Separate names with a comma.
Who did you end up selecting?
These guys /\ /\ /\ They had the biggest flow numbers and are the only ones offering the larger valve size.
he said...she said...get a hold of a Guy on here.... that goes by "IQ82" or something like that...."JIM" I think is his name ?.....he is doing "THE SHIT" ! OOps...I guess his name was already mentioned before I posted... Jim LaRoy is his name.
When I was a kid, the first time I heard, "Man that Dodge is 'bad'!" I thought the guy was being derogatory. Until he explained that "bad" ment good. I keep puttin' the shit in the Smurf Pool. I hope "THE SHIT" is "bad".........I think.
Speier is going to charge $600 to get them to flow over 300. All the ports are inconsistent from whoever ported them before.
Hey Guys. I stumbled across the site while doing a search on heads.. I just wanted to add that since day 1 I have used Performance CNC for all but two programs I offer. The other being with Reher Morrison. I think I have 15 programs with Jason. Jason is one of the most honest people I've known in this business. They are great guys! As far as the RPM head he offers. It's a really nice piece! Flows good air and the velocity profiler is correct. I might know the guy who did it for him. wink wink..:-D
I will start soon!
Welcome to the site Chad!
................Welcome to FABO Chad.............................kim............
Welcome ,Mr Speier.
I'd like to see the flow numbers on the perf RPm porting you offer. It isn't available on your site, only the max wedge port is.
Mid flow numbers would be key for me. Where's the 345 at, .700-.800 lift of cam?
I'd have to agree with you on that. That's probably more important than the max flow number at a high lift that the valves never open to. My hopes are that the heads I have will flow 300 cfm @ .600 lift when Chad gets done with them. If he gets them there, I think the mid flow numbers will be good as well. But that's just me hoping. I'm sure I'll be happy with whatever he gets them to regardless though.
Laroy's perf RPM heads outflow the victors up to .500 lift.
Thanks Guys. I'm not a big flow number guy, more velocity.. Here is some data on the Performer RPM 2.140/1.810 45º seats NO PIPE .200 140/115 .300 214/146 .400 264/174 .500 292/191 .600 307/205 .700 319/216 .800 321/226
Just out of curiosity Chad, are air velocity and flow not directly related? Wondering why one would focus more on the air velocity. I'm just trying to learn.
The velocity of air moving through the port is primarily a function of how much air it is moving vs. the port's volume (more accurately, its cross-sectional area). As the port moves more air, the velocity goes up; eventually getting so fast it blows the shortside turn and separates. When that happens, the port will typically stall, flowing no more or even less air no matter how much further the valve is opened. How much air will get through before the shortside separates and the port stalls will depend on the shape of this critical part of the port. The shortside form is a key limitation on the ultimate flow potential of a head. All ports aren't created equal, and some have a decent shortside form while others are handicapped in this area.
Chad - welcome. Just a couple points of clarification for those who might not be well versed - are you refering to localized velocities of a port and not an arbitrary mean airspeed throughout? Also by "short side" are you referring to the short side of the port (wall), or the short turn in the bowl, or both?
I'll try real hard not to race flow benches here. If it helps, we have an Edelbrock RPM design, 330 cfm @ .600" and 350 cfm @ .700", produced from OOTB RPM flows of 287 cfm @ .600" lift. Our RPM heads on a 451 stroker have dyno'd 787 HP on 91 octane pump gas. I'm pretty sure what I said was, on our bench, OOTB the RPM heads outflow the Victors to .500". I don't recall having "raced" the RPM heads against the Victors flow wise. Generally we'll design a head around the desired engine and cam characteristics. Right now we are testing flow changes at various lifts vs horsepower curves on the dyno. Very interesting. First time we've had the opportunity to do so. Some beliefs are being substantiated and others are being revised.
I'm talking both localized and average (cfm vs cc vs port length).. I'm talking the complete "apex" from the port floor to the turn. I'll say that from a bracket engine to a street engine to a Pro Stocker, the average velocity of the complete induction system is within 20 fps on a "happy", "efficient" engine in any form. Here is a few head pics of the engine we took to this years EMC. It was a knife to a gun fight! Top 10 though!!
What is OOTB? I'm a bit confused when you say they outflow the Victors to .500 but haven't raced them against the Victors? You mean at a dragstrip? I mean if they outflow them below .500 it would seem a lower RPm street engine or a lower RPm engine in general with a cam that is under .600 lift would thrive with the perf RPms.
I mean Out Of The Box (unported). If I was going to run a cam .500" lift or less and not port my cylinder heads, I would choose the RPM heads. If I already owned RPM heads and my horsepower goals were 750 or less, I would have my RPM heads ported. If I had to buy cylinder heads because I had none and my horsepower goals were 600 or more I would by something other than RPM heads. Something like Victors, Indy EZ or 440-1. No OOTB aluminum head will support 750 horsepower unless it comes out of the box ported. Any aftermarket aluminum cylinder for big block Mopars can be ported to 750 HP. ANY of 'em.
After years of being driver/engineer we deal with Critical Velocity in fire hose sizes, as well as the Laminar flow of water. For us the concern was the nominal amount (GPM) of water that we could flow through a given hose size before the efficiency went away. This is to say I could increase the engine pressure but at some point your going to have to deal with the 6 principal's of hydraulics in order to increase Water flow. From listening to the head porters and gurus in this thread, the obstacles seem quiet similar? I am right?
Bernoulli 101!!!! For some reason this man's concepts aren't very common yet they impact what we do greatly..... so THESE ARE THE LAWS OF PHYSICS WHICH ARE NOT QUESTIONABLE... smart people figured these out centuries ago: First... air is a COMPRESSABLE fluid, oil and water are INCOMPRESSABLE. If we don't start with that statement people get lost down the line Second... the principle of conservation of energy requires that the sum of kinetic energy and potential energy remain constant. Energy can't be created just transformed. Third.... fluids only move from a area of high pressure to a area of low pressure. Period. The best example we can relate to is a piston, as it moves down a bore it is creating a lower pressure than that of what is in the port above it so the air fills the lower pressure void until it's pressure is higher than that of what is filling it. FWIW the pressure increases in the cylinder because the mass of air increases and the volume to store that mass stops increasing in size. Basically it's filled up at that pressure level. Fourth.... a orifice can only flow so much volume thru it at a set pressure drop. Think of a orifice plate used to calibrate a flow bench. It is set at a certain diameter so that at a given depression 28" of H2O it will move a set CFM level, then you adjust the bench to read what it should. Pressure and Temp... Higher pressure = Higher temp...... Lower pressure = Lower temp Think about it this way, why do we need an intercooler on a supercharged engine? Because the air is being compressed increasing the pressure which is putting energy INTO the air (since it's a compressable fluid) which causes the air molecules together and they make HEAT. So we need to cool that higher pressure air down before we put it in the motor with a intercooler. Same applies to your compressed air tank, when you put the air gun on the line and use it to dry or clean off parts... it's colder NOT BECAUSE of evaporation (you can actually measure this with a temp gun) but because of the expansion of the air. Conversely when you compress the air into the air tank the tank gets warmer again something you can check with a temp gun. Velocity and Area... Area effects the speed of the air, the larger the area the slower that same volume of air passing thru it will be. I know there are some guys who don't get this because I have seen the crap they grind on, but when you need the velocity in a cylinder head to decrease you increase the area at that point. Which leads into.... Pressure and Velocity... The faster the velocity the lower the pressure. The hood scoop or carb venturi on a race car is a perfect example of this... A carb only draws fuel into the air stream because as the area decreases (going into the venturi), the speed increases and the pressure drops. Then it expands again due to the larger area which increases the pressure and slows the velocity. In terms of the hood scoop the set area only allows a set volume into the scoop. (4th rule above) The air exits the scoop orifice and slows down into the larger area of the scoop the pressure INCREASES due to the conservation of energy. You are turning the kinetic energy of the velocity into the potential energy of PRESSURE. As started above in the 3rd rule... the more pressure you have above the valve the more you can put in the cylinder... hence why a good hood scoop will increase the speed/HP of the car going down the track. So..... Higher Pressure = Bigger Area = Lower Velocity = Lower Temp Lower Pressure = Smaller Area = Higher Velocity = Higher Temp
"Area effects the speed of the air, the larger the area the slower that same volume of air passing thru it will be. I know there are some guys who don't get this because I have seen the crap they grind on, but when you need the velocity in a cylinder head to decrease you increase the area at that point." Call this the "Short, short version"...lol Thanks for taking the time on here Chad.