Duffy's 1/71 Series 1 240z build

[cgsheen1]

Well, any crank wheel is enough to run it all, but how...

What madkaw is getting at is this: The crank travels two complete rotations to complete one engine cycle of "four strokes". Top Dead Center occurs two different times during the complete engine cycle. With a toothed wheel attached to it, the crank can "tell" you when TDC has been reached BUT it can't actually determine if it's on the compression stroke or the exhaust stroke. (no matter how many teeth you have, or lose...) Usually we go to the Cam for that information - it runs at half the crank speed. Since the Cam only makes one rotation for every two crank rotations, a separate sensor on it can tell you when TDC is on the compression stroke - and that's what we're most interested in. Those of us running full sequential ignition with most aftermarket ECU's need input from both the crank and the cam to provide the exact engine position needed. There are other methods I'm sure, but those are most common.

Using just the crank toothed wheel input, I could still run individual coils (COP) in a "wasted spark" mode - and the Haltech ECU is certainly capable of doing that. Wasted spark fires two spark plugs at the same time on opposing cylinders so it doesn't really matter the crank position. It's firing cylinder one at both TDC compression and TDC exhaust - it can't "get it wrong".

(How could it "get it wrong"? The engine doesn't stop at the same place every time. When you shut it off, the ECU can't keep track of it's exact location and "know" it's exact position when you start it back up again -  that's why they need position sensors...) 

IF Haltech can glean enough information from a toothed wheel (not using a cam sensor input) to run full sequential (not wasted spark), I think there are many that would like to know how they do it.

(BTW, I can't see how the Hoke toothed wheel is 60-2... On the linked site it shows his as a typical 36-1. Not that the number of teeth makes any difference. More teeth normally just means better resolution but more teeth can also be harder to "read" accurately at high RPM - so they strike a balance when they invent these things.)

[duffymahoney]

Yeah that is how I understood it as well.  I will wait for haltechs response.  I am a total newbie at all of this.  Thank you for the detailed response.  

 

You can order the hoke in 36-1 or a 60-2.  It's an option.  I own both.  Here it he 60

[cgsheen1]

Ah, looks nice. I'll stick with an optical wheel in an L28ET dizzy though...

[240260280]

I think fly wheel would be most accurate from an angular error perspective, and from a mechanical slop perspective:

1. Distributor has gear lash slop at crank
2. Damper has rubber migration and shear.
3. Flywheel is bolted to crank, teeth are farthest from axis for least angular error, and they move fastest for strongest pulse at same rpm. You can easily add more teeth for finer resolution.

[jonbill]

I imagine Haltech are expecting it to run with paired injectors so it doesn't need to know the cam's position.
AIUI there's not much advantage to sequential. A little better on economy I think.
I'll be converting mine to EFI with Speeduino this winter with paired injectors.

[madkaw]

1 hour ago, 240260280 said:

I think fly wheel would be most accurate from an angular error perspective, and from a mechanical slop perspective:

1. Distributor has gear lash slop at crank
2. Damper has rubber migration and shear.
3. Flywheel is bolted to crank, teeth are farthest from axis for least angular error, and they move fastest for strongest pulse at same rpm. You can easily add more teeth for finer resolution.

Could t agree more with the flywheel being used. 

Like said above , a CAS alone will run your motor just fine .

[duffymahoney]

The flywheel is an interesting idea.  Already bought the hoke kit.  Now to figure out how I should wire the R35 coils in a wasted spark setup.  I think this basic idea would work fine.  

[madkaw]

Sorry , but trying to follow too many threads , but are you running a Haltech? 

Shouldnt you refer to their manual as far as wiring ? There might be a method of wiring it for sequential but firing it wasted spark. This way if you get a cam sensor it’s just a software update and not rewiring issue

[duffymahoney]

I haven't bought an ecu yet, but I think I will get the haltech Elite 750.  

I believe I am the first for doing wasted spark and R35 coils.  I don't think I will do a cam sensor, but if I do, it wouldn't be too hard to change.  The injectors and ignition would be paired by the ecu, so it can be changed to sequential anytime. 

[cgsheen1]

I've been wondering (but haven't asked): Why the R35 coils?

[duffymahoney]

R35 are the Nissan family. 2nd highest tested coil on the market (I’m not an expert) looks cool. Available new. All black and small. 

[madkaw]

2 hours ago, duffymahoney said:

R35 are the Nissan family. 2nd highest tested coil on the market (I’m not an expert) looks cool. Available new. All black and small. 

Are they smart coils?