mootavic said:
ok, now before you go flying off the handle i am not attacking you........
what kind of fuckin 2nd rate cylinder head engineering joint did you go to?
number 1, volumetric efficiency is supposed to be measured with the valves in place and the valves opened to max lift. a measurement of VE with nothing in there is a waste of fuckin time, of course its gonna be at or near 100%, there is nothing in the bloody way.
ok lol... when you asked valves in or valves out... I presumed you ment open... (mind you its pretty hard to flow them if the valves are shut obviously enough) but generally speaking, you don't flowtest heads without the valves in place... thats just silly... i wasn't sure what you were askin to tell the truth... so i took a stab. I admit I fail at english... it was totally the wrong word used... I even said off :/
Regardless, the VE was not obtained via a direct measurement, that is impossible... its actually a calculation. RPM engine displacement and mass flowrate/velocity is all known... so it can be then calculated... That is why it is expressed as a ratio or a percentage. in otherwords... the ports have been opened right up via the removal of some of the valve stem... thats pretty standard practice when it comes to porting. but i will elaborate more on that in a sec...
number 2, i strongly believe that by porting off the lumps around the valve stem [and all of the protruding valve stem mind you] you have detrimentally effected the VE by increasing the cross sectional volume in the middle of the port while not concentrating on making it a gradual neat taper. if you suggest that you did, i call lies. i dont see any material build up inside your ports [high temp epoxy usually] for that to be true. honestly, did you do that porting job yourself? if not, please name them, i would love to give them a call and ask a few questions about their methods. i mean if they are going to butcher your ports like that and then do a valve out VE measurement and tell you "hey guy, we are fuckin awesome, look at this 100% figure!!" and keep a straight face, they are either deadshits or dumbshits...
lol, ok. Now, what I think what you were trying to say is that removing the valve stems detrimentally effected
velocity by increasing cross sectional
area, in turn decreasing VE as it is no longer sucking the gasses due to vacuum pressure after valve closure~opening... this couldn't be much further from the truth... allow me to explain...
Actually by removing the stems (in this case, please keep that in mind), the velocity was almost kept constant. (actually increased marginally due to increased mass flow rate from porting of the intake ports.) this is not because the stem has a neat taper, but infact, because the stem is quite an obstruction. a neat taper on the exhaust port isn`t as important (in this case as the goal of head performance is different to that of stock, please also keep this in mind) as say on the intake side... this is because increasing mass flow and decreasing resistance was more effective then trying to keep a laminar flow, however velocity is still important factor regardless, so it wasn`t completely disregarded... It didn`t effect the vacuum effect so much on valve closure as the ID of the exhaust is still the same and the exhaust port length is very short. Increasing the volume of the exhaust port dramatically increases low lift flow figures. It behaves completely different now.
So this epoxy you speak of, is called zedspa... Lucky enough I didn`t need it in this situation. (if I bored the sleeves thus increasing displacement I would have needed it to change the overall profile... but I would still have a larger internal cross sectional area. there is enough material on the roof of the port. Don`t worry, too much wasn`t removed.
The company that benched it is called "Ghea Race Engines". The bloke who worked on it, his name is Anthony (founder of the company)... and he knows his shit. Actually he has retired now (last time I checked)... he was getting abit old and the labouring work is hard on old people
.
I'm not sure if the business is still continuing... but let us know if you found out anything interesting.
In regards to your C/head, as far as I know... you didn`t even bench smokeys head...so it would of taken a miracle to balance them... and all that polishing was a complete waste of time. that would have got you about 1% of 45ps or maybe even less... which is absolute FA. I'm trying not to be so sensitive... but it does seem kinda like you are trying to take a dig at me... swearing and all. but I will overlook that for now.
*edit* just added some bold to highlight something worth lolling about... there is no such thing as cross sectional volume.
*edit*edit* just thought I would point out that tapers in fluid mechanics are designed to decrease turbulence which effects head loss. dont forget that air is compressable, and when it is at a lower density, a volume flowrate increases when the mass flow rate stays constant. I expected you to know that.
*edit*edit*edit* just also thought that I would point out that the floor of the port wasnt touched so that a uniform cross sectional area could be maintained. if i cut that short turn radius... it would have caused problems.
