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Imho a basic port and polish job with a good multi angle seat job ...
It's more than just "flow more air than stock".
When the time is right, depending on his mileage, I think you hit the nail right there, Whitey, with emphasis on the seat jobs, and blending them in. Polishing isn't worth paying extra for, a little blending is.
I'm not going say a lot as it's the business of the experts offering services to sell it, and you'll each has their own approach, but it's not just about bolting something on and it working. It's about setting up the engine as a whole, eg squish, compression and flow etc.
Earn your money and go to someone who demonstrates what you want as a ready resolved package.
Yes, he's right big holes don't always work best, and some porters uses are other niceties like anti-reversion, squirl and flame path techniques.
Here's an easy way to start understanding why multi-angled seat jobs work. Turn your kitchen facet on and watch the flow. Then take one finger and gently touch the side of the flow. What happens? From going straight down, the water goes 30° side ways. Now do it twice and what happens? You're bending the flow
That's the principle of multi-angled seats working, getting more mix into more of the chamber quickly, and creating more turbulence, which mixes the fuel even more. Smaller globules, more combustion; more combustion, more power (and less pollution).
Don't forget there are other benefits to good head jobs including valve to guide fit, and they can be better starting, longer lasting, and even improve fuel consumption if you lay off the right wrist.
When the time is right, depending on his mileage, I think you hit the nail right there, Whitey, with emphasis on the seat jobs, and blending them in. Polishing isn't worth paying extra for, a little blending is.
I'm not going say a lot as it's the business of the experts offering services to sell it, and you'll each has their own approach, but it's not just about bolting something on and it working. It's about setting up the engine as a whole, eg squish, compression and flow etc.
Earn your money and go to someone who demonstrates what you want as a ready resolved package.
Yes, he's right big holes don't always work best, and some porters uses are other niceties like anti-reversion, squirl and flame path techniques.
Here's an easy way to start understanding why multi-angled seat jobs work. Turn your kitchen facet on and watch the flow. Then take one finger and gently touch the side of the flow. What happens? From going straight down, the water goes 30° side ways. Now do it twice and what happens? You're bending the flow
That's the principle of multi-angled seats working, getting more mix into more of the chamber quickly, and creating more turbulence, which mixes the fuel even more. Smaller globules, more combustion; more combustion, more power (and less pollution).
Don't forget there are other benefits to good head jobs including valve to guide fit, and they can be better starting, longer lasting, and even improve fuel consumption if you lay off the right wrist.
Pretty much this.
Ideally, you want high velocity, low turbulence into the cylinder, with high turbulence into the combustion chamber for better mixing. "Polishing" stock heads CAN aid in velocity, but I think mostly these days, heads aren't going in for "polishing" so much as CFD enhancement. Valve grind certainly plays a part as well.
The reason heads are "stage 3" is that the heads really need to be a designed part of the whole "system" of the build. What should be done to your heads depends on several factors, including final compression ratio, timing of the cams, and overall displacement, among other things.
It's sad that some still think polish part of "port and polish" really does anything. Good old branch even once mention in an interview that the only reason why he polished the ports was to give the purchaser something to Ouuu and Aaahh over. It can actually screw up the port by allowing the flow to detach from the port surface and become turbulent. A rough port is better in getting fuel that dropped out of suspension back into the flow otherwise it simply collects in the bottom of the port and dribbles into the combustion chamber. The result is poor fuel atomization, combustion and mileage.
Porting is more than just hogging out the port. Making a port bigger does not increase velocity, it increases flow.. Finding way to make the port flow better without increasing area for the most of the port can boost performance across the power band even on the low end. You only want more area (along with more efficient flow) when you don't have enough cam to feed the displacement in the RPM range you want to achieve. I've seen motors with lower flowing heads match higher flowing heads for horse power but make 4-6 fp more TQ everywhere below that.
Doing only heads without a cam is sort of a waste. Stock cams have no overlap so you give up on good scavenging. You really need to do both. If you can only do 1, you best bet is a longer cam combined with more compression.. Squeezing it hard can not only help with power from the squeeze but it can also help with fill and emptying of the combustion chamber. Some of the head porters of the past (none here), used hog on the ports with no respect for flow, whack a bunch off the heads, tighten the squish to 0.020 and sell as set off high compression pistons bringing the CR over 11.0 then run a W6h cam.. Some ran well but most pinged like a SOB.
If you can only do heads or cams, you are better off with the cam only.
One of the problems is matching "stages" between difference vendors when doing heads. There isn't any standard so you really need to talk to them. It's also best to set a budget, and see what they can do for what you want. Don't forget to add in tuning and make sure that whatever tuner you use is compatible with the build.
It's sad that some still think polish part of "port and polish" really does anything. Good old branch even once mention in an interview that the only reason why he polished the ports was to give the purchaser something to Ouuu and Aaahh over. It can actually screw up the port by allowing the flow to detach from the port surface and become turbulent. A rough port is better in getting fuel that dropped out of suspension back into the flow otherwise it simply collects in the bottom of the port and dribbles into the combustion chamber. The result is poor fuel atomization, combustion and mileage.
Porting is more than just hogging out the port. Making a port bigger does not increase velocity, it increases flow.. Finding way to make the port flow better without increasing area for the most of the port can boost performance across the power band even on the low end. You only want more area (along with more efficient flow) when you don't have enough cam to feed the displacement in the RPM range you want to achieve. I've seen motors with lower flowing heads match higher flowing heads for horse power but make 4-6 fp more TQ everywhere below that.
Doing only heads without a cam is sort of a waste. Stock cams have no overlap so you give up on good scavenging. You really need to do both. If you can only do 1, you best bet is a longer cam combined with more compression.. Squeezing it hard can not only help with power from the squeeze but it can also help with fill and emptying of the combustion chamber. Some of the head porters of the past (none here), used hog on the ports with no respect for flow, whack a bunch off the heads, tighten the squish to 0.020 and sell as set off high compression pistons bringing the CR over 11.0 then run a W6h cam.. Some ran well but most pinged like a SOB.
If you can only do heads or cams, you are better off with the cam only.
One of the problems is matching "stages" between difference vendors when doing heads. There isn't any standard so you really need to talk to them. It's also best to set a budget, and see what they can do for what you want. Don't forget to add in tuning and make sure that whatever tuner you use is compatible with the build.
Remind me - you're a mechanical engineer, right Bruce? From what field?
Flowing "better" - exactly. Thus designing for better CFD (computational fluid dynamics). Which is usually a higher velocity, not-necessarily more turbulent flow. The high velocity should ideally keep fuel suspended, not turbulence in the intake. Turbulence in the combustion chamber is desired to keep it well blended before ignition.
At least that's how I always understood it...
Keep in mind, all of this I post with a question mark at the end, in the desire to have an open dialogue with someone I have come to believe is a kindred spirit, and a smart cookie...
Remind me - you're a mechanical engineer, right Bruce? From what field?
Flowing "better" - exactly. Thus designing for better CFD (computational fluid dynamics). Which is usually a higher velocity, not-necessarily more turbulent flow. The high velocity should ideally keep fuel suspended, not turbulence in the intake. Turbulence in the combustion chamber is desired to keep it well blended before ignition.
At least that's how I always understood it...
Keep in mind, all of this I post with a question mark at the end, in the desire to have an open dialogue with someone I have come to believe is a kindred spirit, and a smart cookie...
Well my degree is in electrical engineering, mostly digital but my career includes a little bit of everything electrical including interfacing to mechanical devices and some software. I still enjoy mechanics / mechanical engineering / machining but it's more of a hobby. I was a mc mechanic for the first 10 years out of high school while taking classes.
What you are saying seems correct to me simply because any turbulence in the port kills flow. Not sure I wrote anything that disagrees with that. I did mention that port polishing can hurt flow and I've seen it with my own messing around on a flow bench. I've also seen polished ports cause rougher running on carbed motors when the motor was cool. Less of an issue when hot but it's still likely there.
You definitely want turbulence in the chamber to ensure a more homogeneous mixture for a complete burn which is one of the reasons it's good to set the squish tight. I suspect that there is a bit of swirl simply from the shape of the port but I've not spent any time studying it.. IIRC both Don Dorfman (HD Street Perf), Larry Yacko (WFO Larry), and Short-block Charley have experimented with this some.
The result is poor fuel atomization, combustion and mileage.
Ah, that's the word I was looking for.
Yes, it's hard to see inside a port but think of the way rain goes horizontal along your truck side windows. That's to be minimized as much as possible.
Just as an aside, impressive the way the powder coating still sticks to the inside of the combustion chamber in 103ci heads!
Humble opinion from a non technician: All of this fuel atomization,rough surface sounds fine for carbureted engines. In injected engines the fuel is introduced just before the intake valve and the quality of the injector spray and turbulence around the intake valve is about all you have working for you, none of the rain comparisons apply. No matter what is done to the heads, intake runners, throttle body, the "barn door" intake valves will only pass so much air and it will be stirred up in the passing.
My question for the OP is how much are you willing to spend? How far would that same money go for a new machine with the M8 that will flow much more air straight out of the box? Along with that, you also get new tires, new brakes, new belt, heavier forks, improved shocks and a raft of other stuff that you will need to replace on your current ride somewhere down the road.
Humble opinion from a non technician: All of this fuel atomization,rough surface sounds fine for carbureted engines. In injected engines the fuel is introduced just before the intake valve and the quality of the injector spray and turbulence around the intake valve is about all you have working for you, none of the rain comparisons apply. No matter what is done to the heads, intake runners, throttle body, the "barn door" intake valves will only pass so much air and it will be stirred up in the passing.
My question for the OP is how much are you willing to spend? How far would that same money go for a new machine with the M8 that will flow much more air straight out of the box? Along with that, you also get new tires, new brakes, new belt, heavier forks, improved shocks and a raft of other stuff that you will need to replace on your current ride somewhere down the road.
At lower RPMs, fuel injectors spray on closed valves.
So since an old but still relevant thread has been brought back to life...
Who are the good head porters in the various areas of our country?
I bought a beautiful set of 103 heads from a member on here last summer and have not sent them off as of yet and truthfully do not want to "send them off."
I also do not want to do an exchange.
So with that in mind I have to make a trip somewhere.
I was thinking about using this outfit and seeing some folks I know in the Denver area. http://www.nrhsperformance.com/headworktc.shtml
Does anyone in the Denver metro area have any feedback on them and Zach?
Oh and these would be to go with Andrews 57H cams.
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