WR7DC vs WR7DC+
 

Looking to see if anyone knows or understands the difference between the 3 BOSCH spark plugs WR7DC and the original WR7DC+ and the updated WR7DC+?

Background of my research - WR7DC is BOSCH 7501, WR7DC+ is BOSCH 7500, Both versions have been superseded by BOSCH 7900 which is also called WR7DC+ ?

My assumption is that there was originally a difference between the 7500 and 7501 and thus now the 7900. The 7500 and 7501 are no longer produced. However there are stockpiles out there.

I have read different threads about the material of the spark plug (copper core.. nickel covered.. platinum. iridium etc) - DOES anyone know the differences between the 3 models of spark plugs? or what the differences may be (why the change in part numbers)? This is more curiosity on the engineering (technical) rather than functionality - so no need to advise to run whatever (I get it - they all work)




Here are my citations https://www.sparkplugs.com/learning-center/article/459/discontinued-bosch-spark-plugs

https://www.boschautoparts.com/en/auto/spark-plugs/copper-with-nickel-spark-plugs?partID=7900

https://www.boschautoparts.com/en/auto/spark-plugs/copper-with-nickel-spark-plugs?partID=7501

I cannot locate a lot of info on the 7500- search does not come up in BOSCH website. Cross reference number I see often is 242235663-74U

Throwing this back out there..

Anyone got a thought on this?

What is the problem with the 7900 part number? It's the same heat range as the 7500 and the same physical characteristics....

No problem ..

Just trying to understand difference.. my curiosity is showing..

2 difference plugs (7500 and 7501)

Now 1 plug (7900)

Just wondering if someone knew why the change? different metals ? conductivity?

Just a guess, but perhaps one of the old plug part numbers was a resistive plug to reduce radio nose. Now a non issue so just one part number?

WR7DC+

W = 14mm x 1.25
R = with resistor
7 = heat range of 7
D = reach of 19mm
C = copper electrode
+ = Super Plus technology

Link for description of Super Plus technology:

https://in.bosch-automotive.com/en/parts_and_accessories/service_parts_1/spark_plugs_1/bosch_super_plus/bosch_super_plus_2

Thanks Winders!!

I was sitting in a Hotel room in Minneapolis drinking a Grain Belt thinking life couldnt get any better... then I read your posting.. And my happiness went to SuperPlus!

The 7900 and 7501 appear similar - but are made with different gaps.

It'll seem strange to those of us that grew up routinely checking/re-setting plug gaps - but many (most?) manufacturers now suggest you don't do that, in order to maintain the parallel relationship of the top of the central post and the side electrode(s). And specifically warn against doing it for certain high-tech plug types (iridium, I seem to recall).

In other words, if you need a 35 thou plug gap, you're supposed to buy a plug pre-gapped to 35 thou, not try to re-bend the side electrode on one gapped @ 25 thou.