Datsun L28 N/A Build - Need help with Megasquirt???

[jy.s30z]

Hello,

I'm in the middle of a rebuild for my 78 280z. I am doing head work, valve job, flat top Pistons, compression ~10.2:1 with a mild cam, headers/exhaust.
The biggest challenge for me is converting to ITB set up. I bought a set of 6 throttle bodies for a BMW E46 M3 and it came with TPS and I'm going to make a custom manifold to mount to my head. Now I have to convert to megasquirt. Fuel management & electrical are not my expertise and I need as much help as I can get as I am lost on what I need to finish this project.

All the information I can find on the Datsun's with megasquirt are for turbo applications. Can someone that has experience with this set-up please help guide me on what I need to complete my build.

Below are some questions I need help on:
- I have the stock distributor of 1978 280z... do I have to change to the turbo dizzy (I'm having trouble finding one)?
- If I can keep my stock distributor, how do I go about connecting it to the MS... do I need to modify anything?
- What are the benefits of switching from Batch Fire to Sequential? Is it worth the added costs?
- Has anyone here successfully converted a Datsun L-series to ITB's? If so, are they using speed density or alpha-n?
- I'm going to have to buy an intake air temp sensor and for the TPS I will be using the one off the BMW M3 ITBs... Any other sensors I need or should my car have the rest of the sensors needed?
- Do I need to buy a new fuse box and a relay?

Any information would be much appreciated.

Thanks in advance.

Joe

[Matt Cramer]

Hello,

I'm in the middle of a rebuild for my 78 280z. I am doing head work, valve job, flat top Pistons, compression ~10.2:1 with a mild cam, headers/exhaust.
The biggest challenge for me is converting to ITB set up. I bought a set of 6 throttle bodies for a BMW E46 M3 and it came with TPS and I'm going to make a custom manifold to mount to my head. Now I have to convert to megasquirt. Fuel management & electrical are not my expertise and I need as much help as I can get as I am lost on what I need to finish this project.

All the information I can find on the Datsun's with megasquirt are for turbo applications. Can someone that has experience with this set-up please help guide me on what I need to complete my build.

Below are some questions I need help on:
- I have the stock distributor of 1978 280z... do I have to change to the turbo dizzy (I'm having trouble finding one)?

The turbo distributor is the easiest one to use for timing control. You could also lock out the regular distributor advance mechanism or go crank triggered if you want spark control.

- If I can keep my stock distributor, how do I go about connecting it to the MS... do I need to modify anything?

It's a VR sensor; use the notes for VR sensors.

- What are the benefits of switching from Batch Fire to Sequential? Is it worth the added costs?

Somewhat better idle and light throttle response, and you can do individual cylinder tuning if one cylinder is rich or lean.

[jy.s30z]

Thanks for the response Matt!

Since I can't find a turbo distributor and from what I saw, the crank trigger would eliminate my A/C.... I think I would want to go with locking out the regular distributor and using the VR Sensor.

Would you be able to explain what "lock out" the regular distributor details? And would this be reliable method?

[Six_Shooter]

There are a couple different ways that you can use the NA dizzy.

The following is based on having the MS control spark timing in addition to fuel control.

First the dizzy needs to be locked out, so that neither the mechanical nor the vacuum advance changes the timing.

The way I'd likely go if I were in your shoes is to feed the signal from the dizzy right to the MS and have the MS trigger the coil or an external ignition amplifier box such as an MSD. If you have the MS trigger the coil directly you will need a coil driver such as the BIP373 or the IGBT driver common in the MS. The signal of the NA dizzy is a VR type signal, so study up on that and what connection need to be made internally of the MS.

An alternative way is to use a GM HEI 7 or 8 pin ICM (Ignition Control Module). Connect the dizzy to the ICM via the P and N terminals, and then follow the GM HEI connections in manual to complete the wiring and setup. The one advantage the GM ICM has is that the ECU doesn't even need to be in the car to have spark. The GM ICM will run on what is known as base timing (whatever the dizzy base timing is set to) and turn over advance duties to the ECU only once the bypass connection sees 5V.

I used the GM ICM for a while on my L28 when I fist converted it to EFI, I used a Delco EFI system at the time, not an MS, but the connections and use are the same.

The better way, but may be a bit much to get into if this is your fist EFI conversion, or upgrade is to go DIS, either wastespark or COP. GM, again, has some good dual tower coils for wastespark use. There are a multitude of ways to accomplish this with various trigger wheels, and coil control modules.

After running both dizzy and DIS on my L28 I wouldn't use anything other than DIS now. That being said there's nothing wrong with using the dizzy to get the engine up and running if doing everything at once is overwhelming, and it can be for the beginner, there's zero shame in realizing and admitting that. Everything can be upgraded in time.

[Supernova_6969]

Hi joe

for the intake air temp, 2 things:
-make certain you buy an open element one, they react faster.
-Make certain you mount it BEFORE the throttle body. My car came with it mounted in the manifold and it just didn't work. took me 2 years to realized that it's input was essentially completely wrong and messing with my tune. see this: http://forums.hybridz.org/topic/122459- ... gas/page-2

one of the options re: the dizzy is to actually use a toothed wheel on the crank itself with a pick up sensor, run that to the MS, then have the MS choose the timing and send it to the coil (I think some MS versions need an igniter module before the coil), who then sends it to the top half of the distributor, bypassing the stock crank sensor altogether and getting the spark distributed to the right plug. I do think you need to lock the advance mechanism (it's literally as simple as either welding or taping and screwing the moving parts together, from what I understand). It's relatively cheap, and does not need any fooling around.
DIYautotune sells the toothed wheels, but you can make one yourself (I don't quite know how, but it's been done, and can't be that hard..)

this thread is one of some where a guy talks about setting up a 76 dizzy. i didn't quite understand everything as the z set up is different than the zx I have.. could be very good leads.. http://forums.hybridz.org/topic/120394- ... -76-dizzy/

as for the sensors, i think you're covered. I'm pretty certain you can calibrate MS to understand the stock Datsun coolant temp sensor output , and the MAP is included in the MS, i think..

for the fuse box, my 280zx uses the stock everything except for a new 12ga fused wire to my new gas pump (which is triggered by a relay that is itself triggered by the original wiring for the original pump). you might want to set yourself up with an parallel system with a new ignition-on relay that powers the whole car up (or use the stock one if you can find it), but really, everything that stays the same does not need anything new, and anything you add, well, you can add inline fuses. but there is not much of a need for that, since you only need one or two powered wires to run a whole MS setup, i think.

Double check everything I wrote though, as i only know enough to potentially cause a lot of damage....

s