Supra Forums banner
1 - 9 of 9 Posts

·
Moderator, l337 M0d3r4t0r
Joined
·
12,263 Posts
Discussion Starter · #1 ·
I've been doing some math here, but some how I just don't believe the math.

I've been using

http://www.lovehorsepower.com/MR2_Docs/compressor_flow_maps.htm
and
http://www.turbobygarrett.com/turbobygarrett/tech_center/turbo_tech103.html

For my cals. I'm trying to get 500 WHP while finding a turbo that will spool 20 PSI by 4000 RPM on a 1jz.

Anyways, here is soemthing I did using photo shop

http://www3.sympatico.ca/zazzn/pics/temp/gt40.psd
If you press F7 and turn the transparenty down you can graph the turbos over the points I have listed.

Anyways, here is some of my math


WA= 64.9236 LB/min air 600 crank 3.25
WA=43.27 LB/min400 Crank
WA=32.45 LB?MIN 300 Crank p2=45 3.43

6000 crank

7800 MAP = 44.81
p2 = 46.81
p2/p1=3.4

8500 map =41.123
p2=43.12
p2/p1=3.14

9000 map =38.83
p2= 40.83
p2/p1=2.98


400 crank
26.3 CFM
4000 MAP = 57.81
p2 = 59.81
p2/p1=4.36

You can also see the math I was using to calc boost at 4000 RPM form the other website.

Something just isn't right, there is no way a 1jz can make 15 PSI at 4000 RPM on a GT42 but yet the calculations say it can? WTF?


http://www.turbobygarrett.com/turbo...argers/gt42_images/GT4294_731376_1_comp_e.gif


PR =2 LB/min at 4000 RPM = 22
 

·
Moderator, l337 M0d3r4t0r
Joined
·
12,263 Posts
Discussion Starter · #4 ·
thanks for the links guys... anyone look at my PSD file??
 

·
Moderator, l337 M0d3r4t0r
Joined
·
12,263 Posts
Discussion Starter · #6 ·
thing is i'm not quite sure how to read the exhaust turbine compressor maps, am I right to assume where the pressure ratio intersects the LB/MIN I will need that much flow going over the exhaust wheel to obtain that boost pressure?

For instance, i'd need about 31 LB/MIN to hit 1 bar of pressure over the exhaust turbine on the following 1.06 housing?

 

·
RRev Motorsports
Joined
·
668 Posts
At a pressure rato of 2.0 the turbine flow will be 31 lb/min for the 1.06 housing. Using the excel file above you will need to adjust the turbine pressure ratio at each RPM increment until you get a turbine flow (lb/min) that lies on the turbine swallowing lines for each turbine housing.

The excel file is also setup so that once you have your compressor boost pressure desired, and turbine swallowing capacity inputted at each RPM increment you can determine if the boost pressure is possible (Calc % of WG - green) or if you are not extracting enough power from the turbine to reach the desired boost pressure (Calc % of WG - red). To get the best idea of what your spool characteristics will be you should adjust until Calc % of WG ~ 0 %. This takes alot of iteration but it can be quite good at estimating spool.

Note: I also noticed that the exhaust backpressure on the above file is probably too high for use of a Supra, I would recommend that exhaust backpressure = (0-3 psi).
 

·
Moderator, l337 M0d3r4t0r
Joined
·
12,263 Posts
Discussion Starter · #8 · (Edited)
how do i adjust the excel file for 2.5 L?


** NM I figured it out**
 
1 - 9 of 9 Posts
Top