65Z01...or anyone....
Thread Starter
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From: Granby, MA
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65Z01...or anyone....
65Z01
quote: originally from 65Z01
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I hope you bumped your fuel pressure 2-4 psi with the added air flow.
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I don't have an adjustable fuel pressure regulator on the car. Seeing my car is 1990, thought that becuase it is speed density controlled that bumping up the fel pressure would do nothing....
is it because I went to 2.5 inch pipe that I need to bump up the fuel pressure or is it because I did away with the pre-cats?
Jeff
quote: originally from 65Z01
------------------------------------------------------------------------
I hope you bumped your fuel pressure 2-4 psi with the added air flow.
------------------------------------------------------------------------
I don't have an adjustable fuel pressure regulator on the car. Seeing my car is 1990, thought that becuase it is speed density controlled that bumping up the fel pressure would do nothing....
is it because I went to 2.5 inch pipe that I need to bump up the fuel pressure or is it because I did away with the pre-cats?
Jeff
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Joined: Sep 2001
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From: Athens AL
C7 of the Year - Unmodified Finalist 2021
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Re: 65Z01...or anyone.... (XtremeVette)
Both would flow more air, but the bigger pipe would be the the major source. Bumping up the fuel pressure would only optimize performance.
Safety Car
Joined: Dec 2000
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From: Jacksonville Fl
Re: 65Z01...or anyone.... (XtremeVette)
Being that it is speed density controlled means any mod WILL require some type of tuning compensation since there is no MAF sensor to tell the ecm how much air the engine is getting.
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From: SE NY
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Re: 65Z01...or anyone.... (XtremeVette)
As stated when you remove restrictions in the exhaust system air flow increases through the engine and you need to compensate by adding more fuel.
Though you don't have a MAF there is indeed more air flowing. The ECM will compensate at part throttle while in closed loop mode by using input from the O2 sensor.
At WOT the ECM goes into open loop mode and ignores O2 sensor data. Here it will use other sensor data and stored data to control injector pulse width.
So when increasing fuel presssure by 2-4psi (about a 5-10% increase) you will increase fuel flow by about 2-4% at WOT.
Indeed an AFPR can be used to tune fuel flow even with a SD L98.
Though you don't have a MAF there is indeed more air flowing. The ECM will compensate at part throttle while in closed loop mode by using input from the O2 sensor.
At WOT the ECM goes into open loop mode and ignores O2 sensor data. Here it will use other sensor data and stored data to control injector pulse width.
So when increasing fuel presssure by 2-4psi (about a 5-10% increase) you will increase fuel flow by about 2-4% at WOT.
Indeed an AFPR can be used to tune fuel flow even with a SD L98.
