HOW MUCH BOOST IS MY TURBO GOOD FOR THAT IS THE QUESTION!

[Ted Jannetty]

Turbochargers are not rated by boost, they are rated by pressure ratio.

Example would be 2:1, this mean 2 X what ever the inlet pressure is or in our case atmosphere.

If a turbo was rated at 2:1 then at sea level it would be capable of maintaining 14.7 psi boost or 29.4 absolute pressure.

At altitude the same turbo would not be able to maintain this level of pressure because the inlet pressure is lower.

boost is a product of restriction, so in other words the same turbo on a smaller motor would be able to maintain higher boost levels and the opposite it true for a larger motor.

The motor is the restrictor.

Are you with me so far?

Now Turbos are also rated at lb. of air per minute at each pressure ratio this is how they come up with compressor maps.

The lbs. per minute of air determines HP. each lb. of air per minute can produce roughly 9.5 to 10.5 hp depending on how efficient the motor is.

There for; 30 lbs. of air per minute is roughly 300 hp.

So in closing every turbo has a specific HP range where it is efficient.

This is just a breif and I mean Breif overview of how to rate a turbo.

I hope this information is helpful the next time someone asks the question.

 

[HAMMER]

Here’s some educational material I've collected during my research...

http://www.bentleypublishers.com/galler ... leryId=805

http://www.rbracing-rsr.com/turbotech.html#mitsu

http://www.rbracing-rsr.com/compression.htm

http://www.stealth316.com/2-turboguide.htm

http://not2fast.com/turbo/glossary/turbo_calc.shtml

http://www.squirrelpf.com/turbocalc/old ... 2_beta.xls

http://www.squirrelpf.com/turbocalc/index.php

ALTITUDE

Elev --- PSI

0 ------ 14.7
500 --- 14.4
1000 -- 14.2
1500 -- 13.9
2000 -- 13.7
2500 -- 13.4
3000 -- 13.2
3500 -- 12.9
4000 -- 12.7
4500 -- 12.4
5000 -- 12.2
5500 -- 12.0
6000 -- 11.8
6500 -- 11.5
7000 -- 11.3
7500 -- 11.1
8000 -- 10.9
8500 -- 10.7
9000 -- 10.5
9500 -- 10.3
10000 - 10.1

All engines are subject to Relative Air Density.........even boosted.

http://wahiduddin.net/calc/calc_hp.htm

Example:

Atmospheric Pressure = 14.7psi + 10psi boost = 24.7
Atmospheric Pressure @ 8500ft feet = 10.7psi + 10psi boost = 20.7psi
Pressure Loss = 24.7-20.7 = 4.0 --- 4/24.7 = 16.1% @ 8,500 feet

As altitude is increased the impeller must increase rpm to maintain target boost pressure. With large displacement high horsepower engines the impeller may have to spin faster than is efficient, resulting in a loss of horsepower.

 

[HYFLYR]

Once again thank you Hammer and Ted. You guys are always sharing your knowledge and helping the rest of us common folk understand what we are really doing to our sleds, Thank you!

 

[Otis RX]

Love the information.
I'll be down to see you soon Ted.