AC sparkplug heat range
Race Director
Joined: Apr 2000
Posts: 17,641
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From: Who says "Nothing is impossible" ? I've been doing nothing for years.
Other way around 43 is hotter than 44, do a search for spark plug cross reference on the internet I found a very good that lists just about every plug made and their heat ranges 
Team Owner
Joined: Jul 1999
Posts: 26,545
Likes: 46
From: Huntersville NC
from ac delco website:
I dont think all spark plug manufacturers use that convention.
# What's the difference between a R44LTS6 spark plug and one labeled R45LTS6?
The R45LTS6 produces more heat. At ACDelco, we always recommend that you use the right spark plug -- the one recommended for your specific vehicle. Engine damage may result from using a plug that is not designed for your vehicle.
The R45LTS6 produces more heat. At ACDelco, we always recommend that you use the right spark plug -- the one recommended for your specific vehicle. Engine damage may result from using a plug that is not designed for your vehicle.
