1. Login to disable the Ads!

Fueling for stage 2 turbos?

Discussion in 'N54' started by vegasboy, Apr 12, 2018.

  1. vegasboy

    vegasboy New Member

    3
    2009 335i
    How much HP/boost can you get out of stage 2 turbos with only stage 2 LPFP running e85 or a blend?

    I'm seeing most people run PI or shotgun with stage 2 turbos. I would like to upgrade in stages and am wondering what I could get by with before making a jump to PI.
     
  2. buster84

    buster84 Lurker

    20
    335 bmw xdrive
    Stock turbos can't handle full e85 without PI or a vtt shotgun. You probably dont want to run more than 18-20psi. You need to log to find out how well your hpfp is doing because they do get tired and this causes all cars to vary. I'd stick to e30 or at most e40.

    You have to upgrade your fuel system if you want to run full e85 without worrying about mixing. Do some 3rd gear pulls to about 5 or 5.5k and take a look at your logs and if you see your fuel trims maxing at 50, reduce the boost or decrease your e85 content.
     
  3. fmorelli

    fmorelli Sergeant

    390
    E89 Z4 35i, F10 535d
    I thought you E90 guys could run E85 on stock turbos with an LPFP upgrade, fuel line upgrades, and Index 12 injectors (good hygiene)?

    Filippo
     
  4. dyezak

    dyezak Captain

    Plano TX
    335is
    If you want to run full E85 a simple LPFP upgrade will allow you to run 100% E85 on the stock HPFP without PI at all. You will just limit your boost to the max amount of fuel your HPFP can deliver. For me that put me at 21psi on stock turbos, full 100% E85, and factory HPFP setup without PI at all. My rail pressure was just starting to drop below 9,000psi at this level. That left me plenty of headroom.

    There are plenty of people running full e85 with just a LPFP, I'm not the only one.

    As for power output, I'm hitting roughly 480tq and 410hp. My car could make more if I dropped the e85 blend down into the 50% range and turned up the boost. But that isn't something I want to do because I want to just pull up to the pump and fill it up without concern.

    And now that flex fuel is almost released all this can be interpolated inside the DME and you *can* have the best of both worlds.
     
  5. dyezak

    dyezak Captain

    Plano TX
    335is
    As for your original question it isn't a matter of "how much boost". What @buster84 was pointing out is that with the fueling setup you are proposing, you can take that fueling setup to its limit with only stock turbos. Upgraded turbos will give you nothing from a power standpoint unless you upgrade your HPFP or add PI to the mix.
     
  6. zmon1300

    zmon1300 Specialist

    86
    '10 335xi
    Get some type of modular fuel pump for lpfp side so you can upgrade/add more pumps to it, as you increase the boost/timing. While doing that, keep an eye out on the For Sale page, usually there's a few PI kits on sale there for cheap..
     
  7. buster84

    buster84 Lurker

    20
    335 bmw xdrive
    This is only half true. There are many factors in what it takes for a car to claim to be running on full e85 with stock turbos. What most people fail to realize is that there not even running fuel e85. Without a sensor you really have no idea what % your getting out of that pump or what % it'll turn into once mixed into your tank. Almost all e85 pumps have disclaimers saying the minimal ethanol is 50%. This means the pump can be anywhere from 50% to 85%. Some pumps are higher if the has station demands it then you'll see a minimum of 70%.

    Until I see a log that shows someone running 20psi on stock turbos with an e85 sensor logging that it's at least 80% where you can see the hpfp and fuel trims levels then I'll think differently; however, I've yet to come across those logs. Do you happen to have one?

    This was actually a typo, I meant to say stage 2 and said instead I said stock because you cant max out stock turbos on full e85. Most think you can but unless your using it at the track if you run a little lean on e85 on a 3rd gear run your usually ok since e85 is more forgiving than gasoline, but without a proper log to prove it then I'd be scared for my engine especially since hpfps get tired with more use. Thats a gamble most won't take. Even worse if you have overboost issues.
     
    Last edited: Apr 13, 2018
  8. dyezak

    dyezak Captain

    Plano TX
    335is
    I've been running full e85 for almost a year now. Winter blend in Dallas is 70%. That's the lowest it ever goes. Get MHD to release their module so I can add e% to a log and I'll give you one the next day. This isn't rocket surgery and I'm not the only one running full e85 over 20psi on stock HPFP. Though I am at the limit of the HPFP and that is what we tuned to.
     
  9. fmorelli

    fmorelli Sergeant

    390
    E89 Z4 35i, F10 535d
    I'm about to go E85 now. Though many claim the E89 Z4 LPFP is like a stage 2 pump already. I'm doing the LPFP update for ethanol, lines, fuelab filter, HPFP filter delete, ECA, and fresh Index 12s with flexfuel on an FBO car with stock turbos. Logs will make their way. I expect it should work just fine unless my HPFP needs a refresh.

    Then when I do the turbos, I have a VTT single barrel sitting on the shelf. I'm intending on staying DI. But at this point, Stage 2 is hypothetical for me as we're not there yet.

    Filippo
     
  10. N54QC

    N54QC Specialist

    79
    07 E90 335i
    A lot depends on the car also, and logging is crucial. I have a stage 3 lpfp running a ethanol blend with meth and was seeing fuel mixture codes when I ran to high of a ethanol content. So it does vary car to car.
     
  11. buster84

    buster84 Lurker

    20
    335 bmw xdrive
    Im not sure about the Z4's but i do remember reading somewhere that the Z4's have a slightly better fuel system allowing more ethanol use. Logging is the the best way to find out if your car handles it and it seems like your all ready and set for when that time comes. Since you already have the single barrel, you should just install it that will gaurntee full e85 use with lots of headroom.

    No amount of tuning can stop over boost issues if they are hardware related. If he starts overboosting and hes running the fuel system at 99% he could blow his engine if it happens on the track or on a long high rpm run. Just because you can run it at max doesnt mean you should. You always want some headroom otherwise your risking it all. It's why they say if you want a 800hp engine, build it for 1000+ to give yourself some headroom. Same with turbos and also applys to fueling.
     
  12. N54QC

    N54QC Specialist

    79
    07 E90 335i
    Thought my comment was kind of siding towards your thoughts but maybe you read it differently. Lol It's always important to log and have headroom, think we are in agreement with that.
     
  13. bradsm87

    bradsm87 Corporal

    140
    Even E17-E20 does wonders for allowing extra timing and you can get away with running a little leaner than just gasoline/petrol so really you're only looking at maybe an extra 2-3% extra flow in exchange for at least 2 degrees more timing AND leaner AFR which both add power.

    A brand new HPFP with the inlet strainer removed and a decent LPFP setup that never dips below 75psi with E20 fuel is the way to go IMO. Run around 19psi flat to redline and see how it goes. If HP fuel pressure looks fine, try E25 and put some more timing in.
     
Loading...