Increasing valve size-stock heads.

Pablo said:
If you want to see something really neat, grab some modeling clay and put it at the floor of the port to raise the hump. I.e. make a larger radius.
This blocks a huge amount of the port but I was amazed to see that the flow INCREASES and the port flow even sounds a ton smoother. I don't remember exactly how much the flow increased but I think it was around 7 cfm or so on top of what I could already max out at.

I didn't have the guts to try and actually fill a port like this and run it. Someone with more time and money to blow should try it.
Click to expand...

Resurrecting this post in hopes for further discussion on this. Engineers used a similar method in the iron 60*V6 heads found on the 2.8/3.1/3.4 engines. They created a "vane" that increased airflow even though it appears to take up a lot of space in the port, much like what was mentioned above. The "vane", in theory, helps to create a rounder short side transition, and a smoother transition around the valve stem. Removing too much of the vane actually hurts airflow.

I have a theory that with the low port entry, and 10* valve angle, the flow has to make a sharp transition, which is also why I believe there is no improvement with lifts greater than .500". When I ported the 8445 heads, I thought about raising the roof of the port and how, IMO, would offer the greatest improvement when reshaping the port. Thoughts?
 
well if you raised the port roof, then you may alsoi want to entertain epoxy in the bottom f the port, most notably in the short side radius and shape that area to compliment the higher roof. plus a proper SSR will yeild gains as well
 
I have been porting iron Buick heads sin e 1988 and there are some nice heads out there. BUT............. a turbocharger will make seemingly poor flowing heads make BIG power. A flow bench will lie to those that rely on them the produce power. I have found a lot of gain that a flow bench shows NOTHING! I race a car, not a flow bench. I wish someone would swap heads at the track and test different port shapes vs. Flow numbers. In a turbo engine..........a lot of "mistakes" show big power.
 
turbofabricator said:
I gotta add...........I just ported my LAST set of iron heads. I'm now retired from that business. (Anyone want to buy a bunch of carbide burrs?). LOL
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I just noticed you are in my area! I am up the hill from Puyallup/Auburn. I'm hoping to do up a pair of "8445" heads, mostly bowl work. Are you really selling the burrs and won't touch a head anymore or just kidding? I was thinking of having Gosney NAPA Machine in Auburn do the valve/guide/machine work, do you have a recommended place around here? You don't want to do another pair of cast iron heads or show a young guy how to work the magic, do ya? :)
 
turbofabricator said:
a turbocharger will make seemingly poor flowing heads make BIG power. A flow bench will lie to those that rely on them the produce power. I have found a lot of gain that a flow bench shows NOTHING!
Click to expand...


This has always been something that I've thought about. How can the vacuum of a flow bench accurately reproduce how the air really flows or how the path may change under boost pressure? With that said I'll probably have a set flowed that I'm working on now since it's the only practical way for me to get an idea of flow.

Common sense tells me that excessively restricted areas or bottle necks should be opened up to a certain extent. The area that I'm interested in is how the air behaves around radiuses and under pressure.
 
Can't a home made flow bench be made that would simulate boost instead of vacuum? Couldn't be that complicated.
 
I think that the intake and intake runners move air in the same basic function under boost or vacuum...... The only difference is gonna be the amount of energy used to move the air.....

So to those mentioning about a flow bench using vacuum to flow a head that sees boost is the wrong way to flow a head. Well the amount of energy that the flow bench is using is very small when compared to the energy that is being exerted on the compressed air out of the turbo.....

I do agree that slapping a turbocharger on a marginal head yields big gains......

But think of it like this .....To get that same amount of airflow without boost... The amount of energy that the piston will consume to suck/vacuum in that air is gonna be alot VS The energy thats being given away out the exhaust till the turbocharger was added... Its taking that free energy and using it to move the air that the piston is no longer having to use energy to move...... Thats how a turbo helps a shitty head .


So if porting/ bowl work improves the air flow on a flow bench....It's gonna help when boost is applied.... Cuz if that wasn't the case nobody would be going any faster with a ported set of heads VS stock untouched heads...


Flame away
 
No degree here to back up any of my thoughts..... so they can probably be shot down with some sort of formula.
My question was.... wouldn't air or a fluid behave quite different when being pulled through a series odd turns and twist VS being pushed through under high pressure? I feel as if the flow could behave different in the radiuses.
 
Agree with gains on a flow bench is definitely gains in performance, but many mods that do not show gains on the bench, WILL show gains in performance. Flow bench is a tool, only. Use it and learn. Grab a spoon and stand at the kitchen sink with water running and learn a thing or two also. Watch Formula 1 in the rain and learn, too. A lot to learn that can't be explained. (At least by my lame brain). You gotta be able to "see" air.
I must add, that I am not anywhere near as good of a head porter as guys that do it day in and day out.
One of my friends went to a bigger turbo, aluminum heads and bigger intercooler (removing a set of my iron heads) and he gained .20 in the 1/4. Where the gain came from? I dunno. Some of my junk........
 

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turbofabricator said:
Agree with gains on a flow bench is definitely gains in performance, but many mods that do not show gains on the bench, WILL show gains in performance. Flow bench is a tool, only. Use it and learn. Grab a spoon and stand at the kitchen sink with water running and learn a thing or two also. Watch Formula 1 in the rain and learn, too. A lot to learn that can't be explained. (At least by my lame brain). You gotta be able to "see" air.
I must add, that I am not anywhere near as good of a head porter as guys that do it day in and day out.
One of my friends went to a bigger turbo, aluminum heads and bigger intercooler (removing a set of my iron heads) and he gained .20 in the 1/4. Where the gain came from? I dunno. Some of my junk........
Click to expand...
I'd be more interested in the cylinder fill in a turbocharged engine at/near tdc when dealing with high exhaust pressures relatively low CR, and the rod length and rod/stroke ratio. I'm sure there's more than a few hp there getting the valve open/close just right and either having a piston that begins to descend faster/slower from tdc. Not much is mentioned about it ever. Dutweiler has mentioned it before but I never saw an actual test done with small changes for comparison. While most are chasing after a few cfm in head flow they could be playing with other variables that will actually make the car perform better.


Sent from my iPhone using Tapatalk
 
I do agree with that statement. Variable cam timing on modern engines validate this comment. Millions have been spent developing it. Worth discussion here, but is very time consuming (expensive) to validate theories.
 
I am Way out of my pay grade here. Simplified look at this crap.
On a turbo engine isn't the intake valve backing up (stopping the flow) the air stream into the cylinder?
So why isn't it simply bigger = better?
1- valve is closed - pressure building up
2- Valve opens- pressure get released--air flows.
3- Valve closes again - pressure building up again.
The bowl and runners are more of a storage tank for pressurized air WAITING to be released in to the cylinder by the valve.
I can see how the shape of the back of the valve would be more of a restriction over turns into the cylinder. The air is already waiting there the valve it self is blocking it's path. I know valve weight is a concern but why not try more of a cone shape on back side of the valve?
 
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TURBOPOWERED68 said:
I now valve weight is a concern but why not try more of a cone shape on back side of the valve?
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Interesting observation. I don't have the answer but just last week when comparing my OEM intake valves to the larger after market the OEM had much more of a conical shape than the replacement. The replacement was almost flat on the back side....looking at it from what would seem to flow better I'm with you.
 
turbofabricator said:
I have been porting iron Buick heads sin e 1988 and there are some nice heads out there. BUT............. a turbocharger will make seemingly poor flowing heads make BIG power. A flow bench will lie to those that rely on them the produce power. I have found a lot of gain that a flow bench shows NOTHING! I race a car, not a flow bench. I wish someone would swap heads at the track and test different port shapes vs. Flow numbers. In a turbo engine..........a lot of "mistakes" show big power.
Click to expand...

So how many mistakes have you made???

Would you like to share some of them with us????

I want to make the right mistakes and would like some guidance.
 
I’m not a head porter, so I am not trying to sound like one, I know a little about flow. So here is some thoughts looking to promote the discussion.

One of the biggest drivers in pressure drop with compressible flow is going to be boundary layer separation. Once this happens, pressure drop will spike overriding virtually everything else in the flow field. Don’t confuse the description of the boundary layer with the flow field in general. The boundary layer at WOT will be turbulent, but the flow field can still be uniform and non-turbulent, and more importantly still attached to the boundary.

The poppet valve is a total trade off. It is reliable, producible, and gets the job done. It’s flow characteristics suck. Making a cone shape may promote flow with regard to the boundary layer, but reduces flow area, what the ideal is would take quite a bit of experimentation for a given application.

I am speculating that virtually all of the development that has taken place for valves and heads has been for NA applications. The valve shape and port shape has to maximize flow over the entire range of valve lift. In an NA engine, the piston moving down creates a low pressure area using crank shaft power which is filled with air at atmospheric pressure. Maintaining the flow field becomes a delicate balance, and using the energy imparted by the crankshaft is critical. Shape, size, length, valve timing, converting velocity back to pressure …. Plus all kinds of stuff I don’t know I’m sure plays into getting max power.

On a turbo engine, pumping losses on the intake side are not really a concern. If the intake is not excessively restrictive, the intake side pressure will fill the cylinder and also contribute to recovering some lost power by contributing a small amount of force driving the piston down as it fills the cylinder instead of using crankshaft power to fill the cylinder.

I can’t imagine the amount of time and money it would take to experiment properly on head design, and you may find out that there is not much more to be had, given the limits of poppet valves and current head design. My guess on a turbo application would be more straight forward than on an NA design. For max power on a turbo engine, I am guessing that you want the straightest shot with the least flow resistance and a shape that does not promote boundary layer separation through your design operating range. No need to manage ideal velocity and entrained energy like an NA application.
 
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