With the built engines we have been installing recently we have been able to do some more testing with other forced induction kits. @MACAWS Slingshot came in with the HAHN turbo kit on it and as most are aware @rabtech also has a HAHN turbo kit installed on his built DDMWorks engine. While we are installing and testing @MACAWS engine on the dyno we saw some slight differences with the air/fuel ratio on the wideband compared to @rabtech and wanted to look into it further. Both of the builds were almost identical, except for the spark plugs that were being used in the engines. @rabtech was using the stock spark plug that ships with the HAHN kit which is a LZTR5A-13 and @MACAWS we installed the spark plugs that we use on all of our forced induction kits - LTR6ix-11. The LZTR5A-13 is a nickel plated, stock heat range of 5, 1.3mm gap spark plug. The LTR6ix-11 is a iridium tipped, 1 step cooler plug (heat range 6) with a 1.1mm gap. Both plugs use a copper core.
So what we wanted to know is if there would be any difference in the power produced on the dyno and if air/fuels would change with the different plugs, here is the dyno -
On the dyno, there are 2 lines, a orange one and a green one. They are both on the same vehicle with exactly the same setup, just different spark plugs. We installed the spark plugs as they were delivered in the package at the stock gaps, we did not change anything on these plugs, just installed them. The graph shows that the power is very consistent between both spark plugs at this power level between the 2 different spark plugs, the lines almost overlap. We were also monitoring air/fuel ratio's during the run and they were also almost identical, with the HAHN plugs being just a tick richer on all the pulls, around .1-.2 difference on the air fuels. We are hoping to have another test session with a turbo setup soon and will try some more plugs out on that setup hopefully to see how the power and air/fuels perform on that setup also.
Hope that helps,
Dave