Ive asked questions about plenumns before, with my concerns about unequal airflow to each cyl on std and especially all these giant aftermarket cossie plenums that are appearing causing fueling issues (and also becuase the std GTR plenumn is the same), so....
How correct is this? Another problem with uneuqal airflow i didnt really think of before...
What Gav has posted about evening out the A/F ratios by adding more fuel is totally sound. But there is more to it than that. Using Gav's numbers, he is putting 5% more fuel in #6, obviously to match the 5% more airflow that #6 gets from the inlet system. But that means cylinder #6 is producing 5% more power. Similarly 3% for #5.
So (simplistically) if Gav's engine makes 600 bhp then;
#1 = 98.5 BHP
#2 = 98.5 BHP
#3 = 98.5 BHP
#4 = 98.5 BHP
#5 = 102 BHP
#6 = 104 BHP
Now what do you think this does to the crankshaft, which gets a 104 bhp combustion hit from cylinder #6 and a 98.5 bhp combustion hit from #1? My opinion is that it would result in uneven running engine (like out of balance), premature wearing of the main bearings #5, #6 and #7, differential expansion rates (cylinder head and block) and premature block failure. When you get further up the power tree (eg; 1200 bhp) the problem gets worse. Obviously none of this shows up on the dyno.
Makes sence to me, and makes me wana go buy a decent plenumn...
How right is it tho?