What makes round inlet ports flow more?
Custom head
Started by
_Gunmetal LH_
, Feb 25 2010 07:17 PM
49 replies to this topic
#26
TerrA LX
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Posted 02 March 2010 - 10:41 PM
#27
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Posted 03 March 2010 - 12:53 PM
Less turbulence - is it the Bernoulli effect? - the incoming charge isn't pushing itself out of the way trying to get in as it hits the walls and angles......
All of this stuff has been done before. there were fella's in the early 70's making hemi reds in Melbourne in their garages. It's a pity there aren't more around, and we don't have the sheds or skill our dad's had (well most of us!)
Waggott twin cam grey head ( can some old fart remind me if they were crossflow too? Someone made one....).
There are currently two types of head available that sort some of these issues.
Not saying don't look/do it, just saying have a look at what has been done before and incorporate those lessons before starting.
Grant..
Edit -
Turbulence, Wikipedia -
"When designing piping systems, turbulent flow requires a higher input of energy from a pump (or fan) than laminar flow. However, for applications such as heat exchangers and reaction vessels, turbulent flow is essential for good heat transfer and mixing."
All of this stuff has been done before. there were fella's in the early 70's making hemi reds in Melbourne in their garages. It's a pity there aren't more around, and we don't have the sheds or skill our dad's had (well most of us!)
Waggott twin cam grey head ( can some old fart remind me if they were crossflow too? Someone made one....).
There are currently two types of head available that sort some of these issues.
Not saying don't look/do it, just saying have a look at what has been done before and incorporate those lessons before starting.
Grant..
Edit -
Turbulence, Wikipedia -
"When designing piping systems, turbulent flow requires a higher input of energy from a pump (or fan) than laminar flow. However, for applications such as heat exchangers and reaction vessels, turbulent flow is essential for good heat transfer and mixing."
#28
_Gunmetal LH_
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Posted 03 March 2010 - 03:32 PM
http://oldholden.com/node/20202 Repco crossflow head.
http://www.waggottca...om.au/about.php Small pics of Waggot twin cam head.
Direct injection is too costly to even consider. The injectors have to overcome combustion pressures and the Red 202 just isn't high quality enough to gain from it. The real advantage is purely a tuning thing, maybe if you were planning on increasing the boost on a turbo engine then you probably wouldn't have to look at modifying the fuel system to cope.
Dirt cheap alternatives (in comparison) are readily available.
I recall some of the German WW2 Daimler-Benz inverted V12's used direct injection too. (Will have to check that to properly confirm)
http://www.waggottca...om.au/about.php Small pics of Waggot twin cam head.
Direct injection is too costly to even consider. The injectors have to overcome combustion pressures and the Red 202 just isn't high quality enough to gain from it. The real advantage is purely a tuning thing, maybe if you were planning on increasing the boost on a turbo engine then you probably wouldn't have to look at modifying the fuel system to cope.
Dirt cheap alternatives (in comparison) are readily available.
I recall some of the German WW2 Daimler-Benz inverted V12's used direct injection too. (Will have to check that to properly confirm)
#29
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Posted 03 March 2010 - 05:39 PM
Click on those Waggot pics to make them larger. 
#30
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Posted 03 March 2010 - 06:21 PM
Cylinder heads are a bit of a obsession hobby with me so I might chime in with a few points...
A round port has less wall surface area per unit of CSA than any other shape and therefore usually has a very good flow co-efficient. Rectangular ports are common though, often they are a means of picking up a bit of area within the confines of things like head bolts and pushrods. The areas in the corners though are usually pretty dead and don't contribute much to flow.
Back in the days when flow testing first became common place (early 80s) people became a bit obsessed with improving flow, and it took a while to discover that the best flowing heads didn't always run the fastest. Eventually though, they realized that flow was just one of the essential ingredients, the others being efficient flow through having a good co-efficiency, a reasonably constant CSA that encourages cylinder filling through ram and sonic tuning, and a fast efficient burn through open, shallow chamber shaping and swirl/tumble of the intake charge.
Modern engines generally do all these things very well, and can make lots of power with very little fuel and very little cam. Look at recent Honda or Toyota heads for inspiration, but beware that some of the things that make these heads work so well can be quite subtle. Unfortunately there are still a few old Holden tuners who will tell you that the old 9 port heads aren't so bad, and if you just look at the raw flow figures they can be made half reasonable. In almost every other aspect though they really are a steaming pile of shit. The trouble is it's these other aspects that contribute to so much of the power output, and especially over a broad rev range. The Repco and Waggot heads were exceptional in their day, but in 2010 they are way, way behind what comes standard on most cars.
There are a few rules-of-thumb for proportioning things. For a canted 2 valve engine an intake valve diameter of somewhere around 52% of the bore diameter will be close. If the valves are fairly vertical you might have to reduce it a bit because of shrouding. The throat area should be roughly 88% - 90% of the valve diameter, the straight section approaching the turn also is often about the same area or just a bit bigger. At the turn or anywhere else there is a direction change the area will increase, allowing the air to turn at a slower speed.
The exhaust side isn't anywhere near so critical, and while most people go for about 70 - 80% of intake flow it seems that even fairly big variations from this can be made up for with cam changes. Flow efficiency here is just as important if not more so than on the intake side.
A good burn is as important as flow, and this is where the modern stuff really shines. Getting good swirl is critical. Incidentally the Singh grooves were discredited some time ago, though you still occassionally see the odd turbo ricer boy using them. If you're interested in this stuff look into the work of Larry Widmer, he has had some outstanding results from his "soft heads" and probably knows more about combustion efficiency than anyone outside Japan. And if port design interests you then look into the work of Darin Morgan, he's pretty much regarded as the No 1 for US style engines at least.
Don't stress too much about making it cross-flow - there's no advantage to cross-flow in itself but it does make more room available and thereby allows a bit more freedom in port design. Likewise don't stress over injection, direct or otherwise. Good carburetion will make power within a poofteenth of any injector.
Making a head would certainly be challenging, but it would be a lot of fun too. Back in the day radical port relocations were sometimes done to various engines, often by brazing new ports into the existing cast iron heads. You could probably do a lot of prototyping on the flowbench using body filler. It'll take much much much longer than what you expect. And realistically it's unlikely you'll come anywhere close to what's currently available, but that doesn't mean you shouldn't do it. Sometimes the satisfaction of building something like this is the goal itself.
Edit: Jesus, I didn't realize I'd rambled on for so long. Sorry.
A round port has less wall surface area per unit of CSA than any other shape and therefore usually has a very good flow co-efficient. Rectangular ports are common though, often they are a means of picking up a bit of area within the confines of things like head bolts and pushrods. The areas in the corners though are usually pretty dead and don't contribute much to flow.
Back in the days when flow testing first became common place (early 80s) people became a bit obsessed with improving flow, and it took a while to discover that the best flowing heads didn't always run the fastest. Eventually though, they realized that flow was just one of the essential ingredients, the others being efficient flow through having a good co-efficiency, a reasonably constant CSA that encourages cylinder filling through ram and sonic tuning, and a fast efficient burn through open, shallow chamber shaping and swirl/tumble of the intake charge.
Modern engines generally do all these things very well, and can make lots of power with very little fuel and very little cam. Look at recent Honda or Toyota heads for inspiration, but beware that some of the things that make these heads work so well can be quite subtle. Unfortunately there are still a few old Holden tuners who will tell you that the old 9 port heads aren't so bad, and if you just look at the raw flow figures they can be made half reasonable. In almost every other aspect though they really are a steaming pile of shit. The trouble is it's these other aspects that contribute to so much of the power output, and especially over a broad rev range. The Repco and Waggot heads were exceptional in their day, but in 2010 they are way, way behind what comes standard on most cars.
There are a few rules-of-thumb for proportioning things. For a canted 2 valve engine an intake valve diameter of somewhere around 52% of the bore diameter will be close. If the valves are fairly vertical you might have to reduce it a bit because of shrouding. The throat area should be roughly 88% - 90% of the valve diameter, the straight section approaching the turn also is often about the same area or just a bit bigger. At the turn or anywhere else there is a direction change the area will increase, allowing the air to turn at a slower speed.
The exhaust side isn't anywhere near so critical, and while most people go for about 70 - 80% of intake flow it seems that even fairly big variations from this can be made up for with cam changes. Flow efficiency here is just as important if not more so than on the intake side.
A good burn is as important as flow, and this is where the modern stuff really shines. Getting good swirl is critical. Incidentally the Singh grooves were discredited some time ago, though you still occassionally see the odd turbo ricer boy using them. If you're interested in this stuff look into the work of Larry Widmer, he has had some outstanding results from his "soft heads" and probably knows more about combustion efficiency than anyone outside Japan. And if port design interests you then look into the work of Darin Morgan, he's pretty much regarded as the No 1 for US style engines at least.
Don't stress too much about making it cross-flow - there's no advantage to cross-flow in itself but it does make more room available and thereby allows a bit more freedom in port design. Likewise don't stress over injection, direct or otherwise. Good carburetion will make power within a poofteenth of any injector.
Making a head would certainly be challenging, but it would be a lot of fun too. Back in the day radical port relocations were sometimes done to various engines, often by brazing new ports into the existing cast iron heads. You could probably do a lot of prototyping on the flowbench using body filler. It'll take much much much longer than what you expect. And realistically it's unlikely you'll come anywhere close to what's currently available, but that doesn't mean you shouldn't do it. Sometimes the satisfaction of building something like this is the goal itself.
Edit: Jesus, I didn't realize I'd rambled on for so long. Sorry.
Edited by oldjohnno, 03 March 2010 - 06:22 PM.
#31
_Gunmetal LH_
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Posted 03 March 2010 - 08:04 PM
Don't be sorry! Cheers heaps! I don't mind any sort of 'rambling'. Some more things to think about and research.
I have been talking to a couple old-school motorbike tuners who would make their own exhausts and intake runners as they understood what design aspects could be improved. 'Bucket loads' of knowledge...
I don't have knowledge about the finer details of head design and I'm not looking for a way to get a massive improvement: just 'not as s#!t' as factory. Crossflow is more of a possibility than aim, to perhaps give more room for stuff in the engine bay. As you said, the main goal (for me) would be the actual building. I don't think I could really avoid an improvement on the 202 head?
One thing I have learned in respects to flow efficiency was that 'excellent' porting job would be very quiet (in comparison) on a flow bench. I remember at TAFE after cleaning a 202 head (bare, no valves) and hosing it off (high tech- garden hose) and having what looked like more water coming back out the ports than going through the valve area. No prizes for guessing that's pretty s#!t.
How's your project going?
I have been talking to a couple old-school motorbike tuners who would make their own exhausts and intake runners as they understood what design aspects could be improved. 'Bucket loads' of knowledge...
I don't have knowledge about the finer details of head design and I'm not looking for a way to get a massive improvement: just 'not as s#!t' as factory. Crossflow is more of a possibility than aim, to perhaps give more room for stuff in the engine bay. As you said, the main goal (for me) would be the actual building. I don't think I could really avoid an improvement on the 202 head?
One thing I have learned in respects to flow efficiency was that 'excellent' porting job would be very quiet (in comparison) on a flow bench. I remember at TAFE after cleaning a 202 head (bare, no valves) and hosing it off (high tech- garden hose) and having what looked like more water coming back out the ports than going through the valve area. No prizes for guessing that's pretty s#!t.
How's your project going?
Edited by Gunmetal LH, 03 March 2010 - 08:07 PM.
#32
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Posted 03 March 2010 - 08:14 PM
How's your project going?
Slowly. Block is at machinists getting deck cut, will try to spend some time on it on the weekend work permitting.
I guess what I was trying to say (in too many words) is that while you won't make power without good flow, good flow alone isn't enough to do the job...
#33
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Posted 03 March 2010 - 09:37 PM
Main reason i want cross flow is because i have a strange obsession with forced induction, and its just easyer with x flow....
Cheers.
Cheers.
#34
_Gunmetal LH_
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Posted 04 March 2010 - 12:19 AM
oldjohnno Yep, I did gather that.
Also, I've always been taught the ports and the valves should not be polished as such, so the airflow drags on the surface a little and causes some tumbling and aids with creating a swirl which helps cylinder fill. The throat being 88-90% of the valve area is more specific than I was thinking, (I never thought about it as a percentage?) I was working on the inside diameter of the valve seat with some blending either a slight bellmouth or grinding out a touch. I'd have to see before I decide? Sounds funny I know, that's just how I think.
Then there's the vortex generators on the tailplanes of aircraft. Not the fancy crap on the new Lancers but proper zig-zag arrangements. Could be a consideration in small scale for the inside radius of the port.
Oops, just looked at the time...
Also, I've always been taught the ports and the valves should not be polished as such, so the airflow drags on the surface a little and causes some tumbling and aids with creating a swirl which helps cylinder fill. The throat being 88-90% of the valve area is more specific than I was thinking, (I never thought about it as a percentage?) I was working on the inside diameter of the valve seat with some blending either a slight bellmouth or grinding out a touch. I'd have to see before I decide? Sounds funny I know, that's just how I think.
Then there's the vortex generators on the tailplanes of aircraft. Not the fancy crap on the new Lancers but proper zig-zag arrangements. Could be a consideration in small scale for the inside radius of the port.
Oops, just looked at the time...
#35
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Posted 04 March 2010 - 06:15 AM
The throat being 88-90% of the valve area is more specific than I was thinking, (I never thought about it as a percentage?) I was working on the inside diameter of the valve seat with some blending either a slight bellmouth or grinding out a touch.
This stuff is all pretty much cut and dried; the proportions that work are well established. I'll find a good pic and post it later if you like. If you can picture a carb venturi, with its short radius down to the smallest diameter near the top and a long gradual taper underneath, well that's the sort of shape you want directly under the seat and into the bowl. It helps the air turn out of the port and through the valve opening.
#36
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Posted 05 March 2010 - 12:01 AM
A pic would be excellent.
Asked a 'quirky' mate if he did anything out of the ordinary with his head when he ported it himself. (He's just as mad as me) He said he made a clear tube (lexan/ shirt box rolled up) the size of the cylinder and silicon'ed it to the head, with the other end hooked up to his wet&dry vac using a trimmed funnel. He said it was good for catching most of the filings from the die grinding, and his flow test was to use a smoke bomb and 'see' how it flowed into the cylinder. I think it's a brilliant idea! He was also able to see with a valve fitted. He used a stethoscope to 'listen' for dead areas. Less whistle, less flow at that section.
Sounds like the 'quiet sounding port' job. When I asked what sort of improvement he got, he just said: "Bugger knows! Rebuilt the engine at the same time so I could've stuffed it and not even known."
Hmmm, I'd say that's inconclusive really...
Asked a 'quirky' mate if he did anything out of the ordinary with his head when he ported it himself. (He's just as mad as me) He said he made a clear tube (lexan/ shirt box rolled up) the size of the cylinder and silicon'ed it to the head, with the other end hooked up to his wet&dry vac using a trimmed funnel. He said it was good for catching most of the filings from the die grinding, and his flow test was to use a smoke bomb and 'see' how it flowed into the cylinder. I think it's a brilliant idea! He was also able to see with a valve fitted. He used a stethoscope to 'listen' for dead areas. Less whistle, less flow at that section.
Sounds like the 'quiet sounding port' job. When I asked what sort of improvement he got, he just said: "Bugger knows! Rebuilt the engine at the same time so I could've stuffed it and not even known."
Hmmm, I'd say that's inconclusive really...
#37
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Posted 05 March 2010 - 04:43 PM
Good carburetion will make power within a poofteenth of any injector.
Not that I want to argue with someone of your obvious knowledge and experience, but - seriously?
#38
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Posted 05 March 2010 - 05:56 PM
Good carburetion will make power within a poofteenth of any injector.
Not that I want to argue with someone of your obvious knowledge and experience, but - seriously?
i think u are underestimating how good carburation can be.
su's for example, once you get the right tune, idk how but my dad got it 12.4 af ratio all the way through the range with a piece of fuel line.
and the simplicity as well, i love carburation.
#39
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Posted 05 March 2010 - 06:22 PM
It all comes down to the definition of a poofteenth I guess.
But yes, seriously I don't think there's much in it. I know the injection fans will trot out the same old arguments but I'm not entirely convinced that the gap is all that big. There's a fair bit of argument over what class of N/A petrol-burning engine has the highest specific output but NHRA ProStockers would have to be up there with over 2.8hp per cube, spectacularly high VEs and plain old carburetors. What really impresses me though is that they can get these figures with such large cylinders and a pushrod 2 valve valvetrain. Bikes are another area where carbs continue to be used to achieve very high specific outputs and VEs.
Injection proponents usually point out that they don't suffer from the pressure drop that carbs have, but really this is 3 tenths of SFA. Most race carbs perform best if sized to give no more than 0.5" hg pressure drop at peak power, and even if we give the injection fans the benefit of the doubt and assume they have no pressure drop whatsover, we're only talking about a difference of about 1.6%. If we say the injection manifold has a gradient of say 0.2" - 0.3" (probably more realistic) then the difference would be even smaller. I don't know what the difference is in regards to cylinder filling due to sonic tuning - and a slide throttle injector setup would seem to be better suited to pipe tuning - but considering what the ProStock guys are getting with their tunnel rams I doubt there's much in it.
Mixture quality is the other point of contention. But it seems to be becoming apparent that super fine atomisation isn't as important as was previously thought, and that vaporisation in the inlet tract has in fact a negative effect on output. Obviously direct injection has a clear advantage here. Carbs such as the old SUs and dell'ortos supposedly produce a mixture comparable to injectors at 40 psi, Holleys and Webers are more dribbly but as far as power output goes it doesn't seem to matter.
I'm not a fanatic either way; for a stock daily driver give me injection any day. It's just so much more civilised. But for a performance engine that only has a rev range of a couple of thousand rpms carbs are fine by me. I can buy them and get them running optimally for a fraction of the cost of EFI. It just amuses me a bit the way some guys claim injection is sooooooo much more accurate, and yet their cars (on which they've spent thousands on ECUs and tuning) still stink and blow black smoke.
I really must spend less time typing and more time in the shed..
But yes, seriously I don't think there's much in it. I know the injection fans will trot out the same old arguments but I'm not entirely convinced that the gap is all that big. There's a fair bit of argument over what class of N/A petrol-burning engine has the highest specific output but NHRA ProStockers would have to be up there with over 2.8hp per cube, spectacularly high VEs and plain old carburetors. What really impresses me though is that they can get these figures with such large cylinders and a pushrod 2 valve valvetrain. Bikes are another area where carbs continue to be used to achieve very high specific outputs and VEs.
Injection proponents usually point out that they don't suffer from the pressure drop that carbs have, but really this is 3 tenths of SFA. Most race carbs perform best if sized to give no more than 0.5" hg pressure drop at peak power, and even if we give the injection fans the benefit of the doubt and assume they have no pressure drop whatsover, we're only talking about a difference of about 1.6%. If we say the injection manifold has a gradient of say 0.2" - 0.3" (probably more realistic) then the difference would be even smaller. I don't know what the difference is in regards to cylinder filling due to sonic tuning - and a slide throttle injector setup would seem to be better suited to pipe tuning - but considering what the ProStock guys are getting with their tunnel rams I doubt there's much in it.
Mixture quality is the other point of contention. But it seems to be becoming apparent that super fine atomisation isn't as important as was previously thought, and that vaporisation in the inlet tract has in fact a negative effect on output. Obviously direct injection has a clear advantage here. Carbs such as the old SUs and dell'ortos supposedly produce a mixture comparable to injectors at 40 psi, Holleys and Webers are more dribbly but as far as power output goes it doesn't seem to matter.
I'm not a fanatic either way; for a stock daily driver give me injection any day. It's just so much more civilised. But for a performance engine that only has a rev range of a couple of thousand rpms carbs are fine by me. I can buy them and get them running optimally for a fraction of the cost of EFI. It just amuses me a bit the way some guys claim injection is sooooooo much more accurate, and yet their cars (on which they've spent thousands on ECUs and tuning) still stink and blow black smoke.
I really must spend less time typing and more time in the shed..
#40
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Posted 05 March 2010 - 07:28 PM
I agree that peak power outputs between a carb motor and a EFI motor would be close.... but isnt the biggest gain from EFI the fact that you can tune it perfectly at every point and make more power down low
#41
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Posted 05 March 2010 - 08:20 PM
I agree. I'd even say that in lots of applications - most even - EFI is clearly the way to go. All I was trying to say is that for a competition engine that has a limited rev range anyway (because of cam and pipe tuning etc) a carb will run right up there with the injector. Or as greens said, don't underestimate a good carb..... but isnt the biggest gain from EFI the fact that you can tune it perfectly at every point and make more power down low
Either system will only be as good as the quality of its tune.
#42
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Posted 11 March 2010 - 01:27 AM
With a 6 throttle intake I'd probably go injection. I wouldn't want to go to all the trouble only to have an inlet manifold choke it. 6 trumpets would look nice. Unless I could build an inlet looking like a tuned turbo exhaust collector... *thinks 750 Holley and smiles*
Then I had another thought- what if I put on injector bosses in the head so they aim AT the valve? A sequential setup should work well if timed properly. Going to need a custom rocker cover anyway...
Anyone familiar with the factory VT V6 supercharged heads? They have the injectors mounted in the head not the inlet.
Then I had another thought- what if I put on injector bosses in the head so they aim AT the valve? A sequential setup should work well if timed properly. Going to need a custom rocker cover anyway...
Anyone familiar with the factory VT V6 supercharged heads? They have the injectors mounted in the head not the inlet.
#43
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Posted 11 March 2010 - 06:51 PM
Thanks for the responses guys. It's always good to get the technical background on things like this.
#44
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Posted 11 March 2010 - 08:22 PM
Yea I do agree, for a drag car A carbie is fine, as you only need to tune it for 1 area.. Flat out 
#45
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Posted 12 March 2010 - 05:08 PM
Here's a picture showing what I'm thinking about. On the left is my assumption about the standard head, on the right is basically what I'm trying to achieve. Could only be an improvement...
Head mod 4.jpg 43.52K
37 downloads
What I'm thinking is to remove the manifold mounting face of the head and completely cut/grind out the ports so I have nothing left apart from a big F.O. hole and valve seat areas. Using the 'steam pipe bends' and some straight pieces make new ports which will (probably) exit above the head a bit. Put a new 'face' on it with all the bolts/holes.
As soon as I started 'doodling' this pic (ultra-high-tech MS Paint, Yeah!) I realised a few things I hadn't before. =I spent so long at drawing this on the computer I reckon it would probably have been easier to do the actual job. =The valve will have to be much longer (while I'm at it- bigger too). =With a longer valve I'd need chunkier/stronger valve guides and thicker boss(?) =To retain factory pushrods, I'd need to use something like a 1:1.7 rocker arm because of the angle, and would need to raise the rocker shaft/pivot with a block or bush.
The mods would also mean no factory manifolds would line-up with anything and I'd need to relocate some things like coolant temp sender etc. The block to raise the rocker arm pivots could work as an adapter plate bolted in the factory spots and the new pivot points attached to that in relocated positions for possible canted valves, otherwise I could use slightly angled pivots and (old school hemi V8 style) offset rockers.
Quick mental add up of potential costs so far- Oh S#!T.
Then as I was imagining this 'dreamers' head in my Kingswood engine bay, I thought about the cooling effectiveness. Oh Bugger! I realised while it would look fancy, having the ports coming a bit out of the top of the head, they wouldn't be getting any coolant on that part of the ports. I wondered how this may affect things? Would the exhaust ports get that hot that the oil would ignite? Would it weaken the surrounding welds, crack them, and I'd have enough steam to blow off my bonnet? Would I have enough room to fit a water jacket around these and the head bolts? Would attaching cooling fins be pointless?
Shiyut! What to do? Ding! I had a idea while thinking about water pumps. WTF? you ask? I'm thinking of a flat section as a base, level with the top of the head that I could fit a 'wet' cover to. This would provide a gallery for coolant over the top sections of the ports with tubes to isolate the head bolts. A bit like a V8 flathead, but skinnier looking, cover. When thinking of how I'd build it being so complex, I figured bugger that! I don't know how I'd manage to seal it properly without using the head bolts to hold it down. Unless I could use studs for the head then I could use a second nut. My other idea was if the spring seat would be at about the position it is to the port in my picture, then maybe use some thick sheet and make a gallery that goes around the spring seats and over the ports. With a ton of holes drilled around the ports on the top of the head under the gallery then it may get enough coolant in there to do the job? A couple of bleed lines in the very top should work?
Still thinking about that...
A bit (Ok- alot) stuck on the proper cooling idea presuming that it is needed. Any suggestions or input into these, and other problems I could have missed?
Cheers for looking, hope I'm not boring you by now.
Head mod 4.jpg 43.52K
37 downloadsWhat I'm thinking is to remove the manifold mounting face of the head and completely cut/grind out the ports so I have nothing left apart from a big F.O. hole and valve seat areas. Using the 'steam pipe bends' and some straight pieces make new ports which will (probably) exit above the head a bit. Put a new 'face' on it with all the bolts/holes.
As soon as I started 'doodling' this pic (ultra-high-tech MS Paint, Yeah!) I realised a few things I hadn't before. =I spent so long at drawing this on the computer I reckon it would probably have been easier to do the actual job. =The valve will have to be much longer (while I'm at it- bigger too). =With a longer valve I'd need chunkier/stronger valve guides and thicker boss(?) =To retain factory pushrods, I'd need to use something like a 1:1.7 rocker arm because of the angle, and would need to raise the rocker shaft/pivot with a block or bush.
The mods would also mean no factory manifolds would line-up with anything and I'd need to relocate some things like coolant temp sender etc. The block to raise the rocker arm pivots could work as an adapter plate bolted in the factory spots and the new pivot points attached to that in relocated positions for possible canted valves, otherwise I could use slightly angled pivots and (old school hemi V8 style) offset rockers.
Quick mental add up of potential costs so far- Oh S#!T.
Then as I was imagining this 'dreamers' head in my Kingswood engine bay, I thought about the cooling effectiveness. Oh Bugger! I realised while it would look fancy, having the ports coming a bit out of the top of the head, they wouldn't be getting any coolant on that part of the ports. I wondered how this may affect things? Would the exhaust ports get that hot that the oil would ignite? Would it weaken the surrounding welds, crack them, and I'd have enough steam to blow off my bonnet? Would I have enough room to fit a water jacket around these and the head bolts? Would attaching cooling fins be pointless?
Shiyut! What to do? Ding! I had a idea while thinking about water pumps. WTF? you ask? I'm thinking of a flat section as a base, level with the top of the head that I could fit a 'wet' cover to. This would provide a gallery for coolant over the top sections of the ports with tubes to isolate the head bolts. A bit like a V8 flathead, but skinnier looking, cover. When thinking of how I'd build it being so complex, I figured bugger that! I don't know how I'd manage to seal it properly without using the head bolts to hold it down. Unless I could use studs for the head then I could use a second nut. My other idea was if the spring seat would be at about the position it is to the port in my picture, then maybe use some thick sheet and make a gallery that goes around the spring seats and over the ports. With a ton of holes drilled around the ports on the top of the head under the gallery then it may get enough coolant in there to do the job? A couple of bleed lines in the very top should work?
Still thinking about that...
A bit (Ok- alot) stuck on the proper cooling idea presuming that it is needed. Any suggestions or input into these, and other problems I could have missed?
Cheers for looking, hope I'm not boring you by now.
#46
_Bomber Watson_
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Posted 12 March 2010 - 07:14 PM
Yes the cooling is needed, just use head studs, and get longer ones for one side so you can raise the total height of the head to allow room for the coolant passage.
Cheers.
Cheers.
#47
_oldjohnno_
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Posted 12 March 2010 - 08:44 PM
A few more random comments:
The exhaust port needs to be cooled in its entirety; the intake doesn't really need any cooling at all. I'd be inclined to stick with the stock exhaust port and only modify the intake. The standard exhaust port is relatively good and as I think I mentioned earlier you can compensate even for quite big flow imbalances with a bit more exhaust duration. The other reason I'd leave it alone is considering the thermal stresses in the exhaust I think any serious cut-and-shut work would crack up almost immediately.
Rather than raise the port while keeping the low angle of the original head maybe you could make it a semi-downdraft design where the runner angles down at about 45deg and the roof blends into the original port as close as possible to the spring seat. This is how the old 105E Kent conversions were done and they were able to pick up flow while still keeping the original valves and spring seats, so the amount of butchery required was much reduced. Remember the more cutting and shutting you do the less likely it is to stay in one piece. A possible variation on this might be to just fit a dividing wall and a high, sloping roof, and for the floor use an aluminium filler piece. Same type of thing as used in the Chev 6 "lump port" heads only much thicker of course.
I have no idea why you'd want to retain the factory pushrods; I think getting some appropriately long rods would be the least of your worries. Likewise the manifold - if you can successfully perform these kinds of head mods then fabricating a manifold will be a piece of cake..
Maybe the best approach at this stage is to just step back a bit and spend some time studying some existing head designs and engine design and theory in general. A couple of heads in particular you might like to look into would include the Ford 105E (can't find any pics of the mods at the moment but will post any I find), the 2V Ford 250 (which is probably very close to what you should aim for), the Duggan (now JZed, and again a very good one to study), and the Chev lump port conversions. God knows what I've forgotten. Maybe even the old GMC/Chev Wayne heads; these were very interesting in that Horning managed to build quite a good crossflow head while sticking with the original Chev/Holden valve and pushrod layout.
The exhaust port needs to be cooled in its entirety; the intake doesn't really need any cooling at all. I'd be inclined to stick with the stock exhaust port and only modify the intake. The standard exhaust port is relatively good and as I think I mentioned earlier you can compensate even for quite big flow imbalances with a bit more exhaust duration. The other reason I'd leave it alone is considering the thermal stresses in the exhaust I think any serious cut-and-shut work would crack up almost immediately.
Rather than raise the port while keeping the low angle of the original head maybe you could make it a semi-downdraft design where the runner angles down at about 45deg and the roof blends into the original port as close as possible to the spring seat. This is how the old 105E Kent conversions were done and they were able to pick up flow while still keeping the original valves and spring seats, so the amount of butchery required was much reduced. Remember the more cutting and shutting you do the less likely it is to stay in one piece. A possible variation on this might be to just fit a dividing wall and a high, sloping roof, and for the floor use an aluminium filler piece. Same type of thing as used in the Chev 6 "lump port" heads only much thicker of course.
I have no idea why you'd want to retain the factory pushrods; I think getting some appropriately long rods would be the least of your worries. Likewise the manifold - if you can successfully perform these kinds of head mods then fabricating a manifold will be a piece of cake..
Maybe the best approach at this stage is to just step back a bit and spend some time studying some existing head designs and engine design and theory in general. A couple of heads in particular you might like to look into would include the Ford 105E (can't find any pics of the mods at the moment but will post any I find), the 2V Ford 250 (which is probably very close to what you should aim for), the Duggan (now JZed, and again a very good one to study), and the Chev lump port conversions. God knows what I've forgotten. Maybe even the old GMC/Chev Wayne heads; these were very interesting in that Horning managed to build quite a good crossflow head while sticking with the original Chev/Holden valve and pushrod layout.
#48
_Gunmetal LH_
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Posted 12 March 2010 - 11:59 PM
Bomber- Oh! Of course! Thanks.
oldjohnno:
"I have no idea why you'd want to retain the factory pushrods; I think getting some appropriately long rods would be the least of your worries. Likewise the manifold - if you can successfully perform these kinds of head mods then fabricating a manifold will be a piece of cake.."
Retain factory pushrods? Cheap, & I've got tons spare. That would be the only reason.
"Likewise with the manifold" ? I meant there's NO WAY factory would line up any more.
I like the idea of 45deg ports. I agree with you about modifying only the intake ports too. Will have a look at the heads you mentioned. Maybe I have got a bit carried away...
Cheers.
oldjohnno:
"I have no idea why you'd want to retain the factory pushrods; I think getting some appropriately long rods would be the least of your worries. Likewise the manifold - if you can successfully perform these kinds of head mods then fabricating a manifold will be a piece of cake.."
Retain factory pushrods? Cheap, & I've got tons spare. That would be the only reason.
"Likewise with the manifold" ? I meant there's NO WAY factory would line up any more.
I like the idea of 45deg ports. I agree with you about modifying only the intake ports too. Will have a look at the heads you mentioned. Maybe I have got a bit carried away...
Cheers.
#49
greens nice
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Posted 13 March 2010 - 03:08 PM
Retain factory pushrods? Cheap, & I've got tons spare. That would be the only reason.
Cheers.
thick wall pushrods arent expensive, i dont see how you would go to all this trouble just to skimp on stuff like that.
#50
_Gunmetal LH_
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Posted 13 March 2010 - 07:37 PM
IF the rocker to valve geometry works Ok then why not?
If the rocker would move too far across the stem of the valve then of course I would get longer pushrods and 'square up' the lot so I wouldn't introduce too much side-loading which would trash the guide.
My pic has a roller tip rocker which MAY reduce it enough to be used on an angle. Was just an idea.
I was thinking of a possibility, I'm just thinking of the theory of all this and don't plan on doing ANYTHING unless I think it's 100% do-able, will work 100%, AND can be done in my shed...
If the rocker would move too far across the stem of the valve then of course I would get longer pushrods and 'square up' the lot so I wouldn't introduce too much side-loading which would trash the guide.
My pic has a roller tip rocker which MAY reduce it enough to be used on an angle. Was just an idea.
I was thinking of a possibility, I'm just thinking of the theory of all this and don't plan on doing ANYTHING unless I think it's 100% do-able, will work 100%, AND can be done in my shed...
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