Porting tfs 205s
04-14-2014, 07:32 PM
#101
3100 is a steal. a head with a port, vj and chamber anyone can get from a top cly head guy that hasn't been changed like happens when you go to a production run. Changing the tooling that will get a few more sets done, and what you can run at more speed and feed rate to save time for the hourly guy that pulls handles, pushes buttons and babysits machines. And had sales and owners look at the profit and pump that up as much as they can, and get away with. Thats were a badass head form a cly head guy that dose what he wants, casting to finish you get. And knows all his work is dialed, makes 600whp. And a head from a shop with 5 different people working on a set makes 550, and the super cheap "budget/valve" stuff you see 10-30whp difference between the same PN that doesn't get the attention to detail in the program, and finish and human work from skilled guy(s) along the way,
04-14-2014, 09:13 PM
#102
Another 10% could be the tooling used to do the cutting. Too coarse and mid/high lift flow could suffer; too fine and you risk boundary layer dropout.
I'd for sure put another 30% on the valve job used. Usually a multitude of angles and widths on the IN side and often a radius on the EX.
Also the height difference between the two valveseats dramatically affects flow during valve overlap.
I'd guess 10% on the shape of the valves and diameter/undercut of the stems. Where the seat is on the valve as well as the backcut performed can influence the flow at various lift points. EX facial radius changes things also.
Lastly I'd place a solid 20% on the chamber work. Not only unshrouding the valves but shaping of the quench pads as well as hand touching the edge of the valvejob. Realizing that the chamber is an extension of the port in ultimately filling and emptying the coffee can (cylinder).
The difference between a profit based; way too busy; just ship it now operation and an infinitesmally detailed piece of artwork could IMO be a solid
30-35 RWHP. Now is that worth say twice as much money ?? A majority of people would say "no" but if starting with the same casting and yet getting each lung of your engine to "kick the crank" to the tune of another 3.5-4 horsepower...I'd pay that **** all day long !!!!!.......
