What is the voltage output of a stock CDI box

[S2GART]

Does anyone know how many volts come out of a stock Bosch CDI?

[wwest]

~350

[HarryD]

Why do you want to know? Unless you have a scope, I doubt you be able to read anything.

[S2GART]

The reason I am looking for the amount of volts is simply to help me find an alternative for coils. Nobody here was born yesterday and understands that for the large part the price of things is based purely on who the product is being sold to.
I certainly don't mean any indifference to our host, but why is the Bosch coil for the SCs, over $250 when a $50 coil from MSD may do the same thing. Better yet, the coil for a 84-89 Carrea is only $84, why? A MSD coil puts out up to 45,000 volts. I doubt the Bosch coil puts out much more. The MSD coil is designed to be part of a CDI system, which MSD ignition system is. So why can't one simply put in a MSD coil, as long as it puts the voltage needed?

I have never been the type to just accept things for face value. I like to know the "why". MSD will freely give the specs of their coils, yet it seems impossible to get the specs on Bosch coils.

[wwest]

They do....


Search results for: 'cd ignition coil'

[James Brown]

you also need to know the ohms range of the CDI coil, sorry i don't have that value but resistance is just as important as voltage.

[S2GART]

wwest- that coil won't work. The existing wires are individual wires (2) versus a connector like that one would accept. I went to Accel's website and they don't list a coil for a SC.

Here is yet another thing I don't get. Major aftermarket companies like MSD and Accel don't list coils for a SC, yet Autozone, Napa and Advance Auto all have "house brand" coils for the SCs. They are about $190 which that in of it's self is nuts because 5 years ago (when I bought a "spare" coil from Advance Auto) they were $50.

[timmy2]

Our host sells the MSD Blaster II high vibration coil as a replacement for the Bosch coil. I've been running mine for 2 years no problem.

[wwest]

Originally Posted by James Brown

you also need to know the ohms range of the CDI coil, sorry i don't have that value but resistance is just as important as voltage.

The primary winding ohms value is important, but less so than the inductance, and the magnetic coupling coefficient from primary to secondary. The latter is why the "E" & "I" laminated metal cores are so important when using a capacitor dicharge ignition.

[jason2guy]

ive been running an msd blaster for a while, it performs well.
check out the crane lx92, ive heard good things about it

[HarryD]

Per the Porsche Factory manual the CDI puts out about 400v. The coil Primary resistance should be 0.4 to 0.6 ohms, and the secondary is 650 to 790 ohms.

[theiceman]

after buying the Bosch brazillion paper weight i ended up geting the blaster coil .. works great but looks ugly in my opinion. As i just wanted a spare so i am running with my original and have the blaster in my spare parts .. a 50 dollar peace of mind ..

[thumbdoctor]

When I purchased my 1977 911S it had a yellow ACCEL "pro stock" coil and a Pertronix equipped dizzy. The engine runs great !. The only down side is the tach needle bounces from time to time. The CDI unit was removed too

[theiceman]

Originally Posted by thumbdoctor

When I purchased my 1977 911S it had a yellow ACCEL "pro stock" coil and a Pertronix equipped dizzy. The engine runs great !. The only down side is the tach needle bounces from time to time. The CDI unit was removed too

i imagine that cdi unit to be worth a few bucks, maybe even more than your whole upgrade.. .. i hope you hung on to it ..

[thumbdoctor]

Originally Posted by theiceman

i imagine that cdi unit to be worth a few bucks, maybe even more than your whole upgrade.. .. i hope you hung on to it ..

I bought it sans CDI and with the upgrades LOL. I will be installing a Bosch blue coil and CDI in the near future.

[Sunroof]

MSD Blaster II...................

I went through two Brazilian made silver Bosch coils that failed just after installation. Many recommended the MSD Blaster (price was fantastic) and I have been using that coil with a refurbished CDI unit now for over 3 years with no issues. The only good coil was the OEM Bosch black, which you will not find anymore. The silver Bosch replacements in my opinion are junk!

Bob
73.5T

[theiceman]

Originally Posted by Sunroof

MSD Blaster II...................

I went through two Brazilian made silver Bosch coils that failed just after installation. Many recommended the MSD Blaster (price was fantastic) and I have been using that coil with a refurbished CDI unit now for over 3 years with no issues. The only good coil was the OEM Bosch black, which you will not find anymore. The silver Bosch replacements in my opinion are junk!

Bob
73.5T

.. i think EVERYONES opinion my friend .. selling these things should actually be considered fraud.

[HarryD]

Originally Posted by theiceman

after buying the Bosch brazillion paper weight i ended up geting the blaster coil .. works great but looks ugly in my opinion. As i just wanted a spare so i am running with my original and have the blaster in my spare parts .. a 50 dollar peace of mind ..

You could just peel off the hideous label.

[Reiver]

Originally Posted by theiceman

.. i think EVERYONES opinion my friend .. selling these things should actually be considered fraud.

An FYI...lots of 'older style' Bosch plugs are now made in Brazil with the same high quality of the fine coils....the gent that built my motor won't touch them due to issues with them.
Read the labels/box's before you buy.