Correct spark plug?

Peter Schulz pcschulz at
Tue Dec 13 13:41:56 EST 2005


need to keep it in context....

At full boost, Javad's engine is using a gallon a minute...
NOT a typo
(75lb injectors running at 90% duty cycle)

Under the high boost conditions, Javad was running into issues with the 
Platin F5DPORs and switched to the F6DTCs (tru electrode copper).
The plugs only last a limited number of dyno runs and are essentially 
through aways.

Quotes of note from Javad:
"Cheapo 7A copper plugs, have used Bosch and NGK. I need to change them 
about every 5 hrs of high boost. "

"Yes, I've considered them, we used them in a customer car, but when you 
drop a copper electrode, it usually goes thru the motor, harder metals can 
cause more damage, thus the reason for using copper.

Most of the time the ceramic insulator seperates from the steel body, 
basically you can grab the top of the plug and the body, and they spin 
independently. I check them every few hours by putting a thumb on top of 
the plug wire, if I feel a "put, put, put" in the plug connector, I know 
something is wrong (my body not touching the car body of course!)."

- I think that most of us don't have to worry about these issues, even at 
the RS2 level....


At 12:03 PM 12/13/2005, Phil Rose wrote:
>At 9:22 AM -0700 12/13/05, Brandon Rogers wrote:
>>I've heard this as well- however I also know that Javad Shadzi is doing 
>>some pretty amazing stuff (ie high power) with his 20V - about 500-600 
>>whp last I knew.  He's using the stock 7A plug - the F6DTC, IIRC and he 
>>said at one point it was better than the expensive plug that is suppposed 
>>to be used.>>F5DPOR.
>Hi Brandon,
>  I can't say whether or not you recall correctly about Javad's plugs. But 
> in any case,  what might might have been the belief of someone "at one 
> point" might not be true in the long run. And finally, what does "better" 
> mean and how was it determined?
>>I personally question how there can just be one plug that works well with 
>>an engine.....
>So do I,  Brandon, so do I. But after hearing--over the course of 7 
>years--nothing but good experiences with the F5DPOR and many, many poor 
>experiences with alternatives,  using the F5DPOR is the best advice I can 
>give. Also, note that I said "alternatives  are _likely_ to disappoint", 
>not that they will necessarily be inferior. YMMV.
>BTW, whenever I see prices on these plugs, they run about $11/ea. Now I 
>don't know about other 20V engines, but mine uses only 5 plugs (every 
>75-100K miles) and that makes the cost differential (i.e., cheaper plugs) 
>a pretty insignificant issue, IMHO. It's always nice to find something 
>with better performance, so if you can get more info from Javad about 
>_how_ the F6DTC performs "better", it would be appreciated.
>Phil Rose
>Rochester, NY
>mailto:pjrose at
>200q20v mailing list

1991 200 20v Q Avant Titan Grey
1991 200 20v Q Avant Indigo Mica
1991 90 20v Q Red
1990 CQ silver (awaiting S2 engine transplant)

1990 CQ red ( to part or not)
Chelmsford Ma, USA 

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