turtleman
Expert
Name : Codith
Age : 37
Location : Villa Park, IL
Joined : 2007-02-08
Post Count : 3671
Merit : 140
 | | Subject: lost my boost Fri Nov 09, 2007 12:24 pm | |
| I noticed that since I got the 3in DP and 3in exhaust in, my boost dropped from about 12psi peak to 10psi peak. I expected this but do I want to compensate with a smaller pulley to bring it back up to 12psi or should I just play it safe and accept 10psi as a target boost range for my current mods and consider 12psi too high? | |
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AA
Administrator
Name : Aaron
Age : 47
Location : C-bus, Ohio
Joined : 2007-01-13
Post Count : 18452
Merit : 252
| | Subject: Re: lost my boost Fri Nov 09, 2007 12:38 pm | |
| If no KR with 10 PSI, drop the pulley size.
With the new exhaust, boost goes down, and flow is up. You're pushing about the same amount of air through the system with less boost. But if you can drop the pulley size, now you're moving more air, and that's where power gains can be found. _________________ '05 GTO 6.0L • 6-spd • 95k miles • 0-60: 4.8s • 16.9 avg MPG • Nelson Ledges Lap: 1:26'95 Celica GT 2.2L • 5-spd • 165k miles • 0-60: yes'98 SC Riviera • 281k miles • 298 HP/370 TQ • 0-60: 5.79s • ET: 13.97 @ 99.28 • 4087 lb • 20.1 avg MPG • Nelson Ledges Lap: 1:30
3.4" pulley • AL104 plugs • 180º t-stat • FWI w/K&N • 1.9:1 rockers • OR pushrods • LS6 valve springs • SLP headers • ZZP fuel rails
KYB GR2 struts • MaxAir shocks • Addco sway bars • UMI bushings • GM STB • Enkei 18" EV5s w/ Dunlop DZ101s • F-body calipers
EBC bluestuff/Hawk HP plus • SS lines • Brembo slotted discs • DHP tuned • Aeroforce • Hidden Hitch^^^ SOLD ^^^  '70 Ninety-Eight Holiday Coupe 455cid • 116k miles^^^ SOLD ^^^ | |
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deekster_caddy
Master
Name : Derek
Age : 52
Location : Reading, MA
Joined : 2007-01-31
Post Count : 7717
Merit : 109
| | Subject: Re: lost my boost Fri Nov 09, 2007 1:20 pm | |
| 'boost' is a relative term. It means you are pushing more air than the engine can use, thus building up pressure. If you are now allowing the engine to use that air better, your 'boost' number goes down, even though your airflow didn't change that much.
It means you can go to a smaller pulley IF everything is running safely at your current 'boost' level. If your 'boost' gets too high, you need something else to get rid of more air (camshaft, bigger valves, better heads, etc...) | |
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97rivman
Fanatic
Name : alex
Age : 38
Location : Crete,IL
Joined : 2007-06-09
Post Count : 484
Merit : 2
| | Subject: Re: lost my boost Fri Nov 09, 2007 1:21 pm | |
| hence the reason i barely got 5 psi on my motor with a GEN V and a stock pulley  | |
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