need help sizing turbo

g3teg97

Super Moderator
I don't know too much about turbo's, but wouldn't a power goal be in the decision on which turbo to get?
 

GSROWNSU

New Member
g3teg97 said:
I don't know too much about turbo's, but wouldn't a power goal be in the decision on which turbo to get?
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yes you are correct...for instance he could go two ways..a smaller turbo that will spool very quick but will lack in overall peak horsepower (more of a street setup) or a big turbo with a larger trim or a/r ratio that will take a long time to spool but when it does it will hold it's psi level up all the way up to red line which is what you want if your shooting for more hp. What most guys are trying to get is that happy medium between the two.
 

GSROWNSU

New Member
Cheesenip said:
i still say go 50 tim.
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see i think a 50 trim with a .48 a/r would be too small...yes it'll spool quick but i think the psi level would drop as it reaches red line. Guess it's all driver preference.
 

hksb18

GM TECH
would you consider a full race turbo..They say their big trim spools as quickly as the smaller ones..my buddy has one on his 99si n he said it spools nicely n makes power till his foot is through the firewall...plus their kits make good hp on lower boost settings...
http://www.full-race.com/dyno_testing.php They have a selection guide with charts if intrested...
 


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B18TEG

BLACK DA
yea you see guys, im stuck because yes i want the hp, but i do have an ls, so its not going to go to 10 redline, i figure if i go to about 7.6-8k then that'll be pushing it, but i want the turbo to keep going till i cut at that point, but i dont want it to spool so fast that im in boost all the way to work cruising @ 40-45 mph. power wise im looking for about 350-400 at 12 psi for highway and track days, and drive daily at 8psi. atleast thats my mental calc for daily driving. and as far as the full race kit goes yea i wouldlove it and have looked at them but im going full ustom via td autdwerkes in miami fl. they're giving me a great price for it. but i gotta provide the turbo and intercooler. i could let them pick it and thats that but i wnt control over the build and feel good about my choice.
 

hksb18

GM TECH
then i say 57 trim not too small but no too big i think under normal driving conditions youll be fine...the full race one is $615 for just the turbo so you can still do the custom piping and layout..
 
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Cheesenip

I <3 2.4l's
All turbos will drop boost by the time u reach red line
 


B18TEG

BLACK DA
Lol . . .its Fine. . .you Agree Though With A 50 Trim Turbo. I Keep Hearing That Its Not Going To Produce Enough Cfm's For The Motor
 

dc2GS-R

Super Moderator
Well producing 8-12 psi to redline is not hard. I would go slightly bigger personally to give myself head room if I ever wanted more. If you want to just find the perfect size turbo for your engine and leave it at that way, then I would calculate your volumetric efficiency and flow volume of your engine along with the your HP goals and RPM targets. Guesstimating volumetric efficiencies and flow rates are far from guaranteed. That way you can plot your flow volume flow rates along with you RPM and pressure ratio on different compressor maps to find the ideal setup. The way I picked my turbo out was to have my desired pressure ratio at my torque peak right in the most efficient island on the compressor map and to pick a turbo that also holds on to high efficiencies all the way to redline.

For example: GT3037 on my GSX

It's torque peak hits around 4500 rpm's at 16psi at 77% compressor efficiency (+/- 1%) At redline running 24psi it will still happily build boost and be around the 70% efficiency range. Better efficiency creates colder air and less stress on the turbo.

......or you can just guess. I'll probably have time to help you tomorrow if you wanna take a stab at it
 
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