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Gavin

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Posts posted by Gavin

    Tach signal flips out @ 4000 RPM. WTF?

    in MegaSquirt

    Posted

    Ya its starange, I was familiar with the dave cap, but somehow it didnt give me any trouble with the MSI.

     

    My Dad works on exit 1, so its not really out of the way. I'll keep my eye on the club board. I'd love to work on the club car. Also, that dyno, its a DynaPack isnt it? I actualy have a bunch of experience tuning on steady-state dynos through the full EFI University certification course, so perhaps I could help out there as well.

    Tach signal flips out @ 4000 RPM. WTF?

    in MegaSquirt

    Posted

    Oh no its not my tachometer in the dash thats giving me trouble, its the tach signal to MS. I can see this happening on the gauge in MegaTune and the engine pretty much stops firing after 4000.

     

    But yes all ignition system wiring is stock except for the MS being tapped into the -.

     

    So should I maybe try adding resistors to the tach wire? I'm no electrical engineer so I need some help here, no idea what to do.

    Quote seems high? You tell me!

    in MegaSquirt

    Posted

    Yes you could save some money by building it yourself, but rest assured that if you get it built from them it will be top notch. Also, their support is excellent, they have experience with many specific applications including Z's, and in fact Matt Cramer, the main guy frim DIYAuto who I have delt with at least, is on this board and I'm sure has his eye on this thread. So support couldnt be better.

     

    I like having the stimulator on hand for troubleshooting, loading/testing new code, ETC. Its a useful tool but not 100% necessary.

    Tach signal flips out @ 4000 RPM. WTF?

    in MegaSquirt

    Posted

    Just upgraded to MSII on my 99% stock 280z wired up with a 2.2 board, fuel only, using the - side of the coil for triggering.

     

    Moved the tables over and everything AFR related works great, but at 4k RPM my tach signal flips out. It doesnt just oscilate back and forth, it seems to completely loose the signal. I'm not using any resistors in the line. What could be causing this and what could I try to fix it?

    ZX Dizzy + MSII Questions - Think theyre easy ones.

    in MegaSquirt

    Posted

    Ok I'm having a lot of trouble figuring out what the hell I'm doing here. I've set up fuel on three different cars but find the ignition stuff impossible to follow. Just looking for some straight answers, pointing in the right direction, and to be held and told it'll all be OK.

     

    Currently using an MSII daughtercard in a 2.2 board running fuel on my 78 280z.

     

    I have a 83 zx turbo dizzy which I'm planning on using. I see there on the MS install guide how to wire it up, but what about the software side? How do you configure MS to recognise whats going on? Shouldnt these be standard settings for the zxt dizzy that I could get from someone? I guess this info is supposedly on this page, in the 'Setting Ignition Options' section, but I can barely read it-

    http://www.megamanual.com/ms2/configure.htm

    Is most of that even to do with optical wheel setups?

     

    The other thing is that I want to add a VB921 to my MSII/2.2 to run a single coil but am having trouble finding a wiring diagram. Could someone post one up?

     

    Thanks.

    Timing gear problems- broken tensioner?

    in Nissan L6 Forum

    Posted

    Im in the middle of replacing an N47 head.

     

    I have the chain over the gear, but I cant lift it enough to put it over the camshaft. It looks like the chain guides might have moved inwards somehow, since I cant see the crank gear if I look down between the chain and can on my P90 motor.

     

    Is this common? Does it sound like a broken tensioner or has the chain maybe jumped a tooth on the bottom and become tangled? Or should I just pull harder?

     

    Thanks.

    stock L28 turbo on KA good for up to 250whp?

    in Nissan L6 Forum

    Posted

    Hold on a sec..

     

    Had just done this to size one up for the ZX.

    Flows about 218 cfm or 15.4 lb/hr, peak power at 5200rpm...

     

    The low-comp engine needs 7 psi, or about 1.45 bar A, to make 180hp with the stock setup. So N/A it might make arround 125 hp.

     

    So it should take 2.2 bar and 34 lb/hr to make 275hp.

     

    That looks a little rediculous. Sure its a .42/.48?

     

    And Alex is it DSM injectors that people typically use?

    stock L28 turbo on KA good for up to 250whp?

    in Nissan L6 Forum

    Posted

    Ok heres how it goes.

     

    A turbocharged engine has a Brake Specific Fuel Consumption of .60-.65 . This number can be multiplied by your horsepower to give you your needed fuel flow in Lb/Hr.

    .65*350=227.5 Lb/Hr of fuel (So Step 1 is a Warlboro 255)

    Between 6 injectors = 38 lb/hr = 387.6 cc/min

    387.6*1.2 (for 80% max duty cycle) = 465 cc/min injectors

     

    Whoa thats big... Its meant to be an over-estimate.

    Does that sound right to other people?

    stock L28 turbo on KA good for up to 250whp?

    in Nissan L6 Forum

    Posted

    Must be.

     

    So you have-

    2.4L - 145 cid engine

    140hp@5500rpm

     

    assuming 85% volumetric efficiency at peak power, thats-

    (145*5500*.5*.85)/1728 = 196.15 cubic feet of airflow per minute.

     

    Since this map uses Lb/Minute, we have to convert from CFM. Which is done like this (A CFM of air appharently assumes its 112 degrees) -

     

    196.15*.070318=13.8 Lb/Min

     

    So your KA flows about 13.8 Lb/Min at peek power.

    140hp = 13.8 Lb/Min ... Approximately... in your case.

     

    To make 250 Hp, thats a 78% increase in flow. We'll say 80% to make it easier.

     

    Theoretically, if you double the atmospheric pressure in the intake manifold, you'll make twice as much power. So at 2.0 bar absolute (14.7psi above atmo) youre engine will flow twice at much.

     

    Using this reasoning, running 1.8 Bar absolute of boost will give you your 250 Hp.

     

    So-

    13.8*1.8 = 24.84 Lb/Min of airflow is what youre looking for.

     

    Now we can plot these two on the chart-

    t3-42.gif

     

    I'd call it too small, the higher efficiency area should be farther to the right.

    Doesnt look like it would be very well matched for 200 either: 1.42 Bar and 19.6 lb/min.

     

    That was a fun excercise. Please correct me if I'm wrong.

    split pulse manifold

    in Nissan L6 Forum

    Posted

    Looking here in Corky Bell's chapter on manifolds in Maximum Boost, he more or less says that it is much more important for the velocity of the gas in each runner to be consistant, ie that they be equally sized, than for the runners to be the same length.

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