Long tube headers with cats and X pipe
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Joined: Dec 2019
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From: Elko, NV
2004 E55, 2001 GMC Sonoma ZR2, 2000 Dodge Dakota, 1977 Dodge W100, 1972 Dodge Challenger
Long tube headers with cats and X pipe
Has anyone noticed better fuel economy with long tube headers and an X pipe? It's an easier sale if I can justify it with more mpg's.
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Junior Member
Joined: Dec 2019
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From: Elko, NV
2004 E55, 2001 GMC Sonoma ZR2, 2000 Dodge Dakota, 1977 Dodge W100, 1972 Dodge Challenger
Ah yes, the example of the difference between a Mercedes and a porcupine.
Anyone with an actual answer? I know you don't typically buy these cars for their fuel economy, but again, it's an easier justification for the expense if I can save money elsewhere.
Anyone with an actual answer? I know you don't typically buy these cars for their fuel economy, but again, it's an easier justification for the expense if I can save money elsewhere.
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CLS55 AMG
I had the same thought you did RE: headers and shared my thoughts in my build thread in the CLS55 section. Long story short, with the headers, 83mm pulley, and tune, I upgraded my injectors to 550s for safety and took a slight hit to fuel economy in the process. My car computer says that i'm getting 19-20mpg but the hand calculations show closer to 17-18.
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Junior Member
Joined: Dec 2019
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From: Elko, NV
2004 E55, 2001 GMC Sonoma ZR2, 2000 Dodge Dakota, 1977 Dodge W100, 1972 Dodge Challenger
Thanks for the reply. Nothing is free. More air moving through the engine generally equates to needing more fuel. Plenty of other things to worry about on this car right now before I dive into exhaust. Still though, I wonder if stock pulley, stock engine with headers would net some sort of mpg improvement, if only because the engine isn't working as hard. Guess I will have to be the guinea pig...
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'03 Brabus E55 K8, '11 C300 4matic
The biggest change I've seen is huge drop in engine bay temp. I don't know how much of that is longtubes and how much is the heat blanket we put on em. Don't much care. Radiator fan is working no where Near as much as it used to.
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Thread Starter
Junior Member
Joined: Dec 2019
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From: Elko, NV
2004 E55, 2001 GMC Sonoma ZR2, 2000 Dodge Dakota, 1977 Dodge W100, 1972 Dodge Challenger
Just have to come up with another plan to convince my wife, lol.
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From: OC, CA
2006 E55
I was cruising with 26 mpg going home from the drag strip. Normal fwy driving in 80s mph I averaged 18-22 gallons. I saw a big jump on mpg from stock to mods. I have following mods: 72mm FSP, 82mm TB, LTH, x pipe no cats, 550 cc injectors, BWK, upgrade superflo ic pump, RaceIQ ECU, split cooling with bay tank. KnN filters with spacers, C63 mufflers, & Killer Chiller with Drag Kit
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CLS55 AMG
I was cruising with 26 mpg going home from the drag strip. Normal fwy driving in 80s mph I averaged 18-22 gallons. I saw a big jump on mpg from stock to mods. I have following mods: 72mm FSP, 82mm TB, LTH, x pipe no cats, 550 cc injectors, BWK, upgrade superflo ic pump, RaceIQ ECU, split cooling with bay tank. KnN filters with spacers, C63 mufflers, & Killer Chiller with Drag Kit
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From: Sweden
W211 e500 (Sold), w204 c180, w203 c180, w201 190e, W219 CLS 55
I believe your engine will live longer with long tube due to less heat. Is bigger injectors mandatory when you only run smaller sc pulley and longtube?
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From: NZ
2004 E55 AMG, 2006 CLS63, 2004 ML55, 2014 E350 sport
You are also on the money about less heat and stress on the engine.
If you look at the biturbo 5.5 v8 they have issues with bending rods due to the size of the turbo and restrictive log manifolds but mainly due to the rod design on those. And most owners of those will likely never know they bent a rod even on the stock engine without boosting it up and are wondering why their oil consumption is all up the ****.
Luckily for us MB put stout rods in these m113k engines otherwise we'd be likely seeing similar problems to above with that ridiculous factory log manifold and people boosting these things up to ridiculous numbers.
I was cruising with 26 mpg going home from the drag strip. Normal fwy driving in 80s mph I averaged 18-22 gallons. I saw a big jump on mpg from stock to mods. I have following mods: 72mm FSP, 82mm TB, LTH, x pipe no cats, 550 cc injectors, BWK, upgrade superflo ic pump, RaceIQ ECU, split cooling with bay tank. KnN filters with spacers, C63 mufflers, & Killer Chiller with Drag Kit
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From: OC, CA
2006 E55
However, there’s one 313 miles trip I made with average speed of 80-85 mph on 19” CLS63 wheels 245/35/19 & 275/30/19 I saw 24 mpg.
btw, I just installed a 3000 high stall torque converter today so I’m not sure how that will effect mpg.
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CLS55 AMG
I've been doing that on every fill up for almost a year and noticed the 10% difference in MPG after upgrading to 550cc injectors and tune.
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CLS55 AMG
Are you talking about the "After Reset" screen? That is the one I primarily use since I'll reset the trip computer on that screen at every fill up and use that screen to see what the car thinks MPG is between tanks. That is the screen that I see off by 9-10%.
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From: OC, CA
2006 E55
Try completely filling the tank and write down the mileage on the odometer at the time. Then, the next time you fill up the tank subtract the previous odometer reading from the current one to get the number of miles driven between fill ups. Now take the number of miles driven and divide it by the number of gallons it took to fill the tank up. That should get you a more accurate miles per gallon than relying on the car's trip computer.
I've been doing that on every fill up for almost a year and noticed the 10% difference in MPG after upgrading to 550cc injectors and tune.
I've been doing that on every fill up for almost a year and noticed the 10% difference in MPG after upgrading to 550cc injectors and tune.
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CLS55 AMG
Thread Starter
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From: Elko, NV
2004 E55, 2001 GMC Sonoma ZR2, 2000 Dodge Dakota, 1977 Dodge W100, 1972 Dodge Challenger
I once reset the mileage computer while driving in a 55 mph zone. I kept it below 65 and didn't use the cruise control. Was able to see 29-30 on the screen. Once I got back into 75-80 zones, it averaged out to right at 25. Doing the math, I want to say I saw 23-24, so it's fairly close. Also, it's extremely difficult to go between fill ups and not open this car up. Not conducive to good mileage at all. But that wasn't really why I bought it anyways. I think I will keep my eyes open for a diesel W211 down the road for the trips where mileage is a concern.
Senior Member
Joined: Nov 2018
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CLS55 AMG
I once reset the mileage computer while driving in a 55 mph zone. I kept it below 65 and didn't use the cruise control. Was able to see 29-30 on the screen. Once I got back into 75-80 zones, it averaged out to right at 25. Doing the math, I want to say I saw 23-24, so it's fairly close. Also, it's extremely difficult to go between fill ups and not open this car up. Not conducive to good mileage at all. But that wasn't really why I bought it anyways. I think I will keep my eyes open for a diesel W211 down the road for the trips where mileage is a concern.
Thread Starter
Junior Member
Joined: Dec 2019
Posts: 18
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From: Elko, NV
2004 E55, 2001 GMC Sonoma ZR2, 2000 Dodge Dakota, 1977 Dodge W100, 1972 Dodge Challenger
Super Member
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Posts: 699
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From: OC, CA
2006 E55
@MSG 55G Have you had a chance to run some hand calculated mileage numbers?
