cal1

As some of you are aware, I have been knocking around the idea of adding a looped rail and injectors, so I thought I would start a discussion on it and see what the expert thinking is on this.

Since I don't display my mods, I guess I should list them.

EvoSport shorty headers, 80mm TB, Renntech HE, pump and 178 pulley, secondary cat delete, and EC Dyno tune.

WHP is close to 500 and WTQ is 539.

I really don't go to the drag strip anymore and I don't do high speed (above 130, 140) runs.

My goal at this point is just a little added protection against old #8 going lean. A number of guys that lost #8 had it happen during long pulls through the 130, 140 range and under cool dense air conditions.

I am leaning toward just a looped rail with the thought that it will keep the pressures more equal to all the cylinders. I have heard a few stories about bigger injectors like clips breaking and cars ending up being pig rich even after a new tune.

Any thoughts are much appreciated.

alx

most lean outs on "tail" injectors on the 55 cars are due to dirty fuel filter.

replace your fuel fiter often and call it a day.

cal1

Really! even on the modded 55ks? The guys on the E55 boards seem to think rails and bigger injectors are the savior of #8. I know they get a small HP gain from it too, but I don't care about that. I have enough trouble keeping rubber on the rear tires already.

And by the way, it seems to me (don't know much) the bigger injectors are going to change the pump characteristics on the stock fuel pump and maybe cause problems.

alx

once you start playing with injectors ideally you need a tune.

if you have a "big" tune i am sure at some fuel delivery point the stock fuel rails are inadequate. what point? i do not know. i am sure people like shardul can chime in on that.

shardul

iTrader: (1)

i have seen cars with rails and injectors, detonate and destroy no8, no2, no5 cylinders.
Rail and injectors add some safety but i has to be accompanied with a good tune to scale the injectors. I know TTM is a pionner for the lopped rail concept for the 55k motors.

cal1

thanks guys. My delima does continue at this point though.

One thing for sure is to change the fuel filter. I am running a slightly less aggressive tune than many. Could be changing nothing other than the fuel filter is the best move.

kustom2k1

Are you planning to go with a more aggressive tune? I would buy and install an AFR gauge, why fix something if you don't know whether or not you have a problem. AEM has a nice gauge and software you can program to kill the supercharger if it reaches certain selected parameters. Google failsafe AEM afr gauge.

hamann1000

I have just a pulley and tune currently but wanted to do headers and possibly 82mm tb. Jerry at eurocharged told me that anything over pulley/tune/headers like adding a larger tb should at minimum add larger injectors for safety and possibly do the looped rail as well. Anything over 500wheel and the stock injectors can go static. This is the reason I have not done anymore mods, I do not want to do new fuel injectors/rail and all the stories on the e55 forums forums regarding the blown #8 scare me to where it doesnt make sense to risk

cal1

Thanks kustom, that looks like a great option.

My goal with the mods was to make the overweight pig run sub 12s. I managed an 11.86 PB on street tires with a trap of 121.3. I figure a set of drags could get me in the mid 11s if I ever wanted to try. So at this point I am happy with what I have and see no reason to mess with the tune.

I looked at the gauges. They seem like a great way to go. What would be the failsafe point used to shutdown the SC?

By the way, I see you setting a notch above me on dragtimes with a nice run.

cal1

I agree with you. This seems to be the accepted wisdom. I remember a few years back when the E55 boards were having blown engine issues and started flaming the tuners. The looped rail and injectors seemed to be the savior, but one of my E55 buddies was never really able to get his tune right after adding rails and injectors and then Shardul points out pretty much the same thing.

I think a big factor is what you plan to do with the modded car. If you like long high speed (130+) runs, then rails and injectors are probably more important. I tend to be a 4 or 5 seconds at WOT type of guy in lower gears.

By the way, IMHO you should add some cooling mods like a simple HE and pump and call it a day unless you are going for big power. Keep those IATs down and let that boosted SC do its thing.

Hulk

The AEM 30-4900 is the gauge tht kustom is talking about

I installed it last week and works great
Gonna get tuned after 1 more mod and then put in certain parameters that if it reaches will automatically shut off the SC

I believe it's a better system than anything right now because other afr systems have lights or alarms and sometimes that can be too late
This system completely shut off the blower

Kustom tried it and was shocked lol

hamann1000

aww I did not list all my mods just the ones that help make more power but I do have a cm30 pump in, does not really make sense for me to do a larger h/e where I live when im only running a renntech 168 crank pulley

cal1

Yeah, you don't have to deal with the hot humid temps most of us get in the summer and I doubt you are doing back to back to back pulls which would still cause heatsoak even in your conditions. One thing I did a little differently than most, was to not isolate the HE for SC cooling only. I figured since the engine was making more power and obviously more heat, a little greater cooling would be good for the engine.

Hulk

Why didn't you change your thermostat?

cal1

What I meant was I did not split the intercooler coolant circuit like a lot of guys do.

As far as cooler t-stats, I'm not sure I get the advantage. So the stat opens quicker, but if the engine is working hard, it will be mere seconds before the stock t-stat opens and then there is no difference. Say cars are lined up waiting to run the quarter. They are idling of course. The colder stat opens first. By the time the cars get to the lights, both stats are open and I am betting the engine temps are about the same.

Maybe I am missing something on the concept, but in my mind just because the stat opens at a cooler point doesn't mean the cooling system can maintain that temp at least not under heavy loads.

overZealous1

that would only be true if your cooling system was at maximum cooling capacity at original thermostat opening temp. if your cooling system is working properly and cooling the water down enough in the rad, then you will be letting in water that is cooler, thus the exit water cooler, and less temps for the rad to exchange.
the thermostat is just that. like in your house. if you leave it at 72, it will be 72. leave it at 65, it will be at 65. for an engine though, you need to atleast let it get hot enough to go into closed loop though, which normally is around 160.
it will help a little with heat soak is the main thing. keeping combustion chamber temps down a little is good though too.

cal1

But wouldn't the cooling system be at max cooling capacity under WOT?

I am just thinking in terms of power gains as I have heard people say a cooler stat leads to better performance. that is the part I don't get.

If I set my stat at home at 65 or 70 (cooling) and leave the windows open on a hot day, the AC is not going to perform any better at 65 or at least not for long. As the return air temps start rising and given that the delta stays the same, the discharge temps go up much like the a cars cooling system. The AC is running ***** out and losing the battle.

So what are your thoughts of a split intercooler coolant circuit instead of my set up? My thoughts are I am trading slightly higher IATs for a bit cooler combustion chamber temps.

I would also love your insight on my looped rail/injectors dilemma if you wouldn't mind.

overZealous1

leaving the windows open at home would be about the same comparison as putting a piece of cardboard over your grill. it puts both well outside of designed limits.
with the car, it is letting the colder water from the rad enter the engine at a lower temp. in return, it will be leaving at a lower temp. so it does put less load on rad. the water will be in the engine itself for the same amount of time as before, so heat absorbsion will be the same also. the result is overall lower temps.
the thermo also keeps the temps regulated. if you didn't run a thermo, you would see huge variances in your water temp. 120 on the highway, and 220 in traffic. my work truck has a massive radiator. if ambient temps are 50 and below, my thermo is constantly opening and closing due to the huge volume of water and rad, even on freeway and normal city driving.
you will most certainly see a big gain in lower iats by separating the circuits. will will see no gain in lowered engine water temps as the thermostat is controlling the engine temps. you could add a second full size radiator and add a trailer carrying 100 gallons of water and your engine will still run at 180 with a 180 thermostat. it will just be bairily letting water in as is the case with my truck.
a 180 thermo is the temp of the water leaving the engine. a lower temp one will open quicker to let the cooled water in.

i personally did the looped rail. it certainly does make sense of the theory behind it and honestly i think all these new returnless style fuel systems suck. it is a deq mandatory thing that just keeps warm fuel from circulating back to the tank and having a higher evaporating rate. if i go much further with my car i will be making a full return style system.
a full return style keeps the pressures constant no matter the load. if a raising rate or vacuum operated regulator is used, fuel pressure will raise in relation to your boost levels.
for injectors, i went with 550cc. it is what everyone is running primarily but imo still a little small. the problem comes in though with the stock computer having the resolution to control a large injector at idle. so, the 550cc seems to be the one of choice for most. i do know one guy running 1000cc and e85. but said his is idling fine.
so the combo of a non looped rail and injectors running close to max can be a dangerous situation. there is many injector calculators on the web. since you know your hp, just punch in the figures and see where you end up.

cal1

thanks OZ. I guess I will install a cooler stat too. I have been at the track before or sitting in trafic on a hot day and saw the water temp at 90 C or even higher. I was thinking at that point the 180f stat is wide open and still can't keep up so a 170 going wide open a touch sooner would not add much, but it sounds like I am incorrect about that. It will be interesting to see how much cooler the car will be under those conditions with the cooler stat.

What size are the stock injectors?

amok55amg

Being novice in tuning I do have some thoughts about this with a looped fuel rail and cylinders not getting fuel enough .......

When looking at the fuel system, then it operates with 5 BAR pressure ..... supplying the fuel rail with gasoline from the tank in the back. Some say a looped fuel rail and a clean filter is the key ..... it probably is ........ but could it be that these percussions only keep you just barely over to the “safe side”?

I think – pressure and volume. I mean it doesn’t matter if you raise the pressure from the pump if you can’t deliver the volume due to a constriction in the line. Looking in the intake of the fuel rail reveal a “bottle-neck” – it’s kind of an orifice …… could the solution be to increase the size of the tubing from the pump to the fuel rail to raise the volume of gasoline available for the injectors?

overZealous1

i want to say the stock injectors are around 350-375cc. don't remember 100%.

amok- you drill out that bottle neck in the inlet. good idea if doing looped or not.

amok55amg

Well – I still have a hard time accepting that a looped fuel rail is the answer for preventing an engine detonation. It simply doesn’t add up – the fuel rail being a “dead end”. Why have the vehicle manufacturers gone to this type of setup? From the Internet I read that in 2004, emission regulations required lower EVAP emissions from the fuel system.

I wasn’t around when these detonations happened to some unfortunate follower members but there must have been more to it. It must have been more than one thing causing this to happen – it all ways is. You have barriers to prevent things like this from happening …. for a thing like this to occur, there must be several barriers in sequins that must have failed before disaster.

I am aware we talk about modificated engines ….. but I simply don’t see the logic in adding a pipe to a dead end should take care of that “fuel problem”.

Is it really a GENERAL fuel problem or simply just a chain of bad things happening to some special cars where barriers were to fall under special circumstances?

Could it be a combination of dirty fuel filter, “not up to best fuel pump”, not optimal “set-up” … faulty airflow sensor …. etc.? I can see many other things that could have contributed to these “disasters” ……..

What I picked up on the Internet about engines with “returnless” electronic fuel injection (EFI) systems is that they have the regulator inside the fuel tank. The regulator is part of the fuel pump assembly and is usually located downstream of the in-tank fuel filter. Here’s a couple of things that could have played a role……

Returnless EFI systems typically operate at a higher pressure than return-type systems. This is necessary to reduce the risk of fuel boiling and vapor lock in the injector supply rail during hot weather (since there is no recirculation of fuel from the engine back to the tank to keep the fuel supply rail cool). Because of this, a returnless EFI system may not perform well if fuel pressure or flow is less than specifications

Also a returnless EFI system can build up contaminants in the fuel rail on the engine. The rail is a dead end as far as fuel circulation is concerned. Fuel flows one-way into the rail and does not return to the tank, so any junk that gets past the fuel filter will end up in the rail or injectors. The injector(s) at the end of the fuel rail(s) furthest from the inlet are the ones most likely to become clogged with gunk thou ……….

Electronic returnless EFI systems also may be referred to as “On Demand” returnless EFI systems because they use a fuel tank pressure sensor to monitor fuel pressure. The PCM varies the speed of the fuel pump to increase or decrease fuel flow using pulse width modulation (PWM) of the pump’s supply voltage. The PCM determines how much fuel is required based on engine load and inputs from its other sensors. This type of system is typically used on an engine that has an airflow sensor to monitor engine load.

Will a upgrading for larger diameter of the fuel line together with the loop be the answer? or is it a full return fuel line the right way to go? ….. or should we say it was something exceptional that happened due to several special circumstances and then simply just relay on electronic surveillance of the engine?

overZealous1

a return style system is always the best way to go. some of the reasons were mentioned in your post there.
one issue is trying to bypass the regulator in the fuel pump assembly (if it is equipped that way). it can be complex sometimes and you end up with a very weak pick up signal or in a dual or horseshoe shaped tank, loose pickup of one side entirely.
in those circumstances, and imo the easiest way to turn a returnless into a return style is not to touch the fuel pump assembly at all and just add a larger inline pump with a regulator right after the fuel rails. then obviously a return line to the tank that will drop fuel back into the pick up sump.
in this scenario the stock pump will mearly be a feeder pump to the inline pump and never really involve the stock regulator so you have no probs with fuel pick up. the second pump (higher volume pump) will now actually be creating the pressure for the rails.
now, the fuel systems in our sl's have the pump outside of the tank, and i have not investigated enough to see where the stock regulator is. but it would have to be after the pump, which will make it external with a return line already going back into tank. so it may be super easy on our cars to just remove regulator, instead of looping rail together, have them come back into a good efi regulator, and then hook the return line back up that the stock regulator was hooked to.

looping the rail itself does have its advantages though. it will create more even fuel pressure to each injector over the factory design. while you have it out you can also drill out the inlet restriction, which will almost double the orifice going into the rail.

amok55amg

Heres a screen dump over the parts from the fuel system in the back of the car ......... what do you think overZealous?

Will it be "easy" to make a full return system? ...... and heres a possible write-up: http://oldfuelinjection.com/?p=95

RonnieRenaldi

I have 180mm crank pulley, Kleemann headers (no primary cats), EC tune, Meziere IC pump, additional HE, split cooling and soon Shardul smaller SC pulley.
Should I add the 550cc injectors too?