Renesis Street Port complete + dyno
04-11-2005 | 01:12 AM
#1
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From: NJ
Renesis Street Port complete + dyno
Ok guys, here is probly the 1st
http://rotaryheads.com/dyno/rx8_streetport/
http://rotaryheads.com/dyno/rx8_streetport/
From the above website;
For the RX-8, we start by removing and disassembling the Renesis engine. Each piece is meticulously cleaned and measured for wear. The porting is done with only the highest quality equipment, and with the care that you'd expect.
All edges are radius cut for improved flow without greatly altering port timing-which retains the long lasting and emissions legal attributes of the engine.
A great deal of work is done in the exhaust runner, which is very restrictive stock. Exhaust ports are opened just a few degrees early, but not enough to adversely effect emissions. The engine remains clean burning. The best part may be an actual INCREASE in fuel economy. +2mpg has been reported with no change in driving habits.
All intake runners are deburred and smoothed. Primary ports are extended moderately, but no increase in port timing is given (to retain the stock rpm power band range). Epoxy backfilling is also done in the primary ports to decrease the turn-in angle and vastly improve directional flow characteristics.
Secondary ports are smoothed and a radiused cut edge is given-eliminating the side seal impact associated with the port closing edge. This can infinitely increase the life of the side seals and eliminate the compression loss associated with their early wear.
Auxiliary ports can be left with stock timing, extended slightly, or even bridge ported, according to your requirements. Please inquire.
From this porting and good tuning, expect 20-30% hp increase. Below you will see pictures of the porting.
http://rotaryheads.com/dyno/rx8_streetport/
http://rotaryheads.com/dyno/rx8_streetport/
From the above website;
For the RX-8, we start by removing and disassembling the Renesis engine. Each piece is meticulously cleaned and measured for wear. The porting is done with only the highest quality equipment, and with the care that you'd expect.
All edges are radius cut for improved flow without greatly altering port timing-which retains the long lasting and emissions legal attributes of the engine.
A great deal of work is done in the exhaust runner, which is very restrictive stock. Exhaust ports are opened just a few degrees early, but not enough to adversely effect emissions. The engine remains clean burning. The best part may be an actual INCREASE in fuel economy. +2mpg has been reported with no change in driving habits.
All intake runners are deburred and smoothed. Primary ports are extended moderately, but no increase in port timing is given (to retain the stock rpm power band range). Epoxy backfilling is also done in the primary ports to decrease the turn-in angle and vastly improve directional flow characteristics.
Secondary ports are smoothed and a radiused cut edge is given-eliminating the side seal impact associated with the port closing edge. This can infinitely increase the life of the side seals and eliminate the compression loss associated with their early wear.
Auxiliary ports can be left with stock timing, extended slightly, or even bridge ported, according to your requirements. Please inquire.
From this porting and good tuning, expect 20-30% hp increase. Below you will see pictures of the porting.
04-11-2005 | 01:15 AM
#2
Kaiten Kenbu Rokuren
Joined: Jul 2004
Posts: 934
Likes: 2
From: Central Valley, NY
The dynos are a month apart 
It all sounds good but trusting most companies on stuff like this is tough to do. I guess I'll sit back and wait until we see some more results. Guitarjunkie? Rotarygod? Care to chime in?
It all sounds good but trusting most companies on stuff like this is tough to do. I guess I'll sit back and wait until we see some more results. Guitarjunkie? Rotarygod? Care to chime in?
04-11-2005 | 01:20 AM
#3
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From: NJ
04-11-2005 | 02:29 AM
#8
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From: NJ
Well with a good ecu and good time spend on dyno tunning you can really make those ports work for you. Ported + FI = smile
I also heard that ito in NJ has made 240rwhp on just ports! rumor for now...
I also heard that ito in NJ has made 240rwhp on just ports! rumor for now...
04-11-2005 | 02:55 AM
#10
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From: Melbourne, Australia
Originally Posted by Aoshi Shinomori
The dynos are a month apart It all sounds good but trusting most companies on stuff like this is tough to do. I guess I'll sit back and wait until we see some more results. Guitarjunkie? Rotarygod? Care to chime in?
It all sounds good but trusting most companies on stuff like this is tough to do. I guess I'll sit back and wait until we see some more results. Guitarjunkie? Rotarygod? Care to chime in?
04-11-2005 | 03:14 AM
#11
always preoccupied.
Joined: Feb 2005
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From: Kirkland, WA
Why do the edges of the primary and secondary ports closest to the water seal look all wavey instead of straight? Does the renesis require that or something? The ports just look weird compared to other ported rotary engines I've seen and done myself. Never looked inside an rx8 engine yet, though.
04-11-2005 | 03:14 AM
#12
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Joined: Dec 2003
Posts: 276
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From: Rancho, So cal
Well those results are pretty old but the temps were pretty much identical and the results were decent it's all we could ask for. We weren't trying to prove anything either so believe the results or not it was done at the same dyno at almost identical temps, everything that could be controlled was that's all I'm saying. There have since been more ports done on my car but no dynos. We're having issues with the ecu of course even with the canzoomer the stock is fighting non-stop and will not let us do much. BTW there's a mega long *** thread with all of this detailed so do a read through that. When i saw this thread I was like "sweet someone else ported a renesis also" but nope it's still my car.
And also with judge ito I do not buy anything he says at all. At first I want to believe him of course because I want to see those results. But after going through the process with my car there is no way he could do that without altering the computer in anyway. The computer hates porting.
And also with judge ito I do not buy anything he says at all. At first I want to believe him of course because I want to see those results. But after going through the process with my car there is no way he could do that without altering the computer in anyway. The computer hates porting.
04-11-2005 | 04:03 AM
#14
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From: NJ
Porting increases flow, A LOT! Anything you do afterwards will only offer bigger gains than to any none ported engine. FI to a ported unit = amazing gains in every field. spools faster + bigger hp per psi. I'm waiting to see someone go crazy on ports like they did with older engines. My friend had a port job that gave him 80rwhp on his turbo FC.
04-11-2005 | 04:06 AM
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From: NJ
here is a little read about the older engines...just for some info
STREET PORTS
"Street Ports" are basically mild changes that keep "within the lines" (oil and corner seal tracks) and are done for moderate performance gains with few compromises to driveability. Basically, a street port can either go "up", delaying the port closing, or "out", advancing the port opening. In practice, it is more desirable to go "up", as you are only affecting port closing and there is more room to play. Going "out" is more troublesome due to increased port overlap and the corner seal track rapidly becomes an obstacle . In practice, the farthest "out" you can take the port is to the point where at least 50% of the corner seal is supported, so it doesn't fall into the port and get consumed by the engine (which is fatal to the engine). Going "up", however, is limited mainly to the desired characteristics of the engine and the limitations of internal coolant passages. As always, be sure to consult a professional and/or purchase proven porting templates before attempting to enlarge your own ports. A small mistake can destroy valuable engine parts in the blink of an eye.
RACING PORTS
Racing ports come in many varieties, but tend to be as large as possible and introduce significant overlap. Both of these factors impact driveability and are typically not used on the street. Some of the port designs also compromise the water seals, so engine life may be reduced in favor of ultimate high-end power. Also note that these large-overlap designs are not typically used in turbocharged applications because the "boost" will tend to leak directly out the (still open) exhaust port at low to moderate RPM.
Bridgeports are simply a large port that uses a "bridge" to support the rotor's corner seal, thus preventing it from falling into the port and ruining the engine. Since the port goes all the way out to the trochoid surface, there is significant overlap with the exhaust port, reducing low-RPM power in favor of significant power gains in the high-RPM range (5,000+). Sometimes a bridgeport will extend slightly past the trochoid surface, requiring a notch in the rotor housing, but the water seals are not compromised. Of all the racing ports, this design is the most streetable and minimally impacts engine life.
J-ports are basically a bridgeport that extends well past the trochoid surface to the point it does compromise the water seals. The goal is more power at the cost of engine life -- a classic racing scenario.
Monster ports are like a J-port, only so large that they go well into the water jacket and require significant filling of the passages, cutting of the rotor housing, and other measures to allow it to work. As some of the coolant passages are actually filled, engine life is further compromised. Monster ports were developed to give similar characteristics to a peripheral port, where racing rules in some classes prohibited the latter.
Peripheral intake ports (not pictured above) are simply a big hole in each rotor housing (similar to the exhaust ports), with no side intake ports whatsoever. Contrary to side port designs, timing is determined by the apex seal rather than the leading edge of the rotor. This results in massive intake and exhaust overlap and subsequently very little low-RPM power, but the direct intake path permits incredible high-RPM power that typically peaks well over 9,000 RPM. A peripheral port (PP) engine can develop over 300 hp in a non-turbo application, but is not what normal people would consider "streetable" (but some do!). The water seals are not compromised, though some of the coolant passages are blocked by the intake passage (but to a lesser degree than Monster porting) -- the engine life is reduced by virtue of stress from high-power and high-RPM operation, but not so much by coolant leakage or hot spots around the intake area.
STREET PORTS
"Street Ports" are basically mild changes that keep "within the lines" (oil and corner seal tracks) and are done for moderate performance gains with few compromises to driveability. Basically, a street port can either go "up", delaying the port closing, or "out", advancing the port opening. In practice, it is more desirable to go "up", as you are only affecting port closing and there is more room to play. Going "out" is more troublesome due to increased port overlap and the corner seal track rapidly becomes an obstacle . In practice, the farthest "out" you can take the port is to the point where at least 50% of the corner seal is supported, so it doesn't fall into the port and get consumed by the engine (which is fatal to the engine). Going "up", however, is limited mainly to the desired characteristics of the engine and the limitations of internal coolant passages. As always, be sure to consult a professional and/or purchase proven porting templates before attempting to enlarge your own ports. A small mistake can destroy valuable engine parts in the blink of an eye.
RACING PORTS
Racing ports come in many varieties, but tend to be as large as possible and introduce significant overlap. Both of these factors impact driveability and are typically not used on the street. Some of the port designs also compromise the water seals, so engine life may be reduced in favor of ultimate high-end power. Also note that these large-overlap designs are not typically used in turbocharged applications because the "boost" will tend to leak directly out the (still open) exhaust port at low to moderate RPM.
Bridgeports are simply a large port that uses a "bridge" to support the rotor's corner seal, thus preventing it from falling into the port and ruining the engine. Since the port goes all the way out to the trochoid surface, there is significant overlap with the exhaust port, reducing low-RPM power in favor of significant power gains in the high-RPM range (5,000+). Sometimes a bridgeport will extend slightly past the trochoid surface, requiring a notch in the rotor housing, but the water seals are not compromised. Of all the racing ports, this design is the most streetable and minimally impacts engine life.
J-ports are basically a bridgeport that extends well past the trochoid surface to the point it does compromise the water seals. The goal is more power at the cost of engine life -- a classic racing scenario.
Monster ports are like a J-port, only so large that they go well into the water jacket and require significant filling of the passages, cutting of the rotor housing, and other measures to allow it to work. As some of the coolant passages are actually filled, engine life is further compromised. Monster ports were developed to give similar characteristics to a peripheral port, where racing rules in some classes prohibited the latter.
Peripheral intake ports (not pictured above) are simply a big hole in each rotor housing (similar to the exhaust ports), with no side intake ports whatsoever. Contrary to side port designs, timing is determined by the apex seal rather than the leading edge of the rotor. This results in massive intake and exhaust overlap and subsequently very little low-RPM power, but the direct intake path permits incredible high-RPM power that typically peaks well over 9,000 RPM. A peripheral port (PP) engine can develop over 300 hp in a non-turbo application, but is not what normal people would consider "streetable" (but some do!). The water seals are not compromised, though some of the coolant passages are blocked by the intake passage (but to a lesser degree than Monster porting) -- the engine life is reduced by virtue of stress from high-power and high-RPM operation, but not so much by coolant leakage or hot spots around the intake area.
04-11-2005 | 04:11 AM
#16
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From: NJ
04-11-2005 | 05:01 AM
#20
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From: Houston
The RX-8 already runs rich from the factory. Running it richer should give you less power. When this engine was ported, the ecu actually ran the mixture richer than stock and the car still picked up a little power. When it was ported larger, it ran richer still but power did fall off. I don't see the lack of large gains to be the fault of the porting but rather the over controlling nature of the stock ecu. I really want to see this engine tuned properly.
I actually have a different take on porting which seems like it keeps adapting and updating itself. In the past I thought very differently than I do now but have evolved to this current state of mind. I am currently under the opinion that the Renesis ports should not be enlarged at all. This is not to say that I don't feel the engine shouldn't have any port work done. Here's the logic for my thinking.
Remember that on a piston engine there is a camshaft which opens and closes the valves at a certain time and for a certain duration. The valves themselves can be changed out to larger ones to allow more airflow at the same amount of valve lift. However, these 2 things are not directly connected. Sure you can go too large of a valve for any certain duration and lift camshaft but the point is that these 2 traits are independent. You use the camshaft you want to give you the powerband that you want and you use the size valves that you need to flow the required amount of air and the proper velocity to make good power where you need it. This is ignoring a host of other very important things that I'm not getting into.
The rotary engine however does not have these 2 independent traits. They are actually one trait. Our ports are a certain size which will determine their flow potential. Their size is determined by their timing though. If we make them larger to flow more air, we also change the port timing. Imagine being forced to use a larger valve if you changed camshafts on a piston engine. That really limits you and forces compromise. Mazda has done alot of research on port timing and their efects on the rpm range. If we change the port timing to flow more, we have also changed the rpm range at which the ports are their most effective. To top it off we then use the same intake manifold which was designed for the original powerband. Optimally you want the port timing to match the intake tuning for the same rpm range. The only way to do this is too keep it stock or change everything. This is not to say that if you port an engine and keep the stock manifold that it will not make good power. It doesn't mean that at all. It also doesn't mean that you are getting the best results that you can. Many rotary owners have a terrible habit of porting too large. If large is good, larger must be better right? Wrong! It is only better if you need it larger.
The Renesis ports are already large enough that the can flow the required amount of air to make good high rpm power. Their timing is also calculated to make good power in this range. There isn't much point in trying to go for higher rpm's than stock nor is there any need to change the port timing. This means that we don't need to enlarge the ports. We can make them flow alot better though. There is alot of attention that can be given to the insides of the ports more specifically the exhaust ports. Their flow is terrible and can be improved. you don't need to enlarge them to do it either. The intake side can use a little attention but the main focus should be the exhaust. Flow needs to be increased through these ports but most importantly the flow right before the port closes needs to be high. On the intake side this is responsible for inertial ramcharging and on the exhaust side this helps create a vacuum in the chamber as the port closes so that air is more suddenly pulled in as the intake port starts to open. The key is velocity at open and close and not so much how well it flows when totally open. That is not the most important part. Think of port opening, full open and port closing as laps of a race. When are the most critical points in a race? The first attention is paid to getting inital position in the race with the pole position being the most desired. The single most aspect though is the end of the race. In the end it doesn't matter if you led the entire race if someone else did on the last lap and got to the finish line first. This is how airflow works within your engine's ports. The most important parts of the port are the closing and the opening in that order. The amount that it flows totally open is actually the least important aspect. Got it?
Knowing this it is now possible to see that more people concentrate on how large the port is and how well it does in the middle of the race. Stock we have enough port open area to provide us with plenty of power and more than the engine has now. The key should be in increasing velocity through the ports. A smaller port will flow faster, a larger port slower. The key is to flow as fast as you possibly can without getting to the point that you have to go faster and can't. The person who goes fastest usably, wins.
For a race engine, larger porting styles may be desirable not because they necessarily flow more (they should) but because their port timing is optimal for their intended use. The RX-8 port timing is optimal for it's intended use. We just need to find a way to make it flow more but stay the same size. This isn't very hard to do.
Disclaimer (for the crybabies): Please understand that this is all my opinion and in no way insults any other styles, techniques, opinions, or engine builders. Being my opinion, it is also irrelevant if some other "respected" engine builder disagrees with me. That's the nature of opinions. I am not saying that this particular engine can not make more power than stock when tuned properly. I'm sure it can and will. I am just pointing out my way of thinking when it comes to porting. Feel free to agree, disagree, or come up with your own logic.
I actually have a different take on porting which seems like it keeps adapting and updating itself. In the past I thought very differently than I do now but have evolved to this current state of mind. I am currently under the opinion that the Renesis ports should not be enlarged at all. This is not to say that I don't feel the engine shouldn't have any port work done. Here's the logic for my thinking.
Remember that on a piston engine there is a camshaft which opens and closes the valves at a certain time and for a certain duration. The valves themselves can be changed out to larger ones to allow more airflow at the same amount of valve lift. However, these 2 things are not directly connected. Sure you can go too large of a valve for any certain duration and lift camshaft but the point is that these 2 traits are independent. You use the camshaft you want to give you the powerband that you want and you use the size valves that you need to flow the required amount of air and the proper velocity to make good power where you need it. This is ignoring a host of other very important things that I'm not getting into.
The rotary engine however does not have these 2 independent traits. They are actually one trait. Our ports are a certain size which will determine their flow potential. Their size is determined by their timing though. If we make them larger to flow more air, we also change the port timing. Imagine being forced to use a larger valve if you changed camshafts on a piston engine. That really limits you and forces compromise. Mazda has done alot of research on port timing and their efects on the rpm range. If we change the port timing to flow more, we have also changed the rpm range at which the ports are their most effective. To top it off we then use the same intake manifold which was designed for the original powerband. Optimally you want the port timing to match the intake tuning for the same rpm range. The only way to do this is too keep it stock or change everything. This is not to say that if you port an engine and keep the stock manifold that it will not make good power. It doesn't mean that at all. It also doesn't mean that you are getting the best results that you can. Many rotary owners have a terrible habit of porting too large. If large is good, larger must be better right? Wrong! It is only better if you need it larger.
The Renesis ports are already large enough that the can flow the required amount of air to make good high rpm power. Their timing is also calculated to make good power in this range. There isn't much point in trying to go for higher rpm's than stock nor is there any need to change the port timing. This means that we don't need to enlarge the ports. We can make them flow alot better though. There is alot of attention that can be given to the insides of the ports more specifically the exhaust ports. Their flow is terrible and can be improved. you don't need to enlarge them to do it either. The intake side can use a little attention but the main focus should be the exhaust. Flow needs to be increased through these ports but most importantly the flow right before the port closes needs to be high. On the intake side this is responsible for inertial ramcharging and on the exhaust side this helps create a vacuum in the chamber as the port closes so that air is more suddenly pulled in as the intake port starts to open. The key is velocity at open and close and not so much how well it flows when totally open. That is not the most important part. Think of port opening, full open and port closing as laps of a race. When are the most critical points in a race? The first attention is paid to getting inital position in the race with the pole position being the most desired. The single most aspect though is the end of the race. In the end it doesn't matter if you led the entire race if someone else did on the last lap and got to the finish line first. This is how airflow works within your engine's ports. The most important parts of the port are the closing and the opening in that order. The amount that it flows totally open is actually the least important aspect. Got it?
Knowing this it is now possible to see that more people concentrate on how large the port is and how well it does in the middle of the race. Stock we have enough port open area to provide us with plenty of power and more than the engine has now. The key should be in increasing velocity through the ports. A smaller port will flow faster, a larger port slower. The key is to flow as fast as you possibly can without getting to the point that you have to go faster and can't. The person who goes fastest usably, wins.
For a race engine, larger porting styles may be desirable not because they necessarily flow more (they should) but because their port timing is optimal for their intended use. The RX-8 port timing is optimal for it's intended use. We just need to find a way to make it flow more but stay the same size. This isn't very hard to do.
Disclaimer (for the crybabies): Please understand that this is all my opinion and in no way insults any other styles, techniques, opinions, or engine builders. Being my opinion, it is also irrelevant if some other "respected" engine builder disagrees with me. That's the nature of opinions. I am not saying that this particular engine can not make more power than stock when tuned properly. I'm sure it can and will. I am just pointing out my way of thinking when it comes to porting. Feel free to agree, disagree, or come up with your own logic.
04-11-2005 | 08:00 AM
#22
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Joined: Mar 2003
Posts: 9,944
Likes: 2
From: Melbourne, Australia
Properly RG is saying the exacting timing of ignition is (maybe slightly) more important than the actual amount of air/fuel intake. Tuning it right (gains more) than porting alone?!
I am sure it will be a good engine when it tuned to what it is now. The rotary engine intake port is larger with the newer generations of rotary and they become more and more powerful with the same aspiration system. I am sure there is a relationship there.
Good of having a rotary that it can be overhaul and even rebuild to become a new engine... again.
I am sure it will be a good engine when it tuned to what it is now. The rotary engine intake port is larger with the newer generations of rotary and they become more and more powerful with the same aspiration system. I am sure there is a relationship there.
Good of having a rotary that it can be overhaul and even rebuild to become a new engine... again.
04-11-2005 | 10:50 AM
#24
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From: NJ
Originally Posted by rotarygod
The RX-8 already runs rich from the factory. Running it richer should give you less power. When this engine was ported, the ecu actually ran the mixture richer than stock and the car still picked up a little power. When it was ported larger, it ran richer still but power did fall off. I don't see the lack of large gains to be the fault of the porting but rather the over controlling nature of the stock ecu. I really want to see this engine tuned properly.
I actually have a different take on porting which seems like it keeps adapting and updating itself. In the past I thought very differently than I do now but have evolved to this current state of mind. I am currently under the opinion that the Renesis ports should not be enlarged at all. This is not to say that I don't feel the engine shouldn't have any port work done. Here's the logic for my thinking.
Remember that on a piston engine there is a camshaft which opens and closes the valves at a certain time and for a certain duration. The valves themselves can be changed out to larger ones to allow more airflow at the same amount of valve lift. However, these 2 things are not directly connected. Sure you can go too large of a valve for any certain duration and lift camshaft but the point is that these 2 traits are independent. You use the camshaft you want to give you the powerband that you want and you use the size valves that you need to flow the required amount of air and the proper velocity to make good power where you need it. This is ignoring a host of other very important things that I'm not getting into.
The rotary engine however does not have these 2 independent traits. They are actually one trait. Our ports are a certain size which will determine their flow potential. Their size is determined by their timing though. If we make them larger to flow more air, we also change the port timing. Imagine being forced to use a larger valve if you changed camshafts on a piston engine. That really limits you and forces compromise. Mazda has done alot of research on port timing and their efects on the rpm range. If we change the port timing to flow more, we have also changed the rpm range at which the ports are their most effective. To top it off we then use the same intake manifold which was designed for the original powerband. Optimally you want the port timing to match the intake tuning for the same rpm range. The only way to do this is too keep it stock or change everything. This is not to say that if you port an engine and keep the stock manifold that it will not make good power. It doesn't mean that at all. It also doesn't mean that you are getting the best results that you can. Many rotary owners have a terrible habit of porting too large. If large is good, larger must be better right? Wrong! It is only better if you need it larger.
The Renesis ports are already large enough that the can flow the required amount of air to make good high rpm power. Their timing is also calculated to make good power in this range. There isn't much point in trying to go for higher rpm's than stock nor is there any need to change the port timing. This means that we don't need to enlarge the ports. We can make them flow alot better though. There is alot of attention that can be given to the insides of the ports more specifically the exhaust ports. Their flow is terrible and can be improved. you don't need to enlarge them to do it either. The intake side can use a little attention but the main focus should be the exhaust. Flow needs to be increased through these ports but most importantly the flow right before the port closes needs to be high. On the intake side this is responsible for inertial ramcharging and on the exhaust side this helps create a vacuum in the chamber as the port closes so that air is more suddenly pulled in as the intake port starts to open. The key is velocity at open and close and not so much how well it flows when totally open. That is not the most important part. Think of port opening, full open and port closing as laps of a race. When are the most critical points in a race? The first attention is paid to getting inital position in the race with the pole position being the most desired. The single most aspect though is the end of the race. In the end it doesn't matter if you led the entire race if someone else did on the last lap and got to the finish line first. This is how airflow works within your engine's ports. The most important parts of the port are the closing and the opening in that order. The amount that it flows totally open is actually the least important aspect. Got it?
Knowing this it is now possible to see that more people concentrate on how large the port is and how well it does in the middle of the race. Stock we have enough port open area to provide us with plenty of power and more than the engine has now. The key should be in increasing velocity through the ports. A smaller port will flow faster, a larger port slower. The key is to flow as fast as you possibly can without getting to the point that you have to go faster and can't. The person who goes fastest usably, wins.
For a race engine, larger porting styles may be desirable not because they necessarily flow more (they should) but because their port timing is optimal for their intended use. The RX-8 port timing is optimal for it's intended use. We just need to find a way to make it flow more but stay the same size. This isn't very hard to do.
Disclaimer (for the crybabies): Please understand that this is all my opinion and in no way insults any other styles, techniques, opinions, or engine builders. Being my opinion, it is also irrelevant if some other "respected" engine builder disagrees with me. That's the nature of opinions. I am not saying that this particular engine can not make more power than stock when tuned properly. I'm sure it can and will. I am just pointing out my way of thinking when it comes to porting. Feel free to agree, disagree, or come up with your own logic.
I actually have a different take on porting which seems like it keeps adapting and updating itself. In the past I thought very differently than I do now but have evolved to this current state of mind. I am currently under the opinion that the Renesis ports should not be enlarged at all. This is not to say that I don't feel the engine shouldn't have any port work done. Here's the logic for my thinking.
Remember that on a piston engine there is a camshaft which opens and closes the valves at a certain time and for a certain duration. The valves themselves can be changed out to larger ones to allow more airflow at the same amount of valve lift. However, these 2 things are not directly connected. Sure you can go too large of a valve for any certain duration and lift camshaft but the point is that these 2 traits are independent. You use the camshaft you want to give you the powerband that you want and you use the size valves that you need to flow the required amount of air and the proper velocity to make good power where you need it. This is ignoring a host of other very important things that I'm not getting into.
The rotary engine however does not have these 2 independent traits. They are actually one trait. Our ports are a certain size which will determine their flow potential. Their size is determined by their timing though. If we make them larger to flow more air, we also change the port timing. Imagine being forced to use a larger valve if you changed camshafts on a piston engine. That really limits you and forces compromise. Mazda has done alot of research on port timing and their efects on the rpm range. If we change the port timing to flow more, we have also changed the rpm range at which the ports are their most effective. To top it off we then use the same intake manifold which was designed for the original powerband. Optimally you want the port timing to match the intake tuning for the same rpm range. The only way to do this is too keep it stock or change everything. This is not to say that if you port an engine and keep the stock manifold that it will not make good power. It doesn't mean that at all. It also doesn't mean that you are getting the best results that you can. Many rotary owners have a terrible habit of porting too large. If large is good, larger must be better right? Wrong! It is only better if you need it larger.
The Renesis ports are already large enough that the can flow the required amount of air to make good high rpm power. Their timing is also calculated to make good power in this range. There isn't much point in trying to go for higher rpm's than stock nor is there any need to change the port timing. This means that we don't need to enlarge the ports. We can make them flow alot better though. There is alot of attention that can be given to the insides of the ports more specifically the exhaust ports. Their flow is terrible and can be improved. you don't need to enlarge them to do it either. The intake side can use a little attention but the main focus should be the exhaust. Flow needs to be increased through these ports but most importantly the flow right before the port closes needs to be high. On the intake side this is responsible for inertial ramcharging and on the exhaust side this helps create a vacuum in the chamber as the port closes so that air is more suddenly pulled in as the intake port starts to open. The key is velocity at open and close and not so much how well it flows when totally open. That is not the most important part. Think of port opening, full open and port closing as laps of a race. When are the most critical points in a race? The first attention is paid to getting inital position in the race with the pole position being the most desired. The single most aspect though is the end of the race. In the end it doesn't matter if you led the entire race if someone else did on the last lap and got to the finish line first. This is how airflow works within your engine's ports. The most important parts of the port are the closing and the opening in that order. The amount that it flows totally open is actually the least important aspect. Got it?
Knowing this it is now possible to see that more people concentrate on how large the port is and how well it does in the middle of the race. Stock we have enough port open area to provide us with plenty of power and more than the engine has now. The key should be in increasing velocity through the ports. A smaller port will flow faster, a larger port slower. The key is to flow as fast as you possibly can without getting to the point that you have to go faster and can't. The person who goes fastest usably, wins.
For a race engine, larger porting styles may be desirable not because they necessarily flow more (they should) but because their port timing is optimal for their intended use. The RX-8 port timing is optimal for it's intended use. We just need to find a way to make it flow more but stay the same size. This isn't very hard to do.
Disclaimer (for the crybabies): Please understand that this is all my opinion and in no way insults any other styles, techniques, opinions, or engine builders. Being my opinion, it is also irrelevant if some other "respected" engine builder disagrees with me. That's the nature of opinions. I am not saying that this particular engine can not make more power than stock when tuned properly. I'm sure it can and will. I am just pointing out my way of thinking when it comes to porting. Feel free to agree, disagree, or come up with your own logic.
I agree with you about the exhaust flow. Someone (cough, Rotaryu-G@d) needs to tune it properly with a stand-alone unit. I have noticed a lot of RX8 owners are interested in Forced Induction. I wonder where this will lead porting ... :D
I wonder if any of the companies racing the Renesis played with the exhaust ports...