Moreboost.org - Turbo Sizing

Steve's Toyota Supra Turbo
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Turbo Notes (Chart, Detail)

Turbo Visual Comparisons - Surge Line Comparisons - GT info

see the Calcs page for the "why"

note that many of the SP turbos have custom cast housings

SAE J1349 Revision JUN90 corrections are preferred to STD and uncorrected.

SAE corrects the run to the following atmospheric conditions:

29.235" Hg, 77 deg F, 0 % relative humidity, 0 altitude

C_f = 1.18 * (29.235 / (BP - V_p) * (T + 460) ^ 1/2 / 537) - 0.18

C_f = correction factor, BP = barometric pressure, V_p = vapor pressure, T = temperature in degrees Fahrenheit?

SAE can return a lower rwhp than uncorrect (or sometimes STD) For example, if the run is made in colder than standard temps and/or at higher than standard pressure someone might try to avoid SAE correction and report a higher number to thereby increase the boast factor and/or mislead their clients.

the bottom line: choose SAE correction for your dyno runs to try to remove environmental factors from the data and make your data useful in comparisons with others

Download the Dynojet viewer

Relative Horsepower Calculator - useful to determine Cf

Clint P.'s SAE J1349 Calculator adjusted for forced induction

Weather Underground for historical weather conditions

Problem Notes:

T62-1: at high boost pressures (>~26 psi) it requires a larger flow of air than the 2JZ can support to avoid surge according to calculations.

T64: seems to require a larger flow of air than the 2JZ can support to avoid surge according to calculations. However this turbo is used by several people with manual transmissions with success (shorter gears = less rpm drop on the 1-2 shift to help avoid the problematic high 3k, low 4k range when airflow is low).

T68-1: requires a larger flow of air than the 2JZ can support to avoid surge according to calculations.

T70: requires a larger flow of air than the 2JZ can support to avoid surge according to calculations. In fact, this turbo is so far from being usable according to calcs that I cannot imagine anyone trying it.

T76: at high boost pressures it requires a *much* larger flow of air than the 2JZ can support to avoid surge according to calculations. The surge line, max supported PR, and max flow of the T72 is superior to the T76.

T88: at high boost pressures it requires a *much* larger flow of air than the 2JZ can support to avoid surge according to calculations. Of course this isn't a problem if the turbo doesn't spool until 8k rpms. ;)

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last modified on Saturday, January 19, 2008

	T62-1: at high boost pressures (>~26 psi) it requires a larger flow of air than the 2JZ can support to avoid surge according to calculations.
	T64: seems to require a larger flow of air than the 2JZ can support to avoid surge according to calculations. However this turbo is used by several people with manual transmissions with success (shorter gears = less rpm drop on the 1-2 shift to help avoid the problematic high 3k, low 4k range when airflow is low).
	T68-1: requires a larger flow of air than the 2JZ can support to avoid surge according to calculations.
	T70: requires a larger flow of air than the 2JZ can support to avoid surge according to calculations. In fact, this turbo is so far from being usable according to calcs that I cannot imagine anyone trying it.
	T76: at high boost pressures it requires a much larger flow of air than the 2JZ can support to avoid surge according to calculations. The surge line, max supported PR, and max flow of the T72 is superior to the T76.
	T88: at high boost pressures it requires a much larger flow of air than the 2JZ can support to avoid surge according to calculations. Of course this isn't a problem if the turbo doesn't spool until 8k rpms. ;)