Running a Corvette LS1 engine

DaveW · Post by **DaveW** » Thu Mar 09, 2006 6:22 am

I've been asked to look at running one of these engines on MS as it is complete apart from the lack of an ECU.

I need to provide ignition and injection.

The engine has knock sensors, cam sensor, crank sensor, coolant and air temp and a MAP sensor on board. The OEM system uses sequential injection and it has COP ignition.

Gut instinct suggests that the best solution is to add a 36-1 wheel and run EDIS for the ignition with a couple of coil packs, ignoring the existing crank/cam sensors but I thought I'd ask here first....

Can anyone give me any pointers to technical data on the sensors and their compatibility ?
Is this the best way to run it ?
Has anyone done it already ?

FoundSoul · Post by **FoundSoul** » Thu Mar 09, 2006 9:07 am

To my knowledge noone is running the LS1 with the stock crank/cam sensors at this point in time-- I can try to lookup the details on them with the year of the car in question and see if GM published the data, but I don't believe they're going to be compatible from what I've heard thus far. If that's the case then your best bet is the EDIS setup which is pretty cheap and not that hard to implement-- very easy to control with the MS-II as no mods are required, and can also be controlled with the MS-I and MSnS-E though mods are required to do so...

Post by **jsmcortina** » Thu Mar 09, 2006 12:22 pm

I should be MSing an LS1 at some point too.
dieselgeek is the expert on this - Parish's truck runs Megasquirt and an LS1.

Do you have the GM coils? They are logic level drive, so with a 36-1 on the crank and MS1/Extra you could run them in wasted-COP mode without need for VB921.

I too would like to know what the stock crank pattern looks like as I'd like to write a decoder for native support at some point.

James

FoundSoul · Post by **FoundSoul** » Thu Mar 09, 2006 1:18 pm

DG is the expert on this, though Parish's truck was fuel only on the 'squirt.

Give me a year you're interested in and I'll see if I can look up the trigger wheel info...

DaveW · Post by **DaveW** » Fri Mar 10, 2006 4:15 am

I've yet to see the engine other than in a photo, I'm assuming it's a recent version (it's a new engine). If it helps, I've posted some pics here:

http://www.yorkshireoffroadclub.net/corvette_engine/

The coils have 4 LT wires to them so that, and the digging I've been doing, suggests that they are logic level drive coils. As suggested here, it makes sense to drive them direct with MS1/Extra on a V3 board.

I'm going to see the engine today and have a look at the crank sensor/wheel. I've had it described over the phone but I think I need to look at it first hand to make any sense of it. I'll take some photos of it too if I can. It sounds like it has 2 wheels, presumably with 2 sensors in the crank sensor package.

I can always bolt a 36-1 wheel and sensor on if need be.

Post by **jsmcortina** » Fri Mar 10, 2006 6:10 am

Nice!
Someone has a few quid knocking around then.

I think my approach will be a Ford pressed 36-1 wheel on the crank and logic level drive to the coils.

I believe the wires are:
+12v
logic feed
logic ground?
power ground

You _should_ be able to drive them right off the CPU, but I'd stick the 330R resistor inline to each one just incase there is an external short or something. Apparently they are smart-dwell too?

If you fancy loaning me coil for a play I'd like to scope it.

James

DaveW · Post by **DaveW** » Fri Mar 10, 2006 10:33 am

James, I'll see what I can do with a coil - I'm looking at getting some spare ones shipped over with a view to fitting them to my 3.9 V8 so will be able to lend you one then.

I've had a look at the crank sensor setup and tried to figure out how it's encoded by peering in the hole while someone turns the engine.

The ring is made up of 2 x 1/8 in (ish) plates mounted side by side. Each plate is the reverse of the other so that when one side has a tooth, the other has a gap and vice versa. I assume this improves the resolution or reliability of the sensor. The rings seem to consist of long and short teeth in an irregular pattern. It wasn't easy to figure out what was going on but it looked as if there was a block of 4 long teeth, then a block of 3 long teeth, then a block of 2 long teeth then 1 on it's own with smaller teeth filling the gaps between... if you see what I mean ! Each block starting at 90 degree intervals.

I'm hoping to get a close up photo of a crank out of the engine to confirm this. Maybe the description above rings some bells with someone ???

Anyway, for the moment, I'll bolt a 36-1 wheel on and use that !

Post by **jsmcortina** » Fri Mar 10, 2006 10:39 am

The two sets of wheels is likely to give a quick-start setup so the ECU can syncronise really quickly and fire within say 90degrees. A regular missing toothed wheel has to wait up to 360deg before it can think about firing.

James

DaveW · Post by **DaveW** » Sat Mar 11, 2006 4:40 am

It seems I was close... but no cigar

I've uploaded a photo of the ring now which, hopefully, will make it clearer.

See the 2 pics at:
http://www.yorkshireoffroadclub.net/corvette_engine/

I've posted the original pic there and a cutout pic, the cutout pic gets rid of the second wheel which, as you can see, mirrors the first.

The leading edges of each of the 24 teeth are uniformly spaced, looking at the photo the crank rotates ccw. At a guess, the actual crank position is calculated by looking at the last 6 pulses as no matter where the crank is, the last 6 pulse widths will be unique to that position.

If anyone thinks it will help, I'll produce a drawing of it and should now be able (using the engine) to identify where TDC would be at the sensor.

I'm pretty much certain I'll be going down the 36-1 route but it would be nice if the original sensor/wheel could be used. Once it's running on a 36-1 I should be able to provide a scope data log from the OEM sensor too.

Post by **jsmcortina** » Sat Mar 11, 2006 5:23 am

That's clever, but my first response is UGH...
Definately go with the 36-1 !!

I'm sure we will eventually figure that OEM pattern out and I have access to an engine to, but it looks like a job for router board style hardware.

James

mattuUK · Post by **mattuUK** » Sat Mar 11, 2006 6:33 am

I don't know if this will be of any use to you guys, but I remember seeing some info in PPC magazine
*search*
issue 19
*/search*
apparnetly the front pulley isn't keyed. and the people to speak to are Wortech or Boost Performance.

regards

Mat

V8BUG · Post by **V8BUG** » Wed Apr 05, 2006 1:45 pm

Has anyone ever thought of some how splicing into msd's ls1 ignition control box thing?
Maybe you could have the msd box do all the work and MS could control the advance and retard.

Just a thought.

http://store.summitracing.com/partdetai ... toview=sku

Post by **jsmcortina** » Wed Apr 05, 2006 2:09 pm

mattuUK wrote: apparnetly the front pulley isn't keyed. and the people to speak to are Wortech or Boost Performance.

Same on the Northstar. I'm hoping to drill a small hole in the crank snout and use a roll pin to hold the trigger disc in place.

James

shad9876 · Post by **shad9876** » Fri May 12, 2006 11:22 pm

i am putting an ls1 in my 56 and plan on controlling it with an ms-II. i have to get the coil packs. if i go the route of EDIS + 36-1 wheel on the crank i would not need the ls1 coil packs, correct? this is my first endeavor into fuel injection so i'm pretty ignorant and could use any relevant information!!

thanks,
shad

Post by **jsmcortina** » Sat May 13, 2006 4:27 am

Going with EDIS is probably a sound move. Once the trigger disk and sensor are mounted correctly you are 90% of the way to spark.

The original crank trigger wheel looks very strange and appears to have a double pickup sensor, so ignore all of that and get a 36-1 wheel and standard Ford coil packs.

Once you've done that your install is "just" a normal EDIS install. Assuming you get an LS1 intake you should have most/all of the parts you need.

James

shad9876 · Post by **shad9876** » Sat May 13, 2006 7:53 am

with this type of setup, should i use an edis wiring harness that is made to plug into a megasquirt(saw one on ebay like this) or should i just use a wiring harness from megasquirt....or will i need both???

thanks,
shad

shad9876 · Post by **shad9876** » Tue May 16, 2006 9:00 am

how do i attach the 36-1 edis wheel? does it attach direclty to the crank or the the balancer? does it require that my crank have keys? my ls1 crank is not keyed.

thanks,
shad

DaveW · Post by **DaveW** » Thu May 18, 2006 4:10 am

The way we've done it it so mount the wheel on the back of the crank pulley and make a suitable bracket for the sensor that mounts on the timing cover using existing bolts.

Although the crank pulley isn't keyed this is not a big issue, if anything it makes mounting the wheel easier as you can mount the wheel without having to worry about the location of the missing tooth as you can sort the position out later.

Once the installation is finalised we will drill and tap the pulley collar and drill the crank to provide a locating bolt although it probably won't be needed as, having taken the pulley off a couple of times it's not exactly easy to get the thing to move !

We're going to try and use the Corvette coil packs as they are logic level coils, using a V3 MS with MSnS-Extra to drive them in a wasted spark arrangement. The MS is built and configured, the wheel and sensor are fitted... tomorrow I'm going to "play" with the coils to see if MS can drive them as expected.

eliotmansfield · Post by **eliotmansfield** » Thu May 18, 2006 11:00 am

Are you sure you will be able to drill into the crank? - Surely it's hardened. Perhaps do nothing, put a painted line as a tell-tale to see if the damper moves - and see what happens.

-or-

What if any existing LS1 owners paint their dampers now and see if they move at-all?

Eliot.

Posted by email.

dieselgeek · Post by **dieselgeek** » Thu May 18, 2006 2:21 pm

WHOA! just saw this. Hold up!!

Brains already figured this out actually tested it on the bench. Using the wheel decoder, the cam and crank pos signals CAN be used easily with the MS. The VR sensors on the LS1 have electronics that convert to a "square wave" right at the sensor, so it acts like a hall or optical signal. I believe the TRAILING edges of the PCM pattern on the crank wheel are evenly spaced, 24-tooth pattern but I believe he said the signals are either inverted, or such that the MS picked up the RPM signal of a running engine just fine. Using the A/B signal from the cam, you should be able to run a 4-channel wasted spark setup, OR if you use one of the "mega coilers" (we're planning on trying this in a month or so, on the truck) you shuld be able to run 8 sequential channels?

Brains has confirmed this works, you should be able to use the wheel decoder in Extra and get all you need, no EDIS module necessary.

How much of a hurry are you in? we could find a guniea pig to tap into, with a plain MS, just tap the CMP and CKp wires like Brains did, and confirm for you...

Parish's truck is a few weeks away from us testing this, but I could find a stocker and try it out (see if the MS can get stable tach from those sensors)

-scott

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