Morning all. I have found threads on LTCC conversions and 24x conversions, but no where have I found someone who has tested both. Have I just missed those posts in my searches or is there really no data?

Thanks,
Josh

 

I know lots of us have inatalled the LTCC. I did it on my 93 that I no longer own. Current owner of that car is driving it, trouble free. I'm hoping this let 24x conversion people comment.

 

My bet is An OEM quality optispark (with mitsubishi sensor) outperforms both those systems.

and plus you can put a capacitive discharge spark box on the optispark to boot unlike the other systems

 

The documentary evidence shows that your guess would be wrong. Sorry.

If you, as I do, own the not-very-good LT1/4 book by Cottrell and McClellan you'll know that they built a 383 ci LTx engine and ran it on a dyno with a GM Optispark and an MSD 6 AL spark box. They use the MSD box as it does improve power. They then installed the EFI Connection 24x hardware and a LSx PCM. The Opti/MSD equipped engine made 487 lb/ft @ 5,600 RPM and 552 hp @ 6,700. The 24x equipped engine made 507 lb/ft at 5,300 and 566 hp at 6,600. That's 20 lb/ft torque and 14 hp. They write that they have done this several times with the same results.

If we only had a spark energy deficiency the MSD box should have cured that. So we need to look elsewhere for answers.*

Optispark, in theory, provides very good (high resolution) engine position information. The problem may be that the LTx PCM doesn't process that information well/fast enough and the resulting timing and fueling errors cost us quite a bit of power. If true what of this is due to timing and what is fuel? Lingenfelter sells the LTCC and probably knows just what it's worth in power so maybe a phone call clears this up.

My question is still unanswered. Has anyone dyno tested LTCC and 24x hardware on the same engine? I know what each one costs, but what does each system (LT1 PCM + LTCC vs 0411 PCM) deliver?

*Also, inductive ignition can out perform capacitive discharge ignition as the spark duration can be much longer and that one big spark is proven better than a few short sparks. Most MSD boxes lose the "Multiple" part well before the torque peak anyhow.

 

i saw that comparison somewhere but I dont believe it.

everyone knows the first dyno pull always reads a little lower. And if that One pull was where they got their optispark baseline then ...

who knows ‘what’ they did. Did they run the optispark during an 85 F day And the 24x when it was 65F🤷🏻‍♂️

its also possible the authors are ‘in bed’ with someone trying to sell coil on plug systems so they are going to rig fhe results

Id have to be there to believe the results (which im not saying are impossible).

When I scan my 93’s $da2 with datacat, it is very fast reacting

 

Far out. Any other conspiracies you'd like to share?

 

the optispark gets an un necessary bad rap.

So many newbs come on here saying they replaced a perfectly good OEM one with a chinese one (bc they heard they fail) , it doesnt work and then they proclaim the whole optispark system do be a PO$ / beg for advice on LTCC or 24x systems.

whats funny is the LTCC still uses the optispark 😂

yes there are some work arounds (like installing a vent on a 92-94 gen 1) and or a water pump weep hole mod and or putting rtv silicone around the halves edges as a fail-safe in case the seal cracks. Or even setting fans so your lt1 runs at 174F (like mine) instead of 212f like stock bc heat kills electronics

im not saying thats your intentions - which i believe are to explore fhe merits of that book showing a power increase when replacing the optispark.

i would love to find multiple sources promoting a power increase when replacing it .

i do appeciate the discussion, i am just skeptical of a single point of claim.

lastly - i mention these chinese optispark (and MSD optispark is also garbage) ....

so is the author using a correct NOS optispark (with mitsubishi optical sensor) as his baseline or is he using a chinese or MSD garbage optispark as his baseline.
i bet you he is using an MSD optispark in his baseline...

food for thought

 

As I wrote earlier, the authors used a GM OptiSpark and an MSD 6AL spark box as it was their dyno proven previous best. Then they used 24x hardware from EFI Connection with an LSx PCM and gained 14 hp, 20 ft/lbs. The authors appear to have been associated with TPIS, but I don't believe they have any link to EFI Connection.

Let's get real. 6000 RPM is 100 revolutions a second and each revolution has 4 firing events. 400 firing events/second gives 2.5 milliseconds between events. 1 second/400 = .0025 sec. Ignition events are happening every 90° of crankshaft rotation. To have the timing off by 9° at 6k RPM is to be only .00025 seconds early or late.

Can we fully charge the coil and spark it in 2.5 ms? Old school HEI had about 3.5 ms dwell. That's only achievable at or below 4285 RPM. What's the dwell on an LT1?

 

Ideally it would be optispark resolution and individual coil ignition.

The 0411 pcm is a better unit as far as tuning for anything. It just works better, faster, modern system etc.

Things improved points to hei to opti to coil on plug. That's generally how things work. That being said, I've also seen points dynoed against HEI and coil on plug to no appreciable difference... granted a carbed setup is a much different animal and cylinder to cylinder fueling has a more more significant impact than spark at that point as far as power is concerned. Once you get to true EFI then yea, c.o.p. all the way. no questions asked.

 

Maybe I am wrong but switching from a distributor (HEI) to a 36-1 trigger wheel ford wasted spark ignition netted me about 30+rhwp on a vortec headed 357cid sbc. I just don't see an opti coming close to the "resolution" or ability of a next gen spark system. From what I have read the 24x system is a night and day difference on gen2 stuff.

Expensive? Yes, but likely a vast improvement. Price is always a factor when making these decisions.

 

Theoretically the Opti with 360 position windows on the outer track would beat a 24-tooth wheel 180/24=7.5 times the signals per engine revolution. But then there is likely mechanical scatter (jitter for telecom techs) of the Opti signal that would not be present with 24x, 36-1, etc. HEI and other rear distributors are worse for spark scatter than the Opti and mechanical advance systems are far less sophisticated than 3D spark tables. There are many factors at play and without good test data it's difficult to make educated decisions. I'm not even sure I could hold engine speed constant enough to do accurate signal jitter and wander analysis, but I could try.

I am pursuing coil-per-cylinder ignition. I bought a set of coils for $50 so now I am looking for an LTCC system. This gets me more spark energy and less distributor maintenance at a minimum. If I want 24x engine management later I'll at least have coils and secondary/plug wires.

 

I've never seen an LTCC vs 24x comparison thread but would be very interested as well. Which 24x are you thinking of, EFI connection or torquehead? I was ready to pull the trigger last year but while comparing EFI and TQhead I chose neither since they each solved part of the equation but neither had everything I thought was important at the time.

 

Torqhead is the only solution I am aware of for keeping all the 94+ C4 systems functional. It is easier and cheaper to be an F body LT1 owner.

 

EFI connection sells a front timing cover, crank reluctor, and cam sync for under a grand. They also sell a LT1 0411 wiring harness if you have an F-body. I like this setup better than torquehead because it uses standard 0411 PCM instead of modified PCM. The downside is the install is much more involved than TQhead since you have to replace your timing cover.
https://www.eficonnection.com/home/c...efi-24x-lt1lt4

 

EFI Connection's solution does not preserve the PCM to CCM serial connection and therefore trashes the gauges and other functions. Torqhead modifies 0411 PCMs to retain the ALDL serial communications. His 24x hardware doesn't include a timing cover and is over $200 less.