Who actually looks at compressor maps???
02-01-2007, 08:45 PM
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Who actually looks at compressor maps??? I am wondering who actually looks at compressor maps when picking a turbo??
The reason im asking is because when when i called a turbo distributor for a turbo recommendation 2 out of 3 didnt even want to know my engine size. One of the three only ask my engine size in liters thats it ....no vehicle weight,cam, heads just displacement.
The reason im asking is because when when i called a turbo distributor for a turbo recommendation 2 out of 3 didnt even want to know my engine size. One of the three only ask my engine size in liters thats it ....no vehicle weight,cam, heads just displacement.
02-01-2007, 08:59 PM
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Did you give them HP requirements? Desired pressure ratio? RPM of the engine?
Those should be things they would need to know to select a turbo. Even so, it's still a "best guess" scenario for most shops. All they can do is get it in the ballpark. If they've been around for very long I would think they've had experience with different setups and can go off of that.
Those should be things they would need to know to select a turbo. Even so, it's still a "best guess" scenario for most shops. All they can do is get it in the ballpark. If they've been around for very long I would think they've had experience with different setups and can go off of that.
02-02-2007, 12:20 PM
#5
Yep, forcedinductions will hook you up.
However, I wouldn't totally call the other guys idiots just yet. Depending on your engine and goals, there may be a very limited number of turbo's that will work. If you have 350+ cid and are limited on engine bay room, then there's less than a few turbo's that any turbo company can recommend.
One thing that irritates me is that there is one compressor map floating around for the T76. As a compressor engineer, I know that there are many, many things you can adjust in a compressor while leaving the inlet diameter the same. Mine is running somewhere around 55% efficiency right now, but I know it's possible to adjust the blade angle, blade height, and cover A/R to get me over 70%. I know there is a market for this since so many guys run the T76 on 350+ cid and ~15 psi, but no one has developed it.
Mike
However, I wouldn't totally call the other guys idiots just yet. Depending on your engine and goals, there may be a very limited number of turbo's that will work. If you have 350+ cid and are limited on engine bay room, then there's less than a few turbo's that any turbo company can recommend.
One thing that irritates me is that there is one compressor map floating around for the T76. As a compressor engineer, I know that there are many, many things you can adjust in a compressor while leaving the inlet diameter the same. Mine is running somewhere around 55% efficiency right now, but I know it's possible to adjust the blade angle, blade height, and cover A/R to get me over 70%. I know there is a market for this since so many guys run the T76 on 350+ cid and ~15 psi, but no one has developed it.
Mike
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02-02-2007, 10:36 PM
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ha!
I hope the answer here is everyone should read or at least glance at a compressor map. Its almost like trying to tighten a bolt down with the nut spinning on the other side. Aint going anywhere fast!!
I think engineermike just says he's an engineer. I think he has a encyclopedia, only the letter C, and types what he reads!!
I hope the answer here is everyone should read or at least glance at a compressor map. Its almost like trying to tighten a bolt down with the nut spinning on the other side. Aint going anywhere fast!!
I think engineermike just says he's an engineer. I think he has a encyclopedia, only the letter C, and types what he reads!!
02-02-2007, 10:51 PM
#10
Originally Posted by Smearin
I want to know How I can get engineerMikes job..
I read compressor maps... tis fun
I read compressor maps... tis fun
And FYI for everyone else, the latest compressor technology is running polytropic efficiencies of up to 85%. Not too bad when you consider that most of us are doing good to get over 70%.
Mike
02-02-2007, 11:27 PM
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Originally Posted by engineermike
Yep, forcedinductions will hook you up.
However, I wouldn't totally call the other guys idiots just yet. Depending on your engine and goals, there may be a very limited number of turbo's that will work. If you have 350+ cid and are limited on engine bay room, then there's less than a few turbo's that any turbo company can recommend.
Mike
However, I wouldn't totally call the other guys idiots just yet. Depending on your engine and goals, there may be a very limited number of turbo's that will work. If you have 350+ cid and are limited on engine bay room, then there's less than a few turbo's that any turbo company can recommend.
Mike
Its hard to fork over the cash when they say "it should work".
So with a given turbo you`ll make X hp regardless if its a lawn motor engine or a Freight train engine , factory cylinder heads or race heads.
02-03-2007, 12:17 AM
#12
Originally Posted by topend
So with a given turbo you`ll make X hp regardless if its a lawn motor engine or a Freight train engine , factory cylinder heads or race heads.
Mike
02-03-2007, 10:39 AM
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Originally Posted by engineermike
Well. . . on a daily basis, I deal with centrifugal compressors in the 3000 - 45,000 hp range. It's not as fun as it sounds. . .
And FYI for everyone else, the latest compressor technology is running polytropic efficiencies of up to 85%. Not too bad when you consider that most of us are doing good to get over 70%.
Mike
And FYI for everyone else, the latest compressor technology is running polytropic efficiencies of up to 85%. Not too bad when you consider that most of us are doing good to get over 70%.
Mike
In addition, polytropic efficiencies are always numerically greater than isentropic efficiency for the same compressor which makes your post misleading. You're not comparing apples to apples.
Back to the original post...
Sure, a ginormous turbo can be used on a small engine to achieve BIG horsepower numbers, but you'll pay severely in terms of driveabilty and practicallity. You would need to run very high pressure ratios and the thing probably wouldn't spool until you were near the rev-limiter (i.e. dyno queen).
Keep looking for a shop that takes your whole situation under consideration and will actually take the time to estimate where you will be on a compressor map. You'll be much happier in the long run.
I have to sympathize with the shops too. They're trying to make a buck and if they spend alot of time with a potential customer and they give a recommendation only to have them go on eBay and find the same turbo for a few bucks cheaper, they've lost out on a potential sale and make exactly $0 on that sale (how would you feel if you spent 30 mins of foreplay with your girl, and then she goes and finishes the deed with some other guy
). I think alot of these small shops lose out on alot of business and it's extremely frustrating for them. Maybe they're just trying to keep the conversation short until they have cash in hand, and then they'll give you the advice you need. 
02-03-2007, 11:45 AM
#17
Originally Posted by tt460
Why would you quote polytropic efficiencies when they are typically used to compare compressors that need to compress a variety of gases and is valid only for a specific pressure ratio? Isentropic efficiency is still the preferred method of rating compressors that are moving the same gas (in our case atmospheric air) and do so over a range of pressure ratios (hence the compressor map).
In addition, polytropic efficiencies are always numerically greater than isentropic efficiency for the same compressor which makes your post misleading. You're not comparing apples to apples.
Back to the original post...
Sure, a ginormous turbo can be used on a small engine to achieve BIG horsepower numbers, but you'll pay severely in terms of driveabilty and practicallity. You would need to run very high pressure ratios and the thing probably wouldn't spool until you were near the rev-limiter (i.e. dyno queen).
Keep looking for a shop that takes your whole situation under consideration and will actually take the time to estimate where you will be on a compressor map. You'll be much happier in the long run.
I have to sympathize with the shops too. They're trying to make a buck and if they spend alot of time with a potential customer and they give a recommendation only to have them go on eBay and find the same turbo for a few bucks cheaper, they've lost out on a potential sale and make exactly $0 on that sale (how would you feel if you spent 30 mins of foreplay with your girl, and then she goes and finishes the deed with some other guy ). I think alot of these small shops lose out on alot of business and it's extremely frustrating for them. Maybe they're just trying to keep the conversation short until they have cash in hand, and then they'll give you the advice you need.
In addition, polytropic efficiencies are always numerically greater than isentropic efficiency for the same compressor which makes your post misleading. You're not comparing apples to apples.
Back to the original post...
Sure, a ginormous turbo can be used on a small engine to achieve BIG horsepower numbers, but you'll pay severely in terms of driveabilty and practicallity. You would need to run very high pressure ratios and the thing probably wouldn't spool until you were near the rev-limiter (i.e. dyno queen).
Keep looking for a shop that takes your whole situation under consideration and will actually take the time to estimate where you will be on a compressor map. You'll be much happier in the long run.
I have to sympathize with the shops too. They're trying to make a buck and if they spend alot of time with a potential customer and they give a recommendation only to have them go on eBay and find the same turbo for a few bucks cheaper, they've lost out on a potential sale and make exactly $0 on that sale (how would you feel if you spent 30 mins of foreplay with your girl, and then she goes and finishes the deed with some other guy
). I think alot of these small shops lose out on alot of business and it's extremely frustrating for them. Maybe they're just trying to keep the conversation short until they have cash in hand, and then they'll give you the advice you need. The simple fact is most shops don't know. Alot of the so called turbo shops call Jose to ask what turbo they need to run on certain applications. That says alot. If you are going to open a business, then I think you should at least know your product and know how to adapt different parts to meet a customers need. Not just be another catalog turbo shop that just quotes HP figures from the latest literature they recieve. EVERY turbo HP rating should have a BIG * beside it saying (HP figures are dependent on configuration). A T76 will not make 1100hp on every setup. A 180ci engine and a 502 big block will get 2 different #'s at the end.
02-03-2007, 01:58 PM
#18
Originally Posted by tt460
Why would you quote polytropic efficiencies when they are typically used to compare compressors that need to compress a variety of gases and is valid only for a specific pressure ratio? Isentropic efficiency is still the preferred method of rating compressors that are moving the same gas (in our case atmospheric air) and do so over a range of pressure ratios (hence the compressor map).
The bottom line is that polytropic efficiency and polytropic head are more accurate methods of calculating compressor performance because they are independent of pressure ratio and gas properties.
Mike
02-03-2007, 04:05 PM
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Originally Posted by DrTurbo
The simple fact is most shops don't know. Alot of the so called turbo shops call Jose to ask what turbo they need to run on certain applications. That says alot. If you are going to open a business, then I think you should at least know your product and know how to adapt different parts to meet a customers need. Not just be another catalog turbo shop that just quotes HP figures from the latest literature they recieve. EVERY turbo HP rating should have a BIG * beside it saying (HP figures are dependent on configuration). A T76 will not make 1100hp on every setup. A 180ci engine and a 502 big block will get 2 different #'s at the end.
02-03-2007, 10:34 PM
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Basically all the turbo companies i called recommended me the 91 mm as it is "rated" for 1500 hp. Yet the compressor map for t-91 only goes up to 1300 hp. If my motor makes 600+ hp on motor , the t-91 turbo would be done at less than 14 psi of boost???
