That's a little closer to what you should have at the entry to each port... try and bell the mouth as much as possible as long as the radius of the bell mouth is less than half that of the radius of the port itself. Btw -- that picture is of a plenum i'm building for the toyota supra i'm working on.
8.5 custom arias pistons (.020 over)
eagle rods
t70 turbo (man was that a squeeze)
38 mm external wastegate
mild port/polish
3 angle valve job
custom intercooler piping
twin external intakes with z32 maf
rad moved back
3" exhaust with only a resonator
romulator
420cc injectors
custom body work, homemade oil lines and fittings..
walbro 255lph in-line fuel pump.... and lots of headaches... lol
t70 wrote:
That's a little closer to what you should have at the entry to each port... try and bell the mouth as much as possible as long as the radius of the bell mouth is less than half that of the radius of the port itself. Btw -- that picture is of a plenum i'm building for the toyota supra i'm working on.
yea i know. it will all be smoothed out and shaped. it wasnt to hard, just time consuming
hehe.. what you see in the picture is actually a steel design that i did with a drill before i got my die grinder... THAT was time consuming...
8.5 custom arias pistons (.020 over)
eagle rods
t70 turbo (man was that a squeeze)
38 mm external wastegate
mild port/polish
3 angle valve job
custom intercooler piping
twin external intakes with z32 maf
rad moved back
3" exhaust with only a resonator
romulator
420cc injectors
custom body work, homemade oil lines and fittings..
walbro 255lph in-line fuel pump.... and lots of headaches... lol
ur job is gonna turn out better than mine, i had to leave some lifted meat around the ports and maybe a wall were the 1st hole after the elbow is
I am hoping to get a grinder and lop it off and then do the radius's with dremel....again.
*side note- I was talking to a local machinest whole acutally cncs heads from cast blocks of aluminum. I was gettting tips on how to go about with the raduis's and getting a top on it. And he says that you do not need to make the curves perfectly round. On a flow bench on most heads he has seen, a more multiple angle sharp edge flowed better than a nice rounded one. He pointed out that airplane wings are not perfectly smooth, the have little dowel type things that help the air stay to the wing. His advice for those was to start with a 45' and then add two more slight angles on either side. He is a pretty cool guy, kinda old school, and told me to glue sand paper to a popcycle stick. So, i am just passing it on as some potential information.
we appear to disagree slightly -- i got my information from a fluid dynamics physics site. They show how the best and least turbulent flow is created by a flat surface with bellmouth intakes mounted to it and not through raised velocity stack types as seen in a magnus intake. I realize however, that turbulence is necessary and that should be acquired, in my opinion, by the sanding of the journals. I tried to find the sights again but the best flow was discovered to be at a point where the radius of the bell was exactly 1/2 of the radius of the intake tube itself using fluid dynamics software.
8.5 custom arias pistons (.020 over)
eagle rods
t70 turbo (man was that a squeeze)
38 mm external wastegate
mild port/polish
3 angle valve job
custom intercooler piping
twin external intakes with z32 maf
rad moved back
3" exhaust with only a resonator
romulator
420cc injectors
custom body work, homemade oil lines and fittings..
walbro 255lph in-line fuel pump.... and lots of headaches... lol
i know.. i was also just passing on what i had learned.. i'm sure they are just 2 different schools of thought. As we all know... what works in theory doesn't necessarily work in reality all the time.
8.5 custom arias pistons (.020 over)
eagle rods
t70 turbo (man was that a squeeze)
38 mm external wastegate
mild port/polish
3 angle valve job
custom intercooler piping
twin external intakes with z32 maf
rad moved back
3" exhaust with only a resonator
romulator
420cc injectors
custom body work, homemade oil lines and fittings..
walbro 255lph in-line fuel pump.... and lots of headaches... lol
WaZZ300 wrote: side note- I was talking to a local machinest whole acutally cncs heads from cast blocks of aluminum. I was gettting tips on how to go about with the raduis's and getting a top on it. And he says that you do not need to make the curves perfectly round. On a flow bench on most heads he has seen, a more multiple angle sharp edge flowed better than a nice rounded one. He pointed out that airplane wings are not perfectly smooth, the have little dowel type things that help the air stay to the wing. His advice for those was to start with a 45' and then add two more slight angles on either side. He is a pretty cool guy, kinda old school, and told me to glue sand paper to a popcycle stick. So, i am just passing it on as some potential information.
I have also read this in different books. It is why valves are not a smooth curve and are cut at flat angles. It has been flowbench proven with valves but idk about plenum stacks.
the airplane wings have things on the trailing edge to smooth the merging of the flows, like controlled turbulence, a level of randomness without being entirely random
the bumpy things on a wing are called rivets, they don't weld the wings because that would be more prone to stress and fatigue, and rivets installed properly are really really strong
so old school bumpkins can theorize however they like... but a bellmouth will still win
Alex86na2t wrote: I have also read this in different books. It is why valves are not a smooth curve and are cut at flat angles. It has been flowbench proven with valves but idk about plenum stacks.
That's funny. A 5 angle valve job will generally outflow a 3 angle, and a radial blended 5 angle will usually outflow them both at low lifts in my experience so I'm having trouble figuring how having those flat surfaces would be better for airflow. From a fluid dynamics standpoint a bell-mouthed opening is best for flow around any radius that is shaped and sized correctly for the port..
sharp angles cause air to detach from a surface, so in effect a X-angled cut would actually decrease flow at certain velocities, obviously the air has to be travelling with sufficient speed and density and will behave differently at any variation
*add* also by detaching you have the possibility of impacting other air and causing pressure pulses in the wrong direction slowing air further, you can test this by using a funnel of the same diameter as a dispensing hose and at off angles the liquid will begin to backup
but in the simplest physics, a smooth curve will allow the air to plane and not create pockets of vacuum, this is why a droplet is more aerodynamic than a bullet, the trailing edge carrying the air wants to be a smooth and gentle radius
a water will flow faster down a ramp than it will over an equivalent height of steps (like waterfalls), assuming the same width
Jason84NA2T wrote: That's funny. A 5 angle valve job will generally outflow a 3 angle, and a radial blended 5 angle will usually outflow them both at low lifts in my experience so I'm having trouble figuring how having those flat surfaces would be better for airflow. From a fluid dynamics standpoint a bell-mouthed opening is best for flow around any radius that is shaped and sized correctly for the port..
It doesn't make any sense to me either but it is what i have read a couple times in different books.
this is out of my league and i might be totally wrong.. but i suspect that there is a possibility that the radial lengths of the valve cuts could cause a mild resonance and if the flowbench was resonant to that, then the 3 angle valve job would flow faster than a perfectly radiused valve because you could exceed 100% efficiency. Am i wrong?
8.5 custom arias pistons (.020 over)
eagle rods
t70 turbo (man was that a squeeze)
38 mm external wastegate
mild port/polish
3 angle valve job
custom intercooler piping
twin external intakes with z32 maf
rad moved back
3" exhaust with only a resonator
romulator
420cc injectors
custom body work, homemade oil lines and fittings..
walbro 255lph in-line fuel pump.... and lots of headaches... lol
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