Supercharger and MPG (1 Viewer)

Joined
Jun 24, 2010
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I drove to the beach this weekend to see my brother. I was in no rush and kept the cruise at about 70-72 mph. I burned 1/2 a tank (198 miles) and was pleased that my first long trip I got 15.5 mpg.

On my drive home I was in a rush and kept the cruise at 80 mph when I could, same highway so instead of 70-72 mph I was at 80 for about the same time during the trip. I burned almost 3/4 of a tank instead of 1/2 a tank. I haven't filled up so I did not calculate my mpg for my ride home yet. There was also much less traffic on the way home.

My 470 is supercharged, and I was wondering if placing my 470 on cruise at 80 mph would activate the supercharger and that was why I was burning more gas. Is this a possibility or does the added 8 mph on the way home burn that much more fuel?

Any help is appreciated. Thanks!
 
Joined
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One thing you may want to consider in regards to fuel economy is wind resistance. I have found it has been the biggest factor in fuel economy on all my road trips. More than tire pressure/type, load, fuel grade, air filters, oil viscosity, or anything else.

The LC's aren't the most aerodynamic vehicles on the road and generally heading from East to West I get poorer fuel economy.

Your supercharger may or may not affect your economy depending on how it's set up. I'm not very familiar with its application on LC's but my twin turbo BMW 335 is putting down around 400 hp to the wheels and still gets a solid 28mpg on the highway, which is what it put out before I dropped a methanol kit in and tuned the hell out of it.

That's just my experience at least. 80mph is never a very economic speed for our trucks anyways.
 

r2m

Richard
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Don't know where you live, but where I live (at the beach) going anyplace inland you will always be going uphill, unless you live maybe in Florida or someplace like that. Also where I come from, there is usually an off shore wind, which would also case more resistance going back home. Mind you, this is all based upon my location. So I'm thinking your MPG might not be quite as bad as you think.
Or it could be. Just some things to take into consideration.
 
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I just finished the first half of a 900 mile round trip to CO. My supercharged 99 got 10 MPG at 85-90MPH the entire way.
 

Sandroad

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Some tests I did on my non-supercharged '04 showed that drop in gas mileage is non-linear with speed; mpg drops fast as speed increases, probably due to air resistance. I got 20 mpg at 60 mph, 17 mpg at 70 mph, and 12 mpg at 80 mph.
 
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Some tests I did on my non-supercharged '04 showed that drop in gas mileage is non-linear with speed; mpg drops fast as speed increases, probably due to air resistance. I got 20 mpg at 60 mph, 17 mpg at 70 mph, and 12 mpg at 80 mph.
Sounds reasonable. Wind resistance increases with the square of velocity.

My 470 is supercharged, and I was wondering if placing my 470 on cruise at 80 mph would activate the supercharger and that was why I was burning more gas.
That's the downside of SC's. Unlike Turbo's, SC's are always 'engaged' and sucking energy. Turbo's scavenge energy out of the wasted heat/expansion of the exhaust gas and can effectively 'disengage' at low manifold pressures.
 
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Sounds reasonable. Wind resistance increases with the square of velocity.



That's the downside of SC's. Unlike Turbo's, SC's are always 'engaged' and sucking energy. Turbo's scavenge energy out of the wasted heat/expansion of the exhaust gas and can effectively 'disengage' at low manifold pressures.
true, but the LC100/LX470 engine isnt a high revving engine. Redline is what 5000?
So Supercharging up to 7PSI maybe 9PSI is what is recommended for this engine with no internal changes.
Turbo charging on petrol (gasolene) engines come it at higher rev ranges than similar supercharged engines and as i said, this isnt a high revving engine.

"Horses for courses" as we say here, i guess.

And if you're going to do it, checkout the "bulletproof" 1UZ-FE internals vs our 2UZ-FE and you'll see what i mean.
The conrods are huge compared to ours.
peter
 
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One thing no has mentioned is the gearing on the 98-02 cruisers, beyond ~60 or 65, the RPM starts going up more quickly. At 80mph the engine is turning 3000rpm on a stock truck, that a lot of revs. I have actually begun to question if the torque converter locks in 4th gear, cause the math and what i see driving dont match up

At 80 with cruiser control, you are probably getting better mileage than a truck without a supercharger, how much better, i have not clue. Technically the supercharger uses some power from the engine to increase power output, overall at any rpm you still come out ahead. So it would technically do better at any speed.
 

Trunk Monkey

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Get a boost gauge. I was very surprised on my SC'd 80 about how small movements with your foot could keep the truck out of boost and how that would affect fuel economy.

Regardless, at 80 you're going to kill your MPG, supercharger or not. You'll see ideal mileage around 55-60 and then it drops like a rock as you go faster.
 

2000UZJ

Where's My Hammer?
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17.7mpg at 65mph for 50 miles.
13.1mpg at 90mph for 50 miles.

Both speeds on cruise control, minimal elevation changes and slight crosswinds.
 
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17.7mpg at 65mph for 50 miles.
13.1mpg at 90mph for 50 miles.

Both speeds on cruise control, minimal elevation changes and slight crosswinds.
that is pretty good mileage at those speeds....I get around 16-16.5 if I keep it around 2000rpms or less than 62mph....if I get to 2200+ rpms it drops to about 14 on highway. Then again I got heavy ass Nitto Trail Grapplers on her so the rolling resistance due to the tread pattern...and the heavy rolling weight does not help either. And the big BIO front and rear bumpers and 12klb winch.
:censor:
 
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well here in Victoria we have two maximum speeds....English, and Bad English....sorry, hehe 100km/h and 110km/h on the highways/freeways/tollways

so 100km/h is 60mph from memory...so wow 90mph is massively faster than our limit here.

we have 40km/h in school zones in the mornings and afternoons, 60 km/h is normal on the larger roads/streets, but 50km/h in town centres EDIT: and "built up areas" (a grey/gray area of the law).....40km/h in a stock V8 manual is 2nd gear ready to go into third.......so i'm probab;ly 2500 rpm......ready to boot it into third....3rd at 40km/h is probably 1200-1400 rpm....but no...Victoria is "the nanny state" of Australia...some of you might have heard my post with my GPS warning me of the "Red Light Cameras" (if you run a red light) and so called "Road Safety Cameras" aka Speed Cameras....and our Police Force are tied up enforcing this.....meh.
My iPhone 3G driving recording to try and help.
Post no 33 in there listen to the second link and see how many cameras i have to deal with just driving from a supermarket to home, before i switched it (the iPhone) off. I still have 3 more intersections to go thru, all with speed and red light cameras.
EDIT for you lazy ppl that dont want to go into the other topic: ok heres the second sound bite. It's in Apple format, but hey thats what an iPhone records right?
cheers
peter

edit: ps the first sound of the gear changes (1st, 2nd, 3rd), i have the phone in my hand (left hand as we are manual RHD here) and then i throw it on the dash (one of the loud noises)
 
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2000UZJ

Where's My Hammer?
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Mooooooooooooooooooooooooo has the best posts about the most random stuff ever.


Can we give this man an award?



(90 mph is way over our speed limits. We don't have speed camera where I live, you set your speed limit as long as your smart about it, and the cops radar gun doesn't find you). Highest speed limit in GA is 70mph, which if you add GA drivers, it's more like 85mph. So seeing a group of 5-10cars cruising at 80-90mph around here isn't unusual.) seeing 19 miles of dead stopped traffic is though.
 

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