Bigger Fuel Injectors? - PeachParts Mercedes-Benz Forum

S5LorinserF1 · #1 02-13-2009, 01:25 AM

Can the 55 fuel injectors be used in the 500 m113??

what are positives of this and would a retune be needed?

JayRash · #2 02-13-2009, 02:00 AM

Just a hint, am no expert on those cars, but if u do the change, am sure u will need a retune. ok the ecu needs to know an approximate number of the injector size at least that’s how it is in Mitsubishi cars, then you ave fuel trim tables that adjust according to the O2 sensor readings.

go with a bigger injector and the fuel trims will need to work alot more, now in open loop i have no idea how the car would react, but am mostly certain you'll loose power since your running rich. from experience i can tell you that running on AFR 10.5 gives much less power than AFR 12.5.
no point in increasing injectors if everything else on your car is stock

Turbo E320 · #3 02-13-2009, 02:13 AM

They will fit and the computer will just dial them back since it will keep the AFR's in the 14.7 range when your driving normally due to the o2 sensor. I had 30lbs/hr injectors in my e320 before it was tuned and it ran fine. If anything your car may run a bit better on the open loop(floored, o2 sensors not dictating AFR) since the motors run so lean stock and since the lbs/hr or cc/min difference between a 55 and a 500 injector isn't that much.

S5LorinserF1 · #4 02-13-2009, 02:32 AM

nothing is stock on the car.

Evosport Headers
Evosport Undrive Pulley
Evosport Performance Ignition w/Denso Iridium Plugs 8mm wires
55k Airbox w/Green Filters
Secondary Cat delete w/3inch Center elongated X-pipe.
Custom quad exhaust with DMH exhaust bypass

LET custom Dyno tune coming Feb 28.

just wanted to get the best injectors possible in there as i dont think the stock ones are so great

S5LorinserF1 · #5 02-13-2009, 02:34 AM

whats the lbs difference btwn the 55 and 500 injectors.

also what are the best performance injectors for the car??

Turbo E320 · #6 02-13-2009, 03:04 AM

20.7 lbs/hr at 43.5psi for the NA s55, e55, c43, etc. Bosch 0-280-155-839 fuel injector.

EDIT: 19.0 lbs/hr at 43.5psi for the m113 non amg 5.0 and 4.3 enignes. Bosch 0-280-155-744 fuel injector.

Seriously Mercedes uses the tiniest fuel injectors possible. I think your Mercedes runs 54psi of fuel pressure so figure 25 lbs/hr for amg and 22lbs hr for the stock.

Make sure your injector duty cycles aren't close to 85% after the retune. If they are then they need to be upped in size.

My #30 Ford Racing Injectors don't go above 85% duty cycle until I get into the 18-19 psi range which never go to

.

Nice setup, rear mount turbo that bad *****

S5LorinserF1 · #7 02-13-2009, 12:22 PM

you have race injectors?? how did you know what size would fit?

Did you have to modify anything and whats the lbs/rate versions you have??

Rear Mounted Turbo that would be crazy?? how the heck would you do that? what about engine mangment for the turbo etc?

2phast · #8 02-14-2009, 04:17 AM

Quote:

Originally Posted by Turbo E320

20.7 lbs/hr at 43.5psi for the NA s55, e55, c43, etc. Bosch 0-280-155-839 fuel injector.

EDIT: 19.0 lbs/hr at 43.5psi for the m113 non amg 5.0 and 4.3 enignes. Bosch 0-280-155-744 fuel injector.

Seriously Mercedes uses the tiniest fuel injectors possible. I think your Mercedes runs 54psi of fuel pressure so figure 25 lbs/hr for amg and 22lbs hr for the stock.

Make sure your injector duty cycles aren't close to 85% after the retune. If they are then they need to be upped in size.

My #30 Ford Racing Injectors don't go above 85% duty cycle until I get into the 18-19 psi range which never go to

.

Nice setup, rear mount turbo that bad *****

Not quite correct.

The 55 injectors are used in almost all AMG vehicles. Same as in the C32. I run the C32 injectors in my CLK32k, bench flow shows them at 40lb's /hr. Twice the flow of the black CLK injectors.

That said, the ECU can not adjust for such a large increase in fuel flow. My ECU has been reprogrammed by Kleemann, but they have no maps for any MB with larger injectors, so.....I installed a Unichip piggy back ECU to fine tune the fuel trims. It is tricky to get A/F correct while maintaining driveablity. I have a flat 12.5 A/F now, something I couldn't achieve with the Kleeman SC and 70mm pulley. Stock injectors were hitting full duty cycle around 4k.

Spent many hours on the dyno, not sure it was really worth all the effort and $$ for another 20 rwhp and 30lb or torque.

Stock black CLK injector on the left, light blue C32 injector on the right

Turbo E320 · #9 02-14-2009, 01:13 PM

That would make sense since your car is supercharged. The motor's we are talking about are N/A AMG engines. I just got on the parts computer, got the numbers and then looked on a Bosch reference chart. I don't see why a NA AMG engine would need 40lbs/hr injectors. What kind of pressure is that bench putting on those injectors?

I was doing some checking on the injectors and yes the supercharged 55 models all use the same injectors, including the C32, but there were a few cars left out. It was the C55, SLK55 and ML55, the last of the N/A AMG engine'd mercedes. I got the 20.7lbs/hr numbers again for the NA enignes, for some reason there isn't a Bosch number for the 32K, 55K motors.

Any EV6 body injector will install in your s500. The ford ones have the snap rings turned 90 degrees left of the mercedes ones so you have to file the snap ring completely around the injector so they install correctly. You can pick up EV6 injectors at performance auto stores, ebay, etc.

As for a remote mount turbo. The turbo would go in the place of your rear muffler and you use a oil scavenge pump to return the oil to your valve cover or valve cover oil cap. It is easier in that you dont have to modify the oil pan and intercoolers aren't required. I have modified a E55 exhaust to use a T70 turbo but the owner hasn't had the time to finish the kit.

S5LorinserF1 · #10 02-15-2009, 05:29 AM

please pm me regarding this possible turbo idea i might be interested in.

what exactly would be need to be done to make it work?

what about engine management?

thanks

Turbo E320 · #11 02-16-2009, 08:22 PM

/\ PM sent