Turbo Horsepower Numbers
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Turbo Horsepower Numbers How do "they" get the the horsepower numbers from any particular turbocharger (i.e. "Supports 900 HP")? Must be some kind of baseline because obviously hardly no two different engine designs have the same capability or power potential.
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I would say it's good marketing. Take a somewhat stock looking car on the
outside, slap in a turbo...don't tell anyone about the $1000's of dollars spent
on head work, fuel system, cam, tuning and you have yourself a sale.
How many times have we read posts in the LS1/LS6 section about bolt-ons
not yielding the advertised numbers?
"I just spent $2500 on heads, but I only made 15 HP at the wheel; the
heads are good for 600 HP?".
Not really sure if that's the answer you're looking for, but I see that happening
way too often.
outside, slap in a turbo...don't tell anyone about the $1000's of dollars spent
on head work, fuel system, cam, tuning and you have yourself a sale.
How many times have we read posts in the LS1/LS6 section about bolt-ons
not yielding the advertised numbers?
"I just spent $2500 on heads, but I only made 15 HP at the wheel; the
heads are good for 600 HP?".
Not really sure if that's the answer you're looking for, but I see that happening
way too often.
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Originally Posted by Nine Ball
The get the ratings based on the amount of potential flow that the turbo can support. Potential flow can be used to calculate potential HP.
P.S. I before E except after C doesn't work with the word "science".
Last edited by Lasershop; Oct 27, 2005 at 06:13 PM.
Originally Posted by Lasershop
Potential flow based on what standard? Blowers are based on volume (6-71, 8-71 ect.), but EVERYBODY seems to advertise the turbo's based on supported potential horsepower. Just wondering where this originated.
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Originally Posted by 2000 Tran Zam
i think they use flow benches to measure CFM...
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Originally Posted by Lasershop
Thanks for the input, and I am quite sure they know the flow and volume of the unit. But then to say it will support X horsepower had to be based on a particular standardized platform. Or........... they just make the **** up.
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Its quite simple actually, you can only make so much power with a certian amount of air.
Where the differences come are the "efficiencies" of the engine. An engine burning a certian amount of fuel and air puts out an almost exact amount of "heat" a particular engine design would vary on how efficiently it uses that heat in converting it to power.
Combustion effiency, thermal efficiency, mechanical efficiency, etc... Those values are what detract from the maximum power. You can assume certian values for them and that is typically how they come up with thier power #
Where the differences come are the "efficiencies" of the engine. An engine burning a certian amount of fuel and air puts out an almost exact amount of "heat" a particular engine design would vary on how efficiently it uses that heat in converting it to power.
Combustion effiency, thermal efficiency, mechanical efficiency, etc... Those values are what detract from the maximum power. You can assume certian values for them and that is typically how they come up with thier power #
As said already, its all based on airflow capability/potential. A turbocharger, no matter how fast you spin it or at what pressure ratio its running, will only pump so much air. That airflow, combined with the proper amount of fuel, can only make so much horsepower -- no matter what.
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Originally Posted by DanO
Its quite simple actually, you can only make so much power with a certian amount of air.
Where the differences come are the "efficiencies" of the engine. An engine burning a certian amount of fuel and air puts out an almost exact amount of "heat" a particular engine design would vary on how efficiently it uses that heat in converting it to power.
Combustion effiency, thermal efficiency, mechanical efficiency, etc... Those values are what detract from the maximum power. You can assume certian values for them and that is typically how they come up with thier power #
Where the differences come are the "efficiencies" of the engine. An engine burning a certian amount of fuel and air puts out an almost exact amount of "heat" a particular engine design would vary on how efficiently it uses that heat in converting it to power.
Combustion effiency, thermal efficiency, mechanical efficiency, etc... Those values are what detract from the maximum power. You can assume certian values for them and that is typically how they come up with thier power #
Im just sayin'...........
Check Corky Bell's book called Maximum Boost. It goes through a lot of the math and ratings. Turbo flow is pretty easy to map as a head unit - it's when you put it on different motors that the variability comes into play.
It took me 5 or 6 readings to pretty much understand everything Corky was trying to teach, so don't give up!
Jim
It took me 5 or 6 readings to pretty much understand everything Corky was trying to teach, so don't give up!
Jim
This link below will help explain the theory....
Turbo help 101
As for a black and white answer, well the answer would be D. (none of the above). Turbos were not designed and rated using one particular engine.
Turbos are mearly tested on a gas stand and then applied a load, and then the pressure ratio is set manually from 0 to max of what the compressor wheel can efficiently compress. The results from this are what a compressor map is derived from.
Jose
Turbo help 101
As for a black and white answer, well the answer would be D. (none of the above). Turbos were not designed and rated using one particular engine.
Turbos are mearly tested on a gas stand and then applied a load, and then the pressure ratio is set manually from 0 to max of what the compressor wheel can efficiently compress. The results from this are what a compressor map is derived from.
Jose
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LaserShop, listen to Jose, he does know turbos.
Let me add that turbos are rated for MAX hp based on the MAX pounds per minute (ppm) they are able to deliver. That varies according to the boost they are putting out (compressor maps). As an estimate, each ppm of air delivered developes 10.86 hp. Every turbo has a maximum amount of air (ppm) that it can deliver based on the compressor section and its efficiency. So a turbo that is rated at 90 ppm (now that's a MAX, not what you get every time), can produce a MAX of 977 hp at the crank. That doesn't guarantee that you will actually make enough flow to get 90 ppm from that turbo. It just says that the turbo will support that hp if it's done right. It all depends on boost (pressure ratio) and rpm and displacement to maximize a particular setup.
You need to start with the hp at the crank that you are wanting and work backward to estimate which turbo will do that for your setup. Take a hard read at the link for Turbo 101 and you will begin to see what's involved.
Now I'm no expert, I was where you are just a few months ago. You are a smart guy, so you can pick up on the basics pretty quick. HTH GL.
Edited for an easier read...
Let me add that turbos are rated for MAX hp based on the MAX pounds per minute (ppm) they are able to deliver. That varies according to the boost they are putting out (compressor maps). As an estimate, each ppm of air delivered developes 10.86 hp. Every turbo has a maximum amount of air (ppm) that it can deliver based on the compressor section and its efficiency. So a turbo that is rated at 90 ppm (now that's a MAX, not what you get every time), can produce a MAX of 977 hp at the crank. That doesn't guarantee that you will actually make enough flow to get 90 ppm from that turbo. It just says that the turbo will support that hp if it's done right. It all depends on boost (pressure ratio) and rpm and displacement to maximize a particular setup.
You need to start with the hp at the crank that you are wanting and work backward to estimate which turbo will do that for your setup. Take a hard read at the link for Turbo 101 and you will begin to see what's involved.
Now I'm no expert, I was where you are just a few months ago. You are a smart guy, so you can pick up on the basics pretty quick. HTH GL.
Edited for an easier read...
Last edited by TeeKay; Oct 28, 2005 at 12:52 AM.
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Originally Posted by TeeKay
LaserShop, listen to Jose, he does know turbos.
As an estimate, each ppm of air delivered developes 10.86 hp.
As an estimate, each ppm of air delivered developes 10.86 hp.
The simple fact is, you could take a 1,000,000cid engine and restrict it to 100 lb/hr of air, and it will make the same amount of power (roughly) as a 100cid engine boosted to consume 100lb/hr of air. An engine is an air pump, and uses fuel as its motivation to do work. Air and fuel must be consumed in a known ratio to make the most power for the volume ingested. The fuel has a known amount of energy for mass consumed. Plug it all into a formula and you can find the max power for volume of air (or fuel) consumed.
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Where do I get one of those 1,000,000cid engines. I could make it fit......
I appreciate the brain food input from everyone. Im bettin' that im not the only one that has learned a little more about turbo sizing from this. I have ALL the books. I have worn them out. I have copies in each bathroom. This did give me more of an interest in reading turbo maps and maybe even understanding what they mean. Knowledge is power baby!
I appreciate the brain food input from everyone. Im bettin' that im not the only one that has learned a little more about turbo sizing from this. I have ALL the books. I have worn them out. I have copies in each bathroom. This did give me more of an interest in reading turbo maps and maybe even understanding what they mean. Knowledge is power baby!
