10secz

I've been off the boards for awhile due to waaaay too much work, but I'm trying to get back into it. I'll start with a question.

My car has been plagued with a mystery rev limiter for a couple years. You can see it in action in this graph I made of a 1320 pass using a pair of Dynojet Wideband Commanders:

http://www.acceleronics.com/images/AFR-RPMgraph.gif

The current ignition is:
- FAST ECU (rev limiter at 7500)
- MSD Digital 7 (rev limiter at 7500)
- MSD 8251 coil
- MSD Superconductor 8.5mm wires
- NGK BKR9EIX iridium plugs gapped at about 0.028-0.030
- and (drum roll please) a bone stock Opti with new cap/rotor

I know that the hot ignition will kill the Opti high voltage stuff, but I thought I could coax maybe 500-1000 miles out of it. Here's my previous rotor after 600 miles:

http://para.noid.org/~lj/600milerotor.jpg

So, what to do?
- Try the new MSD 84811 cap and rotor?
- Convert to Bob Bailey's LTCC?
- Convert to the Delteq?

I'm thinking that NHRA racers spin distributors way past 7000 with equally hot ignitions, so it seems like the 84811 should handle the job, but I'm getting tired of throwing parts at this problem. And I'm wondering if GM coils used with the LTCC and Delteq systems will provide enough fire in the hole at 20+ psi of boost.

BTW, I don't think it's a fuel delivery issue - the fuel pressure rises as it should as the boost and revs increase.

Suggestions?

Roadie

While I haven't hit that kind of power level yet, I'm in the middle of a big buildup and bought the ignition already. I picked up a Delteq setup and a MSD DIS-4 box.

I'll still run an opti, but only for the optical sensor/signal.

Schurters LT1

With the Fast why not go to a reg distributor, and get rid of the opti..

10secz

I guess I don't see how that helps. The Opti is just a regular distributor with an optical trigger that happens driven off the front of the cam instead of by an helical gear set at the back of the cam. With a old style sbc distributor you still have the cap and rotor contacts to deal with.

markinkc69z

Keep in mind that the traces that run from the terminals inside the distributor to the plug wires are conductive ink, not copper or aluminum wire. These traces may be partially responsible for your overheated rotor. All I can say for sure is that you are not alone. If you are using FAST engine management then you don't need the hi-res signal from the opti. I would suggest a crank trigger and distributor conversion.

Schurters LT1

True, I was in the same boat a few months back and i had the delteq, sold it for a dual sync (Gen 7) The delteq was just extra stuff under the hood, same with the ltcc just extra and in our eng bay there is little room as it is, I guess i really don't have anything to back it up other then there are 100's of mustangs and older GM's that are faster then us put together and they are running a distributor and FI...and i think there is only mayby 6 people with the opti in the 9s .....This is why i went this way...I really asked around and looked hard at this, I asked TJ Wong, Mac at Fast track, and Lonnie, they all liked the idea..so i went for it...now a must say the car is being put back together now and should run i a month....

There is one other thing, i have a Bud with a mustang that is in the drag radail class, 30psi, ATI F1R, 8.55/160+mpr with FAST and a dual sync....if he can go that fast and that much boost with a dis i think may little 700fwhp+ will be fine...

go luck

engineermike

LJ, not to brag or anything, but mine runs clean at 20 - 22 psi with: stock opti, stock ECM, Crane HI-6, Hypertech coil.

Schurters LT1

I think it is a combo of boost and the 7500rpm....Is there any other opti that has been here before?

10secz

Um, OK ... and I've run 9.47/148 with an unwanted rev limiter hitting all 3 gears. Neither of these facts help me solve the problem.

Jeff 96 SS

My opti/digi6 works fine at 22psi too but you are throwing more fire and spinning it faster than me. I'm shooting for 8s this year with my opti

I know I have been looking at the LTCC pretty hard though I think it would work but haven't seen it done with big boost yet. Let us know when you solve this I have a feeling I'llhave the same problem if I spin mine any higher.

Jeff
96 SS BLOWN
96 TA 396 D1

markinkc69z

While not totally on topic, this might be of interest. The LS1 truck coils are capable of igniting blown alcohol engines of over 2500 hp with active dwell control (inductive). KAM Systems has a GM based engine management system that allows this. While not immediately applicable to your LT1 it does demonstrate the effectiveness of the LSx based system and eludes to future products based on that design.

10secz

I pulled off the blower belt and took the car out for a spin. It pulled cleanly to 7000. I think that strengthens the argument for an ignition problem. MSD tech support thinks that their 94811 cap and rotor should stand up to the Digital 7 + 8251 coil, so I guess I'll go drain the block...

97WS6Pilot

I also had an unwanted rev limiter. I switched to delteq only to discover my problem was not with the opti but corrosion on the inside the of connector that connects to the top of the opti. My connector had green corrosion on inside the terminal. I replaced it with a new one from Caspar Electronics. It must be a pretty common problem as Caspar has one ready made. Hope this helps.

Tekprodave

There is something to be said about convenience. I think it would be much easier to work on Delteq or LTCC components compared to the friggen opti which is buried under the water pump and other components.

10secz

I'm gonna test the MSD cap and rotor tomorrow (1/29). If the car gods are not appeased, I'll sacrifice a goat.

http://para.noid.org/~lj/LastGaspOpti.jpg

TekPro, you mentioned convenience. While pulling the water pump for a cap 'n' rotor swap sucks, I'm wondering if there is a place to put 8 coils that won't result in them being in the way.