Can I safely run 750hp FP with big turbos, etc and leave fuel rail, lines stock?

[speedtrapped]

So for sake of starting a new thread, I tried to dyno tune my beast, FMU CAI, DBR hybrid turbos, 3" DBR DP, 100 cell DBR race cats, 5 bar fPR, 750hp rated dbr FP, 52lbs ev14 injectors, and guess what, as my tuner dialed in the boost, easily over 25psi, my AFR was 12.5-12.8. He turned it down, suggested I get 90mm MAF housing, I was 340g/s at 4rpm, and suggested maybe the fueling is starved, ie rails and fuel line, which are stock. Now my set up as many remember was done at KMD, and Maha dyno'ed 644/788 at crank. I never did see an AFR reading on dyno sheet, but I did log, and I was getting same lean condition, only diff this time was tuner would not crank it up and leave AFR's lean, so kudos to Josh the tuner.
Any members have suggestions? Is there a fuel rail that will work, and what size ID line do I need for fuel line.
Tia

[kismetcapitan]

-6AN lines should be fine, but you should design a system that runs 2-4 of these lines as feed lines, and 2 as return lines. It's fine to run -8AN or -10AN singles to the engine, then use Y-blocks to split up the flow.

Japanese tuners have tuned to 12.5 AFR, but they have mystically detonation-free gasoline. I personally like 11.5:1, any richer and you start losing power and response, although when I run a full 30psi boost I will use a map that goes to 11:1 or even down to 10.8:1 - I'm not gaining power at that boost level, but I am gaining torque.

What interests me is that no hardware changes seem to be needed when running this kind of power? A tuner can map and reflash our stock ECUs even at 750bhp...that's cool.

I don't know if Audi used braided fuel lines; if they didn't, they will start popping pinhole leaks once you start pushing more fuel through them.

One way to confirm that fueling is the problem - have a fuel pressure gauge on the fuel rail (1/8" NPT port). Fuel pressure should rise in step with boost, but if the fuel pressure suddenly starts dropping, and if you've got the AFR gauge right there, you'll see AFRs climb as fuel pressure drops. Having 13+ gauges is very ricey, but for self-tuners, having that much info available is invaluable.

If someone can post up a diagram of the stock fuel system, we can start to design a custom fuel setup for you. And set up an account with Summit Racing - when you need serious fueling, you want NASCAR-spec gear. Aeromotive, Earls, etc.

FWIW, fuel rails aren't commonly the bottleneck in a high-flow fuel system. It's always the pump, and it spooks me that you're still using the stock system! But if you upgrade pumping capacity without doing the lines, you'll burst the lines. And if you go with larger diameter lines without upgrading the pump (or adding more pumps), you lose pressure and can burn out the fuel pump. I suspect that if you can feed the stock rail from both ends, and with good braided steel fuel lines and at least a twin-pump system, you should be fine.

Last thought - fuel pump controller. I am sure that Audi, like everyone else, has variable control on the fuel pump. The simplest setups cut voltage to 11 volts at idle and low-load and ramp it up to 14 volts when you really get on the gas. It may or may not be necessary to fiddle with the fuel pump control system. In my Skyline, I just hard-wired my pump relays to the battery, so they are always at maximum flow. This has the downside however of losing fuel efficiency as the constantly recirculating fuel generates a fair amount of vapor that gets vented out of the car.

[na1mt]

He is NOT using stock pump. http://www.dahlbackracing.se/images/Parts/fuelpump/pump670.jpg. This is the pump being used. If this pump will flow what is needed, than upgrading the line size and installing a Y and feeding each side of the rail would work.

[speedtrapped]

I am thankful for your input, but please look at the other thread, the pump is not stock! I swear! It's rated for 750hp, I bought direct from DBr. Are my lines stock yes. Take a look at fluid motor union.com they have a Frankenstein RS6 as an ongoing return customer, and have designed a 1600hp fuel system. I sent an email to Andrew krok there for some advice on fuel rails.

[marklar182]

As I said in the other post, I think with your current setup, the best bet is to change to Parallel feed on the rails. I believe you could modify the stock rails easily.

I am interested what FMU has setup, not that I will ever use it, but I am a nerd ;)

[speedtrapped]

If I remember the rails have a soft line towards the front. So I could run a y there, and split the feed?, never mind the fuel is fed into FPR 1st. Ugh

[marklar182]

You can always install an aftermarket (Aeromotive) FPR on the return side so you could Y the feed, then send it to each rail, and then disconnect (cut) the hardline on the front of the rails and send those individually to the Aeromotive FPR as it has 2 inlets and one return to send back to the tank.

The Aeromotive FPR also has a 1/8NPT port so you can mount a gauge on it as well, kill that bird as well!

[kismetcapitan]

I posted on the other thread...be prepared to cry a river.

for the record, Aeromotive hardware rocks. Not a fan of their pumps, but everything else, is just awesome, USA-made, and CHEAP!

[na1mt]

http://www.fluidmotorunion.com/wp-content/uploads/2010/11/rs6_misc3.jpg
http://www.fluidmotorunion.com/wp-content/uploads/2010/11/rs6_misc4.jpg
http://www.fluidmotorunion.com/wp-content/uploads/2010/11/rs6_misc5.jpg

I think this it what you were looking for

[ben916]

Stephen, these questions might be better answered by Grizz (unit 20) or MRCtuning as I seem to remember that their foundation was:
2 fuel pumps
Larger fuel rail (2 lines in)
Larger injectors
bigger turbos - which you already have
fuel return line - I don't remember if this fits into their game plan
airbox - you have that covered...
TUNE...

[yokust]

I am not saying that the stock lines may be big enough on our engine setups. But just a thought to throw out there. And a larger liter motor may require more fuel volume.

2.7t guys with gt2871's or tial 770's have made well over 700+ WHP with stock fuel lines and just an 044 intank pump.

4.6 Cobra mustang people push well over that hp with stock fuel lines that are same size as ours

[speedtrapped]

ty yokust...yeah, i spoke w/ vast, unit20, and stratmosphere, they think lean1 side rich the other is mechanical, not tune, and not fueling. I am starting to wonder about turbulance, as the FMu box is just that, arms that feed a common box with 2 outlets underneath, that mate to the MAFs....as mentioned in an another thread, the original set up had the dbr intake as well, i sold mine to josh, as i had already ordered fmu. When the car was tuned and dyno'ed on the maha, it wasnt lean as per dion. i just dont know about the other 4 fmu users, if they have logged and seen a lean/rich result. the box always scred me, because velocity of air meets in a large rectangular box, and the outlets are only 2' long, not enough to smooth the flow out before the maf

[yokust]

If you want to pay for shipping I can send you my extra set of Apikol intake pipes, and would just need a set of 3" filters to try. But do want them back of course.

They are the rough first set made to use for the mold of the 1 pc pipes.

[speedtrapped]

Yokust solid offer and I appreciate that. I have a set of DBR pipes in close possession, will have tomorrow. Tonight hopefully I can get direction on which connectors on the firewall are the primary o2 and reverse them, run some logs...Grizz suggested, lean pass and rich driver....if that's not it, then tomorrow pipe swipe, log...etc etc... I will find the gremlin!

[yokust]

You are not just going to be able to easily switch o2 spots. They are on oppisiste sides of the engine bay, and harness's are not that long

[na1mt]

You are not just going to be able to easily switch o2 spots. They are on oppisiste sides of the engine bay, and harness's are not that long

That's what I thought made sense.

[speedtrapped]

Actually the harness was easy, and I did switch both large 4 prong o2 connectors, go figure...but kid messed with computer, so I can not vAG the lambda tonight....damn!

[yokust]

Not sure really how you did that.

Black four prong on pass side is Bank 1 o2, and Black four prong on drivers side Bank 2 o2 primarys

[speedtrapped]

Yep, but I swapped not the top connector from the main harness, but the bottoms, that run to O2's...there was plenty of slack to do that.

[speedtrapped]

What Grizz theory was, that the when engine was lifted back in, mechanic got the bottoms, or the o2 leads backwards. I drove car, nothing strange, but this means nothing, cause I can't vAG. I hope my mechanic buddy comes by in am, and we can drive around a little. To be continued.

[yokust]

I guess if your guys did not attach the harness's to anything and left them loose its possible.

But if you get the rear O2's in the wrong spot the ecu will throw an incorrect O2 allocation fault. So if the fronts were swapped, you would get the same rear O2 code.

[speedtrapped]

Wait what? The rears are color coded no? Green and brown? I did not do swap, as I know it's and accidents can happen, if it's the case I will be pissed. Again, I won't know till tomorrow or able to get my computer unlocked.

[JSRS6]

Yes, as I told you on the phone. Right downstream(secondary) is green plug, left one is brown. Both primary are the blacks you swapped.

[yokust]

Right Green and Brown are Rears, and Blacks are fronts.

But say someone doing the swap installed the rear o2's in the worng exhaust bung, you will have the ecu throw an incorrect alocation position of the rear o2's. And if you had the fronts swapped, you would also have the rear o2 allocation faults because the rear o2 reading would not match what the front is doing. But the ecu is smart enough to pick up the fact the other bank o2 matches the reading it should be seeing.

[speedtrapped]

Here's the rub, never any faults.

[RSSIK]

could they be coded out??

[yokust]

I would doubt any code is removed other then the Cat effeicncy faults removed. So that test pipes or high flow cats can be used.

If I was going to make a random guess without seeing the car, I would start looking at your EGT sensors and readings.

On 2.7t and these 4.2t motors, these have a higher pull in the ecu as far as fuel mixtures.

And the one thing I have never checked, that if the EGT's are installed into the wrong exhaust manifold, if they will throw allocation faults or not. (just have never seen someone do it)

But on our motor setup it would be very easy to do if someone was not paying attention since they both bolt to the drivers side firewal and not to each side of the intake manifold like 2.7t.

[speedtrapped]

Yokust once again, valuable advice...not reversed o2 primary, ask me how I know? Swapped last night and really had bad lean, and thru codes, as Yokust said. Pit those back in original connectors. Won't have DBR intake till Monday night. I tried to reinstall stock box, just see the #, no go, EV14's have an extra connector to the injector to fit our harness, adds about 3/4" to height...stock box won't seat properly....oh well, this is getting fun. Yokust, I am being loaned the DBR for a week. If that works, then I'm buying apikols, same as DBR and cheaper. The FMU open box design really has me believing that turbulence is the issue. The stock box keeps airflow separate. The DBR, apikols separate, the FMU flows into a box, no separation, just dual outlets on bottom to MAF. If this fails, I will check EGT logs, which blocks ? Tia

[na1mt]

After having a close look at the FMU today I noticed that the inside of the unit has a wrinkle coating that matches the outside???? So much for a smooth flowing design. As Stephen said, the air from the individual pipes has to collide before it ever has a chance to get sucked into the throttle body.I was checking out their catch can can setup and drooling over it but the closer I looked at it.....if everyone on here that seems knowledgeable about these motors says how bad oiled air filters are for the MAF sensors.....the nasty blow buy and crankcase vapors must really treat yer MAFs right.....lol.

[na1mt]

http://www.gmpperformance.com/CFJFiles/GMP/15603.jpg

Someone is sitting on 5 of these.....wonder what they would take to rid themselves of all five at once??? Group buy offer?

[yokust]

http://www.gmpperformance.com/CFJFiles/GMP/15603.jpg

Someone is sitting on 5 of these.....wonder what they would take to rid themselves of all five at once??? Group buy offer?

$4k is a little (A LOT) too much for those, they do look nice though

I really want a set of the carbon inlets though!

[4everRS]

I don't have one of these intakes, but a wrinkle coat in it won't make any performance difference, wether it's there or not. Turbulence in that is nearly irrelevant. After the intake, the turbo's force the air through a few feet of charge pipe on each side where it enters through the throttlebody in the front of the engine.

As far as the catch can goes, it is not a part of the plumbing of the intake(airbox). It is simply attached to it. The catch can is plumbed from the hoses on the Y pipe. My point is, that "oil filled air" does not go through the MAF's, so it's not catching anything that would have gone through. It wouldn't have gone through. It's recycled away from the airbox. A catch can is a good idea, but you could make a couple (one for each side) for probably less than 100 bucks.
After having a close look at the FMU today I noticed that the inside of the unit has a wrinkle coating that matches the outside???? So much for a smooth flowing design. As Stephen said, the air from the individual pipes has to collide before it ever has a chance to get sucked into the throttle body.I was checking out their catch can can setup and drooling over it but the closer I looked at it.....if everyone on here that seems knowledgeable about these motors says how bad oiled air filters are for the MAF sensors.....the nasty blow buy and crankcase vapors must really treat yer MAFs right.....lol.

[na1mt]

Oil filled air most certainly does go into the MAF with a catch can that has no atmospheric vent when it is plumbed upstream of the MAF.....how could it not. A catch can is supposed to "catch" that vapor and blow by and vent out to atmosphere as well as contain the oil, instead of it returning to the throttle body for emissions. The design shown in the pics is plumbed right back into the intake tubes before the throttle body. Care to explain that? As far as the wrinkle finish on the inside not slowing down the airflow....that is simple physics. If that were not the case please show me another example of a factory air intake/air box or aftermarket cold air intake system with anything less then a smooth, polished finish for the air to flow freely through. Then as I pointed out.....the two masses of air going through the tubes collide into each other inside of a large chamber before having to find it's way into the tubes leading to the MAFs.



In all fairness to 4everRS......I did not post link to pics of commented on catch can....my bad

[yokust]

No oil filled air goes thru the maf's, sorry. The crankcase breather returns are downstream of the maf's.

The purpose of a catch can is too keep the oil filled air vapos from going thru the turbo and thru engine. The air vapor is still returned into the same spot, but with the catch can you are 'catching' the oil vapors and should be just air getting back into the stream.

But on that note, they FMU catch can does go back into before the maf's instead of using the factory installed inlet locations. Which if you ask me speaks of there design skills. And if we want to get on that note. There new RS6 manifolds they are making, they ditch the stock header style manifolds for a poor known not great design of a log style manifold.

As for the inlet, I HIGHLY doubt the coating causes ANY measurable loss of flow.

The downfall with there desgin is the open plenum. If they would have built velocity stacks inside the airbox, I bet they would actually work well.

[na1mt]

I am well aware of the purpose of a catch can....please reference pic here http://www.fluidmotorunion.com/wp-content/uploads/2011/01/rs6_intake_beta4.jpg

This is the specific catch can I was commenting on..and as you also pointed out I was right on my original comment of it's design. Also agreeing with me on the design of the airbox flaws. While it may not be a measurable difference in that short length of piping, having a rough interior finish is definitely not a standard practice when trying to promote flow.

[4everRS]

Oil filled air most certainly does go into the MAF with a catch can that has no atmospheric vent when it is plumbed upstream of the MAF.....how could it not. A catch can is supposed to "catch" that vapor and blow by and vent out to atmosphere as well as contain the oil, instead of it returning to the throttle body for emissions. The design shown in the pics is plumbed right back into the intake tubes before the throttle body. Care to explain that? As far as the wrinkle finish on the inside not slowing down the airflow....that is simple physics. If that were not the case please show me another example of a factory air intake/air box or aftermarket cold air intake system with anything less then a smooth, polished finish for the air to flow freely through. Then as I pointed out.....the two masses of air going through the tubes collide into each other inside of a large chamber before having to find it's way into the tubes leading to the MAFs.



In all fairness to 4everRS......I did not post link to pics of commented on catch can....my bad

Not really sure what's happening here. Again, the induction of this engine works as follows,

Air is SUCKED into the inlets, then goes through airbox. Then through MAF's.
Air then goes through intake side of turbo. After turbo, air is now being pushed or forced.
Air goes through charge pipe plumbing, through intercoolers, and into Y pipe where it is forced into the center of the intake manifold (alum).
Air goes through cylinders, and out exhaust, and through exhaust side turbo (which spins intake side via shaft) and out downpipes and rest of exhaust.

As far as crankcase ventilation, I won't explain it as you have asked me to do, as our systems are very complicated and I don't care to help THAT much.

I just saw you posted the pic of the FMU. This is a very good reason why I would never buy one of these catch cans(FMU I mean). There is NO good reason, this catch can should vent into the pipe before the MAF.

[4everRS]

I don't mean that a smooth finish is better or worse. I'm saying it doesn't matter in this engines induction system. Volume does matter. What does it matter if the air is turbulent in the airbox if it has yet to go through the turbulence hell of the turbo, and Intercooler? Volume matters.
I am well aware of the purpose of a catch can....please reference pic here http://www.fluidmotorunion.com/wp-content/uploads/2011/01/rs6_intake_beta4.jpg

This is the specific catch can I was commenting on..and as you also pointed out I was right on my original comment of it's design. Also agreeing with me on the design of the airbox flaws. While it may not be a measurable difference in that short length of piping, having a rough interior finish is definitely not a standard practice when trying to promote flow.

[na1mt]

Exactly what my original comment was directed at.....the FMU catch can and it's design. You missed that obviously.

[na1mt]

Volume is directly affected by flow.....again, simple physics

[4everRS]

Obviously without a picture, I missed that.
Exactly what my original comment was directed at.....the FMU catch can and it's design. You missed that obviously.

[na1mt]

I'm gonna get off this now.....cause we clearly both have argumentative personalities.....BUT, if you read post #29, my original post, I clearly stated I was speaking about the FMU catch can design, not in fact catch cans in general. So unless you saw a pic of it you should not have challenged me in the first place because you had no idea what I was talking about. Reading comprehension would have saved us both a little aggravation......I'm done now.

[speedtrapped]

I am disappointed on the design of the FMU, and I never dis understand why in middle of a group buy, they changed the design. I wish they hadn't, apikol, DBR, and 1st generation FMU all had separate pipe into each inlet. He'll even the stock box has 2 separate chambers. But in fairness to FMU, I wonder if any of the 4 other owners logged hard pulls to see the data.

[speedtrapped]

Kyle, google turbulence and MAF, it's well documented, why would the Audi designers go thru trouble of seperating the air chamber internally if it didn't matter.

[4everRS]

After reading my posts back, I made comments that were too strong. I agree that there should probably be separate runners to each MAF. The main thing I was trying to say is that a WRINKLE coat will have little to no impact on flow.

As far as the catch can, I shouldn't have posted my comment before seeing a pic of the design(which I have seen before but forgot). Based solely on post 29, one is left to draw conclusions. Mine were wrong. Yokust seemed to have the same assumption. Then a pic was posted later.

[yokust]

why would the Audi designers go thru trouble of seperating the air chamber internally if it didn't matter.

I would midly disagree there. I think our stock intake system was designed solely on space constraints. That was the best they could do with the space provided.

Now like I said before I think the FMU design "COULD" have worked well if the inside of the Airbox had velocity stacks on top of each maf inside the big plenum area.

But since they dont, I think the individual air filters like Apikol or Dahlback is a better design for our vehicles.

[yokust]

After reading my posts back, I made comments that were too strong. I agree that there should probably be separate runners to each MAF. The main thing I was trying to say is that a WRINKLE coat will have little to no impact on flow.

As far as the catch can, I shouldn't have posted my comment before seeing a pic of the design(which I have seen before but forgot). Based solely on post 29, one is left to draw conclusions. Mine were wrong. Yokust seemed to have the same assumption. Then a pic was posted later.


I would also agree, that the wrinkle coat does not cause any measureable amount of flow loss.

I bet if you put there intake on a flow bench before and after the coating it would be very minimum differences of actual numbers. Where the raw finish, will probably flow more. But the amount of difference I would doubt would be noticable on any dyno. Only flow bench

[speedtrapped]

conjecture unless someone else logs...03,31,115 3 rd WOT the FMU. I still not sure even w/ space constraints why would they have bothered during injection molding process to make 2 seperate chambers? If space, an open internal cavity under the CF top would have been cheaperr to produce(logically speaking that is)

[speedtrapped]

conjecture until I install dbr set i am borrowing and log.

[Spidercat]

I'd agree that the flow difference between a pipe that large with either smooth finish or wrinkle coat would be almost immeasurable- it's still going to be laminar flow with air or any other low-viscosity substance, provided there are no choke points/narrow sections.

I'd be a little more worried about the wrinkle finish flaking off and getting sucked into the engine in a year or two (if the finish was applied to the box after the filter elements). Not saying it wasn't applied well, just that it would worry me, given multiple heat cycles and time.

I assume the filter elements are contained in those two big carbon-fiber muffler-looking things similar in position to Dahlback, and the large central box is after the filters?

[speedtrapped]

So I called and spoke with dahlback yesterday, actually the man himself, Hans. He was very helpful, just to bury the fueling, no it's not fueling. He told me only 2 kits were ever sold in states...cool. But a decent amount in Europe. I described my condition, discussed logs, lean/rich, when this occurs etc. I also described my CAI...so Hans immediately said, please make sure your maf's are seated correctly. I never thought of that. I had an issue with FMU and the install originally. I cut the rings that hold pipes, filter cans in place. The unit was NOT bolted down anywhere. The DBR goes on tonight and I will log and share. Thanks for everyone's input.

[ttboost]

I tend to agree Stephen. I have had a CEL's on and off for quite a while now, with a bunch of errant codes, some of which I always had, just never fixed (left engine mount code for one). The other day I opened the hood and just pushed down on the airbox for a few seconds to make sure the MAF's were sealed, and I have put about 400 miles on now, with no codes...I don't know...seems suspicious at best...piece if sh*t design...I only have the nut on the passenger side and the bolt in the middle holding my box on...NOTHING in the back to hold the box down....idiotic...

[speedtrapped]

its amazing, an area where secured fittings matter, just under the MAF, and the engineers designed an $80 rubberized steel ring to seal each side. Now I get it, there really would be no way to securely tighten anything back there once you have stock airbox on.
Its funny, even after I cut the 'rings' on the fmu, I still had small issue lining up passenger side pipe and carbon filter box. Josh is getting my FMU, and he is having a welder, fab an arm with bolt hole to secure each side down, ala DBR/Apikol...

[ttboost]

its amazing, an area where secured fittings matter, just under the MAF, and the engineers designed an $80 rubberized steel ring to seal each side. Now I get it, there really would be no way to securely tighten anything back there once you have stock airbox on.
Its funny, even after I cut the 'rings' on the fmu, I still had small issue lining up passenger side pipe and carbon filter box. Josh is getting my FMU, and he is having a welder, fab an arm with bolt hole to secure each side down, ala DBR/Apikol...

Yeah...when I get my garage done and I have somewhere to work, I will design a strap to hold the back of this box down somehow...and it will be easy to get to too!!!!

[na1mt]

If after you put the Dahlback on these issues disappear FMU should take these units back and weld the bracket on at n/c for everyone that has them.

[speedtrapped]

Woohooo no more lean! I used a DBR loaner, basically just the pipes and 2 dirty filters, and since I was missing rings sucking in pure hot air.....lol, still button her up, Josh has logs...I pulled battery, drover her only a couple of miles and logged, very happy to say, passenger side spec .85 and actual was there! The driver side is rich, spec .85 reads .90, rather rich then lean. Going to log block 32, and have tune finished. I think my rich might be to still messing with seating of MAF, was actually hard getting arms of DBR to line up with manifold bolt holes....I am relieved. And if any members using FMU, log it! My car never drove badly, and never a code, but the lean would jump off page went I logged using FMU.

[MaxRS6]

Congrats!!!!!!

[Spidercat]

Great news!

[JSRS6]

Will post today Stephen. Got busy last night.

[speedtrapped]

Josh, No worries...ty

[JSRS6]

Haha, I think you are gonna have to start calling us Josh1 and Josh2.

[speedtrapped]

josh tuner is easy i will call him fonzi since his co. name is jfonz...oh wait we have a fonzi already....ok ur J1 he's J2

[jfonz]

i'm good with being j2 lol.