Power VS MPGs

[surferofthesnow]

I'm gonna be putting a 7mgte in my car and would like to have 280-300+ horsepower at the wheels. But with the prices of gas these days, I'm a little hesitant. Whats the highest power setup that will still get 20+ mpg? What are you running and what are your hp and mpgs?

Thanks

 

[adampecush]

your gas mileage is all based upon how you drive the car. A geo metro will achieve shitty mileage if it is driven at WOT and high revs all day long...

 

[surferofthesnow]

It is not only determined by that. The MPGs should be average between city and highway btw.

 

[themadhatter]

mpg's are really dependent on how you drive. My car has a downpipe,lower hard pipes, k&n intake, 3" exhaust and a shimmed wastegate. When i drive like a sane person i get 23-24mpg when i beat on the car and get in boost i get like 15 mpg

 

[CRE]

It is not only determined by that. The MPGs should be average between city and highway btw.

I disagree. The average of the two is meaningless to someone like me who drives almost solely in the city.

As for the assumption that mileage will only get worse the more power you make, that's not entirely true. A poorly tuned car can get horrible mileage and perform terribly too. Tune it well and you'll not only improve the mileage but you'll get more power. A lot of factory tuned cars run a certain tune because it is considered "safe" for most types of driver and will help assure a greater longevity of the drive train. These cars can usually get both better power as well as mileage when tuned well.

And it does depend on how you drive. To make things even more interesting two people who both drive the speed limit can get very different results as one always accelerates hard and cruises at higher RPM yet the other drives the same average speeds but at a lower RPM consuming less fuel per instant.

 

[Keros]

Milage is mostly right foot, partly vehicle design.

My best bad milage was 9MPG driving at WOT continuously for 150km on secondary highways on a weekday afternoon.... we passed one transport truck, and a sedan, the whole time.

Best would be 29MPG.

It really is all depending on if you stay out of open loop (idle/WOT), and in closed loop (part throttle)... though my understanding of these terms isn't very good, lol.

If you have a highly efficient engine with rediculous power, you'll get excellent milage if you drive sanely.

 

[mirage83]

It is not only determined by that. The MPGs should be average between city and highway btw.

Trust us, how you drive is just as important as any other factor. As an example of this, I can usually get 5-8 mpg more from my wifes car when I drive it than when my wife drives it. It's just a matter of how you accelerate, how you decel, how you work the throttle while cruising.

Driving characteristics definately matter to what mileage you'll get out of your Supra.

 

[suprahabsfan]

A lot of upgrades increase the efficiency of the engine if you keep your right foot out of it. IE intake, downpipe, exhaust

 

[GrimJack]

I'm gonna be putting a 7mgte in my car and would like to have 280-300+ horsepower at the wheels. But with the prices of gas these days, I'm a little hesitant. Whats the highest power setup that will still get 20+ mpg? What are you running and what are your hp and mpgs?

Thanks

Cripes, a lot of drama for a simple question.

Simply put, the gas mileage between a 200 rwhp Supra and a 600 rwhp Supra driven in the same manner in the same roads will be negligible. The only time you'll see a significant degradation is when you're racing at the track or breaking the posted speed limit.

Cruising at 55-65mph will take the same amount of fuel whether you have a crapload of power available or not.

 

[Poodles]

Cruising at 55-65mph will take the same amount of fuel whether you have a crapload of power available or not.

To a certain extent. If you're talking a N/A engine that you have to increase the displacement of to get more power, you're fuel economy will go down.

Turbo cars are very different. Low loads, it runs like a small displacement engine sipping gas. At WOT and the turbo spooled, it uses as much gas and air as an engine far larger.

Turbos: The original variable displacement.


To answer the question, I've actually got BETTER gas milage after doing intake/hardpipes/downpipe/high flow cat/3" catback. I get on the gas a lot (people drive this idiots here, and driving in traffic doesn't help it) but i get close to 20MPG in the city.

Also, guys with big turbos usually knock down good MPG because the turbo never spools...

 

[surferofthesnow]

Thanks poodles. Sounds like it's mostly gonna depend on my right foot. A lack of backpressure can also cause your mpgs to drop btw. Thanks anyways.

 

[CRE]

A lack of backpressure can also cause your mpgs to drop btw.

100% incorrect. A lack of scavenging can reduce your engine's efficiency as the engine then has to work to push out the exhaust gas. BUT, ANY buildup of pressure in the exhaust plumbing is BAD. It's a common misconception, but the two effects are VERY different. There's a lot more information on this topic already present on this forum though, so I'm not going to bother repeating it all here.

 

[suprahabsfan]

While we're on the subject. Is the best gas mileage in a turbocharged car at 0psi? I realize that at zero psi the car will keep accelerating, and you can't keep it at that, but with no vacuum/boost the engine doesnt have to work as hard correct?

 

[Orion ZyGarian]

N/A cars at WOT have very low vacuum, very close to 0 psi. The more pressure you have, the more fuel will be added. As such, the more vacuum your car is under, the better the mpg. This is one reason why cars with more aggressive cams can get worse mileage.

 

[ViR2]

suprahabsfan, yes. With no boost, no additional fuel is being added so it helps with mpg

 

[blackturbona]

i think suprahabsfan was reffering more to 0psi vs 15 psi of vaccuum going off ur boost gauge. may be wrong but thats what i gathered

 

[cry4me_sky]

I'm gonna be putting a 7mgte in my car and would like to have 280-300+ horsepower at the wheels. But with the prices of gas these days, I'm a little hesitant. Whats the highest power setup that will still get 20+ mpg? What are you running and what are your hp and mpgs?

Thanks

i have a basically stock 7mgte that used to get about 18 mpg until recently now it gets like 15.


idk why.

Good luck with that 20+mpg

 

[MRSUPRA]

Turbo cars, especially heavy turbo cars will such gas with the best of them if driven aggressively. Like most everyone has talked about, with a stock ECU in closed loop, it will not matter how much power your will make since the ECU is always leaning out the fuel.

However, you start putting in agressive cams and messing with the compression ratio, or lower gearing, than you might start seeing a significant difference in fuel economy.

 

[Poodles]

Little update...

I'm consistently getting at least 20MPH around town in mixed driving.

Keep your foot out of it and it makes all the difference.

 

[Tae361]

wouldnt the weight of the vehicle and wheel size play a factor into this?... or would more power outweigh the factors of weight and wheel diameter?

i got 19mpg on my old N/A motor with just an intake, 2.5" catback and A/C delete. my A/F gauge would say it was running very rich, but i assume it was just the old O2 sensor it was hooked up to throwing a bad reading.

cant wait to test out the mpg on this new jap motor. i want to push for 25mpg but its pretty much impossible with all the idiots and country roads around here.