Almost done 97 fuel rail conversion
Thread Starter
Le Mans Master
Joined: Oct 2001
Posts: 5,577
Likes: 3
From: Southern Maryland Maryland
Almost done 97 fuel rail conversion
I am almost done swapping out the 99 fuel rail for the 97 + return line. The parts are readily available and the biggest hassle was routing the return line around the bell housing and the pesky clamps that hold the lines in place. I need to order the 97 fuel supply braided line because the 99 is definitely too short for my taste. Will report back once its all finished
Veteran
Joined: Jan 2000
Posts: 2,082
Likes: 1
From: Louisville KY
Re: Almost done 97 fuel rail conversion (Phil97SVT)
I am almost done swapping out the 99 fuel rail for the 97 + return line. The parts are readily available and the biggest hassle was routing the return line around the bell housing and the pesky clamps that hold the lines in place. I need to order the 97 fuel supply braided line because the 99 is definitely too short for my taste. Will report back once its all finished
GM went from double lines to a single line and you're doing just the opposite.
What's the advantage?
Thanks
Thread Starter
Le Mans Master
Joined: Oct 2001
Posts: 5,577
Likes: 3
From: Southern Maryland Maryland
Re: Almost done 97 fuel rail conversion (ROCKnROLL)
Why are you changing it out?
The return style fuel system will handle roughly 50-150 more RWHP and have consistent fuel pressure
GM went from double lines to a single line and you're doing just the opposite.
What's the advantage?
Higher Horsepower capabilities
Thanks
The return style fuel system will handle roughly 50-150 more RWHP and have consistent fuel pressure
GM went from double lines to a single line and you're doing just the opposite.
What's the advantage?
Higher Horsepower capabilities
Thanks
Veteran
Joined: Jan 2000
Posts: 2,082
Likes: 1
From: Louisville KY
Re: Almost done 97 fuel rail conversion (Phil97SVT)
Why are you changing it out?
The return style fuel system will handle roughly 50-150 more RWHP and have consistent fuel pressure
GM went from double lines to a single line and you're doing just the opposite.
What's the advantage?
Higher Horsepower capabilities
Thanks
The return style fuel system will handle roughly 50-150 more RWHP and have consistent fuel pressure
GM went from double lines to a single line and you're doing just the opposite.
What's the advantage?
Higher Horsepower capabilities
Thanks
I didn't realize it could make such a difference!
So I guess GM made the change because it was cheaper (saved them money)?
Drifting
Joined: Apr 2003
Posts: 1,764
Likes: 31
From: Fort Collins CO
Re: Almost done 97 fuel rail conversion (ROCKnROLL)
So I guess GM made the change because it was cheaper (saved them money)?
-Jake
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Veteran
Joined: Jan 2000
Posts: 2,082
Likes: 1
From: Louisville KY
Re: Almost done 97 fuel rail conversion (JakeL)
So I guess GM made the change because it was cheaper (saved them money)?
Emissions. Hot gasoline in a line returning to the tank makes a lot more vapor than relatively cooler gas in just one line.
-Jake
Emissions. Hot gasoline in a line returning to the tank makes a lot more vapor than relatively cooler gas in just one line.
-Jake
Burning Brakes
Joined: Sep 2001
Posts: 1,173
Likes: 1
From: Aguila AZ
Re: Almost done 97 fuel rail conversion (Phil97SVT)
Can you please explain why the '97-'98 fuel system would have higher flow (HP) capasity... Both the early and late systems use the same diameter fuel delivery line... The only difference is the point where the return line is located. I just made the opposite conversion (early to late fuel system) and I am very familier with the lines and systems.
Please advise as to who did the testing and what data is available to back up this claim... I don't see the high output C5 guys doing this change... Most people install a higher capasity fuel pump if additional capasity is needed. I'm very skeptical.
Shirl
SDRE
Please advise as to who did the testing and what data is available to back up this claim... I don't see the high output C5 guys doing this change... Most people install a higher capasity fuel pump if additional capasity is needed. I'm very skeptical.
Shirl
SDRE
Burning Brakes
Joined: Nov 1999
Posts: 1,221
Likes: 59
From: Abingdon VA
Re: Almost done 97 fuel rail conversion (MrEracer)
Shirl, the advantage is properly controlling the pressure drop at the injector. The returnless system has the regulator located at the filter and controls the drop at that location....you may show 60 psi there, but under high pump flow the pressure at the injector will drop lower as the regulator is too far back to properly control line loss,accel,boost pressure (if boosted).
The lines are the same size,etc so a constant flow would be the same.
But with an improved pump,boost,etc, the regulator needs to be located as close to the injector as possible to maintain the tuned psi at the injector.
If your tune is for 60psi at the injector and you have 60psi at the filter you may drop off to 55 psi at the injector and throw the tune lean.
LPE does it for the high hp boosted cars to maintain 60psi under boost with a boost referenced regulator as you will lose fuel psi per boost psi. 60psi fuel - 10psi boost = 50psi at the injector = lean. :cheers:
The lines are the same size,etc so a constant flow would be the same.
But with an improved pump,boost,etc, the regulator needs to be located as close to the injector as possible to maintain the tuned psi at the injector.
If your tune is for 60psi at the injector and you have 60psi at the filter you may drop off to 55 psi at the injector and throw the tune lean.
LPE does it for the high hp boosted cars to maintain 60psi under boost with a boost referenced regulator as you will lose fuel psi per boost psi. 60psi fuel - 10psi boost = 50psi at the injector = lean. :cheers:
Burning Brakes
Joined: Sep 2001
Posts: 1,173
Likes: 1
From: Aguila AZ
Re: Almost done 97 fuel rail conversion (onfire)
Thanks for the explination Tom... As I suspected, it is not a fuel flow capasity (HP limiting) problem and as you have explained it is a pressure regulation/variation problem... In most NA cases the tune is correctly established with a wide band 02 sensor in conjunction with IFR and PE modifications that will compensate for any low pressure (lean) conditions that may be occuring across the rpm band... I do not see the need for using the '97-'98 fuel system if the engine is tuned in this way...
In applications where rwhp is above 600 or in boosted applications all bets are off since line size may not be adequite and fuel pressure variation must be minimized. In such a cases I would use aftermarket regulators, boost pumps and larger fuel lines rather than either the early or late factory system. BTW, the original premis of this thread was that the early system would allow for higher HP than the late system and I think that your comments and mine have shown that this is not the case... :cheers:
Shirl
SDRE
In applications where rwhp is above 600 or in boosted applications all bets are off since line size may not be adequite and fuel pressure variation must be minimized. In such a cases I would use aftermarket regulators, boost pumps and larger fuel lines rather than either the early or late factory system. BTW, the original premis of this thread was that the early system would allow for higher HP than the late system and I think that your comments and mine have shown that this is not the case... :cheers:
Shirl
SDRE
