Where should I send my engine to be streetported.
02-02-02, 07:02 PM
#1
Where should I send my engine to be streetported.
I will be rebuilding my 12a this winter.
I want to streetport it. Intake and exhaust.
I was thinking Racingbeat. but they wont port used housings.
Who should I send it to.
Could I do it myself. I am a automotive student at dunwoody and I have done some grinding.
Is it really difficult.
Where can I find info on how to streetport.
I want to streetport it. Intake and exhaust.
I was thinking Racingbeat. but they wont port used housings.
Who should I send it to.
Could I do it myself. I am a automotive student at dunwoody and I have done some grinding.
Is it really difficult.
Where can I find info on how to streetport.
02-02-02, 07:21 PM
#2
http://www.revolutionrotary.com ask for tim or skip, the toll free # is on there site too 
theres the answer to :who:
theres the answer to :who:
02-02-02, 08:53 PM
#3
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You can buy porting templates from Mazdatrix and do it yourself. From what I have heard it is not very difficult, but I have never done it myself. I had mine done by Atkins Rotaries when I bought one of their rebuilts.
hanman
hanman
02-03-02, 02:07 AM
#4
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As you are an engineering student it will be simple. As Hanman says you can buy a template. Only doing a streetport will give you a bit if tolerence. Start with a small handheld grinder like a Dremel, then gradually work down to a polished finish. It will save you at least $300 plus the cost of freight. The work will give you great satisfaction.
As a student can you turn it into a project? While you are doing the port try to work out what you are trying to achieve. Commercial tune shops work to a price, you have the time to make a better job. You could even turn it into a profitable part time business including charging the cost of doing your car against tax!
As a student can you turn it into a project? While you are doing the port try to work out what you are trying to achieve. Commercial tune shops work to a price, you have the time to make a better job. You could even turn it into a profitable part time business including charging the cost of doing your car against tax!
02-03-02, 02:50 AM
#5
Old [Sch|F]ool
NO!!! NEVER EVER EVER polish intake ports unless you want lots of low load/low RPM problems.
If you polish the ports the airflow can get perfectly laminar, and the fuel will separate out and cling to the port walls in sheets. Then the sheets will tear off, and it'll run like crap because the engine runs lean and alternately gets big wads of un-atomized fuel sucked in. Leave the port runners as-cast and try to keep the surfaces you do touch fairly rough, so that there is enough flow disruption at the walls to keep the fuel from clumping together and wetting out.
Polishing exhaust ports, however, is just fine if you want to go to the trouble.
If you polish the ports the airflow can get perfectly laminar, and the fuel will separate out and cling to the port walls in sheets. Then the sheets will tear off, and it'll run like crap because the engine runs lean and alternately gets big wads of un-atomized fuel sucked in. Leave the port runners as-cast and try to keep the surfaces you do touch fairly rough, so that there is enough flow disruption at the walls to keep the fuel from clumping together and wetting out.
Polishing exhaust ports, however, is just fine if you want to go to the trouble.
02-03-02, 05:44 AM
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Good point Peejay. Most tune shops go for a relatively polished finish.
Your point if very interesting, in sail racing we go for a 600 grit finish as the water sticks in the roughness and provides less friction to the flow. Anything smoother provides more friction. This is why water beads on a perfectly polished car but flows off with a 600 grit level of matt.
What I think you are implying is that air and fuel are not homogenous and seperate out in a laminar flow. The fuel being heavier is forced outwards. With variations in total flow, the fuel 'sheeting' becomes even more variable, causing uncontrolable changes in the air/fuel ratio. However you want the mixture mixed which is helped by a rough passage and results in a constant ratio. Turbulence is good!
As I said you a good point which I will have to remember.
Your point if very interesting, in sail racing we go for a 600 grit finish as the water sticks in the roughness and provides less friction to the flow. Anything smoother provides more friction. This is why water beads on a perfectly polished car but flows off with a 600 grit level of matt.
What I think you are implying is that air and fuel are not homogenous and seperate out in a laminar flow. The fuel being heavier is forced outwards. With variations in total flow, the fuel 'sheeting' becomes even more variable, causing uncontrolable changes in the air/fuel ratio. However you want the mixture mixed which is helped by a rough passage and results in a constant ratio. Turbulence is good!
As I said you a good point which I will have to remember.
02-03-02, 07:39 AM
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Streetracer have a look at Peejays website, it contains a good description of how he ported his engine. I should have used the word smoothed rather than polished as the finish to go for.
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02-03-02, 09:31 AM
#8
Originally posted by Paul Fitzwarryne
Good point Peejay. Most tune shops go for a relatively polished finish.
Your point if very interesting, in sail racing we go for a 600 grit finish as the water sticks in the roughness and provides less friction to the flow. Anything smoother provides more friction. This is why water beads on a perfectly polished car but flows off with a 600 grit level of matt.
Good point Peejay. Most tune shops go for a relatively polished finish.
Your point if very interesting, in sail racing we go for a 600 grit finish as the water sticks in the roughness and provides less friction to the flow. Anything smoother provides more friction. This is why water beads on a perfectly polished car but flows off with a 600 grit level of matt.
depends what you are sailing I guess.
02-03-02, 04:41 PM
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I never expected to see Frank Bethwaite's name on the Forum. He has been a friend for some 30 years, and I hope I am as fit and competitive as him at the same age.
As a meteorologist and ex glider pilot he has great views on weather, but air flow and water flow do not necessarily have the same characteristics. Ironically Frank's glass tumbler illustration is defective because your average tumbler is rougher than a finish 600.
Smoothness is a question of degree, his views on a smooth shape are very true for both cars and boats, but at the micro level a 600-800 level of finish appears to give a less resistant flow. However where there is a pressure difference, such as a foil, 1200-1500 appears to be better and reduces cavitation. Some of his flow ideas are generally correct but not optimal, for example foils af the top level now have concave sections rather than the aerodynamic NASA profiles predicted from air flow.
I am uncertain what flow characteristics an air/fuel mixture has, so trust practical results from Peejay are correct
In my younger days I raced some of Frank's and his sons designs, and still coach 29 and 49ers. Its now mainly Sportsboats such as Thompsons and Elliots. My ex-crew made Atlanta, but I could only watch and dream!
As a meteorologist and ex glider pilot he has great views on weather, but air flow and water flow do not necessarily have the same characteristics. Ironically Frank's glass tumbler illustration is defective because your average tumbler is rougher than a finish 600.
Smoothness is a question of degree, his views on a smooth shape are very true for both cars and boats, but at the micro level a 600-800 level of finish appears to give a less resistant flow. However where there is a pressure difference, such as a foil, 1200-1500 appears to be better and reduces cavitation. Some of his flow ideas are generally correct but not optimal, for example foils af the top level now have concave sections rather than the aerodynamic NASA profiles predicted from air flow.
I am uncertain what flow characteristics an air/fuel mixture has, so trust practical results from Peejay are correct
In my younger days I raced some of Frank's and his sons designs, and still coach 29 and 49ers. Its now mainly Sportsboats such as Thompsons and Elliots. My ex-crew made Atlanta, but I could only watch and dream!
02-03-02, 05:09 PM
#10
Old [Sch|F]ool
The difficulty with an air/fuel mixture, as opposed to normal fluid flow, is that the fuel must stay suspended in the air. The ports not only have to get the air inside the engine, but must also keep the fuel atomized and suspended so that it can do its job.
Now, if we were dealing with fuel injected vehicles (and I assumed we were not because it's an '82) then it's generally okay to polish the port runners, because only dry air flows through them. Some fuel injector strategies are not to atomize the fuel as it comes out of the injector, but to shoot a sharp stream out of the injector and atomization takes place after it bounces back off of the backside of the hot intake valve, or in our case the hot port-runner wall. After that there is only a couple inches to the inside of the engine, being ****-retentive I'd leave those areas rough
Now, if we were dealing with fuel injected vehicles (and I assumed we were not because it's an '82) then it's generally okay to polish the port runners, because only dry air flows through them. Some fuel injector strategies are not to atomize the fuel as it comes out of the injector, but to shoot a sharp stream out of the injector and atomization takes place after it bounces back off of the backside of the hot intake valve, or in our case the hot port-runner wall. After that there is only a couple inches to the inside of the engine, being ****-retentive I'd leave those areas rough
02-03-02, 09:12 PM
#12
Rob at Pineapple provides good solid/fast engines at a very reasonable price. Not to mention, a good warrenty.
As far as the porting goes, rob told me when doing my intake, unless going for all out racing, a semi rough surface is best. Just like everyone else says. CJ
As far as the porting goes, rob told me when doing my intake, unless going for all out racing, a semi rough surface is best. Just like everyone else says. CJ
02-03-02, 09:27 PM
#13
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Originally posted by pp13bnos
Rob at Pineapple provides good solid/fast engines at a very reasonable price. Not to mention, a good warrenty.
As far as the porting goes, rob told me when doing my intake, unless going for all out racing, a semi rough surface is best. Just like everyone else says. CJ
Rob at Pineapple provides good solid/fast engines at a very reasonable price. Not to mention, a good warrenty.
As far as the porting goes, rob told me when doing my intake, unless going for all out racing, a semi rough surface is best. Just like everyone else says. CJ
Last edited by SOLORX7; 02-03-02 at 09:29 PM.
02-04-02, 08:22 AM
#14
Paul,
An avid sailor myself (designer and builder too). I had actually not considered the behaviour would be different for foils versus tube flow(for lack of a better term), good points - I should have thought a little more about it (although it has not really come up in my work or play life). I am still young (meaning stupid) enough to believe that boats like Javelins and Int 14 are fun - despite their being glorified swimming platforms... Any, back to cars...
Peejays comments echo what I have been told by my local race car builder - rough intakes keep the air and fuel mixed, if smooth they will separate, smooth is good for injector cars cause its just air so you want to minimize turbulence to maximize flow.
An avid sailor myself (designer and builder too). I had actually not considered the behaviour would be different for foils versus tube flow(for lack of a better term), good points - I should have thought a little more about it (although it has not really come up in my work or play life). I am still young (meaning stupid) enough to believe that boats like Javelins and Int 14 are fun - despite their being glorified swimming platforms... Any, back to cars...
Peejays comments echo what I have been told by my local race car builder - rough intakes keep the air and fuel mixed, if smooth they will separate, smooth is good for injector cars cause its just air so you want to minimize turbulence to maximize flow.
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