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Any issues with accessories, gauges, etc with the Holley ecm?
This would be a question for the company that is doing the Holley based conversion.
Its very likely that they're just piggybacking the factory LT1 PCM with the Holley to retain all of the factory functionality of the LT1 PCM.
This is done with the Holley a lot on Gen 4 LS engines in their respective factory vehicles to retain all OEM functionality, with the advantages of the Holley.
Its very likely that they're just piggybacking the factory LT1 PCM with the Holley to retain all of the factory functionality of the LT1 PCM.
Let me say, by no means do I know or understand programming.....
But the above quote is where the problem lies, (I think)
The LT1 computers, (92-96) are very dependent on a signal from the opti. .........
If I want to convert to a stand alone, I basically need to gut the electrical system, and install the holley, along with a new dash. Then of course I would loose the antilock, ASR, and not sure what else.
In reality, its going to cost around $3,000.00 for the computer, dash, etc. and lots of labor.
At this point, best off to work with what we have.
Early C4's are a different story.
Let me say, by no means do I know or understand programming.....
But the above quote is where the problem lies, (I think)
The LT1 computers, (92-96) are very dependent on a signal from the opti. .........
If I want to convert to a stand alone, I basically need to gut the electrical system, and install the holley, along with a new dash. Then of course I would loose the antilock, ASR, and not sure what else.
In reality, its going to cost around $3,000.00 for the computer, dash, etc. and lots of labor.
At this point, best off to work with what we have.
Early C4's are a different story.
This isn't true for the Torqhead setup at all. Can't comment on Holley.
Let me say, by no means do I know or understand programming.....
But the above quote is where the problem lies, (I think)
The LT1 computers, (92-96) are very dependent on a signal from the opti. .........
If I want to convert to a stand alone, I basically need to gut the electrical system, and install the holley, along with a new dash. Then of course I would loose the antilock, ASR, and not sure what else.
In reality, its going to cost around $3,000.00 for the computer, dash, etc. and lots of labor.
At this point, best off to work with what we have.
Early C4's are a different story.
You don't have to operate the Holley as a stand-alone. Leave the Opti in the engine, and let the stock LT1 PCM read it.
The Holley will only be there to control the engine. Your stock LT1 PCM will still be able to read sensors/Opti signal and operate the dash and everything else inside.
Piggybacking has been done for as long as aftermarket ECUs have been available. Its not rocket science.
You don't have to operate the Holley as a stand-alone. Leave the Opti in the engine, and let the stock LT1 PCM read it.
The Holley will only be there to control the engine. Your stock LT1 PCM will still be able to read sensors/Opti signal and operate the dash and everything else inside.
Piggybacking has been done for as long as aftermarket ECUs have been available. Its not rocket science.
Joe, just trying to learn here, but how would you handle the crank sensor and keep the opti in place?
In both of the kits above, the crank sensor seems to replace the opti.
Joe, just trying to learn here, but how would you handle the crank sensor and keep the opti in place?
In both of the kits above, the crank sensor seems to replace the opti.
I would like to learn too!
Technically the opti is both a cam and crank sensor. So if the aftermarket EFI could connect to where the chip is (similar to Ostrich emulator) could it work that way and retain the dash function?
Thanks!
Steve
Last edited by STEVEN13; Nov 21, 2020 at 08:53 AM.
Well its partly true.... They dont show anything for 92-93....
That's because the connectors are designed to interface with the 94-96 PCM though. That's not the fault of their CCM/EBTCM communications protocol.
Originally Posted by STEVEN13
I would like to learn too!
Technically the opti is both a cam and crank sensor. So if the aftermarket EFI could connect to where the chip is (similar to Ostrich emulator) could it work that way and retain the dash function?
Thanks!
Steve
Yes. This is how the LTCC and its other derivatives operate. They intercept the opti timing signals and use those (and the commands from the ECM/PCM regarding ignition advance/retard) to fire the coils while leaving the rest of the electronics intact.
Last edited by Nomake Wan; Nov 21, 2020 at 05:49 PM.
That's because the connectors are designed to interface with the 94-96 PCM though. That's not the fault of their CCM/EBTCM communications protocol.
Do you know this for a fact? The reason I ask, in a previous post, (around 2018) it was reported that torquehead was working on a kit for the 92-93 vetttes. To date it is still not available, according to their web site. I am going to try and call latter today and ask.
Edit to add, I know the 92-93 ECM has different connectors vs 94-96 pcm.
Last edited by 93 ragtop; Nov 23, 2020 at 10:21 AM.
Nope. I just know by looking that their PCM won’t plug into anything other than a 94-96. So if you mean something beyond the physical harness, I’m afraid that’s something I’d refer to Torqhead themselves since I’m not affiliated with them.
You don't have to operate the Holley as a stand-alone. Leave the Opti in the engine, and let the stock LT1 PCM read it.
The Holley will only be there to control the engine. Your stock LT1 PCM will still be able to read sensors/Opti signal and operate the dash and everything else inside.
Piggybacking has been done for as long as aftermarket ECUs have been available. Its not rocket science.
Would the piggyback harness have to be custom made? Do you know who could make one?
As I stated in my other post- can aftermarket EFI connect to where the chip is (similar to Ostrich emulator) and retain the dash function?
In my case I do not utilize ABS/ASR or MPG functions. This almost sounds to good to be true.
It’s the high voltage side of the opti that is problematic. The optical sensor itself is reliable and accurate. If your just looking to delete the high voltage side for reliability, then get the LTCC Kit, used LS coils, makes some plug wires and brackets. $750 all in with opti worries a distant memory.
Last edited by TorchZ51; Nov 23, 2020 at 08:42 PM.
It’s the high voltage side of the opti that is problematic. The optical sensor itself is reliable and accurate. If your just looking to delete the high voltage side for reliability, then get the LTCC Kit, used LS coils, makes some plug wires and brackets. $750 all in with opti worries a distant memory.
Not sure if this was intended for me.
Looks nice! I am supercharged and was just thinking if it would be easier to tune.
Working on the tune now with Greg@BlowerWorks and also have a BIN from DizWiz that I have not tried yet..
Nope. I just know by looking that their PCM won’t plug into anything other than a 94-96. So if you mean something beyond the physical harness, I’m afraid that’s something I’d refer to Torqhead themselves since I’m not affiliated with them.
Yeah, that is pretty much what I (and most everyone) knows..... The plugs (connectors) are different....
In post 28 where you wrote. "That's because the connectors are designed to interface with the 94-96 PCM though. That's not the fault of their CCM/EBTCM communications protocol."
I took this statement ," That's not the fault of their CCM/EBTCM communications protocol." to mean the CCM/EBTCM was the same from 92-96..... which I suspect are very different, and that is why a kit for 92-93 was never released.
FWIW, I sent an e-mail to torquehead asking about a kit for the 92-93.
I took this statement ," That's not the fault of their CCM/EBTCM communications protocol." to mean the CCM/EBTCM was the same from 92-96..... which I suspect are very different, and that is why a kit for 92-93 was never released.
FWIW, I sent an e-mail to torquehead asking about a kit for the 92-93.
Ah, I see what you mean. I can tell you that the EBTCM comms are likely the same from 1992 to 1994. This is because the ABS module used in the 1992-1994 base and 1992-1995 ZR-1 are all the same. So at least that much should be unaffected by changes in ECM/PCM. The 1995 base and 1996 cars all used a different ABS, the Bosch 5, and yet Torqhead supports those too, so again, it doesn't seem that EBTCM would be affected. The bus comms must be similar enough for it not to matter.
The CCM, that I'm not sure since I don't have a 92-93 to test. But 94-96 CCM comms are the same. This is actually why on a '96 you can plug an 'old' ALDL connector in and still talk to everything in the car other than the PCM; the rest of the car didn't change to OBDII, only the PCM did. So that being the case, I'd at least be willing to guess that the 92-93 CCM isn't very different from the 94-96 cars communication-wise. Why redesign it if it already worked properly?
Thanks Nomake Wan.....
All good info.!! I did hear back from Torquehead..... Below is a copy and paste.
This is what I wrote. Hello,
Could you tell me if you have developed a kit to eliminate the opti-spark and convert to a LS set up?
I had read on the Corvetteforum, back in 2018 that there was plans for it, but I only see kits for the 94-96 corvettes
If you have not developed a kit, do you plan to, in the future?
And this was Paul's answer.
At this time we do not have a kit for the early 1992-1993 C4 Corvettes. They are quite different animals with their early style engine wiring and early style PCM. As such our kits aren’t compatible and in order to do the conversion on a 1992-1993 C4 you will need to swap engine harnesses to 1994+ style or have custom engine harness made with standard LS PCM connectors. Also to date we have no information if our LCD/CCM module tech (that keeps these elements happy for cluster) will work with the early year CCM modules.
I cannot say for sure if we will never have a kit for 92/93 C4’s, but I can say it isn’t planned at the moment or any time soon. Back in 2018 when we released the C4 kit for 94-96 cars we were going to start to have a look at the 92/93 cars. Being they are so different they presented very large challenge and ultimately would be quite costly. The 94-96 cars represent about 10% of business. The 92/93 would be less than this and the kit would be about $700 more expensive. To the point where its very risky of a kit to sell combined with the unknown and time of development.
Regards, Paul
Owner/Product Designer
Last edited by 93 ragtop; Nov 24, 2020 at 03:30 PM.
The major down fall of the opti is its inherent location, Cars ran on dizzys for decades but of course technology moves forward, But people saying make more horsepower by using an LS pcm, FAST system and others is simply not true, air fuel is air fuel as timing, how do I know? a friend had a performance shop with a chassis dyno and we tested mufflers, air foil, step headers, ect and saw no gains or maybe a couple of horsepower. I tuned a stock C4 and gained 36 RWHP, a GM engineer claimed he gained 50, Of course all vehicles are different and one might gain only 10 RWHP, but the point is, the stock PCM, Opti is perfectly capable for a everyday street car, My Turbo LT4 with stock GM heads/intake, on the stock PCM makes 710 RWHP on 11lbs, How? the correct go fast parts and tune.
The major down fall of the opti is its inherent location, Cars ran on dizzys for decades but of course technology moves forward, But people saying make more horsepower by using an LS pcm, FAST system and others is simply not true, air fuel is air fuel as timing, how do I know? a friend had a performance shop with a chassis dyno and we tested mufflers, air foil, step headers, ect and saw no gains or maybe a couple of horsepower. I tuned a stock C4 and gained 36 RWHP, a GM engineer claimed he gained 50, Of course all vehicles are different and one might gain only 10 RWHP, but the point is, the stock PCM, Opti is perfectly capable for a everyday street car, My Turbo LT4 with stock GM heads/intake, on the stock PCM makes 710 RWHP on 11lbs, How? the correct go fast parts and tune.
As I posted in another thread, you are fighting a physical limit with the opti (or any distributor for that matter). Your physical limit is the rotor itself. Coil-per-cylinder setups have no such limitation because their "rotor" in a piece of code running in whatever computer is handling the ignition system. You can do all sorts of fun things when you have direct control over individual cylinder timings.
I'm not saying the opti is bad, or that a stock car is going to magically benefit 50 HP or anything like that. I'm just pointing out that coil-per-cylinder systems are just plain superior because at the end of the day, the optispark still has to spin a physical rotor around.
Welcome to the forums, though! Sounds like a sweet build!
From: Las Vegas - Just stop perpetuating myths please.
I'm surprised no one has mentioned the YouTube series on replacing the optispark computer with an LS 411 computer and using a 24X crank wheel. This guy on HorsepowerTube covers both the distributor timed and the crank 24X wheel. He repins the original wire harness to work with the 411 computer. Here's the first part of 6 parts (or maybe more):
I did take a look, and it doesn't have any way to make the CCM or ABS/ASR happy, as you can see it's not in a Corvette. But if you don't care about the CCM (digital dash) or ABS/ASR, then yessir, it's yet another option to throw onto the pile. I guess it's basically the DIY version of the Torqhead, minus the niceties they include in their kit that make it a plug-and-play install for C4 Corvettes.
