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SC or NA better MPG and Drivability?

Old 12-04-2018, 07:47 PM
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JetEngineJoel
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Default SC or NA better MPG and Drivability?

Like many others seeking performance upgrades, Iím torn between keeping my 2017 GS Naturally Aspirated (NA) or going Supercharged (SC). While I crave more power, I donít want to loose drivability or too much fuel economy. I love the sound of some cam lope and donít mind it sucking all the fuel it needs when Iím having fun. However, I still want decent MPG when on long trips.

So, with respect to fuel mileage and overall around town driveabily, how would a 550 whp NA setup compare with a 600 whp SC setup? Will a stage 2/3 cam NA setup suck too much fuel?
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Old 12-04-2018, 08:51 PM
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BlueDevilZ51
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If you want it to drive like stock I'd recommend going with a supercharger. I make just under 600whp and the car drive exactly as it did stock. The mpg also is like stock until you get into boost.
i also love the sound of a car with a lumpy cam but they tend to shake your fillings out of your head. I went with the Edelbrock E force with Eaton 2300 rotors, they give you a 3 year 36k mile full drive train warranty.

Last edited by BlueDevilZ51; 12-05-2018 at 06:04 PM.
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Old 12-04-2018, 11:04 PM
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kc stingray
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remember when installing a bigger camshaft valve spring replacement is needed every 20k or so
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Old 12-05-2018, 12:12 AM
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Originally Posted by kc stingray View Post

remember when installing a bigger camshaft valve spring replacement is needed every 20k or so
False. There is no specific mileage number. A lot depends on how the car will be used and if springs are shimmied to proper height and coil bind.
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Old 12-05-2018, 09:01 AM
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JetEngineJoel
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Thanks. Spring replacement will be something I will have to consider for long term maintenance cost. However, my main fear is loosing something like 5-10 mpg while cruising. I donít mind it when my foot is in it, but Iíd be disappointed if it got worse highway mileage than my truck.

Anyone with a big cam have some input on expected mpg?
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Old 12-05-2018, 10:06 AM
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wadenelson
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I'm not a C7 owner. I don't know if a turbocharger upgrade is one of your choices or something you'd consider.

I've owned both supercharged and turbocharged cars. Personally I prefer turbos. Why?

Superchargers get you off the line, up to 3000 rpms or so, a whole lot faster. They make torque. At the cost of noise, gas, and maintenance. Longevity is more of an issue with a SC than a turbo. (IMHO)

Turbochargers require frequent oil changes, and cooldowns, but... they can make incredible gas mileage. There's this "sweet spot" where the turbo is lightly spinning BEFORE boost enrichment kicks in ...

I used to get 31 mpg out of a crappy old Subaru doing 70+mph mph keeping her right in that sweet spot. Didn't have a vacuum gauge but I could feel it.

I could also do 80+ mph headed up a steep mountain pass to the ski area in the same car with that **** floored and the turbo going to town, err, away from town.

The GF's big, heavy BMW X3, twin turbo, accelerates like a rocketship AND gets 22-24 mpg's highway. I'm amazed both at its performance AND gas mileage. (inline six)

In contrast, my supercharged MR-2 was great off the line, around town. The SC took a gutless 4 cylinder motor and made it torquey, at the cost of a lower
redline, maintenance, etc. I actually preferred the gutless NA MR-2 which revved to 7500 and sang like an opera star.

I also like the whine of a turbo. All ya gotta do is change the oil frequently and cool 'em down before shutdown. I've personally
never had to replace one but replacements are cheap (well, except for anything stamped BMW)

My opinions. YMMV.

Last edited by wadenelson; 12-05-2018 at 10:09 AM.
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Old 12-05-2018, 10:31 AM
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subieworx
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Originally Posted by wadenelson View Post
I'm not a C7 owner. I don't know if a turbocharger upgrade is one of your choices or something you'd consider.

I've owned both supercharged and turbocharged cars. Personally I prefer turbos. Why?

Superchargers get you off the line, up to 3000 rpms or so, a whole lot faster. They make torque. At the cost of noise, gas, and maintenance. Longevity is more of an issue with a SC than a turbo. (IMHO)
Depends on the type of supercharger. A positive displacement blower will do this, but not a centrifugal unit.

Turbochargers require frequent oil changes, and cooldowns, but... they can make incredible gas mileage.

There's this "sweet spot" where the turbo is lightly spinning BEFORE boost enrichment kicks in ...

I used to get 31 mpg out of a crappy old Subaru doing 70+mph mph keeping her right in that sweet spot. Didn't have a vacuum gauge but I could feel it.
Ain't no old turbo subaru that would get that mileage. Look at my user name, I mess with A LOT of Subarus. Bolting a turbo onto an engine will not increase gas mileage and in fact will reduce it due to the restriction to the exhaust flow that is created. Not saying a supercharger won't do the same as the restriction on the crank rotation will also reduce mileage at cruise.

I could also do 80+ mph headed up a steep mountain pass to the ski area in the same car with that **** floored and the turbo going to town, err, away from town.
Turbos are great at this.

The GF's big, heavy BMW X3, twin turbo, accelerates like a rocketship AND gets 22-24 mpg's highway. I'm amazed both at its performance AND gas mileage. (inline six)
BMW has never made a twin turbo x3. They make an n55 x3 which is a single turbo with a twin scroll turbine housing. They are also not that heavy as a 6 cyl x3 is only about 400 pounds heavier than a z06. Drag coefficient is much higher though without a doubt and much of that gas mileage comes from the crazy awesome transmission that car has (ZF8). I also have one of these and lots of first hand experience with BMW's.

I also like the whine of a turbo. All ya gotta do is change the oil frequently and cool 'em down before shutdown. I've personally
never had to replace one but replacements are cheap (well, except for anything stamped BMW)
You don't have to let them cool down. Years ago that was the case, but modern ball bearing cartridges and water cooled cartridges do not need it. There is a lot of complexity to a turbo setup on a car like this that is not present with a supercharger. Doing a turbo correctly will cost more and be more difficult to fit.

Last edited by subieworx; 12-05-2018 at 10:33 AM.
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Old 12-05-2018, 10:32 AM
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Around town driving a high power NA car you will lose mpg. Highway driving cruising at low rpm’s you should get the same as stock or close.

Supercharged car around town and highway mpg are almost the same as stock.
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Old 12-05-2018, 12:03 PM
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robert miller
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Originally Posted by 123sugey View Post
Around town driving a high power NA car you will lose mpg. Highway driving cruising at low rpmís you should get the same as stock or close.

Supercharged car around town and highway mpg are almost the same as stock.
Only with a good tuner 2 diff set up's I lost a ton of mileage in town & highway until I got a good tuner on the car. I even had it a two diff vendors in here big names that didn't do crap for my MPG with a tune on the car. Plus both vendors in here ask me who did this crap on the tuning of it. I told both of them car ran good it was just my MPG was bad. 9 MPG in town with my foot out of it no boost r nothing & 12 MPG on highway at only 70 to 75 MPH was the best I got.

Then got it to someone & went up to 12 in town & 17 ON THE HIGHWAY..
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Old 12-05-2018, 12:11 PM
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wadenelson
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Originally Posted by subieworx View Post

Ain't no old turbo subaru that would get that mileage. Look at my user name, I mess with A LOT of Subarus. .
Umm, I've owned over a dozen Subarus. The '87-88 GL-10 turbos were indeed capable of 31mpg. Typically I got 27-29 because I couldn't keep my speed down.
I had a 55 mile commute. I knew what MPGs I was getting to 1/10 mpg, thank you very much.


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Old 12-05-2018, 05:24 PM
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Oh, you're talking old old. All of my experience is post 01 turbo subarus.
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Old 12-05-2018, 05:58 PM
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I came from a Magnuson supercharged C5 and I have been looking into the same setup for my C7. The Magnuson supercharger disengages at light throttle and engages at more throttle.

For everyday driving fun, WOT thrills, mild manners for the GF, and good gas mileage when not getting after it, I do not think there is a better setup than the Eaton Supercharger adapted for the Corvette by Magnuson. I am a bit biased though, I love the low end torque that a PD supercharger gives.
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Old 12-05-2018, 09:54 PM
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Originally Posted by 123sugey View Post
Around town driving a high power NA car you will lose mpg. Highway driving cruising at low rpmís you should get the same as stock or close.

Supercharged car around town and highway mpg are almost the same as stock.


With a blower you will be about the same normal driving under all conditions except while your in boost. A H/C NA setup will use some more around town but highway wont be far off from stock.

We are not too far from you so if you want to talk about the setups give us a call or email. We could get you pricing on both setups.
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Old 12-06-2018, 09:33 AM
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Robert - I agree. It’s amazing how important the skills of the tuner comes into play. Many variables can be tweaked to improve power, but fully understanding how all interact is key to balancing power, efficiency, drivability and longevity.

The Chev - Thanks for the input. Magnuson SC is definitely high on my list. For more street fun I’m looking for the low end grunt of PD blower, but the half of me that wants to occasionally track the car says stay NA.
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Old 12-06-2018, 01:24 PM
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Originally Posted by BlueDevilZ51 View Post
If you want it to drive like stock I'd recommend going with a supercharger. I make just under 600whp and the car drive exactly as it did stock. The mpg also is like stock until you get into boost.
i also love the sound of a car with a lumpy cam but they tend to shake your fillings out of your head. I went with the Edelbrock E force with Eaton 2300 rotors, they give you a 3 year 36k mile full drive train warranty.
doubt your MPG is the same unless your supercharger is 100% efficient. There's always a drivetrain loss. I think I lost 2 mpg when I added the procharger to my car.

OP your car will drive better on a supercharger than NA. the biggest problem with NA will be the annoying idle. The only reason people can tell my car is supercharged around town is the faint whine. If you don't know cars you might think it's just my electric fan is on or something similar.

Last edited by BrunoTheMellow; 12-06-2018 at 01:29 PM.
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