Permatune vs. Classic Retrofit CDI+

[toddetch]

Hi all,

I've been chasing a gremlin where my 80 SC Targa starts stuttering under load/acceleration once it is hot. My mechanic and I have been going back and forth looking at things and today the mechanic thinks he found it. They replicated the issue with my car, then since they had an 82 SC in the shop they put that CDI box in mine to test. Problem solved (seemingly). They're going to do some more testing tomorrow to make sure that is truly the issue, but if so they are going to recommend using the Perma Tune CDI replacement and associated coil.

I emailed back and asked if they had ever looked at the Classic Retrofit CDI+ and have suggested it for their consideration (I haven't heard back - my email probably got there after they left for the day). I reached out directly to Jonny at CR this evening, but then I decided he would be fine if I asked this question here as well.

I searched the forum but I haven't seen this direct comparison. It seems many feel the Perma Tune is not that reliable. Most who have installed the CR CDI+ seem happy. Does anyone have any experience with both? How would you compare them? Any other thoughts?

Thanks!

Todd

[red77911s]

The original perma-tune unit in my 77 just burnt up the other day, probably from a bad coil, which apparently happens. only lasted 40 yrs, I'll never buy another, lol. new ones are supposedly less prone to this. There are several threads on this issue and after much reading my take is they all work and all have their weaknesses. I'm going to try an MSD unit for a third or less the price.

[toddetch]

You're right, there are lots of threads about CDI. Many that discuss the Classic Retrofit solution, and many that discuss Perma Tune vs. MSD. However, my specific question was for anyone with experience of Perma Tune and CR, which I have not been able to find. If you know of a thread that directly compares those two, I'd be happy to see it. If anyone has any experience of both, I'd love to hear it.

[tirwin]

PermaTune took a reputation hit in the past for quality issues. There are some old threads on here where PermaTune representatives came on here to defend themselves. I haven’t seen anyone recommending PermaTune as a replacement in a long time. I don’t know if their issues are addressed but once a company earns a negative reputation it’s hard to shake. And there are plenty of alternatives available today.

Both MSD and CDI+ use multi-spark technology. The CDI fires the coil multiple times in order to get a complete fuel burn. Typically this only happens up to a certain RPM — I think it’s 3000 for both but not sure.

The CDI+ unit also supports the ability to lock the distributor and set the advance curve through software in the CDI+.

Aesthetically, the CDI+ looks like an original Bosch CDI. If you care about looking original then maybe this matters.

Full disclosure, I run the MSD Streetfire. I do think the CDI+ is a very well thought out product but I have no direct experience.

Bottom line, there are several good products on the market worthy of consideration. PermaTune wouldn’t be on my short list, but that’s me.

[tobluforu]

Like stated above, and I know its not the answer to your questions, but there a lot of options, not just the two you mention. ischmitz Is a great option from what I hear. You can have yours rebuilt.

[dfhtrhjn]

^ I like tirwin's response. I know it doesn't answer your question, but I chased down a similar problem on one of my 2.7 liter motors and dropped a MSD in about a month ago; hesitation accelerating gone

I had a similar dilemma, pay $1200+ for a CDI+ unit that looks like stock. Or pay $250 for an MSD 6AL that does the same and has a built in rev limiter.

PermaTune dropped off my short list after one search of the forum. Hope that helps

[Porchdog]

I went with the MSD when my OEM CDI failed. I couldn't be happier.

I need to get around to sending my CDI to Ischmitz for a rebuild. Even once that is done I don't know what to do for reliable matching coils.

[Jonny H]

Originally Posted by tirwin

Both MSD and CDI+ use multi-spark technology. The CDI fires the coil multiple times in order to get a complete fuel burn. Typically this only happens up to a certain RPM — I think it’s 3000 for both but not sure.

CDI+ is multispark to 10,000 RPM. (MSD reverts to single spark at 3400)

CDI+ spark interval set to 300us when shipped (3 times faster than MSD which is 1ms / 1000us)

[shoooo32]

If you like the idea of keeping the factory look but with updated internals, check out Parts Klassik in Arizona. They use the original Bosch housing and have the option of setting a rev limit internally or having an adjustable dial. Similar to Jonny's unit but significantly less expensive. After I returned my core, I was out $475 for a 6 pin unit with a fixed rev limit.

[jjeffries]

My read is that CDI+ is a genuinely top shelf component, and that this is a case where the quality merits the price, as explained by Neil Harvey, a serious and respected engine builder whose responses you’ve likely seen hereabouts....a search is worth while if you haven’t. I couldn’t afford one for my stock-ish SC, but that’s besides the point...price no object, I’d have one by now (and SSI’s, and....). I run an old Bosch CDI and have the PermaTune my car came with as a spare; I’d personally avoid MSD because I perceive their products to have higher failure rates...the one in my neighbors’s Vette failed last month. But do check out Neil Harvey’s thoughts...much higher-level discussion than I could provide. John/CT

[groovydude]

I’ve been using a CDI+ for over a year, no issues. My CDI unit was still working when I upgraded, it was just preventative medicine for me, the point being that I drove them both on the same day. I have no experience with permatune, but I will say I felt a noticeable increase in engine power with the CDI+. I can’t tell you if it’s torque or hp or where exactly the boost is strongest in the rev range or how much, just that the car immediately felt more powerful.

[toddetch]

Thanks for all the serious responses.

@jjeffries - thanks for the reference on Neil. I had actually read through that thread, but I did not have the context for who Neil is. Now I do (Google is useful).

So, now I'm waiting to hear back from the mechanic today with the final diagnosis. Assuming it is the CDI box I have decided to go with Jonny's CDI+ - either with the mechanic installing or doing it myself. Hopefully, I can get one from our host by Friday, get it installed, and test it over the weekend. (Again, assuming that is the problem.)

[RDM]

I think that's a great choice. The possibility to lock the distributor and use the CDI+ to custom control spark timing opens all kinds of possibilities.

[tirwin]

Originally Posted by Jonny H

CDI+ is multispark to 10,000 RPM. (MSD reverts to single spark at 3400)

CDI+ spark interval set to 300us when shipped (3 times faster than MSD which is 1ms / 1000us)

Now I know!

That’s pretty impressive!

[toddetch]

Okay, CDI+ ordered from our host to be delivered Friday. Installation on Saturday. Hopefully take my wife for a great ride through the Columbia Gorge or the Willamette Valley that afternoon or Sunday.

[fintstone]

Late to the discussion...but have had great luck with the 6-pin Permatune on my hotrod '74 3.0 . One can often find them quite cheap here and on eBay (brand new and in he box) for a pretty reasonable price. I imagine a lot of folks swap out parts as troubleshooting and then find out it does not fix the problem...and they put the old part back in. I thought I had a bad CDI once and ordered a replacement...but before it arrived, discovered that one of the wires on the back of the connector to the cdi was making intermittent contacting causing my problem, not the CDI.

It is hard to argue with the fancy CDI+ other than on price. Looks like a quality part/nice upgrade. Good luck with that fixing your problem.

[1979-930]

Originally Posted by Jonny H

CDI+ is multispark to 10,000 RPM. (MSD reverts to single spark at 3400)

CDI+ spark interval set to 300us when shipped (3 times faster than MSD which is 1ms / 1000us)

That's awesome! But can I program my own timing curve and a boost retard curve?
Common Johnny quit leaving us turbo guys out of the equation. Get a MAP curve in there too. If MSD can do it you can.

[Jajohnsen]

Originally Posted by 1979-930

That's awesome! But can I program my own timing curve and a boost retard curve?
Common Johnny quit leaving us turbo guys out of the equation. Get a MAP curve in there too. If MSD can do it you can.

What he says

[wreckah]

FWIW i have the CDI+ for more than a year now, and i have good experiences with both the product and with Jonny as well. Great support, quick too.

The CDI+ is plug and play, but also lets you lock the dizzy, and put in your own curve, basically a digital recurve of your old distributor. Too bad it's not a full timing map :-)

cheers, Jan