: LSA and LS9: Why supercharging and not turbocharging?



GMX322V S/C
06-24-10, 02:51 AM
According to Dean Guard, GM small-block chief engineer and program manager:

"Supercharging is preferable to turbocharging," Guard explained. "There's better packaging, and it better handles the thermal and emissions challenges." Then there's the availability of the sixth-generation supercharging technology from Eaton. Guard called it simply "the best charging tech available."

Chevy High Performance: An Inside Look At The Conception & Construction Of GM's Startlingly Powerful New LS9 (http://www.chevyhiperformance.com/tech/engines_drivetrain/shortblock/0811chp_chevrolet_corvette_zr1_ls9_engine_specific ations/index.html)

So there. Well, for our cars at least :p

tedcmiller
06-24-10, 04:51 PM
Turbocharging, unlike supercharging, depends on exhaust gases to run the compressor. There is a lag in turbocharging that is not present in supercharging. It is said that modern turbocharging eliminates most of the lag, but it is still there. I have always preferred supercharging over turbocharging.

JFJr
06-24-10, 04:58 PM
The only worry that I have about supercharging is the belt that drives the supercharger. Does anyone have any idea concerning the life span of that belt in our cars, and if it is advisable to change it after so many miles? I didn't see anything in the manual about that.

Jud

neuronbob
06-24-10, 05:14 PM
I read the manual on this point. On page 6-8, the manual calls for inspection of the belt every 25,000 miles, with replacement as necessary.



CTS-V Only: Inspect supercharger drive belt. See footnote (m).

(m) Visually inspect belt for fraying, excessive cracks, or obvious damage. Replace belt if necessary.

No specific mention of lifespan other than to inspect every 25k miles.

kgb14
06-24-10, 06:41 PM
According to Dean Guard, GM small-block chief engineer and program manager:

"Supercharging is preferable to turbocharging," Guard explained. "There's better packaging, and it better handles the thermal and emissions challenges." Then there's the availability of the sixth-generation supercharging technology from Eaton. Guard called it simply "the best charging tech available."

Chevy High Performance: An Inside Look At The Conception & Construction Of GM's Startlingly Powerful New LS9 (http://www.chevyhiperformance.com/tech/engines_drivetrain/shortblock/0811chp_chevrolet_corvette_zr1_ls9_engine_specific ations/index.html)

So there. Well, for our cars at least :p

Thanks for posting this, great article.

My favorite quote is "Can you say massive acceleration, anytime?". Well said!

garfin
06-24-10, 08:12 PM
I read the manual on this point. On page 6-8, the manual calls for inspection of the belt every 25,000 miles, with replacement as necessary.



No specific mention of lifespan other than to inspect every 25k miles.

If my 11 year experience owning a modified L67 supercharged Bonneville is any indication, feel free to inspect the belt even more regularly than suggested and replace it if you see obvious cracking in the belt. My S/C belt would not last 25,000 mi... but then again it had a smaller pulley and worked harder than a stock setup.

While we're on the subject of superchargers, I always kept a little bottle of GM supercharger oil/lubricant on hand and changed it every couple of years... it didn't need much and I don't know if it was necessary, but WTH. An allan key opened the reservoir on the snout and you could pull the oil out with a turkey baster and squirt the fresh oil right into the filler hole right from the bottle! LOL! Too easy!

Does anyone know if the same option for changing the S/C oil on our cars is available (or is as easy?) Haven't checked this out yet...

Best regards,

Elie

JFJr
06-24-10, 09:19 PM
Good thoughts from all of you. This is my first "blown" engine so I'm a little nervous and don't like the usual, flaky noise from the supercharger interfering with the normal high performance V8 music. Besides increasing weight, why wouldn't the supercharger be chain driven for durability?

Jud

snzuloz
06-24-10, 11:17 PM
From my experience, owning both a turbo'd and supercharged setup, i'd still take the turbo over the blower. Before you HANG ME, i'll tell you why. The old turbo lag days are in the past, the new billet wheel full ball bearing turbo's are incredible, lag is not even noticable if the turbo's are sized correctly to the application. My Buick G.N. would destroy my V in a race, rolling or from the start, with almost 130 less cubes. Look at all the turbo vs blower races, they impose extra weight for the turbo cars for a reason. I think that supercharging is just far easier for installation, cost effectiveness for car manufacturers etc etc. The one thing i really notice between the two, it takes a moment for the Buick to come alive, the Caddy is on immediately but always seems so dependant on rpm for the boost, also on deceleration the caddy has a lot of engine braking where the Buick never slows down. Curious how much power is robbed by driving the blower vs free power from the spent exhaust gases. That being said i still love the V for all it does. Just my .02$

GMX322V S/C
06-24-10, 11:43 PM
I thought I read somewhere that GM said it took something like 60-80 HP to run the supercharger, but I can't the reference right now. BTW, turbochargers aren't exactly parasite-free; they do create backpressure, which translates into pumping loss across the system (even turbos have to obey the 2nd law of thermodynamics :)).

haterinc
06-25-10, 12:04 AM
Bov?

snzuloz
06-25-10, 12:54 AM
I thought I read somewhere that GM said it took something like 60-80 HP to run the supercharger, but I can't the reference right now. BTW, turbochargers aren't exactly parasite-free; they do create backpressure, which translates into pumping loss across the system (even turbos have to obey the 2nd law of thermodynamics :)).


Definately agree with you, i believe though that the back pressure on a well designed and sized turbo application is very minimal (design and a/r ratio of turbine wheel), and horsepower loss is nothing compared to the loss from driving the blower. I wonder why supercharging is so common nowadays, turbo's are very efficient for emissions-are blowers any better? I still think it's much easier and cheaper to slap a blower on it than to get complicated with a turbo system. Would love to see a zr-1 with a well designed turbo kit, sure it would make more than 630+ hp, and probably get better mileage to boot. Well now i will see the link that was posted here and see if it answers any of my thoughts on the matter...

mugatu22
06-25-10, 03:24 AM
Superchargers aren't all that common nowadays; almost all efficient and powerful engine systems are using twin turbo technology to increase power and fuel mileage. Off boost, you can increase efficiency in ways you never could with a supercharger.

In fact the vast majority of high performance vehicles use turbochargers, not superchargers. Porsche 911 Turbo, Panamera Turbo, BMW X5M and upcoming M5, upcoming Mercedes 5.5L Twin Turbo E-Class, Bentley Continental Speed, etc. They're all going this direction for power and efficiency.

It takes more engineering work, parts and cost to create a turbo system than it does to install a supercharger on a pre-existing V8 w/a few modifications. It makes sense that GM goes this direction since they are not in the ultra high-end segment anyway.

GMX322V S/C
06-25-10, 04:18 AM
...Off boost, you can increase efficiency in ways you never could with a supercharger.That's debatable; the efficiencies achieved by the TVS series through close tolerances, numbers of vanes, degrees of vane twist, boost bypass control, etc. at least place it in the same realm as turbocharging today. Packaging, thermal management, emissions compliance, and no denying it, cost played factors also--at least in this application. Maybe the new V8 will get turbo for HO applications.

mugatu22
06-25-10, 04:22 AM
It would be cool to see a TT model for the increased fuel mileage alone. Cylinder cutoff, no boost, freeway speeds...low 30mpg would be nice!

V&Vette
06-25-10, 01:47 PM
From my experience, owning both a turbo'd and supercharged setup, i'd still take the turbo over the blower. Before you HANG ME, i'll tell you why. The old turbo lag days are in the past, the new billet wheel full ball bearing turbo's are incredible, lag is not even noticable if the turbo's are sized correctly to the application. My Buick G.N. would destroy my V in a race, rolling or from the start, with almost 130 less cubes. Look at all the turbo vs blower races, they impose extra weight for the turbo cars for a reason. I think that supercharging is just far easier for installation, cost effectiveness for car manufacturers etc etc. The one thing i really notice between the two, it takes a moment for the Buick to come alive, the Caddy is on immediately but always seems so dependant on rpm for the boost, also on deceleration the caddy has a lot of engine braking where the Buick never slows down. Curious how much power is robbed by driving the blower vs free power from the spent exhaust gases. That being said i still love the V for all it does. Just my .02$

I assume the Grand National is modded correct? I personally love GN's and have hopes that they will return to the lineup soon but stock for stock...it shouldn't be close.

Razorecko
06-25-10, 02:06 PM
i have 18k on my V and see cracks in the belt. I'd say at 20k it's time to replace- alot of that depends on the climate your V is in and how extreme the hot/cold cycles are that it endures

snzuloz
06-25-10, 02:13 PM
I assume the Grand National is modded correct? I personally love GN's and have hopes that they will return to the lineup soon but stock for stock...it shouldn't be close.

The Buick is modded, just comparing the difference between turbo and blowers (the turbo's seem to get much better hp per cubic inch IMO). Stock G.N. would not be a very good competition against the V. Wish i could get off the line like the G.N. does though...

Luna.
06-25-10, 02:24 PM
i have 18k on my V and see cracks in the belt.
I'd say at 20k it's time to replace- alot of that depends on the climate your V is in and how extreme the hot/cold cycles are that it endures


Aye, well said, especially if you run a smaller blower pulley (belt slip blows)

I just don't understand the love affair many have with turbocharging. Yes, I do understand that, at the same PSI, a turbocharger will probably generate more power than a supercharger, but who cares about that nowadays?

Car manufacturers are building power plants that are putting down just crazy power stock, to say nothing about what power they put down when we get done modding them.

700+ rwhp seems barely streetable anyways and we are within spitting distance of that right now.

I'll just take the "instant" power of a supercharger, which is what the car came with, and just be done with it.

Besides...some of you haven't considered the fact that a supercharger can build boost just by revving the motor (say, like at the racing tree); you can't do that with a turbocharger. :p

V&Vette
06-25-10, 03:13 PM
The Buick is modded, just comparing the difference between turbo and blowers (the turbo's seem to get much better hp per cubic inch IMO). Stock G.N. would not be a very good competition against the V. Wish i could get off the line like the G.N. does though...

I'm playing around now and the launches are getting a bit better. Minimal wheel hop but still enough to cost a few ticks. I plan to test a few launches at ATCO in the coming weeks. I only wish launching was as easy as in a G.N. It seems with a proper launch (if one can be achieved), these cars are high 11's stock.

V&Vette
06-25-10, 03:16 PM
Also, in my 335i, the power generated by the turbo has almost no lag at all. Even stock the lag was almost non-existant. Of course, the car doesn't touch the brute speed that the V produces, though, its a high 12 second car with minimal work (seems to get great traction as well/very easy to launch).

GMX322V S/C
06-25-10, 04:11 PM
Isn't it amazing how we talk so casually about our 11-12 second cars? Back in the good ole gristle-car days of the 60's and 70's there was no friggin' way you could run these kinds of times AND be streetable AND go around turns AND not think twice about taking a spontaneous 1000-mile road trip. It IS a great time to be a car enthusiast!

Jeffrey
06-25-10, 06:21 PM
Isn't it amazing how we talk so casually about our 11-12 second cars? Back in the good ole gristle-car days of the 60's and 70's there was no friggin' way you could run these kinds of times AND be streetable AND go around turns AND not think twice about taking a spontaneous 1000-mile road trip. It IS a great time to be a car enthusiast!

Hi,

Exactly!

Last summer, I decided to add this hobby, to my long list, and seriously considered buying a '65 GTO. Then, I thought about reliability, parts availability, handling issues, etc. and realized that the best USA muscle cars are being built right now. So, I scored an '09 V and an '09 Vette and now have none of the concerns the GTO would have probably caused me. I wanted to spend my weekend enjoying my toys, not fixing them.

Best regards,
Jeffrey

LITTLEELVISDAN
06-26-10, 12:33 AM
I have 80,000 miles on my STS-V and have the stock belt. I might have it replaced just before it goes out of its 100k warranty.