i'm looking into compressor matching. this month's SCC has a big article on it and i'm going by their math to size a turbo.

i can get through the math alright but i'm missing info. i can't find compressor maps for garrett turbos. Nor can i find "compressor inlet temp" for any garrett or mitsu turbos. does anyone know where i could go to find this info?

http://www.turbocharged.com will have a lot of ur garret maps

awesome. thanks!

ok need some help. i'm guaging 6psi st 3800RPM. i'm looking for mid range power on low boost. for pressure ratio i have 1.510 and Corrected Mass Airflow of 48.4065. now according to www.turbochargers.com's compressor maps i need a garret T60 series turbo to acheive 72% efficiency. does this sound right to anyone? sounds off to me. i'm going to do things again and raise my RPM to 5000 and see if that changes my Pr. never mind Pr is desired boost + atmosphere + Intercooler compensation. so unless i raise my boost or increase my pressure loss from the IC i'm not going to get higher Pr.

here's a pic of the hair dryer this math says i need.

I've done the math before and I'll go ahead and tell you what you want.

You want a T3 .48 A/R turbine with a compressor A/R between .42 and .60 (use the .42 since you're boosting low pressure). When you want to up the boost, swap the T3 compressor with a T4 .60 compressor. If you have a choice of wheels, get the "50" trim.

I came up with a 75% efficiency rating when I plotted the 50 trim compressor map matched with the stock 420a. I'm running one on my machine and I can tell you that it makes GREAT power... at low and high boost.

where did you get the formulas? i'm doing the math because my motor won't be stock. i'm going to boost on 10.5 pistons and #14 cranes

please show me where you got your math. after following SCC's "simplified" version i'm sitting with a CMf that seems to high for any reasonably sized turbo yet my pressure ratio is mad low even if i goto 15psi (comes out to 2.1) i'm using 28.4 for my compressor inlet pressure. that's what's on the formulas on turbocharger.com's maps.

This is a simple description of how to read a flow map.

http://www.mercurycapri.com/technical/engine/turbo/htratm.html

Theres alot of Mitsu and a couple of Garrett maps on this page - http://www.stealth316.com/2-3s-compflowmaps.htm There's also alot of good information about reading maps in there as well.


95 Eclipse RS : 5 speed
Jeep TB writeup - http://www.dimensia.com:81/jimbo/JeepTBfor2gnt.html

ok so here it is.

for Pressure Ratio you use
Pr= desired boost + atmosphere (14.7) + 1.5 (to compensate for intercooler) divided by atmospheric pressure

so 7+14.7+1.5=23.2 / 14.7 = 1.5782

than using the forumla on the last link you gave

Airflow = (2/1000)*.9*(desired RPM / 110 )* (desired boost in bar + 1)*(303/360)*146.5

so for 7psi and 5000RPM

*.002*.9*45.454*1.482632*.841667*146.5 = 14.957393 sounds alot better

by these numbers a T3 60 trim is golden at 73% efficiency (as high as it goes)

my only issues are how do i change this to reflect my mods. is 303/360 cams? or should i leave that and use my HP after 10.5 pistons and #14's if the latter than i could use 180HP for the formula and get 9.140811 as my airflow. making a T3 45 trim ideal. guess i should do the short block with 10.5's and the #14's and UDP with the rest of my stuff (intake and 2.5 catback) and get a real HP estimate (dyno time). than plug that into the same formula.

oh yeah. the turbo's i described above are from turbochargers.com. that's the only maps i had to look at. going to check that stealth one now.

reading the map is the easy part. it's like cartesian plane in high school. X is airflow Y is pressure ratio. go to the right to your airflow and up to your pressure ratio. try to land in the circles with higher percentages.

the hard part is working out corrected airflow. the link with the formula i used initially used engine displacement where the one i was linked to used horsepower.

the mitsu map is in CFM. how do i convert 14.957393 lbs/min to CFM convert lbs to feet^3?

basically i have a measurement in Mass / time and i need it changed to Volume / time.

You read that whole site in 4 minutes?


95 Eclipse RS : 5 speed
Jeep TB writeup - http://www.dimensia.com:81/jimbo/JeepTBfor2gnt.html

the important parts. most of it i already knew. went back and figured things out on how to convert lbs/min to CFM. i read well i guess.