Unfortunately, the system outlined earlier in this thread did not make it to market.
dave w
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Unfortunately, the system outlined earlier in this thread did not make it to market.
dave w
Given the Opti system is been around for 20 plus years, I was hoping for a innovative DIY solution. From what I can gather, the heart of any conversion away from the Opti is the ability to use OEM cam and crank sensors to get a signal to the 411 PCM.
This would entail of mounting a 24X reluctor (machine work required) from a compatible existing OEM part, and a 1x reluctor for the cam signal (perhaps using the existing Opti base as the drive and placement base?). Anyone have any suggestions of compatible OEM parts (that could be modified) for this? This would be a combination of machining capability, but then, as I'm new to this, how/what is the process or objective to properly line up the senor to give the right/accurate placement/reading?
The EFI kit is nice, but at $500 for the base kit, and then getting a (for earlier lt1's) a 96-97 crank hub and timing cover puts the starting price of this up near $800 - $1000 before all the other parts.
I think the main reason there hasn't been more development on this is the effort and expense compared to just swapping over to an LS based engine.
Attached are some pics of my 4x '0411 harmonic balancer mounted crank trigger.
With some forward thinking, a dual trigger wheel (cam / crank) could be designed and mounted to the harmonic balancer of a LT1 engine. I like the idea of a 24x crank trigger and 1x cam trigger which allows using the '0411 LS per coil ignition system.
dave w
A swap is never (rarely) as cheap and easy as one might originally think. My attempt is to find a DIY (ie cost effective) solution for the innovative driveway mechanic that doesn't want to go to an all out swap given they've a solid platform with the LT1.
The 2 major hurdles are finding a OEM 24X reluctor from another application that could be modified to externally mount on the LT1 crank hub. The next thing is finding a 1x reluctor that could be modified to be mounted on the Opti (using it as the base as the 1x reluctor drive). Any ideas of what engines would have the right donor parts?
After that is where my growing (but still limited) knowledge leaves me stranded. How and what is the mounting position for the 2 sensors?
I've access to a friend with a lathe, so that will help with the keeping the fabrication cost down to a DIY budget, as well as being able to find sensors on CL or salvage yards etc.
Any help with thoughts on donor parts (year of vehicle, etc.) and mounting position of the sensors, would be greatly appreciated.
The plan (or hope) is to be able to get the required parts for under $250, which on the EFI Connections kit (which btw is a nice kit) starts at close to $550 to $600 for the basic kit, and that before timing cover, crank hub (for pre 96 Lt1's). For a pre 96 Lt1, he EFI solution really starts at close to $800 or more $, and I'm thinking that about $500 more than most DIY budgets.
I have read of attempts to make a new reluctor wheel for the Opti that had both the 1X and 24X signals in it. Basically, it's done by duplicating the 24X pattern twice around the wheel since the cam turns 1/2 revolution for each crank revolution. Then, I think just a level conversion to the PCM would be required. The rumour is that EFI Connection attempted this and it just didn't work right.
I've also read of attempts to use the Opti signals and convert them to the 1X and 24X signal patterns the '411 PCM needs.
But, I have never found any cases of running, driving, fully working success when attempting any of these.
But you can't have a 1x wheel on the crank simulating the cam sensor. The 1X cam setup switches between "on" and "off" each crank revolution.Quote:
Originally Posted by dave w
I too would only bother doing the work if converting to a CNP setup. I already have a 96 LT1 with the 4X crank setup installed which is currently running 95 '8051 code but I can't be bothered making my own 1X cam sensor when the conversion won't use CNP.Quote:
Originally Posted by dave w
Where does the cam signal on your set up? Is this prototype stage or is it fully functional?Quote:
Originally Posted by dave w
:doh:Quote:
Originally Posted by lionelhutz
You are correct, the crankshaft rotates 2x turns to the camshaft 1x turn. The L31 Vortec distributor mounted cam position sensor is 175.5 degrees, not a full 180 degrees.
I thought there was a place that modified LT1 intakes to accept a distributor? Maybe use a fabricated / engineered 24x crank sensor mounted to the harmonic balancer, then install a L31 Vortec distributor in a modified LT1 intake manifold?
dave w
The LT1 intake is fairly easy to mod if you can weld aluminum. You cut off the EGR portion at the rear of the intake and plate it. Then use a normal SBC intake and make a template of the distributor hole. Transfer that to the LT1 intake and hole saw it for the Vortec CMP Sensor (Distributor). Cut out a plate with a hole or machine a circular boss that will fit into your LT1 intake hole. Mock up the LT1 intake on a SBC block with its oil pump installed and install the Vortec dist. Let the dist find its sweet spot and weld in the boss.
Jeff
Found a part #12559353 for a LS1 crank reluctor wheel that might work for fab'ing a custom crank mounted relcutor, and am guessing this is the right part for triggering the LS1/411 PCM signal. However had also found some comments about (requiring?) a dual track reluctor and but this reluctor wheel (from the pictures I was able to find) is only a single (track) wheel.
Anyone able to help clarify for a newbie. Thanks
Ya, that appears to be the right part.
I've never researched it, but the sensor must use that second opposing ring somehow. Here's a cool document.
http://www.bowlingss.com/DownLoads/P...Holden_LS1.pdf
Page #30 (35th page in document) shows the 24X pattern. You can follow the pattern on the back ring of that wheel starting with 0 degrees around the 10:30 position. That section also says there were dual tracks but no real description of how the sensor used them.
12552480 is the big block 24x crank reluctor which mounts behind the timing cover and is similar to the part EFI Connection uses. But, pictures show a dual track wheel. 10456248 is the crank sensor for this reluctor. I would think it'd have to be used with the BB reluctor to properly detect the dual tracks. EFI Connection's pictures show a single track wheel and say it can be used with the LT1 crank sensor which was originally used on a single track 4X wheel.
But, if you don't want to source the proper timing cover to fit such a reluctor behind then using an external damper hub mounted one would be your only option.
Here is a 1998-2001 Vortec 454 L21 used in medium duty trucks. It was the 1st BBC to get both CNP(Coil Near Plug) and Electronic Throttle COntrol(ETC). It uses a 512kb PCM. It thinks its an over grown LS1 Corvette engine.Quote:
Originally Posted by lionelhutz
Attachment 9671
Attachment 9672
Yes the 1998-2001 Vortec L21 24x reluctor 12552480($20 from GM) must use the specific L21 CKP sensor 10456248($100).
This is the 24x SBC reluctor I bought for $99 on sale. It is designed so that I don't have to use the L21 CKP sensor. I can use the less expensive 12596851 CKP sensor from the 96-2000 Vortec 305/350's, that originally was used with the 4x CKP reluctor.
Attachment 9666
Attachment 9667
Attachment 9668
.
If you drill the LT1 intake to accept a Vortec V8 distributer, you can buy one of these EFIConnection caps.
Attachment 9669
Attachment 9670
The L21 uses the camshaft to drive the distributer like device sometimes known as the camshaft synchronizer. It uses p/n 01104068 $284. Its pretty much a Vortec V8 distributer, which drives the oil pump, and holds the CMP sensor (1x)
peace
Hog
Thanks for all the info and suggestions.Quote:
Originally Posted by Hog
I'm leaning towards drilling the LT1 intake and using a Vortec Distributor for the 1x cam signal.
So, it looks like I'm down to 2 choices for the 24x signal, which would be mounted externally - the LS1 reluctor #12559353 or the L21 reluctor 12552480. I've a few questions re orientation of the reluctor, as well as the sensor mounting.
The LS reluctor doesn't have a keyway, but there's a small hole close to the edge of the wheel (on one end of the 5 larger holes) which is between the 5 holes and the hole hat has a arrow shaped cut out in the hole. Is the small hole #1 TDC, and how would this wheel be mounted in relationship to the 1:30 position (#1 TDC) of the keyway in the LT1 crankshaft, which seems to be a indicator or reference point of some sort. Is this #1 TDC? Once the wheel orientation is correctly made, would the sensor be mounted at the 7:30 position, or some other position (as from what I can tell from a few LS pics - the sensor seems to be mounted on the side of the LS block and its not clear to me if that is also at the 7:30 position (directly opposite the keyway / 1:30 position).
The same question of orientation applies for the L21 wheel, but that one looks like its easier to figure out as it has a key way. Would it be as simple as lining the L21 wheel to the LT1 keyway position, and also using the 7:30 position for the sensor mounting? I've not been able to find anythng that shows me how/where teh crank sensor is mounted on the L21 timing cover.
There's a lot of info around and I've learned a lot in the last week, but the one issue where there doesn't seem to be a lot of clear info is this crank/reluctor and sensor mounting relationships. Once this is figured out correctly, I'm pretty much ready to finalize the design of the mounting modifications.
Thanks in advance for any help.
I suggest you come up with an adjustable bracket to mount the sensor and then put the engine at #1 TDC and install the wheel to match the location of the bracket.
Quote:
Originally Posted by lionelhutz
Thanks for the quick feedback, but I’m still not clear on what the relationship between #1TDC, the position of the reluctor wheel, and the where the sensor is mounting in relationship to this.
May be best to try and walk me thru this.
First, make an adjustable mount for the sensor. By adjustable, I’m guessing this means the mount allows for a few degrees of adjustment?
Once the sensor location is set/made, AND the engine is at #1 TDC, what is the reference point on the reluctor wheel that should be pointed at the sensor?
I was able to find a pic of the LS wheel where someone has marked #1TDC. Is the pic accurate, and is that reference point to align with the sensor (while the engine is at #1TDC)?
Attachment 9693
With the BB wheel (pic below), it has a key way, so am I correct to understand that the keyway is #1TDC and the reluctor should align at that reference point to the sensor? In the pic, the keyway is at the 1:30 position (which I'm guessing is at #1TDC), and I'm guessing the sensor is mounted at the 7:30 position (as most GM timing covers seen to mount the sensor at that position)?
Attachment 9694
In Dave's post #34 above, he made a reluctor and mounted the sensor at approx. the 3:30 - 4:00 position, but I couldn't tell how the wheel was positioned/oriented at #1TDC and the sensor mounting position.