Roots or Turbo?
12-12-2012, 01:40 PM
#81
Le Mans Master
Thread Starter
Absolutely, I was just playing.
12-12-2012, 01:56 PM
#82
Le Mans Master
Thread Starter
There is No Compensating for a Supercharger, ROL!
Not to mention the horror list:
*Boost-Creep, when a waste-gate fails an a lean condition ensues the whole motor can go kaput
*hoses that leak
*pipes that come off
*exhaust manifolds that crack
*If the engine goes kaput and stuff exits through the exhaust manifold the turbo goes too
*Upon turbo failure small parts can end up in the shared oil supply and foreign objects are pumped in the engine
Or the day to day annoyances:
let the car idle until the oil temp stabilizes before moving
drive car slowly at first
driver car slowly before stopping
let the car idle before shut off
And all of these risks when a Rotrex can achieve the efficiency of an average turbine.
*Boost-Creep, when a waste-gate fails an a lean condition ensues the whole motor can go kaput
*hoses that leak
*pipes that come off
*exhaust manifolds that crack
*If the engine goes kaput and stuff exits through the exhaust manifold the turbo goes too
*Upon turbo failure small parts can end up in the shared oil supply and foreign objects are pumped in the engine
Or the day to day annoyances:
let the car idle until the oil temp stabilizes before moving
drive car slowly at first
driver car slowly before stopping
let the car idle before shut off
And all of these risks when a Rotrex can achieve the efficiency of an average turbine.
And you noted that a centrifugal is out of the question in a Chevy, since, it sticks out!
Superchargers tear up drive trains more, obviously!
Last edited by johnglenntwo; 12-12-2012 at 04:54 PM.
12-12-2012, 03:56 PM
#84
Team Owner
I even think the clutch might even be a wash. They have to lower the compression no matter what for FI. The clutch would eliminate all paristic losses, but, the compression would then be the inefficiency. If the supercharger was running low pressure AND FLOW the parisitic losses would be minimal and it would be simpler. The ZR1 supercharger still puffs up the torque even though it starts off with only 2lbs of boost so how all that could work out is beyond me.
On the C7, with the DI, I don't believe they will have to lower the compression ratio to go with the supercharger, so I doubt if the efficiency would be that much lower(if any) vs a NA of the same horsepower. Plenty of people(includding Callaway) installing roots style superchargers on high comprerssion(10.7:1 & 11:1) LS3/7's and not seeing reductions in gas mileage. With the benefits of the cooling effect of having DI, I can't see why a 11.5:1 CR LT1 can't easily handle a supercharger, and maintain most of the great gas mileage(ie; efficiency).
Last edited by JoesC5; 12-12-2012 at 04:07 PM.
12-12-2012, 05:20 PM
#85
Le Mans Master
Thread Starter
Interesting!
On my Mercedes, the exact identical car with NA has a 10.4:1 CR and is rated 23/30 MPG. With the Roots style blower(and clutch) is has a 8.8:1 CR and is rated 21/29. But it does not have DI.
On the C7, with the DI, I don't believe they will have to lower the compression ratio to go with the supercharger, so I doubt if the efficiency would be that much lower(if any) vs a NA of the same horsepower. Plenty of people(includding Callaway) installing roots style superchargers on high comprerssion(10.7:1 & 11:1) LS3/7's and not seeing reductions in gas mileage. With the benefits of the cooling effect of having DI, I can't see why a 11.5:1 CR LT1 can't easily handle a supercharger, and maintain most of the great gas mileage(ie; efficiency).
On the C7, with the DI, I don't believe they will have to lower the compression ratio to go with the supercharger, so I doubt if the efficiency would be that much lower(if any) vs a NA of the same horsepower. Plenty of people(includding Callaway) installing roots style superchargers on high comprerssion(10.7:1 & 11:1) LS3/7's and not seeing reductions in gas mileage. With the benefits of the cooling effect of having DI, I can't see why a 11.5:1 CR LT1 can't easily handle a supercharger, and maintain most of the great gas mileage(ie; efficiency).
I was thinking that a complete bypass would be easier with a turbo. Using both the wastegates and the smaller bypass setup they already have on the ZR1 they could easily control the boost down to nothing. I've done it on my car blowing off a hose. It just ran super rich. I can't even imagine trying to bypass a supercharger that much.
DI and 9.8CR:
http://www.porsche.com/usa/models/91...turesandspecs/
Let the aftermarket setups get the crap run out of them, and be tested for MPG like a production car. And what happens when the car gets older and picks up carbon increasing the compression? Knock!
Last edited by johnglenntwo; 12-13-2012 at 07:37 PM.
12-12-2012, 05:39 PM
#86
Safety Car
I think I got ~3 mpg gain with 90hp gain on one of my cars with a high flow cat, proper header, tune, and 3 inch exhaust. It would not pass any laws OEM cars have to pass. It's soo much easier in aftermarket for sure.
12-12-2012, 11:47 PM
#87
Le Mans Master
Thread Starter
Yes, But, 0-60?
12-13-2012, 01:18 PM
#88
Le Mans Master
Thread Starter
MPG, not 0-60!
On my Mercedes, the exact identical car with NA has a 10.4:1 CR and is rated 23/30 MPG. With the Roots style blower(and clutch) is has a 8.8:1 CR and is rated 21/29. But it does not have DI.
On the C7, with the DI, I don't believe they will have to lower the compression ratio to go with the supercharger, so I doubt if the efficiency would be that much lower(if any) vs a NA of the same horsepower. Plenty of people(includding Callaway) installing roots style superchargers on high comprerssion(10.7:1 & 11:1) LS3/7's and not seeing reductions in gas mileage. With the benefits of the cooling effect of having DI, I can't see why a 11.5:1 CR LT1 can't easily handle a supercharger, and maintain most of the great gas mileage(ie; efficiency).
On the C7, with the DI, I don't believe they will have to lower the compression ratio to go with the supercharger, so I doubt if the efficiency would be that much lower(if any) vs a NA of the same horsepower. Plenty of people(includding Callaway) installing roots style superchargers on high comprerssion(10.7:1 & 11:1) LS3/7's and not seeing reductions in gas mileage. With the benefits of the cooling effect of having DI, I can't see why a 11.5:1 CR LT1 can't easily handle a supercharger, and maintain most of the great gas mileage(ie; efficiency).
Some high HP SC aftermarket guys do use full boost control bypassing like turbo guys use wastegate boost control on the street.
If GM doesn't do something different (power/gear ratios(MPSC): MAX'd out!) the traction limited vette will not get significantly quicker off the line, and below 100MPH (but, two quicker auto shifts)!
Last edited by johnglenntwo; 12-13-2012 at 07:27 PM.
