VRP vs Fabtech looped fuel rail - which one?
MBWorld Fanatic!
Joined: Sep 2006
Posts: 1,921
Likes: 173
From: Long Island New York
2003 SL55,2020 GTC ,2017 GTS sold ,2002 G500 Sold,2003 SL500 Sold,
Wow surprised nobody commented,
I did an experiment a few years ago because the drivers side was always leaner then the passenger side, initially the looped rail evened that out ,but when I kept increasing the boost it went back ,now at high boost levels and a dual feed dual pump set up and even as high as 90 psi WOT it is still leaner on the drivers side ,wierd, I have an SL but that amount of fuel and pressure you would think that wouldn’t happen, did it on pump,race and C85 fuels.can be as high as .7 dif , 11.5 AFR pass side,12.2 AFR drivers side ,yes changed out 02 s and Widebands .Also did it with 550 ,750,1000cc injectors.
I did an experiment a few years ago because the drivers side was always leaner then the passenger side, initially the looped rail evened that out ,but when I kept increasing the boost it went back ,now at high boost levels and a dual feed dual pump set up and even as high as 90 psi WOT it is still leaner on the drivers side ,wierd, I have an SL but that amount of fuel and pressure you would think that wouldn’t happen, did it on pump,race and C85 fuels.can be as high as .7 dif , 11.5 AFR pass side,12.2 AFR drivers side ,yes changed out 02 s and Widebands .Also did it with 550 ,750,1000cc injectors.
Last edited by cnterline; Dec 14, 2018 at 01:28 PM.
Super Member
Joined: Nov 2017
Posts: 922
Likes: 164
From: Virginia
N/A
Wow surprised nobody commented,
I did an experiment a few years ago because the drivers side was always leaner then the passenger side, initially the looped rail evened that out ,but when I kept increasing the boost it went back ,now at high boost levels and a dual feed dual pump set up and even as high as 90 psi WOT it is still leaner on the drivers side ,wierd, I have an SL but that amount of fuel and pressure you would think that wouldn’t happen, did it on pump,race and C85 fuels.can be as high as .7 dif , 11.5 AFR pass side,12.2 AFR drivers side ,yes changed out 02 s and Widebands .Also did it with 550 ,750,1000cc injectors.
I did an experiment a few years ago because the drivers side was always leaner then the passenger side, initially the looped rail evened that out ,but when I kept increasing the boost it went back ,now at high boost levels and a dual feed dual pump set up and even as high as 90 psi WOT it is still leaner on the drivers side ,wierd, I have an SL but that amount of fuel and pressure you would think that wouldn’t happen, did it on pump,race and C85 fuels.can be as high as .7 dif , 11.5 AFR pass side,12.2 AFR drivers side ,yes changed out 02 s and Widebands .Also did it with 550 ,750,1000cc injectors.
Like the avatar, -Ghost in the Machine. Great album.
MBWorld Fanatic!
Joined: Sep 2006
Posts: 1,921
Likes: 173
From: Long Island New York
2003 SL55,2020 GTC ,2017 GTS sold ,2002 G500 Sold,2003 SL500 Sold,
MBWorld Fanatic!
Joined: Jul 2014
Posts: 3,328
Likes: 586
2005 e55 AMG
I ran dual wide bands and saw the same thing. What I did was run a number 8 steel line from the pumps to the center of the rail,looped it ,ran a regulator and then a return line back to the tank. I also removed the in tank fuel filter and run an inline at the rail.My pressures are only around 65-70psi under boost but the side to side difference is much better now. Not sure what really contributed to it since I changed a lot.
Last edited by SICAMG; Dec 15, 2018 at 09:55 AM.
Trending Topics
MBWorld Fanatic!
Joined: Sep 2006
Posts: 1,921
Likes: 173
From: Long Island New York
2003 SL55,2020 GTC ,2017 GTS sold ,2002 G500 Sold,2003 SL500 Sold,
I ran dual wide bands and saw the same thing. What I did was run a number 8 steel line from the pumps to the center of the rail,looped it ,ran a regulator and then a return line back to the tank.My pressures are only around 65-70psi under boost but the side to side difference is much better now. Not sure what really contributed to it since I changed a lot.
MB World Stories
The Best of Mercedes & AMG
6 Mercedes Models That Did NOT Age Well (But Are Somehow Still Cool)
Verdad Gallardo
Manual Mercedes? 6 Times Sindelfingen Let Drivers Have All The Fun
Verdad Gallardo
Mercedes SLR McLaren 722 S Is Extremely Rare Example Modified by McLaren
Verdad Gallardo
8 Classic Boxy Mercedes Designs That Have Aged Like Fine Wine
Verdad Gallardo
Flawlessly Restored Mercedes 190E Evo II Heads to Auction
Verdad Gallardo
Electric Mercedes C-Class Unveiled: 11 Things You Need to Know
Verdad Gallardo
Mercedes EQS Gets A Major Update: Everything You Need to Know
Verdad Gallardo
5 Underrated Mercedes-Benz Models That Don't Get the Love They Deserve
Verdad Gallardo
Mercedes 300D Has Pushed Well Past 1 Million Miles and It Ain't Stopping
Verdad Gallardo
MBWorld Fanatic!
Joined: Aug 2011
Posts: 3,428
Likes: 288
From: New Zealand
My understanding was that most of the lean issues over the years were finally attributed to poor fuel pressure from clogged fuel filters and failing pumps drawing too much current. For people with mild to moderate mods at least. Everyone seems pretty on to it with fuel filter maintenance these days.
MBWorld Fanatic!
Joined: Sep 2006
Posts: 1,921
Likes: 173
From: Long Island New York
2003 SL55,2020 GTC ,2017 GTS sold ,2002 G500 Sold,2003 SL500 Sold,
MBWorld Fanatic!
Joined: Aug 2012
Posts: 1,790
Likes: 109
From: DownEast Maine
CLS 55 AMG E500 ML320
I'm curious about this. When I had the blower off the first time I noticed the air is concentrated to one side by the noise reduction casting and the rotor design. I also noticed that if I made it a single pass cooler, one side would be colder, always having the incoming water. Not sure what your setup looks like exactly, but is it possible you have an air difference? Either flow or temperature?
MBWorld Fanatic!
Joined: Sep 2006
Posts: 1,921
Likes: 173
From: Long Island New York
2003 SL55,2020 GTC ,2017 GTS sold ,2002 G500 Sold,2003 SL500 Sold,
I'm curious about this. When I had the blower off the first time I noticed the air is concentrated to one side by the noise reduction casting and the rotor design. I also noticed that if I made it a single pass cooler, one side would be colder, always having the incoming water. Not sure what your setup looks like exactly, but is it possible you have an air difference? Either flow or temperature?
MBWorld Fanatic!
Joined: Jul 2014
Posts: 3,328
Likes: 586
2005 e55 AMG
I don't think any one will ever have a problem if you run richer than normal. I am always at 10.5 to 11.1 depending on temps. Am I leaving power on the table ? Sure. Did my engine look perfect inside after 3 years of killing it ....YES !
cnterline your car run's real well.....like beyond most anyone so your AFR must be perfect for your engine to live through every pass !
I also wonder if your car would start to go a little leaner if you did a 1/2 mile event where more heat is being accumulated over a longer period of time. That's the boat I am in.
cnterline your car run's real well.....like beyond most anyone so your AFR must be perfect for your engine to live through every pass !
I also wonder if your car would start to go a little leaner if you did a 1/2 mile event where more heat is being accumulated over a longer period of time. That's the boat I am in.
Member
Joined: Mar 2021
Posts: 166
Likes: 17
From: Long Island, New York
2006 SL55 AMG
To answer your question directly - I just ordered a looped rail from Fabtech. Whether I need it or not, don't care. The $700 spent is insurance to me. Do I need hurricane insurance, probably not, but I have weather-related insurance on my house. The reason why I went with FabTech over VRP is twofold - customer service and that fact that FabTech uses a NEW OEM fuel rail in order to make the modification instead of asking for a core. I don't want someone else modified garbage. I would rather get new because I can. That's my answer.
