Exotic-metal55

I have made a few threads on our fuel systems and this is the 3rd test. Granted there are pump and control differences but still have simulair systems..


Shardul`s car has the exact same fuel drop and at the same rpm range.. We also made 8-10 runs and heaqt soaked the IAT`s to 175 deg.. That means his car had pulled most all this timing and was making well under 500 hp at those temps.. All runs showed same psi drop.


My conclusion (I am sure some out there know this but keeping quiet) , is that are ECU or regulator is controlling the pressure drop.. This is the theory why: We have approx. 5MM ID fuel lines and we have 79-80 PSI systems to atomoze the fuel.. This is for max fuel economy and emissions. Here is the hook, A 5mm ID line has a max flow effeciancy (Not sure what that is yet) but guesssing AMG did when they set our sytem up. High PSI DOES not equall high volume.. Myh guess is that AMG drops the pressure above 5K to increase fuel flow volume.. Again, only tested two cars and 3 pumps now but seems to be a good theory..


I am going to find the max fuel flow through a 5mm ID line and double check that.. For now, it is looking like larger injectors is the way to go , since fuel drop is now a constant..

Here is a pic of Shardul`s fuel PSI on its way down to 65 psi during a 1st gear run..It is at 70 psi in the pic.

Thanks to Larry (forgot his screen name) for use of his gauge and tools..

Gondon

So every modded E55 with a tune faces this issue?

Zod

and this is bad because?
heat soaked from what size pulley?

n Thx for thw write up

Exotic-metal55

Nothing is bad, if AMG is lowering the pressure to increase volume.. Then we have a constant change and larger injectors will solve fuel needs..

What I meant about heat , heat soak and loss of timing is that his car may have only been putting out 470 RWHP (50 less) due to +2500 DA, timing being pulled and heat.. That means at ONLY 470 RWHP he still has the same fuel PSI drop.. I feel AMG built this in to increase volume at high RPM or high HP needs. Not sure, needs calculations to be done..

If this theroy is correct, then injectors are all most of us will need above 520RWHP.. If not, then we are all F-ed!!

skratch77

can we use the slr 722 injectors?

Exotic-metal55

I woudn`t. They show very little increase in flow and are expensive.. I was hoping someone had a part number for a plug and play aftermarket 45-48 lb injector..

vietjdmboi

hey brooke, do you have pictures of what a stock injector looks like? i can get Injector dynamic (bosch) 750cc, 1000cc or 2000cc injectors made to fit with the correct tophats depending on the situation. do you know if our inj low or high impedance?

http://www.injectordynamics.com/injectors.html

Exotic-metal55

55k fuel injector bosch p/n 0-280-156-072 37.5lb at 43 psi.. 422cc at same psi.

sneakyneon

Well its an intresting theory but I see one issue so far, the low psi also comes with leaner afr's. It may work well in a stock car but on a modd'ed one the lean spot becomes an issue.

Exotic-metal55

We see that too on high HP cars and they become hard to increase injector pulse above 5500K.. It seems to start around 525 RWHP on the dyno we use.. It showed up on my car , when I added the headers but concerns started in the 525 hp range..

Shardul`s car was not getting leaner with fuel drop on the dyno or on the narrow band today.. If all 55`s do this, then most do not go lean on the drop , based on the fuel maps I have seen..

If the pressure drop is designed into the fuel system, then it has to be to keep volume up.. If the injectors are maxed,, then volume will not help.. If you increase PSI in a 5mm ID line, then volume may drop and you go lean anyway..

A 5mm ID line has a max effeciency flow rate of PSI VS Flow.. 80 PSI is for fuel and pollution effeciency.. What is the max PSI needed to flow the max amount of fuel at X temperature through a 5mm ID line?

Zod

How can you say they are not good enough, when the 722 is making near enough 520whp or more and reves a bit higher no?

just wondering

Exotic-metal55

Where did you get that I said " not good enough"? Never said that at all..

Why would I want an injector for 520 rwhp , when I make 560 rwhp? Just wondering

Also, one part of a fuel system from another car format, does not mean it will solve problems.. SLR may have larger fuel lines, different pumps, regulators and ECU voltage control program.. Be hard to find out, as not many tuners or users share that kind of info..Just looking for a quick painless way to get 30% more fuel..

vietjdmboi

do you happen to know what the inj duty cycle was during your dyno run brooke?

Exotic-metal55

Nope, our data loggers do not give us that info.. Would save a lot of time though! Just using basic online fuel calculators also show that we do not have the fuel above 520hp range.. 37.5 lbs or 422 cc at 65 PSI above 5k is not good! Even at 80 psi, it is border line..

Here is another pic of the injector..http://injectorwarehouse.com/injecto...enz/mp5101.htm

Zod

My bad then

Is it not easy enough to just look at the part numbers etc for fuel pump, regulators etc, to see if there is a difference?

Best of luck on the quest!
n thx for sharing

SmokinCRC6

I should be able to scan injector duty cycle for you. See third item down on the left. HP Tuners says they can scan most unsported cars now if you would like to give it a try.

Exotic-metal55

Ok, lets go for a RIDE!!!!!!!

SmokinCRC6

Come on over!

I had turned my engine off on that screen shot although I was still connected reason most items reported zero.

stevebez

I always thought these cars ran too rich ... ? So how come we now running out of fuel?

Exotic-metal55

Because we all are increasing our HP by 25% to 35%!! Injectors and fuel capacity needs to go up with that.. Factory gave us a lot of wiggle room but eveything has its limits..

I think 50Lb injectors , is what I need. 550CC range..

stevebez

Yep but even 630 HP (motor) Kleemans run rich..... And every dyno I have seen of a major modded engine has rich afr's....

Is it not ecu pulling fuel (power) for engine preservation on a long run when engine temps jump up? Not sure if pulling fuel in this context is same as leaning the motor out ...

I am just trying to work this out in my head - no criticism intended to anyone!

Exotic-metal55

630HP by Kleeman is flywheel HP, I assume.. I am refering to 560 RWHP or you can add 18% to that figure.. We are talking 700 hp crank!

ECU pulls fuel at the injectors (pulse width), not by lowing PSI.. Lower PSI could equall more volume of fuel.. Flow engineer needs to calculate this.. I gave the info needed above to make this calculation.

Shardul`s Fuel PSI was dropping but he was getting richer on the narrow band monitor.. Even before timing was pulled and before IAT reched 130 deg.

Ali_E55

i think the guys with METH that their IAT are lower than 140 can help us to know if it is reducing the fuel because of engine temps which makes it reduce the stress on the engine.

ur theory may not be wrong.

Shadow5501

Hmmm. Do you suppose fuel pressure drops simply because the injector pulse width at high throttle/high RPM is so wide the fuel system is approaching its maximum flow? Seems a simplistic answer, but on the other hand, mass produced products tend to be engineered with every unnecessary nickel of expense taken out...

Exotic-metal55

Be nice to have results on a stock 55 fuel PSI? I know of 4-5 cars that are all at different HP levels (Fuel needs) and they drop the same way..

This is a fact: High pressure (PSI) does not equall max flow volume! So what PSI is the most efficient rate to flow fuel through a 5MM ID fuel line ??? That is a fair question.. I bet the regulator is designed to flow more fuel above 5K and drops PSI to do it. My guess..