I wanted to turbocharge my tib for 400bhp, but found out an interesting fact: without proper guidance it basicly comes down to hit and miss, with a lot of luck thrown in. Yes many members of this forum are good sources of information, but mostly about what they own in particular, and with a healthy dose of bias in for good measure. Don't get me wrong, asking can get you good answers, there is a lot of knowledge here at NT.
What I wanted was a step by step guide to bringing my tiburon upto the power I wanted. There is no such thing to my knowledge. Well.... HERE IT IS! Ok, well it's a general outline. But as I was struggling to crunch the numbers to get what I want from my tib, I I realized that with a little feedback and direction, it really isn't that difficult. If I don't explain something or take for granted that something is known that isn't, just ask.
All the tools you need to work along for your own particular demands are:
-A spreadsheet program or word processor, if you don't have one google Open Office, it is 100% free and compatible with excel. I prefer spreadsheet because once formulas are set you can change one aspect and the rest updates automaticly
-A solid understanding of applied mathematics, don't worry, I'm sure any competent highschool education will be sufficient.
-A copy of Maximum Boost by Corky Bell would be benificial, you can find it here: http://www.newtiburon.com/forums/showthread.php?t=120986
I'll try to be as logical in my layout as possible. Again, feel free to ask and answer questions (stay on topic), we are all learning and all make mistakes.
Vital stats:
2003 Tiburon SE 2.0L
Engine Displacement: 1975cc -or- 120.52 cubic inches
Cylinders: 4
Stroke Length: 93.5mm
Bore: 82mm
Compression Ratio: 10.3
Redline: 7000rpm
Peak Power RPM: 2/3 * Redline = 4666rpm
Ideal Boost Threshold: 1/3 * Redline = 2100rpm
Goal: 400 bhp
Turbo sizing
First we need to select a turbo size, this takes a few steps:
-Determine boost pressure required to get desired hp. *boost pressure and boost ratio are the same, one is metric (ratio, in barometric pressure) and the other in standard imperial (pressure, in pounds per square inch)
>Boost pressure = [horsepower / bhp per cubic inch displacement / engine displacement] - atmospheric pressure
>boost pressure = [400 / 0.077 / 120.52] – 14.7
>boost pressure = 28.4 psi
*convert to barometric pressure (boost ratio)
>[28.4 + 14.7] / 14.7 = 2.93 bar
-Determine the airflow rate required to sustain combustion at this pressure
Stock airflow rate:
>stock airflow = [engine displacement * peak power rpm * 0.5 (4 stroke engine) * volumetric efficiency] / 1728 (converts cubic inches to cubic feet)
>stock airflow = [120.52 * 4666 * 0.5 * 85%] / 1728
>stock airflow = 138.3 cfm (cubic feet per minute)
*convert to lb/hr:
>138.3 * 0.070318 = 9.7 lb/hr
Required airflow rate under full turbo:
>turbo airflow = pressure ratio * stock airflow
>turbo airflow = 2.93bar * 138.3cfm
>turbo airflow = 410.7cfm
*convert to technicaly correct units lb/hr:
>410.7 * 0.070318 = 28.9 lb/hr
>>Boost ratio = 2.93 bar
>>Airflow = 28.9 lb/hr
This is a good start to determining turbo size.
-larger means greater threshold, more top end
-smaller means lower threshold, less top end
![Image]()
How to read a turbo map:
X-axis is airflow rate in pounds per hour
Y-axis is pressure ratio in barometric pressure
The "islands" are efficiency zones, center being the highest
The lines crossing the islands represent the turbo rpm
Leftmost line is the surge limit, turbo cannot operate past this point
Sketch out your pressure ratio and airflow onto the map (paint works), and draw a diagonal line from the intersection to the stock airflow at 1 Bar. The line should fall as close to the center as possible, easier said than done, but must not cross the surge limit. This is the efficiency of that particular turbo with respect to your engine.
I'm not going to explain what an A/R ratio or trim is, just that a small A/R has a low boost threshold and causes more back pressure at higher output, and a large A/R is the oposite. Trim is the ratio of the inducer/excucer, a smaller trim will be more efficient at higher pressures than a larger trim. Research further to get a better grasp of what exactly you need.
!!!stealing the next several posts to keep all critical information and calculations in one place!!!
What I wanted was a step by step guide to bringing my tiburon upto the power I wanted. There is no such thing to my knowledge. Well.... HERE IT IS! Ok, well it's a general outline. But as I was struggling to crunch the numbers to get what I want from my tib, I I realized that with a little feedback and direction, it really isn't that difficult. If I don't explain something or take for granted that something is known that isn't, just ask.
All the tools you need to work along for your own particular demands are:
-A spreadsheet program or word processor, if you don't have one google Open Office, it is 100% free and compatible with excel. I prefer spreadsheet because once formulas are set you can change one aspect and the rest updates automaticly
-A solid understanding of applied mathematics, don't worry, I'm sure any competent highschool education will be sufficient.
-A copy of Maximum Boost by Corky Bell would be benificial, you can find it here: http://www.newtiburon.com/forums/showthread.php?t=120986
I'll try to be as logical in my layout as possible. Again, feel free to ask and answer questions (stay on topic), we are all learning and all make mistakes.
Vital stats:
2003 Tiburon SE 2.0L
Engine Displacement: 1975cc -or- 120.52 cubic inches
Cylinders: 4
Stroke Length: 93.5mm
Bore: 82mm
Compression Ratio: 10.3
Redline: 7000rpm
Peak Power RPM: 2/3 * Redline = 4666rpm
Ideal Boost Threshold: 1/3 * Redline = 2100rpm
Goal: 400 bhp
Turbo sizing
First we need to select a turbo size, this takes a few steps:
-Determine boost pressure required to get desired hp. *boost pressure and boost ratio are the same, one is metric (ratio, in barometric pressure) and the other in standard imperial (pressure, in pounds per square inch)
>Boost pressure = [horsepower / bhp per cubic inch displacement / engine displacement] - atmospheric pressure
>boost pressure = [400 / 0.077 / 120.52] – 14.7
>boost pressure = 28.4 psi
*convert to barometric pressure (boost ratio)
>[28.4 + 14.7] / 14.7 = 2.93 bar
-Determine the airflow rate required to sustain combustion at this pressure
Stock airflow rate:
>stock airflow = [engine displacement * peak power rpm * 0.5 (4 stroke engine) * volumetric efficiency] / 1728 (converts cubic inches to cubic feet)
>stock airflow = [120.52 * 4666 * 0.5 * 85%] / 1728
>stock airflow = 138.3 cfm (cubic feet per minute)
*convert to lb/hr:
>138.3 * 0.070318 = 9.7 lb/hr
Required airflow rate under full turbo:
>turbo airflow = pressure ratio * stock airflow
>turbo airflow = 2.93bar * 138.3cfm
>turbo airflow = 410.7cfm
*convert to technicaly correct units lb/hr:
>410.7 * 0.070318 = 28.9 lb/hr
>>Boost ratio = 2.93 bar
>>Airflow = 28.9 lb/hr
This is a good start to determining turbo size.
-larger means greater threshold, more top end
-smaller means lower threshold, less top end
How to read a turbo map:
X-axis is airflow rate in pounds per hour
Y-axis is pressure ratio in barometric pressure
The "islands" are efficiency zones, center being the highest
The lines crossing the islands represent the turbo rpm
Leftmost line is the surge limit, turbo cannot operate past this point
Sketch out your pressure ratio and airflow onto the map (paint works), and draw a diagonal line from the intersection to the stock airflow at 1 Bar. The line should fall as close to the center as possible, easier said than done, but must not cross the surge limit. This is the efficiency of that particular turbo with respect to your engine.
I'm not going to explain what an A/R ratio or trim is, just that a small A/R has a low boost threshold and causes more back pressure at higher output, and a large A/R is the oposite. Trim is the ratio of the inducer/excucer, a smaller trim will be more efficient at higher pressures than a larger trim. Research further to get a better grasp of what exactly you need.
!!!stealing the next several posts to keep all critical information and calculations in one place!!!
