dllhg

Not trying to start anything just gather more information as I get more familiar with these cars from all the information I have found in this forum.

As I am building my car I wanted to make sure I did it right. Several people steered me towards looped fuel rails along with 550cc injectors. I understand there being a slight pressure drop near #8 and that is the most common piston to pop. I have a few things I heard and a few questions.

I have heard of people popping #8 who had looped rails but most dont want to talk about it Why I dont know.

I also heard a theory that #8 is the furthest from the water pump and doesnt get as much cooling there.

To me the tune seems like the most important factor for keeping these motors intact. I just had a few personal emails with a member running 10.8s@130 MPH who was still on the stock injectors ! He had an OE tune as do several other members I am copying my mod list from. tune seems critical here to me.

My questions are ;

A: Can you tune it so that #8 gets a little more fuel than the other cyl ? Its been a while since I tuned my own car but I thought you could add to each cyl individually.

b: With good large injectors is it still really possible that #8 would go lean and pop with a proper tune ?

C: Without a wide band how do half of these guys really know if they are truly lean or not ?

Personally I have a feeling with all these canned tunes going around these blown motors are happening because the cars are running lean to begin with.#8 is the most susceptible due to running slightly leaner than the rest.


Not saying the looped rails arent a good idea but are they really just a band-aid for improper tuned car running too lean ?

Sir-Boost-a-Lot

iTrader: (1)

A+B
Install larger fuel injectors. Have them professionally flow tested before install. Put the one that flows the highest on 8.

C
Install an inexpensive EGT meter in your #8 header tube. Monitor it for temps.

ahmad0658

It has a lot of benefits, just look at the SLR that has same engine design how the rail on it is looped.

If you go to older threads, there are few of them on detailed review with discussion about them, including extra power gained, engine safety, lower fuel consumption, etc...

AMGPilot

It's not a water pump/coolant problem these are open deck blocks, it's damn near impossible to overheat these motors

dllhg

This sounds like good advice. But cant you tune it to run a little richer on #8 ?

dllhg

Yeah I did read some of those and was pretty convinced afterwards too. Power gained and fuel consumption were from injectors though not the rail .

Mikesamg

Someone jump in and correct me if I'm wrong as I haven't been down this road in a while, but if I remember correctly the issue with the stock rail comes down to it's inability to provide equal pressure throughout the system? #8 is not the only point in which lean conditions occur, it's just the one that suffers the most. Therefore larger injectors or added fuel from a tune may still suffer if the stock rail fails to provide adequate fuel when needed?


I could be completely wrong which is fine, after all I pay someone to do the work on the car so I can just drive it. For me I went the route of safety and over did it with the looped rail, 550 injectors, two wide-bands, two alarm boxes and trigger boxes to active should conditions get to dangerous. This doesn't provide me with a full proof safety measure, it just helps me monitor it to prevent and correct the conditions if needed.

PACougar

I think if everything is working perfectly you can get a lot out of the stock fuel system. That being said who wants to take the chance of running their injectors near static? Now let's say you have a fuel pump that's on it's way out or something else that's not quite right in the fuel system, it seems that #8 tends to be the one that takes the cake. Personally I think if you're trying for 10's you'd be crazy not to run larger injectors if not just for safety. I know there's debate about the looped rail with the modified inlet, but I feel some same way about it. This doesn't seem like the way or place to save money. Good luck.

e55amgrocket

Open deck or not the rear of an engine is always the hottest. I think injectors are more of a safety measure than anything and peace of mind. Kleemann actually will not tune a car with larger injectors and have some extremely powerful cars out there for what it's worth. #8 isn't the only injector that experiences a flow difference and that's been tested with and without a looped rail. Like someone stated already I wonder how many engine failures that were blamed on #8 injector were due to fuel pump issues. If your pump is weak it would be hard to know if your not watching fuel pressure. The fuel inlet size is most of the problem with the volume getting into the rail and can be opened up a decent amount. There has been several cars that have blown engines WITH looped fuel rails so take that for what it's worth. Like anything else you modify there's always that chance.

GregMB

You are treading into a "religious discussion" on MBWorld when you start asking too many questions about fuel rails and injectors...

I will say only this.... For every high-quality part that has ever been developed for the E55 aftermarket, there seems to be at least a few people who try to clone that product to sell it for a cheaper price. Unfortunately, there is some garbage out there. When you read stories about a blown engine with a fuel loop try to figure out if it was a "real deal" product or a "cheap knockoff".....

Some people insist that there are no "tricks" to building a quality fuel loop, and that all injectors are the same. You'll need to decide whether you believe that yourself or not.

Ultimately, everyone loves saving money on speed parts until something goes catastrophically wrong.....a blown engine will make those "cheap parts" some of the most expensive around.


-G

E55Greasemonkey

Stupid question...Which cylinder does everyone refer to as #8?

SPatykAMG

I went ahead and got the looped rail and injectors since the price is not all that bad being that even if they don't prevent lean they do give more tuning ability down the line in case you ever push it that far.

Does anyone know a good place in Houston to get injectors tested?

cij911

A few mistakes that should be addressed - adding fuel injectors and a looped rail WILL NOT increase hp (unless you had maxed out your injectors, were running lean, knocking, and the car was pulling timing).

Get a wideband and log AFR if you are going to start modding your car....

Hulk

Wideband is the best thing you can get, you will know where you stand

e55amgrocket

If you doing the looped rail I would go with TTM. He uses -8AN fittings and the whole purpose of the rail is to get a larger volume of fuel. Not sure if he drills the inlets or not.

cij911

I cannot believe there are no aftermarket rails out for the e55....

e55amgrocket

I had some made but cost was higher than expected. What would people be willing to pay for billet rails? -8an fittings with the inside diameter slightly larger than a -8? Inlet will be at the rear to keep pressure as equal as possible. Ill post pics later but there's some pics into build thread.

RedBullJnky

This.

cij911

Well given that SO many cars are now being modded (3+ owners), I am guessing the fueling system will be the next thing that needs to be addressed....It would be great if we could address the stupid fuel sender leak at the same time and use an external pump ....

DarthVader2

If you understand hydraulics, all injectors will flow the same amount regardless if you double feed the rails or single feed it or where the injector is in the line.

Of course, all injectors have to have same actual flow ratings and all orifices feeding each injectors must be the same size.

SilverStrk

Bruce at TTM is making me a package as we speak, (82 ported TB, 550 Inj, and looped rail).. After doing my research HE is the only way to go in making this system.. Not cheap, but I beleive worth the extra cost as his products are known to be the absolute highest quality.. Just my two cents...

Blown_V8s

Why not just run a larger injector on the #8 cylinder.


How much power can the factory fuel pump support?

PACougar

You'd end up with your motor out of balance and then a blown motor or a really washed down cylinder.

groove66

What about going to a larger diameter feed line from the tank. it comes out of the sender which looks like a 3/8 hose line then connects to a metal tube. change the metal tubing to say like 1/2 aluminum tubing and and atleast you will have some more volume and would be relatively inexpensive. couple that with a looped rail and you should have a pretty solid system.

GT-ER

How about paying more attention to cylinder 8 by doing datalogging of your knock sensors and putting a wideband on the drivers side at the very least. Pay attention to what your ecu is doing.