John B

iTrader: (10)

Evidently it has been confirmed that unlike the LS1/2/6 the LS7 will use a 58x reluctor wheel to determine the crank positioning as opposed to the current 24x system. This makes it sound like only an LS7 PCM will work with the motor.

Anyone out there have the expertise to tell us options here short of dissassembling a brand new LS7 motor to retrofit a 24 tooth reluctor wheel on the crank in order to use currently wiring and software? Thanks!

Bink

Email GMPX at EFILive - he'd probably know of a work-around in the calibration. Just a thought.

Bill Reid

iTrader: (14)

Official press release pics of the crank confirm it will be the newer reluctor wheel. HOWEVER, I have heard that GM will initially build the LS7 with the older reluctor wheel. We'll see. If one is in the market for the LS7 crate motor... I would wait until a couple of tuner shops have had a chance to look at the motor and post up solid info.
BTW, the reluctor wheel is just one of a couple of potential show stoppers for retrofit into a GENIII based GM vehicle.

Richiec77

iTrader: (3)

Well. This might be harder to figure out.

There is this thread where a guy Transplanted a Gen III into a C6 and the sensor worked

https://ls1tech.com/forums/showthrea...ight=48X+crank

The crank gear is a 24X reluctor in the GEN III.

http://www.hsvdriversclub.co.uk/ls1.pdf

Goto the Crankshaft position sensor. That shows the digital output from the 24x reluctor.

John B

iTrader: (10)

Thanks for catching my typo!

Gary Z

Rather than fit a 24X reluctor wheel in place of a 58x (or 60x), it should be possible to electronically convert the new signal to 24x. This would only require inserting a bit of circuitry in the line from the LS7 CPK sensor.

John B

iTrader: (10)

Now we're talking potential options! What does this involve?

Richiec77

iTrader: (3)

Correct, BUT the signal from a 60 (-2) is a realy straight forward signal. It has 60 equal spaced notches. 2 are removed. Very simple output logic.

The 24x is a nother story all to together. It has a more random pulse (not really but looks like it) and would be harder to transplant on to the signal. It would almost be a Signal Generator. Not a simple Flip-Flop like I hoped.

I'm still looking into this.

Builder

As Gary Z indicated, it won't be too hard. It would require measuring and capturing the 24-tooth sensor output and the 58-tooth sensor output, building a translation table (in a PIC, for example), and packaging it to handle the under-hood environment and to fit somewhere near the existing circuit.

Richiec77

iTrader: (3)

That would be a simple fix, but won't easily happen. The 60(-2) uses 1 fixed timming point within 360deg of timming. The 24x uses a logic that keys it with-in 45deg (8x) per 360deg rotation. That is the tricky part. You could simply tranlate, BUT if timing is skewed by the Transistor (PIC or IC) than the timming would be off.

This is much trickier than it looks. In a lab, this isn't too hard to figure out, In the real world, other factors will make it harder to be acurate.

Go here and look @ the Crankshaft Sensor. It has the logic output for the 24x reluctor.

http://www.hsvdriversclub.co.uk/ls1.pdf

Builder

Easier said than done? Of course, it has to be correct. Still, not that complicated. My suggestion isn't the only option and I am sure there are many more and better solutions. I will leave that to the people that are much smarter than I. Another (perhaps less elegant) option might be an external reluctor. Maybe the tweak can be done in the PCM.

Frizzle Fry

iTrader: (1)

Just out of curiosity here; if someone has the $$$ to buy the LS7, then why not just buy the LS7 ECM? Or, are there other issues there such as no edit capability yet?

Bill Reid

iTrader: (14)

What I find weird is that when GM released the part number for the LS7 engine no other good info was released. If the motor REQUIRES a new PCM wouldn't GM have released that info when they released the part number? That might make too much sense.

Another thing, block pic I've seen shows the dip stick boss present but not machined for a dip stick tube.

Also, we do not yet know if the crank snout is different (length and perhaps diameter) in order to accomodate the twin rotor oil pump... this might make the reluctor wheel a moot point.

Watch the Motortrend mock assembly video and you'll see for a split second the new reluctor wheel on the crank... and I had heard that GM might still use the older reluctor wheel for a bit longer. DAMN! http://www.motortrend.com/av/112_050...nebuild_video/

I'm also wondering if the (corporate) reluctor wheel change has something to do with future displacement on demand... and perhaps the need for increased or different signaling from the crank.

Richiec77

iTrader: (3)

Correct. the main issue with using the LS7 pcm is the tunning capability is not there yet, so it would have to be a barelly modified or have to use alot more external devices.

Also, Is the LS7 MAF or MAF-less? I haven't seen the sensor in any pictures I've looked @.


Cool. I never looked for the dipstick boss being casted in place. So it would seem that the LS7 block can be used in a traditional GEN III build. Good news.

You have a damn good point about the crank snout. Seems like we are all so excited, but there will be issues to combat.

I have to assume that this crate engine whould be for both DBW (drive by wire) TB and Cable TB. The PCM needs to be included for this engine to work.

The switch to the 60(-2) standard just shows that GM is going to a more proliferated design. More engines use the 60(-2) design than any other type, by a Really large factor. I believe it was implemented by Bosch 1st and has been for a long time. Makes for less RD work when designing a Product to use a Standard that is/has been working for a while.

For now, We'll have to wait and see what is actually there. I don't know who would want to open an assembled engine though.

Bill Reid

iTrader: (14)

Regarding the reluctor wheel, if all else fails I would think one could purchase the older reluctor wheel and have it installed prior to installation of the motor into the car. Assuming the reluctor wheel would not change the balance of the crank and the mounting diameter is the same then this mod wouldn't be all that expensive in the scheme of things.

Regarding the cable TB, doesn't the FAST 90MM intake manifold have the same bolt pattern as the LS2/7? I am still asumming at this point that the LS2 and LS7 share the same DBW TB. If so, then FAST already has a 90MM cable TB available. Ya, a bit more of an expense... but... no one ever said this retrofit would be cheap.

I know... alot of assumptions... but I'm just pointing out what I see along with some speculation and just trying to stay optimisitc that this motor won't require cost prohibitive mods to install.

At first glance it looks like the LS7 does not have a MAF... but a closer look reveals what looks like it has one. I have seen an 01 Duramax Diesel MAF and it is basically just a "sensor head" that mounts into the intake tract... the pic shows basically the same thing.


Bill

Richiec77

iTrader: (3)

Ok. I'ver heard about the sensor head, just never saw it due to the angle being 180deg out from that picture.

So, TB is pretty much done, The reluctor is still the issue I see. You can put the 24x on the crank, but you'll have to diasemble the engine to due so. Kind of defeats the point for buying the Crate engine. I have an idea that may work, but i'm iffy if it'll work under the hood. I thought this would be a simple fix, but has become a tricky one to solve.

99Fbody99

The new reluctor ring is a new corporate standard for all GM engines. The biggest advantage to them is its divisable by all engines 4,5,6,8,10 cyl etc.
The inhearant drawback of it is the extended cranking till it figures out cyl #1.

Dave

Bill Reid

iTrader: (14)

Hmm... maybe thats part of the reason why GM put in the smart start where you just rotate the key (or push the button) for a split second and have the computer complete the starting routine... interesting...

John B

iTrader: (10)

New for '06? The '05 LS2 doesn't use this....

Richiec77

iTrader: (3)

That makes alot of sence now.

And the use of the 60(-2) does cut down on costs. That is something I wasn't even paying attention too.