custom manifold pics
09-09-02, 07:34 PM
#1
custom manifold pics
O.K. I screwed up the last thread and it wouldn't let me change it or delete it so here we go again. I designed and built this for my 2nd gen. I didn't actually do the welding but I did cut everything out and line it up where I wanted. I can easily build more if I have to. The inside edges are all smooth. If you look closely you can see that my bov is on the throttlebody about a quarter of an inch in front of the throttle plate. The tb is a 75mm. Mustang unit. My wastegate is also mounted on my turbos exhaust housing. I have many other pics available. Just can't figure out how to load more than one at a time. These pictures show the engine bay in a very torn apart condition. The manifold flows tons of air compared to the stock one.
09-09-02, 07:55 PM
#5
Here are my custom machined exhaust sleeves. I went to Marcus Williams in Houston for help on this. I told him how I wanted them and he cut them out. Good job too! These came about after my many conversations with Paul Yaw about exhaust port flow problems. He did this on an aircraft engine using steel tubing with great results and we thought it would be cool to machine a set. Marcus has used several sets now with great results. Basically they are the exact same size as the port openings in the rotor housing but the size and shape remain constant. This results in about 30% more airflow through the same size port! It spools a turbo up much faster than the larger pipe with a port job.
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09-10-02, 12:16 AM
#9
Thanks Marcus. I want those extra sleeves. Damn and I just built my GSL-SE engine last month.
Air distribution through the plenum is very uniform. By looking at it you would think that the primary runners would get more flow since they are straight in line with intake pipe. Not the case. Ran many tests using smoke and a vacuum and compressed air. Always turns out to be uniform and evenly distributed.
I believe I designed the plenum volume at 100 cu. in. Can't quite remember but can go measure it. The volume formula given for piston engines has to be modified to get the proper volume for a rotary. Upper runners are about 5 inches in length. Lower manifold is stock J-spec '89-'91 T-II. Primary runner diameters are 1 5/8" while the secondaries are 1 3/4". Main intake pipe is 3". All aluminum tubing is from Burns Stainless. Aluminum plate I can get at a local machine shop. I had to trace and cut out flanges by hand using a jigsaw. I will build a more efficient lower manifold later. Got too lazy to try and mount injectors to one so I only built a top one. My upper runners are slightly larger in diameter that the T-II lowers. I port matched the lower manifold to match. Had to be gradual though. I want the air to accelerate as it proceeds down the runners.
Air distribution through the plenum is very uniform. By looking at it you would think that the primary runners would get more flow since they are straight in line with intake pipe. Not the case. Ran many tests using smoke and a vacuum and compressed air. Always turns out to be uniform and evenly distributed.
I believe I designed the plenum volume at 100 cu. in. Can't quite remember but can go measure it. The volume formula given for piston engines has to be modified to get the proper volume for a rotary. Upper runners are about 5 inches in length. Lower manifold is stock J-spec '89-'91 T-II. Primary runner diameters are 1 5/8" while the secondaries are 1 3/4". Main intake pipe is 3". All aluminum tubing is from Burns Stainless. Aluminum plate I can get at a local machine shop. I had to trace and cut out flanges by hand using a jigsaw. I will build a more efficient lower manifold later. Got too lazy to try and mount injectors to one so I only built a top one. My upper runners are slightly larger in diameter that the T-II lowers. I port matched the lower manifold to match. Had to be gradual though. I want the air to accelerate as it proceeds down the runners.
09-10-02, 06:49 AM
#11
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Nice work guys!
About those exhaust sleeves!
I've been thinking about the stock exhaust port sleeves for a while. Can you give us some generalities from your conversations with Paul?
I'm sure the reshaped ports flow much better.
I don't want to get in a hurry second guessing a building full of engineers, and several years of development (even if they are Mazduh engineers
. Got numbers?
TIA for any insights, and nice work!
How much for a set, BTW?
Steve C
I've been thinking about the stock exhaust port sleeves for a while. Can you give us some generalities from your conversations with Paul?
- are the sleeves in the pic shaped like stock port openings, or have they been "opened-up"? I can't tell from the pic.
- what material?
- any idea what design criterea forced Mazda engineers to go with the stock port shape (what were they thinking!)?
- have you done any over-the-road testing?
I'm sure the reshaped ports flow much better.
I don't want to get in a hurry second guessing a building full of engineers, and several years of development (even if they are Mazduh engineers
. Got numbers?TIA for any insights, and nice work!
How much for a set, BTW?
Steve C
Last edited by qwck10th; 09-10-02 at 06:58 AM.
09-10-02, 10:49 AM
#12
The stock exhaust port shape just plain sucks. Pure and simple. You have a certain shape and size leaving the combustion chamber but then it expands to over 300% larger in the next couple of inches. This expansion kills velocity and increases turbulence everywhere in the port. The picture (low quality ) shows the port shape as it is stock internally. I just kept the same dimensions all the way out of the engine. I could have opened them up but I wanted to maintain the original port timing to promote better low and mid range power. Besides the stock size port with the sleeves installed flows just as much as many larger streetport jobs but with much higher velocity. The turbo primary tubes are 1 3/4" but the flow through them is much faster. It is important on these that the first 3" go straight out of the engine before they turn towards the turbo. Any less than this and there is turbulence within the port opening itself. A larger pipe does not flow more air since the port opening in the engine is smaller. Just keep all the sizes the same and you get tons of performance. If piston engine exhausts were done like the rotary they wouldn't be making any power.
Not sure what Marcus made them out of. I call it unobtainium. PITA to grind through. Can't use stainless since it expands too much. Sleeves are held in the motor using set screws not cotter pins. If I blow the engine one day I can go back and take them out very easily.
The stock port shape on the rotor housings didn't come from the eyes of the real engineers. They came about from a marketing sense. The first engines back in the 60's and 70's actually had ports like mine but they had no sleeves at all. Just cast into the shape of the housing. The problem with rotary heat and noise came about and they had to do something to combat this. The solution was to have a high expansion rate. The turbulence in the port helped quiet the engine down along with the lousy shoebox of an exhaust manifold they fitted to the engines. The slower velocity also helped the air cool down much faster after leaving the engine. You have no idea how hot the exhaust air really is when it leaves that engine! Once the designers killed the flow then they later went back and tried to solve many of the problems that arose from what the did. They used several cats so the small ones could heat up faster for emissions, smaller twin scroll turbos for faster boost, etc.
Marcus has some neat insight into how well these actually work. He had a Q-trim exhaust wheel with a 1.72 a/r and still had incredible boost response! A stock port job probably couldn't even spool that monster up. The big problem was that without an inconel wheel he was burning turbos up from the incredible heat. Think about the potential flow of such a large exhaust housing with good response. Less backpressure = more power for any given boost level. Remember what happed when you took you cats off for the first time? Power! Now imagine doing it again even if you have a big turbo AND having your boost response increase!
An n/a engine with these sleeves and a proper port job, intake, and header can easily hit higher power levels than most people thought possible with a streetport.
I could ramble on forever but will just deal with any other questions as they come. Thanks for the compliments guys!
) shows the port shape as it is stock internally. I just kept the same dimensions all the way out of the engine. I could have opened them up but I wanted to maintain the original port timing to promote better low and mid range power. Besides the stock size port with the sleeves installed flows just as much as many larger streetport jobs but with much higher velocity. The turbo primary tubes are 1 3/4" but the flow through them is much faster. It is important on these that the first 3" go straight out of the engine before they turn towards the turbo. Any less than this and there is turbulence within the port opening itself. A larger pipe does not flow more air since the port opening in the engine is smaller. Just keep all the sizes the same and you get tons of performance. If piston engine exhausts were done like the rotary they wouldn't be making any power.Not sure what Marcus made them out of. I call it unobtainium. PITA to grind through. Can't use stainless since it expands too much. Sleeves are held in the motor using set screws not cotter pins. If I blow the engine one day I can go back and take them out very easily.
The stock port shape on the rotor housings didn't come from the eyes of the real engineers. They came about from a marketing sense. The first engines back in the 60's and 70's actually had ports like mine but they had no sleeves at all. Just cast into the shape of the housing. The problem with rotary heat and noise came about and they had to do something to combat this. The solution was to have a high expansion rate. The turbulence in the port helped quiet the engine down along with the lousy shoebox of an exhaust manifold they fitted to the engines. The slower velocity also helped the air cool down much faster after leaving the engine. You have no idea how hot the exhaust air really is when it leaves that engine! Once the designers killed the flow then they later went back and tried to solve many of the problems that arose from what the did. They used several cats so the small ones could heat up faster for emissions, smaller twin scroll turbos for faster boost, etc.
Marcus has some neat insight into how well these actually work. He had a Q-trim exhaust wheel with a 1.72 a/r and still had incredible boost response! A stock port job probably couldn't even spool that monster up. The big problem was that without an inconel wheel he was burning turbos up from the incredible heat. Think about the potential flow of such a large exhaust housing with good response. Less backpressure = more power for any given boost level. Remember what happed when you took you cats off for the first time? Power! Now imagine doing it again even if you have a big turbo AND having your boost response increase!
An n/a engine with these sleeves and a proper port job, intake, and header can easily hit higher power levels than most people thought possible with a streetport.
I could ramble on forever but will just deal with any other questions as they come. Thanks for the compliments guys!
09-10-02, 11:19 AM
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Originally posted by rotarygod
This results in about 30% more airflow through the same size port! It spools a turbo up much faster than the larger pipe with a port job.
This results in about 30% more airflow through the same size port! It spools a turbo up much faster than the larger pipe with a port job.
This could be an end to exhaust porting on street cars
09-10-02, 12:27 PM
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what kind of power band are you shooting for? i take it you are not trying to turn more rpms? those sleeves look pretty neat, maybe i should play with a set
mike
mike
09-10-02, 01:06 PM
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Originally posted by turbostreetfighter
nice job Fred,BTW i still have another set of those exhaust inserts left! check your pm
MWW
nice job Fred,BTW i still have another set of those exhaust inserts left! check your pm
MWW
09-10-02, 03:25 PM
#18
Old [Sch|F]ool
Originally posted by rotarygod
You have a certain shape and size leaving the combustion chamber but then it expands to over 300% larger in the next couple of inches. This expansion kills velocity and increases turbulence everywhere in the port. !
You have a certain shape and size leaving the combustion chamber but then it expands to over 300% larger in the next couple of inches. This expansion kills velocity and increases turbulence everywhere in the port. !
When the exhaust gases exit the chamber, they are still under a whole lot of pressure. (I can't quantify 'a whole lot' but you all know how LOUD a rotary with open headers is!) It's going to exit at a very high velocity. When air moves at such a high velocity it acts a lot like water exiting a hose - it's a hard stream that keeps its shape.
Now, notice that stock engines have the air injection ports at about the point of maximum expansion, and you'll start to see why (I theorize) Mazda did things the way they did. For an OEM, emissions is more important than ultimate power - an engine that is lower in power but passes federal testing can be sold, while more power and poor emissions cannot.
My theory, then, is that Mazda deliberately designed the exhaust port to be turbulent, to better mix the injected air with the exhaust gases so that unburned HCs can light off more readily.
09-10-02, 03:57 PM
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rotarygod, what would happen if you placed the manifold closer to the engine and offset to the side more so that you could have shorter runners like on high performance piston engines. could you make more high rpm power w/ shorter runners. how did you calculate the size of the plenum for a rotary application? i suspect it should be smaller than a comparable displacement piston motor, because the extra length of the runners serve to give more overall volume. as for you sleeves do you have pics of your sleeve side by side w/ a stock one? what's it do to the exhaust flow at the junction between the exhaust port and the manifold when your primary runners are of a much larger diameter than your sleeves?
09-10-02, 04:06 PM
#20
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Originally posted by rotarygod
It is important on these that the first 3" go straight out of the engine before they turn towards the turbo. Any less than this and there is turbulence within the port opening itself.
It is important on these that the first 3" go straight out of the engine before they turn towards the turbo. Any less than this and there is turbulence within the port opening itself.
So does this mean they wouldnt be good on a 3rd gen with the stock twin turbo manifold then???
Also, will you or Marcus be selling these??? I'm also very interested in buying a set. I'm building a motor very soon and would like to try some out if you guys sell them.
STEPHEN
09-10-02, 04:27 PM
#21
fdracer- Yes shortening the runners will make more top end power. You can go too short though where you will make no power anywhere in your rpm range. I do alot of autocross and road type of events so I wanted the most power I could get across the whole power band up to 8K rpm with no more than 1 bar of boost. I don't do any drag racing so turbo response is very important. This car also gets drive on the street so I had to be able to make it pass emissions and idle smoothly. Yes it is possible to do all of this!
As far as the junction between the sleeves and the exhaust manifold goes, you have to make a new one with the corresponding pipes to the turbo being the same size and shape. If you use the sleeves and don't make a proper manifold then you just defeated the whole point of using them in the first place. You would probably make more turbulence and less power.
The stock 3rd gen turbos will die in a very short amount of time with this much flow and heat going to them. You'd probably get boost at idle but I'm only theorizing. The stock twins won't line up with the sleeves anyways. Even if they did you would have no top end due to exhaust restrictions.
Marcus made only a few sets of which I got one of them. This was probably 3 years ago now so its not a new development. I don't know if he still has access to the cnc lathes he used to work with. If not I know someone who can make them but I know they aren't cheap. Marcus is building an awesome back half 3rd gen drag car. Look for him setting records out there soon!
rx7passion- I can make others if I have to. I'd have to work out a price with my welder and then design it around what engine you want to use, if you want the stock throttlebody, 4 port, 6 port, etc. It probably wouldn't be terribly cheap. At a guess I would say in the $500-$600 range. I can't do it very quick either. If I have enough feedback I'll contract it out to a friend at a machine shop and just manage, design, and ship them. Until then they are a one off type of deal.
As far as the junction between the sleeves and the exhaust manifold goes, you have to make a new one with the corresponding pipes to the turbo being the same size and shape. If you use the sleeves and don't make a proper manifold then you just defeated the whole point of using them in the first place. You would probably make more turbulence and less power.
The stock 3rd gen turbos will die in a very short amount of time with this much flow and heat going to them. You'd probably get boost at idle but I'm only theorizing. The stock twins won't line up with the sleeves anyways. Even if they did you would have no top end due to exhaust restrictions.
Marcus made only a few sets of which I got one of them. This was probably 3 years ago now so its not a new development. I don't know if he still has access to the cnc lathes he used to work with. If not I know someone who can make them but I know they aren't cheap. Marcus is building an awesome back half 3rd gen drag car. Look for him setting records out there soon!
rx7passion- I can make others if I have to. I'd have to work out a price with my welder and then design it around what engine you want to use, if you want the stock throttlebody, 4 port, 6 port, etc. It probably wouldn't be terribly cheap. At a guess I would say in the $500-$600 range. I can't do it very quick either. If I have enough feedback I'll contract it out to a friend at a machine shop and just manage, design, and ship them. Until then they are a one off type of deal.
09-10-02, 07:52 PM
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500-600 ehh i dont know if i really want to spend that much for one, im just looking for a way to get around the stock 13bt throttle body adaptor so i can hook up my front mount..
