Supercharge or Turbo
04-19-2009, 12:17 AM
#34
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I love how these comparos degenerate. The only question is how quickly it does so.
Personally, I'd have one of each if I could - John's turbo, which I've seen up close a couple of times on John's car (work of art and real good performance stats), and Tim Murphy's sc set up - also senn it and it has great performance specs too.
Personally, I'd have one of each if I could - John's turbo, which I've seen up close a couple of times on John's car (work of art and real good performance stats), and Tim Murphy's sc set up - also senn it and it has great performance specs too.
04-19-2009, 09:23 AM
#35
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04-19-2009, 10:16 AM
#36
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04-19-2009, 05:13 PM
#39
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I believe there are parasitic losses in a turbocharger installation. I would expect that if you were to measure the exhaust gas pressure in the exhaust manifold ( ie. between the piston and turbo) it would be found to be at least equal to boost pressure.
This is consuming power....hmmm... horsepower or torque?
The difference is, that in a supercharger installation we can measure these losses, in a turbo installation we can't. Rolls Royce once built a military engine with a auxillary motor driving the supercharger for a larger engine!
Cheers Roy
This is consuming power....hmmm... horsepower or torque?
The difference is, that in a supercharger installation we can measure these losses, in a turbo installation we can't. Rolls Royce once built a military engine with a auxillary motor driving the supercharger for a larger engine!
Cheers Roy
04-19-2009, 05:18 PM
#40
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Nitrous has no parasitic losses and can be easily run "dry" Look at Brett's new instal with the fuel nozzles right above the stock injectors. No more wet than a stock manifold. Pooling in the manifold is a true issue for wet nitrous systems. Intake manifold design may dictate a direct port system to avoid. Generally going down then up is bad. So injecting wet before the throttle body can lead to pooling in the lower plenum. Go lean, backfire then kaboom. However injecting above the TB plate is fine. I have pulled my plenum right after a heavy spray and found no pooled gas. A little oil, but no gas.
If you want to spend $6k+ for a permanent power adder, a SC or Turbo is a great way to go. However, if you want to keep things under $1K and still get the same or better HP/TQ benefits, go with N2O. Nitrous, just like any SC or Turbo setup is never plug and go. You need to really think out the instal, control and make sure it's a good fit for your car and needs. Nitrous is about straight line power, 0-60 and 1/4 mile. Not road racing or going through the twisties.
If you want to spend $6k+ for a permanent power adder, a SC or Turbo is a great way to go. However, if you want to keep things under $1K and still get the same or better HP/TQ benefits, go with N2O. Nitrous, just like any SC or Turbo setup is never plug and go. You need to really think out the instal, control and make sure it's a good fit for your car and needs. Nitrous is about straight line power, 0-60 and 1/4 mile. Not road racing or going through the twisties.
04-19-2009, 05:27 PM
#41
Nordschleife Master
You are absolutely right. The additional power needed to drive the turbocharger is not just coming from increased efficiencies.
The compressor uses about half of the additional power generated in excess of the NA engine. This is true irrespective of whether it is a turbo, centrifugal supercharger, or a twin screw. Thus, if you burn extra fuel worth of 100 hp, 50 hp has to come somewhere to drive the compressor.
In a mechanical supercharger system, that 50 hp comes from the crankshaft, which then leaves the net increase of 50 hp.
In a turbocharger, about 40 hp comes from exhaust gas energy that would otherwise be wasted. About 10 hp comes from the crankshaft in the form of additional pumping losses. Thus, the net hp increase is 90 hp, 40 hp more than for a supercharger.
For this reason, a turbo engine will always have a higher max hp potential than a supercharged engine. Whether the max power is relevant for a street car is another matter.
All numbers above are approximate, but in the ball park.
The compressor uses about half of the additional power generated in excess of the NA engine. This is true irrespective of whether it is a turbo, centrifugal supercharger, or a twin screw. Thus, if you burn extra fuel worth of 100 hp, 50 hp has to come somewhere to drive the compressor.
In a mechanical supercharger system, that 50 hp comes from the crankshaft, which then leaves the net increase of 50 hp.
In a turbocharger, about 40 hp comes from exhaust gas energy that would otherwise be wasted. About 10 hp comes from the crankshaft in the form of additional pumping losses. Thus, the net hp increase is 90 hp, 40 hp more than for a supercharger.
For this reason, a turbo engine will always have a higher max hp potential than a supercharged engine. Whether the max power is relevant for a street car is another matter.
All numbers above are approximate, but in the ball park.
I believe there are parasitic losses in a turbocharger installation. I would expect that if you were to measure the exhaust gas pressure in the exhaust manifold ( ie. between the piston and turbo) it would be found to be at least equal to boost pressure.
This is consuming power....hmmm... horsepower or torque?
The difference is, that in a supercharger installation we can measure these losses, in a turbo installation we can't. Rolls Royce once built a military engine with a auxillary motor driving the supercharger for a larger engine!
Cheers Roy
This is consuming power....hmmm... horsepower or torque?
The difference is, that in a supercharger installation we can measure these losses, in a turbo installation we can't. Rolls Royce once built a military engine with a auxillary motor driving the supercharger for a larger engine!
Cheers Roy
04-19-2009, 07:27 PM
#42
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Nitrous has no parasitic losses and can be easily run "dry" Look at Brett's new instal with the fuel nozzles right above the stock injectors. No more wet than a stock manifold. Pooling in the manifold is a true issue for wet nitrous systems. Intake manifold design may dictate a direct port system to avoid. Generally going down then up is bad. So injecting wet before the throttle body can lead to pooling in the lower plenum. Go lean, backfire then kaboom. However injecting above the TB plate is fine. I have pulled my plenum right after a heavy spray and found no pooled gas. A little oil, but no gas.
If you want to spend $6k+ for a permanent power adder, a SC or Turbo is a great way to go. However, if you want to keep things under $1K and still get the same or better HP/TQ benefits, go with N2O. Nitrous, just like any SC or Turbo setup is never plug and go. You need to really think out the instal, control and make sure it's a good fit for your car and needs. Nitrous is about straight line power, 0-60 and 1/4 mile. Not road racing or going through the twisties.
If you want to spend $6k+ for a permanent power adder, a SC or Turbo is a great way to go. However, if you want to keep things under $1K and still get the same or better HP/TQ benefits, go with N2O. Nitrous, just like any SC or Turbo setup is never plug and go. You need to really think out the instal, control and make sure it's a good fit for your car and needs. Nitrous is about straight line power, 0-60 and 1/4 mile. Not road racing or going through the twisties.
I do agree with one poster, it all depends on what you are looking for.
Some cars and drivers are better suited with a fixed displacement blower (Roots or TS), some are better off with a variable type (Centrifugal), some are better off with Turbocharger, others use n2O.
I have one with a Centrifugal, one that is getting a TS and one that just left with N2O.
You are absolutely right. The additional power needed to drive the turbocharger is not just coming from increased efficiencies.
The compressor uses about half of the additional power generated in excess of the NA engine. This is true irrespective of whether it is a turbo, centrifugal supercharger, or a twin screw. Thus, if you burn extra fuel worth of 100 hp, 50 hp has to come somewhere to drive the compressor.
In a mechanical supercharger system, that 50 hp comes from the crankshaft, which then leaves the net increase of 50 hp.
In a turbocharger, about 40 hp comes from exhaust gas energy that would otherwise be wasted. About 10 hp comes from the crankshaft in the form of additional pumping losses. Thus, the net hp increase is 90 hp, 40 hp more than for a supercharger.
For this reason, a turbo engine will always have a higher max hp potential than a supercharged engine. Whether the max power is relevant for a street car is another matter.
All numbers above are approximate, but in the ball park.
The compressor uses about half of the additional power generated in excess of the NA engine. This is true irrespective of whether it is a turbo, centrifugal supercharger, or a twin screw. Thus, if you burn extra fuel worth of 100 hp, 50 hp has to come somewhere to drive the compressor.
In a mechanical supercharger system, that 50 hp comes from the crankshaft, which then leaves the net increase of 50 hp.
In a turbocharger, about 40 hp comes from exhaust gas energy that would otherwise be wasted. About 10 hp comes from the crankshaft in the form of additional pumping losses. Thus, the net hp increase is 90 hp, 40 hp more than for a supercharger.
For this reason, a turbo engine will always have a higher max hp potential than a supercharged engine. Whether the max power is relevant for a street car is another matter.
All numbers above are approximate, but in the ball park.
I am sure one of the smarter guys here could work out what % of power that would be.
The three recovery turbines on a R-3350 added about 500 HP or so.
So there is no doubt that there is power going out the pipes, but to get it is complex, costly and heavy.
These big engines were supercharged and had recovery turbines to help power the crank, best of both worlds.
So many things that seem new, or could seem new, were tried many years ago.
I really like the old weird motors, sleeve valves, H-engines, etc......
04-19-2009, 08:26 PM
#43
I meant from the factory... 
It takes roughly 50 hp (probably a bit more) to drive a supercharger belt that delivers a net of 200 additional horsepower (I use 1:4). A turbo's energy comes from the exhaust gas. A twin turbo will have some increased backpresure but the parasitic loss impact on the engine's native hp will probably be at most 5~10 hp. So for the same amount of boost, a turbo should yield roughly 50HP more than a supercharger.
Naws... Well that's just dowrite giddy! *huf *huf *huf
I believe there are parasitic losses in a turbocharger installation. I would expect that if you were to measure the exhaust gas pressure in the exhaust manifold ( ie. between the piston and turbo) it would be found to be at least equal to boost pressure.
This is consuming power....hmmm... horsepower or torque?
The difference is, that in a supercharger installation we can measure these losses, in a turbo installation we can't. Rolls Royce once built a military engine with a auxillary motor driving the supercharger for a larger engine!
Cheers Roy
This is consuming power....hmmm... horsepower or torque?
The difference is, that in a supercharger installation we can measure these losses, in a turbo installation we can't. Rolls Royce once built a military engine with a auxillary motor driving the supercharger for a larger engine!
Cheers Roy
Naws... Well that's just dowrite giddy! *huf *huf *huf
04-19-2009, 08:38 PM
#44
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It takes roughly 50 hp (probably a bit more) to drive a supercharger belt that delivers a net of 200 additional horsepower (I use 1:4). A turbo's energy comes from the exhaust gas. A twin turbo will have some increased backpresure but the parasitic loss impact on the engine's native hp will probably be at most 5~10 hp. So for the same amount of boost, a turbo should yield roughly 50HP more than a supercharger.
04-19-2009, 09:18 PM
#45
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