Beiträge von John in DC

  • Clutch horror......

    Zitat von 8Tech;101404

    What SC 850 in New York?


    If thats true, he either doesnt make 450 bhp or he certainly doesnt use a BMW clutch!


    8Tech.


    Although it was many years ago, my recollection is that BlueAllan's 850 Twin Turbo lived at 450hp-ish levels for some time with the stock clutch. However, a 500hp pull on the dyno promptly exceeded its clamping power (read: roasted it).


    If Allan is on this board, perhaps he will chime in with the details.


    BTW Gerry - Didn't Allan source his current Spec clutch from you?


    Rgds...


    - John

  • New Dyno run

    Zitat von Noggie;101555

    PS: look at the dates, these graphs are 5 years old.


    My heart skipped a beat when I first saw these thinking that they were recent (ie supercharged) graphs. Thanks for pointing out that they were made before you were boosted.


    Rgds...


    - John

  • Supercharger install

    Zitat von fuzzifikation;76254

    Did that help? Or was it something completely different that you've asked?


    Very well written. Indeed, that was what I was looking for.


    In summary, the engine management (ECU) has base fuel/spark maps to tell it how things *should* be and then uses the feedback loop (ie from various sensors including the O2 sensors) to determine how things actually are.


    With regards to the O2 sensors, the ECU detects a lean condition and adds more fuel - - but it adds slightly too much fuel causing the ECU to detect a rich condition, which causes it to reduce fuel - - but it reduces too much, which causes a lean condition - - and so on and so on, etc. In short, the ECU is always chasing its own tail.


    Of course, this is a gross oversimplification of things but I think the datalog graph (which is just a few seconds across the X-axis) demonstrates this behavior nicely and may help some readers here to gain a more complete understanding of how the O2 sensors work in conjunction with the ECU's to ensure that air/fuel ratios are within the desired ranges.


    Rgds...

  • Supercharger install

    Zitat von fuzzifikation;76245

    ... and it would mean that no matter what map - the engine might always be on the lean or rich side (I don't know which way the oxy sensor drifts) because of the oxy-control loop (which keeps the engine lean instead of rich/stoichiometric...)



    Here's a data log from when I was tuning my 850 Twin Turbo a few years back. Notice the square waves from the oxygen sensors.



    Anyone care to guess as to why they are going up-down, up-down ?

    Rgds...

  • Supercharger install

    Zitat von stevep840;76075

    The Old superchaged 840 of mine went from averaging 22 mpg to 26 mpg after the S/C:harhar: Maybe I should have kept it.


    Were these numbers taken from the car's on-board-computer?

  • Supercharger install

    Zitat von fuzzifikation;76210

    (and, maybe, that no turbo compressor has 98% efficiency in any point.. sorry, but I am willing to bet a keg of beer that 98% is a blunt lie from whoever is manufacturing that thing! :-)).


    I'll bet you a keg of beer that the drive system for Egil's supercharger is more than 98% efficient !


    BTW, I believe you've mistaken supercharger drive system efficiency for compressor wheel efficiency. If you re-read Gerry's post, you will discover that he was referring to parasitic loss of the drive system (not compressor efficiency).


    Insofar as compressor efficiency, the unit in Egil's car has efficiency range of 70-76%.


    Hope this helps...

  • Supercharger install

    With this success, we can finally announce the availability of the supercharger kit for M70-based E31's (with stock camshafts) for both the North American and European (ECE) markets.


    The only remaining step for Egil is to refine the Air/Fuel ratios to more closely match the Hartge camshafts.


    Way to go Egil !!!


    Rgds...

  • Supercharger install


    We're pretty confident that this is a DME programming issue. We did experience similar issues on one other SC kit install but that particular E31 was without O2 sensors. Therefore we're currently investigating whether the two issues are related.


    It may take some time to sort it since I'm in the States and Egil is in Norway.


    I will provide feedback here once we know more.


    Rgds...

  • Supercharger install

    Zitat von anguswolfendale;66154

    John,
    This is shaping up to be a really neat install - have you considered a kit for the M62 V8?


    Yes. However with my time constraints, I fear it may be quite a long ways off.


    Rgds...

  • Supercharger install

    Zitat von DickB;66145

    Thanks John, I also have sc's that doesn't need external oilcooling, but when you drive longer with more pressure, the motoroil is becomming hotter, therfore we installed a cooler.(there is a standard cooler for tropic regions available at the dealers).
    I'm impressed by the compact unit you developed!
    Success!


    Thanks again for the kind words, Dick -


    Going forward, I will be sure to provide guidance for those owners who wish to have the "tropical" bits by updating my installation guide to reflect this.


    I do want to reiterate, though, that additional engine oil cooling is not compulsory with this kit when driven under normal street driving conditions.


    This is due to the extremely high efficiency of the made-to-order supercharger unit we're using which is able to achieve 98% drive efficiency and ~80% compressor efficiency. Most superchargers have much lower efficiency ratings (typically in the 65% range) and therefore inject much more heat into the intake tract.


    Our higher efficiency supercharger coupled with the large intercooler keeps contributory engine heating to a minimum. The result is that engine operating temps are well within the design limits of the stock cooling system.


    Of course, if you're tracking the car or going flat out on the autobahn then I would strongly recommend adding the CSi engine oil cooler to the car as well.


    Rgds...

  • Supercharger install


    Thanks Egil for sharing your install progress with everyone. Thanks also to others here for the kind comments.


    Dick - The supercharger kit uses a single air filter that feeds air into the supercharger head unit which in turn flows out through an air-to-air intercooler before flowing through the MAF's and DK's on it's way to the cylinders. Unlike all turbocharger systems and most older generation supercharger systems that use engine oil for lubrication (and therefore contribute to heating it), this kit employs it's own oil supply, integral oil pump, and oil cooling system.


    Therefore, additional engine oil cooling is not compulsory with this system whilst driven under normal street driving conditions.


    Hope this helps...

  • Supercharger Kit Completed - Dyno Results Here...

    Zitat von fuzzifikation;57742

    interesting, John. I would have bet money on the very-soon failure of the auto gearbox.



    I would have made the very same bet 5 years ago, Fuzz -

    In fact - - knowing the abuse that the transmission would receive during the tuning phase of the twin turbo project - - I actually budgeted for a transmission rebuild before turning the first bolt on the engine. Fortunately, despite the thrashing that the 4HP24 unit in my twin turbo car received, it just wouldn't die.

    But let's be clear: An automatic transmission of any make with any level of HP/TQ being pushed through it can die at any time for any number of reasons. Therefore your concerns are not at all unreasonable.


    Zitat von fuzzifikation;57742

    One more thing about the auto-box: Did you change the torque converter to a stiffer one? I would like to do that but have troubles finding torque converters for the ZF 4HP24.. any suggestions?

    No but any transmission shop worth their salt should be able to build a custom stall converter to your specs if you provide them a donor unit.

    Zitat von fuzzifikation;57742

    John, as far as your twin turbo or supercharged version goes: What did you change engine and ignition/injection wise? Anything at all?


    The supercharger kit is completely bolt-on and includes everything needed to control fuel and spark (ie fuel injectors, chips, etc) using the stock Bosch Motronic.

    Zitat von fuzzifikation;57742

    Do you have any heat problems?


    None whatsoever. However I will require anyone installing the SC kit to prophylactically replace their fan clutch and fan blade with the tropical cooling bits from BMW.

  • Supercharger Kit Completed - Dyno Results Here...

    Zitat von fuzzifikation;57709

    The 4spd automatic can not hold that kind of torque.


    Actually, you'd be surprised how durable the 4spd automatic's can be...


    My '92 850iA car with approx 500HP/600TQ (crank) has done almost 20k miles in twin turbo trim and I have experienced absolutely zero slippage on the original/stock 4HP24 transmission.


    I believe ~100 Dinan Stage II (500HP) and at least one Dinan Stage III (625HP) twin turbo cars had slushboxes as well.


    So the 4spd automatic 4HP24 transmission can handle the power. It's all a matter of what you have to do to make the transmission endure 10's of thousands of miles while pushing that kind of power through it.


    In my case, I was fortunate to have purchased a well cared for car that had the transmission fluid changed on a regular basis.


    However, if it ever becomes necessary - - my plan is to simply have the stock friction surfaces replaced with kevlar bits as part of the rebuild and be done with it. If I ever increase the power to approach or exceed the 600HP level, then I'll likely need to increase the fluid pressures and shore up some of the internals as well.


    For now, though, things are just fine.


    Frankly speaking though - - if one doesn't have the budget to rebuild the slushbox when it goes south, he probably doesn't have any business owning an 850 to begin with (much less a supercharged one).


    Rgds...

  • Supercharger Kit Completed - Dyno Results Here...

    Zitat von dudu;57233

    Do you use the standard gearbox or a customized one ?
    No need to made changes at the gearbox and/or shift ratio in order to achieve all of this torque /power ?


    Apologies for the late reply.


    We used the standard 6 speed gearbox with stock/original clutch (car had approx 70k miles at the time). Other than the supercharger system itself, no modifications of any sort were made to the drivetrain.


    Rgds...

  • Supercharger Kit Completed - Dyno Results Here...

    .
    For those wondering, the design criteria for the kit were as follows:


    • Stage I: Achieve CSi HP levels at the crank.
    • Stage II: Achieve 450+ HP at the crank.
    • Engine bay should appear as close to stock as possible.
    • Bolt on installation - ie no cutting of any metal parts in the engine bay.
    • No (or minimal) cutting of plastic parts in the engine bay.
    • Installation by experienced mechanic possible in less than 8 hours for Stage I and less than 12 hours for Stage II.


    I'm happy to report that we achieved all of these goals with the following exceptions:


    • Stage I & II: Two oxygen sensor bungs must be welded into the exhaust system just ahead of the catalytic converters. This should require less than one hour of labor by an experienced welder.
    • Stage II: A small 3cm hole must be drilled in the plastic shroud just ahead of the radiator to accommodate the oil cooling lines for the supercharger.
    • Stage II: The lower black plastic air duct and spoiler must be modified to accommodate the intercooler.


    These three plastic bits could be acquired for approx US$300 (see items #2 and #5 here and item #3 here) from Gault for those that wish to retain the option of returning the car to stock in the future.


    Just to echo the goal of keeping the engine bay as stock as possible, I would like to mention that it is actually possible to retain the stock air filter boxes if one chose to modify them. However, given that this would require cutting the filter boxes up - - violating the no/minimal cutting design goal - - that possibility was not chosen for the production kits.


    Rgds...