I think the T-4 was originally raced to out do the 3 litre OMC's that showed up late 1978 and early 1979 I think. I'm not sure Merc was even aware that OMC were working on and going to be racing V-8's in the near future.
In Valleyfield, Quebec 1979 Fred Hauenstein and Ken Stevenson ran our MOD U class with 3L engines and the 2.4 Merc's were absolutely no match for these engines, in fact they posted lap times faster than the Grand Prix inboards.