression 24lb injectors and on a full tank (11-12 gallons) I get 200-250 all depends how I drive.

^^^ And I forgot to mention that as well ^^^ Good call BTW.....

 

[donniekak]

That small turbo is going to put a damper on the mpg's.

 

[llxkevinxll]

That small turbo is going to put a damper on the mpg's.

Why do you say that? Because the car will come on to boost in the lower rpms?

 

[donniekak]

Why do you say that? Because the car will come on to boost in the lower rpms?

The small exhaust housing chokes the engine, and it will be in boost more.

 

[r-rracing]

im hitting close to 460 whp and im getting about 24 mpg

 

[llxkevinxll]

im hitting close to 460 whp and im getting about 24 mpg

What compression are you running in your car?