How to read compressor maps.
06-15-2003, 08:39 AM
#11
0.0 BAR
Join Date: Apr 2003
Posts: 25
Re:How to read compressor maps.
This is cool, but all it does is make me more confused than before.
Could someone explain what is pressure ratio. What it does, what pressure ratio is good what is bad??
What do the blue yellow purple green and teal lines mean
How can this be used for your particular engine, D16 B16 etc.
This seems like very good info, but it doesn't help those who don't know about turbos.
Could someone explain what is pressure ratio. What it does, what pressure ratio is good what is bad??
What do the blue yellow purple green and teal lines mean
How can this be used for your particular engine, D16 B16 etc.
This seems like very good info, but it doesn't help those who don't know about turbos.
06-15-2003, 02:25 PM
#12
0.5 BAR
Join Date: Apr 2003
Posts: 188
Re:How to read compressor maps.
well, since i'm the one who drew the maps above, i suppose i could get off my *** and answer a q or two..
the different colored lines represent the airflow of the engine at different rpm/pressure ratios. dark blue corresponds to 3000rpm, and it shifts to the right as the pressure ratio increases because the effective airflow of the engine increases (yellow=4000, purple=5000, green=6000, light blue=7000, and interpolate an extra line to the right of the light blue, spaced the same for the demand line for the B18C engine at 8000rpm). about twice a week i read some dumbass post about someone "plotting" their engine on a compressor map using only their max rpm airflow and max boost. this gives a **** poor turbo match because you are only matching ONE point on the entire airflow map of the engine. basically, those people are completely ignoring the compressor's efficiency at all the other rpm ranges that they'll be in boost for. as you can see on the T04 maps, spooling too soon leaves you with massive compressor surge.
pressure ratio is basically boost. to convert pressure ratio to psi, use the formula: (pressure ratio x 14.7) then subtract 14.7. so boost PSI= (PR*14.7)-14.7
10 psi is roughly 1.68PR. 14.7psi is 2.0PR and so on.
basically, if you look at the 14b mitsu map, the demand lines are covered by the compressor map WELL into the higher pressure ratios. if one could open up the exhaust a bit more for better flow, or perhaps mate that compressor to a TD06 turbine from an NPR truck or something, i believe this turbo would better suit our engines at higher boost than any T04. you can see that we are still above 65% efficiency up to 2.8PR (26 psi) and it will out-spool a T04.
the different colored lines represent the airflow of the engine at different rpm/pressure ratios. dark blue corresponds to 3000rpm, and it shifts to the right as the pressure ratio increases because the effective airflow of the engine increases (yellow=4000, purple=5000, green=6000, light blue=7000, and interpolate an extra line to the right of the light blue, spaced the same for the demand line for the B18C engine at 8000rpm). about twice a week i read some dumbass post about someone "plotting" their engine on a compressor map using only their max rpm airflow and max boost. this gives a **** poor turbo match because you are only matching ONE point on the entire airflow map of the engine. basically, those people are completely ignoring the compressor's efficiency at all the other rpm ranges that they'll be in boost for. as you can see on the T04 maps, spooling too soon leaves you with massive compressor surge.
pressure ratio is basically boost. to convert pressure ratio to psi, use the formula: (pressure ratio x 14.7) then subtract 14.7. so boost PSI= (PR*14.7)-14.7
10 psi is roughly 1.68PR. 14.7psi is 2.0PR and so on.
basically, if you look at the 14b mitsu map, the demand lines are covered by the compressor map WELL into the higher pressure ratios. if one could open up the exhaust a bit more for better flow, or perhaps mate that compressor to a TD06 turbine from an NPR truck or something, i believe this turbo would better suit our engines at higher boost than any T04. you can see that we are still above 65% efficiency up to 2.8PR (26 psi) and it will out-spool a T04.
06-20-2003, 10:55 PM
#13
0.0 BAR
Join Date: Apr 2003
Posts: 25
Re:How to read compressor maps.
Hey thanks for answering my questions.
however, You just keep using new words with your answer.
What are demand lines?
How do you interpret the isometric lines, I mean I see them but they don't tell me anything?
Say if you were to draw a horizontal line at 1.8 pressure ratio how do you correlate RPM lines to efficiency of the turbo? Is getting to the center most isometric line prefferable, at what RPM?
Is there a book I can read that will tech me this stuff from the begining?
I feel I startd reading this book on page 100.
Thanks a bunch.
however, You just keep using new words with your answer.
What are demand lines?
How do you interpret the isometric lines, I mean I see them but they don't tell me anything?
Say if you were to draw a horizontal line at 1.8 pressure ratio how do you correlate RPM lines to efficiency of the turbo? Is getting to the center most isometric line prefferable, at what RPM?
Is there a book I can read that will tech me this stuff from the begining?
I feel I startd reading this book on page 100.
Thanks a bunch.
Originally Posted by scarecrowX
well, since i'm the one who drew the maps above, i suppose i could get off my *** and answer a q or two..
the different colored lines represent the airflow of the engine at different rpm/pressure ratios. dark blue corresponds to 3000rpm, and it shifts to the right as the pressure ratio increases because the effective airflow of the engine increases (yellow=4000, purple=5000, green=6000, light blue=7000, and interpolate an extra line to the right of the light blue, spaced the same for the demand line for the B18C engine at 8000rpm). about twice a week i read some dumbass post about someone "plotting" their engine on a compressor map using only their max rpm airflow and max boost. this gives a **** poor turbo match because you are only matching ONE point on the entire airflow map of the engine. basically, those people are completely ignoring the compressor's efficiency at all the other rpm ranges that they'll be in boost for. as you can see on the T04 maps, spooling too soon leaves you with massive compressor surge.
pressure ratio is basically boost. to convert pressure ratio to psi, use the formula: (pressure ratio x 14.7) then subtract 14.7. so boost PSI= (PR*14.7)-14.7
10 psi is roughly 1.68PR. 14.7psi is 2.0PR and so on.
basically, if you look at the 14b mitsu map, the demand lines are covered by the compressor map WELL into the higher pressure ratios. if one could open up the exhaust a bit more for better flow, or perhaps mate that compressor to a TD06 turbine from an NPR truck or something, i believe this turbo would better suit our engines at higher boost than any T04. you can see that we are still above 65% efficiency up to 2.8PR (26 psi) and it will out-spool a T04.
the different colored lines represent the airflow of the engine at different rpm/pressure ratios. dark blue corresponds to 3000rpm, and it shifts to the right as the pressure ratio increases because the effective airflow of the engine increases (yellow=4000, purple=5000, green=6000, light blue=7000, and interpolate an extra line to the right of the light blue, spaced the same for the demand line for the B18C engine at 8000rpm). about twice a week i read some dumbass post about someone "plotting" their engine on a compressor map using only their max rpm airflow and max boost. this gives a **** poor turbo match because you are only matching ONE point on the entire airflow map of the engine. basically, those people are completely ignoring the compressor's efficiency at all the other rpm ranges that they'll be in boost for. as you can see on the T04 maps, spooling too soon leaves you with massive compressor surge.
pressure ratio is basically boost. to convert pressure ratio to psi, use the formula: (pressure ratio x 14.7) then subtract 14.7. so boost PSI= (PR*14.7)-14.7
10 psi is roughly 1.68PR. 14.7psi is 2.0PR and so on.
basically, if you look at the 14b mitsu map, the demand lines are covered by the compressor map WELL into the higher pressure ratios. if one could open up the exhaust a bit more for better flow, or perhaps mate that compressor to a TD06 turbine from an NPR truck or something, i believe this turbo would better suit our engines at higher boost than any T04. you can see that we are still above 65% efficiency up to 2.8PR (26 psi) and it will out-spool a T04.
06-21-2003, 11:01 AM
#14
0.5 BAR
Join Date: Apr 2003
Posts: 188
Re:How to read compressor maps.
sorry man. the demand lines are the colored lines. if you drew a line at the pressure ratio 1.8, straight across, each intersection of the colored lines represents the turbo's efficiency at that boost level and that rpm (rpm represented by each color).
the "isobars" basically seperate each section of compressor efficiency. the center island is the highest efficiency, with efficiency dropping off as you move outward. most people think that the turbo has to stay in the center island to be a decent match. totally false. yes, you want to keep as close to max efficiency as possible, but a decent intercooler will more than make up for a little inefficiency in the compressor.
basically, when you take all the colored rpm lines (demand lines), they should totally cover the compressor map and not exceed the surge limit at your boost level (ideally not at all). some people prefer to have max rpm/boost in that center island, but it's really not necessary.
the "isobars" basically seperate each section of compressor efficiency. the center island is the highest efficiency, with efficiency dropping off as you move outward. most people think that the turbo has to stay in the center island to be a decent match. totally false. yes, you want to keep as close to max efficiency as possible, but a decent intercooler will more than make up for a little inefficiency in the compressor.
basically, when you take all the colored rpm lines (demand lines), they should totally cover the compressor map and not exceed the surge limit at your boost level (ideally not at all). some people prefer to have max rpm/boost in that center island, but it's really not necessary.
07-30-2003, 01:59 PM
#17
0.0 BAR
Join Date: Jul 2003
Posts: 1
Re:How to read compressor maps.
Could you plot some points on T3/To4e compressor maps for my D16z6?? 
I've been told to go with anything from a 46 trim to a 60 trim..
My goal is for 350-400hp on my sleeved d16z6 block, 9:1 cp pistons/hondata s200b/etc/etc..
Please?
I'd love to settle this for sure so i can begin purchasing
Thanks
I've been told to go with anything from a 46 trim to a 60 trim..
My goal is for 350-400hp on my sleeved d16z6 block, 9:1 cp pistons/hondata s200b/etc/etc..
Please?
I'd love to settle this for sure so i can begin purchasing
Thanks
10-27-2003, 07:53 PM
#20
3.0 BAR
Join Date: Mar 2003
Posts: 21,479
Re:How to read compressor maps.
Now added to the "USER FAQ"
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