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NA to turbo conversion - questions and answers...


mikeatrpi

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hey mike, nice thread man. i have to say this post has most likely helped alot of people. i for one can safly say it is going to help me.

i do have a question though, you added MS because boosting an NA engine means you also have to do some fuel, air and timing adjustments right? what exactly is megasquirt? i no its an EMS but what else did you have to do to incorporate it. especially when it comes to the dizzy...

i have a 82 na with a p79 head im looking to boost and i no i dont have a crank angle sensor?

thanks and good job

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Yea, I guess it did turn into a build thread (oops?!) but I think its important that we continue to learn from each other.

 

Megasquirt is a new computer for the car. It replaces the existing computer, and the existing engine wiring harness. You can buy a Megasquirt in various versions - MS1, MSII, and in various forms - kit, or assembled. diyautotune.com is the place to shop, and their staff is active on these forums. I chose to build my own wiring harness from spools of wire, but you can buy a harness too. You can re-use some of the datsun sensors, but you'll need other sensors as well. I got mine from the junk yard.

 

So basically you get your megasquirt installed in the car, wire it to the engine and other things. Then you run software on your computer called Megatune - it will let you control the fuel, timing (timing is actually optional), and a bunch of other stuff.

 

For the distributor - I welded the advance as several folks on this forum have done. The distributor on my 82 is a VR distributor - it generates an A/C sine wave as the engine spins 'round. The megasquirt is setup to take the analog sine wave input and use that to sense the RPM of the motor. The reason you lock the distributor is so that the signal does not change as the revs increase. You then use the megasquirt computer to fire the coil... the computer figures out when to send the spark, offset from the distributor signal.

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  • 4 weeks later...
  • 1 month later...

Finally, an update! Over the past few weekends I brought the car out of storage, installed an AEM wideband, and started tuning. I also put some heat wrap on the downpipe and heat sleeve on the oil feed line.

 

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The wideband is the lower bung, the upper one is for the stock oxygen sensor. For now, its just plugging the hole. The wideband needed to be far from the turbo; this is about 30 inches from the turbo outlet.

 

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Here's a new boot for the j-pipe. Its from the plumbing department at lowe's. I have to watch and see if it melts... I hope not

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The gauges. With a little filing of the radio, they fit where the tape deck used to be. I made a front and back plate, and use the clamps for the gauges to pull everything tight. The boost gauge is mounted upside down - otherwise I couldn't see it from the driver's seat.

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I'm not sure if I like the gauges here yet. Once I get the car tuned, I shouldn't have to watch these gauges much - but, time will tell if I get annoyed and want to move them.

 

Finally, I connected the j-pipe to the air regulator. I cut a fitting on my lathe for the j-pipe.

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Edited by mikeatrpi
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Mikeatrpi.....you will need to change that clear hose coming from your manifold if it runs to anything other than the boost gauge....when the engine bay gets hot that kind of tube goes very soft and will collapse under vacuum......I found out the hard way :)

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Mikeatrpi.....you will need to change that clear hose coming from your manifold if it runs to anything other than the boost gauge....when the engine bay gets hot that kind of tube goes very soft and will collapse under vacuum......I found out the hard way :)

 

Yep, someone reminded me on the last page about that too. I'll make a note to do it soon!

 

mike

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Sorry if I'm asking this in the wrong thread, but I'm doing something similar. Taking the intake/exhaust/turbo from an 83 280Z and putting it on a 78 L28E, running EDIS for the Megasquirt.

 

Is TDC on the 78 vs 83 different? I am under the assumption that it is not, but wanted to make sure before I try to track down another issue.

 

The reason I ask, I just put the pulley/36-1 wheel onto this motor from the bad motor, and used the existing notch, assuming that would put it in the same positioning as TDC on the previous motor?

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Is TDC on the 78 vs 83 different?

 

You can easily find TDC. Remove all the spark plugs. Put your thumb over the #1 hole, and crank the engine with a ratchet on the crank pulley nut. When you feel it build pressure you know you're on the compression stroke. You can feel when it stops building pressure if you slowly rotate and release your thumb. Or, you can use a flash light to look inside the hole.

 

I'm not using EDIS, and don't have a trigger wheel, so I'm sorry if my response is too amateurish! :)

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Mat - I dunno yet!! :( My MS isn't tuned, and I feel like an idiot. Its beautiful weather where I live, and my Z is stuck at home.

 

I'm experiencing noise on the tach input, and my AFRs shoot lean when I rev it. I have a thread going in the MS section (hint!).

 

I'm also second-guessing my home-brew relay board. The main power wire broke off the DB-37 this weekend, I'm assuming due to fatigue on a cold joint. I had the board in and out of the car a few times on Saturday, then Sunday I was driving and the MS shut off! I fixed it, but purely for reliability I'm thinking about buying the MS relay board and 4 foot plug section. Its $140ish, ouch! Cheaper than getting stranded I suppose. Decisions. Anybody got advice in that regard?

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That's unfortunate, I hope you get the issues ironed out.

 

I am going to attempt to run the stock EFI with a wideband [for tuning purposes], partly because I have the stuff to do it, partly because I'm cheap, and partly because then I'll have done it myself.

 

I'm glad to see the Z is seeing some road time again, I can't wait to dig into mine as well!

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Sorry if I'm asking this in the wrong thread, but I'm doing something similar. Taking the intake/exhaust/turbo from an 83 280Z and putting it on a 78 L28E, running EDIS for the Megasquirt.

 

Is TDC on the 78 vs 83 different? I am under the assumption that it is not, but wanted to make sure before I try to track down another issue.

 

The reason I ask, I just put the pulley/36-1 wheel onto this motor from the bad motor, and used the existing notch, assuming that would put it in the same positioning as TDC on the previous motor?

 

The main problem is when changing the pulley for another which has a different diameter, that puts the TDC mark out of alignment with the marker (which can be off anyway). Remove #1 spark plug and slide and alloy rod into the bore, turn the crank by hand until the pistons stops and scribe a line on the marker inline with the notch on the pulley, then turn the crank the other direction until the piston hits the rod again and scribe another line...divide the space between the 2 lines and you will have TDC....well near enough anyway.

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I replaced that MAP hose with some 5/32" rubber hose, finally. I also replaced the VR sensor lines with some 50 ohm coax from the scrap bin at work (its not the same as cable tv coax). I ran the VR+ and VR- as the data on the coax, and grounded the sheathing at the MS side only. I re-did the DB-37 connector as well. Last weekend I had the main power lead break off. I paid attention and did a neater job soldering.

 

MAP hose and coax during re-wire:

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Coax and gnd; the ground is the sheath. You peel it back, twist it, solder it to a small lead, then heat shrink it.

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As a result, the tach noise I was experiencing is completely gone, and I'm sure this new MAP hose will be better in the long run than the PVC stuff.

 

 

Also - not sure if I ever shared this. This connector is located under the dash and is connected to the coil. I'm using it as my switched 12v input for the megasquirt main relay. For the ZX guys, this is real easy to tap into. I do have a weird problem if I crank too long, sometimes it dips below about 9v and the relay clicks off and on again. I think this is something in my relay, not the wire I've chosen.

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  • 4 weeks later...

Time for an update.

 

I blew the head gasket a week ago. I took the car to work for the first time with the turbo, and I was being stupid and showing off. Whoops.

 

Now, the interesting part is why it blew in the first place. I was having a problem with pinging, especially in boost. My waste gate opens at about 4.6 PSI, and I pulled the timing in boost back to around 23 degrees - so I figured "hmm that's odd". I talked myself into thinking colder plugs would fix it. Wrong!

 

Anyway - it turns out that my lock-it-up job on the VR distributor was bunk. "X64v" reminded me to check the timing, which I did this morning, blown gasket making PSSH PSSH sounds and all.

 

You set the MS to a trigger angle of 20 degrees, then you can check it at idle and rev it. If the timing changes when you rev, then you botched the VR mods. Well, mine advanced big time when I rev'd it. I never locked out the mechanical advance. I thought I did, but I didn't. So, I copied "x64v"'s method and welded the top shaft to the lower shaft. Note to anyone else doing this - I wish I left the screw in, it would have been easier to weld the screw to the side. Instead, the hole is so deep that my weld looked pretty sloppy. You'll know what I'm talking about if you try this. I did keep the mechanical advance parts inside, as I don't expect them to be able to move now.

 

So, after fixing that - I started the tear down today. I'll use this as an opportunity to tidy up some brackets, wiring, etc that I wasn't happy with. The rest of you - learn from my mistakes - CHECK the timing across the RPM RANGE!

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Had you already pulled the head on this motor? I'm using ARP studs and I'm very happy with deciding to go with them.

 

Just wondering because my buddy Chris [TrumpetRhapsody] and I were having a conversation about X64v blowing head gaskets on his L24ET today at lunch. What head gasket are you going to get for this?

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Hey Mat -

 

Nope, I have never had the head off the car. I ordered two head gaskets and intake / exh manifold gaskets from MSA. Two, so that I'd have spares 'next time'. You know, like carrying an umbrella when the forecast is 50% rain...

 

Why does everybody say the ARP studs are so great? I'm tempted to re-use the head bolts that came with the car. Unless somebody tells me that's a seriously bad idea.

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