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Das Beast: My E30 track / street build

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  • dvallis
    replied
    Yep. I'm with you on that. PTE won't give up the data so we're going to "try it and see". Under 2K RPM we'll probably be riding the surge line, but I'm not too concerned since it's partial throttle. At WOT flow builds -fast-, even with a 0.84 turbine, so we get into a good part of the map quickly and stay there. The 0.58 turbine will spool like a maniac. If it gives us the flatter torque curve and the compressor doesn't explode, we've got a win. The PTE rep didn't freak out and say "Never put that 0.58 turbine on a 6262" which is good. They may have even tested the two together, LoL. Our tuner has a lot of practical experience and felt a T4 0.58 will flow enough for the 400ish HP target. Also encouraging. Like I said, we'll see.

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  • citizen_insane
    replied
    I think your estimate of compressor flow is a bit on the low side, but none-the-less, the turbo is oversized for the amount of power you're making now. You really don't want to be riding the surge line. If you are planning to stay at this power level, a smaller turbo with a 76mm compressor exducer would probably be a better fit than your current turbo with a much smaller A/R housing. Going to lower A/R will help with transient response from a flow perspective, but you're also going to shift the turbine's peak efficiency to higher expansion ratio which means at very low ER, efficiency will be pretty bad. I'm not sure if you have turbine maps available, but you may find that going really small on the turbine may be a losing proposition, but I can't say for sure without seeing the maps of the wheel w/ various A/R housings.

    I'm guessing you're already familiar, but I find it very useful for an off the cuff estimate of turbo estimates. I realize most of the data is likely not available, but these reasonable guesses will get you closer than approximations like 1.4-1.6 hp/cfm.
    https://www.borgwarner.com/go/2J4V2B

    Closes map I could find (BorgWarner S300SX). Ideally your peak power point would be somewhere closer to the red star I marked on the map.
    Last edited by citizen_insane; Yesterday, 08:20 AM.

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  • dvallis
    replied
    Turbo Revisited

    We want the turbo to spool faster. Back to simple physics: Take the same mass air flow, send it through a smaller tube, you get higher velocity and the impeller spins faster.

    We're hoping this new 0.58 A/R housing isn't too small, but we'll see. Tuner thinks it will be fine, since it's T4.



    In the meantime, here's some turbo math.

    1. Our turbo compressor has a 0.7 A/R, 62 mm inducer, 82 mm exducer, 2.5" inlet, 4" outlet.
    2. Pressure Ratio is (19 + 14.7)/14.7 = 2.3
    3. Flow is 420 HP / 1.44 = 292 CFM x 0.078 = 23 LB/MIN

    Since PTE are (cough - unhelpful) they won't provide a compressor map for the 6262 or even tell me where I am on the map.

    I found a compressor at Garrett that's pretty similar: GTW3684R. Map is below. We're on the middle left side at PR 2.3 and Flow 23. Not totally ideal, but not way off the map in the boonies either.



    We'll see how the new turbine housing does. Will get that downpipe exhaust leak fixed and have the downpipe ceramic coated while we're in the process.
    Last edited by dvallis; 02-16-2020, 06:36 PM.

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  • dvallis
    replied
    Car is in for graphics at Sign Effects in Austin. The owner Beth is a BMWCCA member who has had many BMWs over the years. So glad gearheads are doing the job.

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  • dvallis
    replied
    Rereading old Das Beast blog posts is fun. Glad we weren't this guy on the dyno.

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  • dvallis
    replied
    So, we may get a reprieve on the clutch. From way back when in the build, it's a 6 puck ceramic Clutch Masters FX400 which should have plenty of holding force for the power we're making.

    We didn't break in the clutch. #facepalm

    Will change out the turbine housing, drive it "normally" at 10 psi (cough, wife laughs) with no WOT for 500 city miles, then report back.
    Last edited by dvallis; 02-13-2020, 10:19 AM.

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  • dvallis
    replied
    0.58 turbine gets here Thursday

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  • dvallis
    replied
    Absolutely. Car goes in Friday for graphics. Woooo!

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  • zaq123
    replied
    Originally posted by dvallis View Post

    This project started by accident.

    Ultimate goal is turn it into something resembling this.

    Gongrats!!!

    Going back to your first post....graphics time yet?

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  • Elysian
    replied
    Hell yeah

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  • dvallis
    replied
    DynoJet Printout and NASA spec average HP with 0.84 turbine housing.

    Expecting the 0.58 turbine to move the power to lower RPMs



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  • Elysian
    replied
    Originally posted by dvallis View Post
    Sure. Where and when do they happen in Austin?
    There's one on Feb 16th at COTA. Next one after that is March 15th. They're from 8am to noon.

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  • dvallis
    replied
    Sure. Where and when do they happen in Austin?

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  • Elysian
    replied
    Originally posted by dvallis View Post
    Went for my first drive yesterday in the newly dyno-tuned car. Wow! What a difference. With our previous "butt tuning" the engine ran strong but felt rough. Now it's super smooth.No hesitation at any RPM and the power comes on like a freight train. When you hit 4500 RPM it slams you back into into the seat like a punch in the chest from Mike Tyson. Had a long time BMW shop owner friend in the passenger seat and he was grinning like a maniac. I was fascinated by the change in boost behavior. With open loop the turbo seemed to meander its way to max boost. With closed loop control the boost gauge instantly snaps to target boost once you get around 4500 RPM.



    I'm really happy with how the build turned out. Only gets even more fun from here.
    Any chance you bring it to Cars and Coffee? I was planning on going to the next one, assuming my S3 is back from service.

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  • ForcedFirebird
    replied
    Such a great feeling, isn't it?

    Up here Georgia racing the 14hr, one of the team drivers is the current TT3 record holder for HMS and SIR. He said the same rules apply for TT as GTS as far as avg HP. The Dyno classification form has you record the RPM at max HP, then the power at 250 RPM less, then less 250 RPM etc until you have 8 values. Then divide total by 8. Basically you have a 2000 RPM window where you average power.

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