Imatk

Ok so I've read a couple posts about gas mileage actually increasing from using a supercharger.

I always thought that a supercharger would do two things to an engine... reduce it's life and lower the gas mileage.

Can any of you tech masters out there help me with the logic behind this??

Thanks

1trickpony

I noticed the Saleen with a supercharger fuel economy was 15/24. That's 2/1 lower than a normal GT, so it looks like fuel economy was hurt alittle bit.

Wookdawg

A supercharger actually increases the efficiency of an engine. Depending on the tune, it can give you better gas mileage. However, most tunes run a little rich to help prevent detonation. With my supercharger, I'm into the throttle a lot more, so my mileage has gone down a bit. Keep in mind, any supercharger kit will probably require you to use premium fuel, so it won't be saving you much even if it is more fuel efficient. But my philosophy has always been if I wanted a car for fuel economy, I certainly wouldn't have picked a V-8 powered vehicle. What's another couple of bucks to fill it up anyways? It's a lot more fun to drive, and that's what I look for in performance modifications.

JST4FN

I've had two cars that gained mileage and they both used centifugals. I do have a light foot also and the mileage was minimal. I also picked up mileage (.5-1 mpg)on my Lightning when I first installed the KB. After I built the motor, added cams etc.. it went back to factory mileage 13 mpg in the city.

Longevity is a hard one. It depends on how aggresive the car is tuned and how you drive number one, or if you ignore poor tuning problems etc.. A centrifugal that has constant tension like on a 87-93 Fox body can reduce bearing life by side loading the crank. This would be minimal at most. If you have a car that uses the factory tensionor to keep tension it would cure that, but have less traction. I guess the best answer is if the car is tuned correctly and maintained it should have good engine life. I would not expect it to make 300,000 miles though. It should be a small percentage less than the NA counter part.

Thanks Mike

fin1

I picked up 2-3 MPG.

Imatk

Thanks for the answers guys.

Mike thanks, this is exactly what I was wondering. I would expect to get 300k out of the engine anyway really, but if the impact on longevity is that minimal then it certainly makes for a much more attractive addition for my new '06

I generally don't speed, never race, but on the occasion I like to drive through the hills up here in Hollywood... it's fun going around those corners and such.

But just the fact that I have that power if I need it is very attractive to me. AND the fact that you actually can get better mileage and very minimal engine wear makes it VERY attractive.

I usually put premium in the car anyway so that's not much of an issue either.

Anyway thanks again guys

SkylineUSA

How is that possible? Supercharger will always use power to make power? Think about it, it does not make sense.

SkylineUSA

Do you guys still think a Supercharger will make an engine more effcient? I hope not, just want to make sure you guys understand, thats all.

killo-11

I don't know for sure but I would think some of the increases in efficiency come from the increased cylinder pressures. Just like diesels running 20 to1 compression ratios. I would think this the same principles applies here.

SkylineUSA

It takes power to make power. SC are around 70-75% efficient, while turbos are in the 90% range.

When you increase the cylinder pressure is the engine, does the engine not increase it gas consuption? Just by increasing the engines comp ratio, does not mean the engine is more efficient, it just means the engine will have the ability to make more power. Any mechanical device installed on an engine, that uses the engines power to make power will decrease the engines efficiency.

Stoenr

I was gonna say hey now! I got 252k on my 4.6! unmodded. and alot of remote start idle time too.

Then i noticed the typo on the word would. I think/assumed you meant would'nt in that statement

SkylineUSA

I agree, it would not.

That's just it, you got 3 guys claiming an increase in milage with a supercharger. I had a S-trimed 306, and I can tell you that I lost about 2-3mpg depending on driving style of course. heck, as long as your not in it, the S-trim was basically in idle mod, so not much crank robbing to be done, but once it starts to spool the efficiency of the engine would have to drop, and so would your MPG, at least that is how I understand it.

A KB is a postive displacemnet SC, right? I really could not see that getting better MPG. That one has me stumped even more so.