Join Date: Nov 2011
Location: Moyock, North Carolina
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Lets talk valve size
So, I've been doing lots of thinking, and had a lot of discussions about airflow through the 6.0 heads lately, and ive heard lots of guys say immediately that bigger valves are needed. out of curiosity I measured a few valves and figured up the area of the valves, a few interesting observations...6.0's have more intake area than ANY of the other engines, 7.3's have identical sized intake and exhaust valves, as does 24v cummins, and duramax intake and exhaust valves were closer in size tha. 6.0/6.4...this is what I found:
intake valve size:
intake valve area: 1.405 square inches (x2) = 2.810 square inches total
exhaust valve size:
exhaust valve area: .953 square inches, (x2) = 1.906 square inches total
intake valve size : 1.675"
intake valve area: 2.201 sqaure inches total
exhaust valve size : 1.675
exhaust valve area: 2.201 square inches
intake valve size: 1.296
intake valve area: 1.318 square inches (x2) = 2.636 square inches total
exhaust valve size : 1.218"
exhaust valve area: 1.164 square inches (x2) = 2.328 square inches total
12v 5.9 cummins:
intake valve size: 1.770"
intake valve area : 2.459 square inches total
exhaust valve size: 1.654"
exhaust valve area: 2.147 square inches total
24v 5.9/6.7 cummins:
intake valve size: 1.298"
intake valve area: 1.322 square inches (x2) = 2.645 square inches total
exhaust valve size: 1.298"
exhaust valve area: 1.322 square inches (x2) = 2.645 square inches total
now, these are all just simple measurements, but it shows a few things, 6.0's have the most intake valve area of any of the common engines in the medium duty market (dont know about the 6.7 ford. ..and I forgot 6.4, but the intakes are the same size as 6.0...exhaust valves are 1.5mm bigger than 6.0, so it would be a small gain in exhaust valve area over 6.0). I wonder how much of a restriction the port on a 6.0 head is compared to the valves...im working with a port work professional to determine this, and see what can be done to maximize airflow. ive been a huge proponent that the 6.0 heads need improvement badly, and that its very difficult to use much larger valves because of the small bore size (3.740 iirc). it would appear that 6.0's have way more valve area than even the 7.3's...but obviously waaaay less displacement. I know for a fact that duramax intake ports are way bigger, my guess would be 20-40% bigger in volume than 6.0's...but the intake valve area is way smaller. I would love to know the engineers thoughts for their decision making process in determining valve size and whatnot. hopefully here very soon ill have flow numbers for stock 6.0 heads, and ill have a durmax head flowed just for curiosity. I also plan to 'CC' the port volume of a 6.0/6.4 and the duramax. a duramax (6.6 liter) has a much larger bore...4.065 iirc, so I wonder how much that has to do with port size vs valve size vs engine displacement vs intended use/rpm. anyway more flow data to follow, ill post up my results as I get them.
2005 F-250 Harley Davidson Edition
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Machining the 6.0: