Off-beat supercharger questions...

[Bmatth1162]

My dad has always been very analytical about my ideas, and I am usually able to answer his nit-picky questions, but he stumped me tonight. When I was talking to him about my plans to put a maggie on my car, he first asked how the MPG would change overall with the blower and secondly if the heat buildup of running the blown car for, say, 4+ hours straight on the highway would hurt the engine at all?

He then asked if any superchargers can be turned on/off with a switch the same way the air conditioner can be turned off, because both run off of the engine's power. I don't know why one would, but is this possible??

Thanks

[SannerRacing]

Tell him the Maggie has a by pass valve so at cursing speed there's very little to no change in your mpg. I've had mine on for a good 20,000 miles now and at 10 psi with no problems. Do it it's the best thing you'll ever do if you like to smile every time you hit the throttle.

[SStealth Vert]

There are S/C systems that I remembered that you could shut off with a switch. Jaguar is one company that comes to mind. In regards to your other question about running 4+ hours straight. No! it won't hurt the engine if you're just putting it at a low boost setting. MPG will change only by the power of your foot. There are people that won't lose MPG's at all and those who notice a dramatic change. However you need to look at their driving habits.

[LS7 427]

Hope this helps...

• Fuel mileage will increase about 2-4 highway MPG
• Run the car for 4+ hours, lift the hood and put your hand on the supercharger, it will be warm to the touch.
• Doesn't need a switch. When you turn off the a/c, the compressor continues to turn on the belt but produces nothing. The maggie will also spin continuously on the belt but will only produce boost under heavy throttle. In essence, the switch is your foot.

Bryan

[Supercharged Red]

You will lose about 2 MPG. I own one I know! It is always spinning but will not make any pressure until the bypass valve closes (when you put your foot to the floor). You, for the most part, will not even know it is there till you mash it!!! Let the fun began!

[Badbubba]

Originally Posted by LS7 427

Hope this helps...

• Fuel mileage will increase about 2-4 highway MPG
• Run the car for 4+ hours, lift the hood and put your hand on the supercharger, it will be warm to the touch.
• Doesn't need a switch. When you turn off the a/c, the compressor continues to turn on the belt but produces nothing. The maggie will also spin continuously on the belt but will only produce boost under heavy throttle. In essence, the switch is your foot.

Bryan

There's an electro-magnetic clutch on the a/c compressor. So the pulley is disengaged from the compressor when the a/c or defrost is switched off.

OP:
I believe in one of the old Mad Max films, the "supercharger" was turned on with a switch.
Here it is,
MAD MAX 2 - supercharger sequence: http://youtu.be/PjQA8lqyqfw

Not sure how an added parasitic loss of spinning a supercharger can gain mpg. Maybe due to the tune?

[1985airborne]

I drove from NC to NJ over 8 hrs straight without a problem...

[EDFHOBBIES]

yes elctro clutched is the way to go most all golf course and larger hyd mower use them to turn on and off the hydraulics for the Blades. there are a few ribbed style belts and most are 13mm v belts..

but in theory if you driving habits stay the same any thing you do to create HP more efficiently shouldn't cause it be a gas guzzler..

it might put more of a strain to drive a supercharger belt but it could be made up with underdrive pulleys i bet..

I had my efore for 3 years no problems

[hrpiii]

just enjoyed my trip to Baytown, TX from Indianapolis, IN. Drove 11 hrs first day, 5 hours second day, drove it on the drag strip and hit great times. Then cruised back home.

Avg speed was 70.6
Avg miles per gallon was 20.3

I have also made other long trips to coast of NC. Runs like a champ.

[Bmatth1162]

Awesome info, thanks guys.

Just one follow-up: when you're not at full-throttle there is a "by-pass valve"... does this mean the blower is still producing boost but it's not going into the engine? Or it's not producing boost at all, even though it's still spinning continuously? Little confused about that.

And at full throttle, what mechanically closes the by-pass valve to get the boost into the engine?

Thanks again!

[376LS3]

When the bypass valve is open, a butterfly opens that puts the air directly into the manifold, bypassing the rotors. When the valve is open, parasitic loss is less than 1/4hp. Heres a pic of my MP90 from my other car. You can see the butterfly that opens and closes.

[Jason@JacFab]

The only one I know of that can be turn off with a switch is the Eaton M62 that can be found on some Mercedes cars... It's got a setup much like an AC compressor. I've always wondered if that pulley/clutch affair could be fit onto a larger unit...

[old motorhead]

A clutch to turn the blower off and on is very doable. But why fool with it? If the blower uses little or no power when not in boost, there's no reason to add the complexity of a clutch. The clutch on an A/C compressor has to account for a very slight amount of load. A clutch that can carry the load of a belt driven supercharger would have to be pretty substantial (read that heavy and expensive). Just not needed nor is it practical.

[Mr. Nasty]

MPG LOL I see some get great mileage but with my set up I've never got over 10.5 MPG on a short trip or long trip.