Is there anyone with a f-body '93-94 that went 100,000 miles without Opti problems? Should be renamed Opti-scrap...
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Misspelled Opti-Spark?
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sorcererTags: None
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It's a distributor. It doesn't last forever. Does a regular SBC cap and rotor last 100k? Not even close. The opti does a pretty good job in comparison. It's just mounted in a funky place.
I have read lots of threads with people over 100k with the original opti, if that is your question.Rob B 95Z A4 Tech Page (Part numbers / locations, how to's, schematics, DTC's...) Home Page - shbox.com
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Originally posted by Rob B (shoebox)It's a distributor. It doesn't last forever. Does a regular SBC cap and rotor last 100k? Not even close. The opti does a pretty good job in comparison. It's just mounted in a funky place.
I have read lots of threads with people over 100k with the original opti, if that is your question.
I've never seen one go bad in person. This is my 3rd LT-1 car sinse 1995. It's not really that big a deal. So if it goes bad, you replace it.Tracy
2002 C5 M6 Convertible
1994 Z28 M6 Convertible
Current Mods:
SLP Ultra-Z functional ramair, SS Spoiler, STB, SFCs, Headers, Clutch, Bilstein Shocks, and TB Airfoil. 17x9 SS rims with Goodyear tires, 160F T-Stat, MSD Blaster Coil, Taylor wires, Hurst billet shifter, Borla catback with QTP e-cutout, Tuned PCM, 1LE Swaybars, 1LE driveshaft, ES bushings, White gauges, C5 front brakes, !CAGS, Bose/Soundstream audio, CST leather interior, synthetic fluids
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106,000 on the odo, had to clean it once, but knock on wood its still good. car also has original plugs and wires. i do have a new opti sitting here, and plugs and wires also. just to get a water pump and headers before i dive in.2000 WS6 T/A M6. Monster stage 3 clutch, flowmaster cat back, 4.10's, SLP lid, Hurst shifter.
1996 Mustang GT 5 speed STOCK DD
past rides:
1996 Mustang GTS bright tangerine orange
2003 Mach 1 azure blue drag car (10.90@118 record holder for fastest N/A mach)
1969 Mach 1 house of colors candy apple red393 stroker 100 shot (10.829@125 in street trim)
2003 Mach 1 Torched red FRPP aluminator/vortech 666RWHP
2008 Mustang GT JDM stroker long block, Saleen 2.3 twin screw
1980 Mustang L 13.7: 418 stroker
1994 Z28 A4 rebuilt from wreck
1994 Z28 A4 totaled
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Originally posted by lt1redzMy 93 Camero lt1 has 135000 with original opti..No real problems so far. It does stumble last time it went thru car wash.. Don't use car washes now.Use Zanio and hand wash..1993 TA SOLD
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"Unless It's Fatal, It's No Big Deal"
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sorcerer
Well, everybody i've speak to that own one f-body 93-up with opti around here ended up replacing it. At $1056.00 retail, plus the work involved to get it, it's no small affair. I'm about to replace it AGAIN ( lasted 13 months) so don't tell me it's a great piece of engineering.
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The Opti itself is A great piece of engineering yes, Where it is placed on the motor, is not. That water pump, as we all know, isn't indistructable, and when it goes, the opti goes. I've had to put 3 on mine, and can't even remember how many I've done at work, and most were from the pump leaking.1996 WS6 T/A - M6,not stock
2004 GTO - M6, stock
lost rides
2003 Silverado SS - stock
2000 Yamaha R1 - fast enough stock
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Originally posted by sorcererWell, everybody i've speak to that own one f-body 93-up with opti around here ended up replacing it. At $1056.00 retail, plus the work involved to get it, it's no small affair. I'm about to replace it AGAIN ( lasted 13 months) so don't tell me it's a great piece of engineering.
It is possibly the best distributor ever put on a small block engine, IMO.Rob B 95Z A4 Tech Page (Part numbers / locations, how to's, schematics, DTC's...) Home Page - shbox.com
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sorcerer
The concept is hi-tech,no doubt about it, but the engineering to make a durable is not. That's too bad because you loose confidence of the car.
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Originally posted by Rob B (shoebox)It is possibly the best distributor ever put on a small block engine, IMO.1996 Arctic White Z28, A4, K&N CAI, TByrne MAF ends, BBK Twin-52mm TB, TB Bypass, SLP 1 3/4" Shorties, Richmond 3.42's, Dynomax Bullet Muffler W/Turn Down, BMR Adj. Panhard, EIBACH Pro-Kit, AFS ZR1 Wheels W/17x11" out back!
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When it was first introduced in the 92 Corvette, the Optispark was the subject of an Society of Automotive Engineeers (SAE) paper that cited unprecedented levels of spark timing accuracy. The accuracy was measured in terms of "spark scatter".... the ability of the unit to provided a spark at precisely the required point. When you plot the actual spark timing for a large number of events vs. the intended spark timing, you get a "scatter" diagram (statisticians will know exactly what this means). The closer the actual spark event is to the intended event, the better the combustion. Reducing scatter reduces emissions, improves power and improves fuel efficiency.
Several of us have been using the optical section of the Optispark to feed the cam position to an aftermarket engine management system (ECU) and using that signal for timing the injection and spark. The high voltage function (cap & rotor) section of the Opti is not used, but external drivers are used for spark. I use a MoTeC M48Pro ECU, with their 8-channel ignition driver, through 8 LS1-style coils. The MoTeC is capable of programming precise and variable injector timing based on a table of load and rpm. Each cylinder is individually adjustable. Ditto for the spark timing, with individual cylinder offsets. This system has been used on LT1 engines making up to 1,125HP and turning up to 8,000rpm.
Getting the high voltage function out of the Optispark case seems to make it much more reliable, and there are now two "black box" add-on systems that allow the Opti to function in this manner - optical section only - using the stock PCM. Do a search on "LTCC" and "Delteq" to learn more about these options.
The Optispark is NOT a GM invention. It was first used by Chrysler/Mitsubishi in late 1980's 3.0L V6's that were used in various Chrysler and DiamondStar products. That application suffered of the problems inherent to the GM design, most likely because Chrysler/Mitsu had the sense to put the dirstributor on top of the engine, where any other "conventional" distributor was typically located.
Opti = great idea, poor execution.Fred
381ci all-forged stroker - 10.8:1 - CNC LT4 heads/intake - CC solid roller - MoTeC engine management - 8 LS1 coils - 58mm TB - 78# injectors - 300-shot dry nitrous - TH400 - Gear Vendor O/D - Strange 12-bolt - 4.11's - AS&M headers - duals - Corbeau seat - AutoMeter gauges - roll bar - Spohn suspension - QA1 shocks - a few other odds 'n ends. 800HP/800lb-ft at the flywheel, on a 300-shot. 11.5 @ 117MPH straight motor
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Originally posted by AmericanZ28Interesting comment, Rob. I dont think I've ever heard anyone say that before. Can you elaborate?
It is just unfortunate that all of them are not sealed so well and not more protected from the elements.Rob B 95Z A4 Tech Page (Part numbers / locations, how to's, schematics, DTC's...) Home Page - shbox.com
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Ok, that definetly cleared things up. Its hard to believe that location would be the thing to make such a great design a bad idea. Didnt the fact that it was driven via- the cam dowel pin contribute to its accuracy though?1996 Arctic White Z28, A4, K&N CAI, TByrne MAF ends, BBK Twin-52mm TB, TB Bypass, SLP 1 3/4" Shorties, Richmond 3.42's, Dynomax Bullet Muffler W/Turn Down, BMR Adj. Panhard, EIBACH Pro-Kit, AFS ZR1 Wheels W/17x11" out back!
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Obviously direct coupling the Opti to the cam dowel (or using the splined shaft in the cam gear, as in the 92-94 unvented units) will be more precise than using a gear set on the end of the cam, with its inherent "lash". But the main feature of the Opti is the use of the 360 slots in the disc, allowing the PCM to know EXACTLY where the cam is at any point in time. Most systems use eight impulses per cam revolution, meaning that the ignition system is "blind" for a large part of the rotation between impulses. If the cam is accelerating or decelerating, there is error (= scatter) during the "blind" period.
The Opti, on the other hand, increases or decreases the pulse rate to tell the PCM exaclty where the cam is, and how its rotational velocity is changing. The weak point of the control system for the LT1 is the lack of a true crank position sensor. While the Opti low res pulse pattern effectively identifies the correct cylinder to fire, any play in the timing chain can affect the cam's postion relative to the crank, and throw off ignition and timing events relative to TDC. It isn't any different in this respect than a reference signal using a conventional cam driven distributor. One can only assume that any inaccuracies introduced by timing chain play are more than offset by the PCM knowing whether the engine is accelerating or decelerating in close to "real time".Fred
381ci all-forged stroker - 10.8:1 - CNC LT4 heads/intake - CC solid roller - MoTeC engine management - 8 LS1 coils - 58mm TB - 78# injectors - 300-shot dry nitrous - TH400 - Gear Vendor O/D - Strange 12-bolt - 4.11's - AS&M headers - duals - Corbeau seat - AutoMeter gauges - roll bar - Spohn suspension - QA1 shocks - a few other odds 'n ends. 800HP/800lb-ft at the flywheel, on a 300-shot. 11.5 @ 117MPH straight motor
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