P-port project
11-22-07, 10:19 AM
#76
There is far more to making power that just pure airflow. Port timing has a humongous affect. Everyone complains that the Renesis exhaust ports are restrictive yet a 13B needs to be streetported just to match it's power. This is because the exhaust ports on a 13B are open for far too long in relation to the intake. The Renesis has a far more optimal intake and exhaust timing relationship and more power is made. If you had more intake and/or exhaust ports you'd have really weird timing but more importantly you'll lose exhaust velocity and scavenging not to mention mess up any intake tuning and would probably end up making less power than you started with.
11-22-07, 01:53 PM
#78
u must have not seen how big the intake ports r on the renesis. there huge compared to the stock ports on the n/a plates. the exhaust ports on the renesis is not the reason it makes power. everything else around it is. truth is, the rx8 is only making a little over 180rwhp stock, but it has a huge port. ive heard of some older rx7s making near that on the stock ports. the renesis exhaust is very restrictive.
The exhaust ports are the main reason that engine does so well. Yes the intake ports are big. If you can't get the exhaust out, that doesn't really matter though. The compression ratio really has no effect. You won't get any appreciable power difference between 9.0:1 and 10.0:1. Outside that range and it'll fall off.
I agree that the Renesis exhaust ports need to be improved when it comes to flow. They are a very good example of why flow isn't the only thing important. Port timing plays an equally large role in how much power is made and where the powerband is. That is why the Renesis does so well.
The intake manifold is nice compared to the 13B engines but even aftermarket intakes on a 13B have a hard time approaching the same power results. The intake does a little but it's really an average power increase that it gives. You can make as much power as a stock Renesis by streetporting a 13B and doing everything else nicely too. However you can not get the Renesis powerband. Full throttle is one thing and usually the only thing that people like to compare but the Renesis will have a superior power curve at every other load level under full throttle. That's the beauty of no overlap and proper intake and exhaust port timing.
Next you're going to tell me you absolutely need overlap to make power. That's another myth.
11-22-07, 03:27 PM
#79
Senior Member
Thread Starter
i've had some heating problems. both water and oil. ended up extending the radiator and sticking 1 big 16" fan in there. Also had some steel braided oil hose made up and relocated the oil cooler further forward. so far, problem solved ! just piling on the miles now. have done about 1000m since rebuild. Have also had a set of 25mm 4x100 adaptors made up and stuck a set of 15" lenso's on there shod with 195/50/15 bridgestone rubber. then dumped the stock seats and stuck in a pair of buckets. also stuck in a nice set of tinted gauges :-) yes...i've been busy. now just for a cool spray job to finish it off.
videos and pics soon....keep watching this thread
videos and pics soon....keep watching this thread
11-22-07, 04:09 PM
#80
Racing Spirit
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I've ported a Renesis and even posted pictures of it. Have you? Check the 8 forum. As many people here know, I've also owned a flowbench for several years. Trust me, there's more to it than just static flow numbers.
The exhaust ports are the main reason that engine does so well. Yes the intake ports are big. If you can't get the exhaust out, that doesn't really matter though. The compression ratio really has no effect. You won't get any appreciable power difference between 9.0:1 and 10.0:1. Outside that range and it'll fall off.
I agree that the Renesis exhaust ports need to be improved when it comes to flow. They are a very good example of why flow isn't the only thing important. Port timing plays an equally large role in how much power is made and where the powerband is. That is why the Renesis does so well.
The intake manifold is nice compared to the 13B engines but even aftermarket intakes on a 13B have a hard time approaching the same power results. The intake does a little but it's really an average power increase that it gives. You can make as much power as a stock Renesis by streetporting a 13B and doing everything else nicely too. However you can not get the Renesis powerband. Full throttle is one thing and usually the only thing that people like to compare but the Renesis will have a superior power curve at every other load level under full throttle. That's the beauty of no overlap and proper intake and exhaust port timing.
Next you're going to tell me you absolutely need overlap to make power. That's another myth.
The exhaust ports are the main reason that engine does so well. Yes the intake ports are big. If you can't get the exhaust out, that doesn't really matter though. The compression ratio really has no effect. You won't get any appreciable power difference between 9.0:1 and 10.0:1. Outside that range and it'll fall off.
I agree that the Renesis exhaust ports need to be improved when it comes to flow. They are a very good example of why flow isn't the only thing important. Port timing plays an equally large role in how much power is made and where the powerband is. That is why the Renesis does so well.
The intake manifold is nice compared to the 13B engines but even aftermarket intakes on a 13B have a hard time approaching the same power results. The intake does a little but it's really an average power increase that it gives. You can make as much power as a stock Renesis by streetporting a 13B and doing everything else nicely too. However you can not get the Renesis powerband. Full throttle is one thing and usually the only thing that people like to compare but the Renesis will have a superior power curve at every other load level under full throttle. That's the beauty of no overlap and proper intake and exhaust port timing.
Next you're going to tell me you absolutely need overlap to make power. That's another myth.
Is there a dyno from the motor you ported?
11-22-07, 04:56 PM
#81
He's been driving the car for about 10,000 miles now. He had an issue for most of it and has only now gotten it resolved. The Renesis uses 3 sets of injectors. The primaries which are one size and then the other 2 sets are larger. He had the primary plugs and what Mazda refers to as primary 2 wires reversed. Different sized injectors equal poor running. He's got it worked out now and intends to get to a dyno soon. He has posted his thoughts on it though and it is quite positive. Especially when compared to other RX-8's.
I'm actually not expecting it to gain much power. There wasn't a whole lot that could be done. The exhaust ports are a pain in the *** to port. There isn't much meat around them. You can not bridgeport them as the water jacket is in the way. It doesn't sound possible but if you could see them you'd understand why. It's really stupid. The tread over there entitled "Rebuilding my Renesis" has pictures. It's got way too many pages and has gone off topic way to many times so finding them will be a chore.
I could really only do a little work on the exhaust ports but they are improved. I have one housing which I purposedly ground into the water jacket so I could see what the ports would look like if I could do them the way I want to. I'd like to find a way to weld them back up. The first attempt was a dismal failure due to the small space involved. I intend to try some other techniques though. When one mistake costs you $350, it's hard to want to experiment again! Fortunately I have one dead housing so messing up on it again is free! Once I get it figured out, I'll try it on a good set again. I know it can be done. How is what I need to learn.
The intake ports did get some work. The secondaries didn't change at all. I cleaned up the runners as the castings really suck on the Renesis. They are much rougher than the 13B runner castings. The aux ports changed slightly. I opened them a little bit earlier. They can do that as they open later than the secondaries anyways. The closing edge is slightly different too. I didn't make the mistake that most people do of making this port really large. That will only hurt power. I angled the closing edge a little bit but not much. The outermost side of the closing edge was moved up a little bit. This is so the side seal starts riding across the closing edge from inner to outer rather than hitting it all at once. I didn't do it for power. I did it for seal longevity.
The only big intake port change was the primaries. They got quite a bit larger but still not as large as they could have gotten. There's no point in going as big as you physically can. The primary runners can't flow that much. They don't open any earlier. None of the ports do. You can't. They do close later though and the bottom edge went down. This is an intersting side of the Renesis intake ports. There is a lip that is not there on the older rotaries. The long side radius, which is the back wall of the port, extends past the oil seal edge of the port. It's hard to explain. The port can't go this far in though so there is a lip there. This creates lots of turbulence. Mazda did this on purpose. They call it AWP or anti wet port. The primary injectors point straight at this part of the port rather than more downwards as the 13B primaries do. This high turbulence area helps with fuel atomization. I got rid of it! I roughed up the area and dimpled it with a Dremel like the surface of a golf ball and filled it in with epoxy. It is now nice and smooth and flows much better. This was the biggest airflow gain in the engine.
The result is an engine that really pulls hard in the midrange through 3rd and 4th gear and never backs down through redline. The midrange is what is most noticable. It's nice. The car sounds good. He even picked up some mileage. Overall if was a good gain. I don't think he got 20+ hp peak out of it or anything but his midrange is very nice. All I care about is average horsepower. That's what makes you fast and what makes it more fun on the street.
Why am I talking about this here? This is a P-port thread. Sorry guys. Back to our regularly scheduled program...
I'm actually not expecting it to gain much power. There wasn't a whole lot that could be done. The exhaust ports are a pain in the *** to port. There isn't much meat around them. You can not bridgeport them as the water jacket is in the way. It doesn't sound possible but if you could see them you'd understand why. It's really stupid. The tread over there entitled "Rebuilding my Renesis" has pictures. It's got way too many pages and has gone off topic way to many times so finding them will be a chore.
I could really only do a little work on the exhaust ports but they are improved. I have one housing which I purposedly ground into the water jacket so I could see what the ports would look like if I could do them the way I want to. I'd like to find a way to weld them back up. The first attempt was a dismal failure due to the small space involved. I intend to try some other techniques though. When one mistake costs you $350, it's hard to want to experiment again! Fortunately I have one dead housing so messing up on it again is free! Once I get it figured out, I'll try it on a good set again. I know it can be done. How is what I need to learn.
The intake ports did get some work. The secondaries didn't change at all. I cleaned up the runners as the castings really suck on the Renesis. They are much rougher than the 13B runner castings. The aux ports changed slightly. I opened them a little bit earlier. They can do that as they open later than the secondaries anyways. The closing edge is slightly different too. I didn't make the mistake that most people do of making this port really large. That will only hurt power. I angled the closing edge a little bit but not much. The outermost side of the closing edge was moved up a little bit. This is so the side seal starts riding across the closing edge from inner to outer rather than hitting it all at once. I didn't do it for power. I did it for seal longevity.
The only big intake port change was the primaries. They got quite a bit larger but still not as large as they could have gotten. There's no point in going as big as you physically can. The primary runners can't flow that much. They don't open any earlier. None of the ports do. You can't. They do close later though and the bottom edge went down. This is an intersting side of the Renesis intake ports. There is a lip that is not there on the older rotaries. The long side radius, which is the back wall of the port, extends past the oil seal edge of the port. It's hard to explain. The port can't go this far in though so there is a lip there. This creates lots of turbulence. Mazda did this on purpose. They call it AWP or anti wet port. The primary injectors point straight at this part of the port rather than more downwards as the 13B primaries do. This high turbulence area helps with fuel atomization. I got rid of it! I roughed up the area and dimpled it with a Dremel like the surface of a golf ball and filled it in with epoxy. It is now nice and smooth and flows much better. This was the biggest airflow gain in the engine.
The result is an engine that really pulls hard in the midrange through 3rd and 4th gear and never backs down through redline. The midrange is what is most noticable. It's nice. The car sounds good. He even picked up some mileage. Overall if was a good gain. I don't think he got 20+ hp peak out of it or anything but his midrange is very nice. All I care about is average horsepower. That's what makes you fast and what makes it more fun on the street.
Why am I talking about this here? This is a P-port thread. Sorry guys. Back to our regularly scheduled program...
11-22-07, 06:19 PM
#82
look at all thats done to the renesis. bigger port, lighter rotors, lighter e-shaft, better intake, and all new technology around it. now if your saying that it has a better range ok, but i never mentioned or disagreed on that. yes the rx8 has a more torqey feel then the older n/a rx7 but the car is still only making 180whp stock. thats the main point. u can get 200rwhp out of the older 13b easily with a streetport and standalone and supporting mods. now some rx8s r making alittle more than that, but that with mods on top of the advantages it has on the older
13b. theres nothing u can say that will make me believe that the side port exhaust is the reason for its horsepower. sorry, it mostly comes from that huge intake port, and then everything else around it.
13b. theres nothing u can say that will make me believe that the side port exhaust is the reason for its horsepower. sorry, it mostly comes from that huge intake port, and then everything else around it.
11-26-07, 08:22 AM
#85
I know I'm going off topic with this right now too, but the more I read Rotary God's Results (read results not theory), the more Port timing is making sense ... mind you I have never ported yet, but plan to do so sometime this week with a 13b T2 engine.
11-26-07, 08:39 AM
#86
i wanted to be understanding, but it wasnt making any since to me. ive heard other people say it so u could be right. whats holding me back from believing it is the actuall hp the renesis put out. i would like to see more. it still hasnt made more power than a streetported 13b.
sorry i went off topic, this will be my last post about this. i do want to hear more about this car
sorry i went off topic, this will be my last post about this. i do want to hear more about this car
11-29-07, 10:51 PM
#92
Ya know I really don't care for the protruding air filter. While on the other hand, I think it looks real aggressive. I think if it matches the aggressiveness and potential of the engine then it's cool, but only if it's a match. (which in this case it is).
11-30-07, 07:25 PM
#98
OBEY YOUR MAZDA
11-30-07, 07:33 PM
#99
OBEY YOUR MAZDA
BTW I agree with rotarygod, Aux. bridging does next to nothing on a FI 6-port.
My old FC conservative streetport felt ALOT faster than my current set-up.
Also the renesis exhaustport dispute: Think No overlap / dillution / port area / duration
My old FC conservative streetport felt ALOT faster than my current set-up.
Also the renesis exhaustport dispute: Think No overlap / dillution / port area / duration
