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View Full Version : What is up with this CAS sr20det


Kingtal0n
06-07-2021, 10:28 AM
Its from an S15 but I've never seen one like this before

https://i.postimg.cc/5Nh6c1qd/IMG-7775.jpg
https://i.postimg.cc/SRwNp797/IMG-7773.jpg
why does it look like that?

Kingtal0n
06-07-2021, 10:40 AM
The disc inside is also different than usual

https://i.postimg.cc/5t3BNjnF/IMG-7790.jpg

PoorMans180SX
06-07-2021, 11:51 AM
That is a distributor for a KA24DE.

Kingtal0n
06-07-2021, 11:59 AM
That is a distributor for a KA24DE.

LOL thanks man

hilarious... rolling right now.... I've never seen one before

PoorMans180SX
06-07-2021, 12:14 PM
LOL thanks man

hilarious... rolling right now.... I've never seen one before

Haha for sure. I think that's an S13 one, S14 might be a little different due to the integrated coil, I've never taken one of those apart before.

RalliartRsX
06-07-2021, 12:42 PM
LOL thanks man

hilarious... rolling right now.... I've never seen one before

NA S14 and S15s came with a distributor as opposed to COP and CAS. The NA distributor setup is very similar to to the USDM SR20 FWD distributor system. Which is also similar to the KA24DEs

Looks like a 360/4 slit (slits of differing width depending on Cyl 1-4) CAS wheel

Kingtal0n
06-08-2021, 02:10 PM
NA S14 and S15s came with a distributor as opposed to COP and CAS. The NA distributor setup is very similar to to the USDM SR20 FWD distributor system. Which is also similar to the KA24DEs

Looks like a 360/4 slit (slits of differing width depending on Cyl 1-4) CAS wheel

the slits in this one are all the same length.... leaving me to think its for distributor, no way to ID the cylinder (spark jumps to nearest terminal)

strangest thing though... i got it from a guy who swears its out of an s15 sr20det. he gave it to me free... no reason to lie....

And another weird thing... how would the computer know when to fire the injectors if the slits are all the same length? It would need some other kind of crank sensor. I should take a closer look at the disc... was there ever an SR or KA engine that uses batch fire injection or has some alternative crank sensor?

RalliartRsX
06-08-2021, 02:38 PM
It's definitely a distributor. But yeah, the guy is probably 1/2 right; it's from a S15, just not a DET. A standard DE, sure.

Rotate the wheel some more. This also may be a 360/1 (where 1 slit is larger than all three) which signifies TDC.

ECU really only needs one reference point for TDC, and it just counts the slits for the remaining 3 cylinders.
https://www.diyautotune.com/support/tech/install/nissan-datsun/megasquirt-your-240sx/

Don't think any SR or KA used batch fire (unless the KA24E maybe??)

Kingtal0n
06-08-2021, 08:00 PM
Well now I'm dying to try it inside a det just to see if the ecu can make sense of it. The guy never owned a sr20de engine; I tuned his s15 silvia a couple times over the years and thats the only engine he ever owned so... I just wonder. If, you know, the ecu could make sense of it, even though its wrong for the engine. Hmmmmm

So weird.

RalliartRsX
06-08-2021, 09:27 PM
Not sure. The DET ecu has the coil drivers. The DE ecu does not

Also, if the CAS wheel is different and the optical pickup is different it won't work

P.s DE and DET engines are almost identical external sans the ports for the oil and coolant feed being tapped on the DET as opposed to the DE where they are not. Valve cover is raw/khaki color as opposed to painted on the DET. He may had had a converted DE to DET and not have know...or got it from a random parts stash. Who knows lol

Everything else bolts up. CAS in place of the dizzy. Etc

Kingtal0n
06-09-2021, 08:09 PM
Not sure. The DET ecu has the coil drivers. The DE ecu does not

Also, if the CAS wheel is different and the optical pickup is different it won't work

P.s DE and DET engines are almost identical external sans the ports for the oil and coolant feed being tapped on the DET as opposed to the DE where they are not. Valve cover is raw/khaki color as opposed to painted on the DET. He may had had a converted DE to DET and not have know...or got it from a random parts stash. Who knows lol

Everything else bolts up. CAS in place of the dizzy. Etc

Well here is what I am wondering and may never know... Many OEM ecu have backup/failsafe for running an engine without camshaft sensors. For example my 4.8/5.3L LS oem ecu can run on a crank-trigger alone without the camshaft sensor, it simply makes a guess when you first try to start and you get a loud backfire "BANG" on first attempt, second try it starts up and runs fine. The crank trigger is priority for determining piston position, the cam sensor is just for quickly identifying whether you are on compressor or exhaust stroke.

So I am wondering if the DET ecu can do the same thing with a CAS like this one. Maybe it can use the one large window to determine piston position forthright and from that point on it can run the engine just fine...

Too bad sr engines are extinct antique priceless legendary artifacts