Cracked front housing
06-27-2007, 09:21 PM
#51
"Mazda themselves says the greatest shocks to the rear iron is full engine misfire,not detonation at full engine power. Detonation will dent the rotor and break other parts, before the rear iron falls apart.but when the rear iron is allowed to go from full engine torque to almost nothing during misfire and back to full in a split second, regardless of what is done, the rear iron will probably still crack somewhere, sometimes part of the bell housing flange breaks off, other I have seen spit the frost plugs out."
06-28-2007, 12:10 AM
#52
Sorry, sorry, sorry - The corner seals, not the rings. Forgot to get out of my piston mode. Busy on my racecar as well at the moment. hehehe
There's slight marking of the housing at the exhaust ports where the corner seals pass over the exhaust port. This is very faint and only on the side after the seal has passed the port.
There's slight marking of the housing at the exhaust ports where the corner seals pass over the exhaust port. This is very faint and only on the side after the seal has passed the port.
06-28-2007, 03:32 AM
#53
sas
Thread Starter
"Mazda themselves says the greatest shocks to the rear iron is full engine misfire,not detonation at full engine power. Detonation will dent the rotor and break other parts, before the rear iron falls apart.but when the rear iron is allowed to go from full engine torque to almost nothing during misfire and back to full in a split second, regardless of what is done, the rear iron will probably still crack somewhere, sometimes part of the bell housing flange breaks off, other I have seen spit the frost plugs out."
06-29-2007, 11:41 PM
#55
07-02-2007, 07:59 AM
#56
sas
Thread Starter
Back to RX-8 rotors
After looking carefully at the stripped parts we've decided to go back to RX-8 rotors with 3mm Hurley apex seals. I didn't like what I saw overall in the engine and think RG is correct, there will be premature failure due to the lack of protection when the oil control rings are omitted using the RX-7 rotors.
It was also a learning curve which showed that the engine cannot take the extra stress of boosting over 1 bar without risking a serious failure of the front housing due to flexing.
I didn't like the potential damage of the corner and side seals and the housings due to what happens at the exhaust ports.
However....
I will try to find a way to install a device similar to the standard Renesis oil control seal into FD rotors if I can, to prevent carbon on the seals.
Though I said earlier there was very little evidence of carbon in the seals I may have been wrong, as we used heated trico-ethylene in our cleaning tank to clean the rotors properly (don't do this at home, it's extremely poisonous) and the amount of soot that was evident was too much for my liking. In my opinion the muck is getting in everywhere and will eventually spoil the engine. Pity, as it was running very, very sweet.
It was also a learning curve which showed that the engine cannot take the extra stress of boosting over 1 bar without risking a serious failure of the front housing due to flexing.
I didn't like the potential damage of the corner and side seals and the housings due to what happens at the exhaust ports.
However....
I will try to find a way to install a device similar to the standard Renesis oil control seal into FD rotors if I can, to prevent carbon on the seals.
Though I said earlier there was very little evidence of carbon in the seals I may have been wrong, as we used heated trico-ethylene in our cleaning tank to clean the rotors properly (don't do this at home, it's extremely poisonous) and the amount of soot that was evident was too much for my liking. In my opinion the muck is getting in everywhere and will eventually spoil the engine. Pity, as it was running very, very sweet.
07-06-2007, 03:30 PM
#58
kevin@rotaryresurrection
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Without pointing the finger at any one poster in particular as to avoid mods getting butthurt, I would like to pose a question to the "forum elite" here. Why do you guys think everything can only be your way or the highway? There are OTHER WAYS to do things in the world, versus the "set path" that most people follow.
Why bash someone for trying something different? Even if you don't think it will work...just say, "Hey, I dont think it will work, because..." and leave it at that. Leave the name calling and insults at the door when you log in.
Look at this very post. A nice guy with a lot of experience posts that he is trying something new and gets bashed by multiple "keyboard tuners" for trying a different approach. In the end, it appears that his approach did not work out. BUT, that is HOW WE LEARN THINGS. Instead of just following in the footsteps of everyone who has modified a car before you. So, in this example, we learned something that we would never have verified, had the "forum elite" been listened to from the getgo.
Oh...and as to the point about tuning and AFR's. Theoretical power predictions aside, why is it that EVERY noted rotary tuner in the "game" today likes to tune well into the 10's under heavy load, while the "forum elite" here claim that 11.5 is "choking the ignition"?
Hopefully no one whines to the mods about my post questioning "the powers that be" and gets this thread deleted, because there is a bit of useful information floating around here.
Why bash someone for trying something different? Even if you don't think it will work...just say, "Hey, I dont think it will work, because..." and leave it at that. Leave the name calling and insults at the door when you log in.
Look at this very post. A nice guy with a lot of experience posts that he is trying something new and gets bashed by multiple "keyboard tuners" for trying a different approach. In the end, it appears that his approach did not work out. BUT, that is HOW WE LEARN THINGS. Instead of just following in the footsteps of everyone who has modified a car before you. So, in this example, we learned something that we would never have verified, had the "forum elite" been listened to from the getgo.
Oh...and as to the point about tuning and AFR's. Theoretical power predictions aside, why is it that EVERY noted rotary tuner in the "game" today likes to tune well into the 10's under heavy load, while the "forum elite" here claim that 11.5 is "choking the ignition"?
Hopefully no one whines to the mods about my post questioning "the powers that be" and gets this thread deleted, because there is a bit of useful information floating around here.
07-06-2007, 03:54 PM
#59
Oh...and as to the point about tuning and AFR's. Theoretical power predictions aside, why is it that EVERY noted rotary tuner in the "game" today likes to tune well into the 10's under heavy load, while the "forum elite" here claim that 11.5 is "choking the ignition"?
Not being one of the " forum elite" I'd like you to back this up with a bit of data...
EVERY and "game" are big words without any backup.
07-06-2007, 04:39 PM
#60
Registered
There is more to the story that just tuning to afr's in the 10's. There are some important reasons why people do this. Most importantly to control detonation. People use overly rich mixtures as a form of thermal management as fuel like water has the ability to absorb heat and too much heat leads to detonation. Once an optimally rich afr is found for producing maximum power, which is usually somewhere around 12.5:1 or so, the only benefit of additional fuel is to keep chamber temperatures down and hence lower the risk of detonation. Dyno tests have shown that a fairly wide range of air fuel ratios can be used with forced induction and power isn't really affected.
Now saying this, it doesn't mean it is safe to run leaner even though on paper it would technically make the most power. At the very least it wouldn't make appreciably less. The reason people need to run overly rich is to make up for something they are lacking. It could be poor tuning. It could be an overly high compression ratio. If you need to tune the afr's into the 10's, there is one common issue that will always apply. You are trying to push your boost limits too far for the octane level of fuel you are using with your setup. If you can't improve efficiency elsewhere, use a better fuel.
Sure you can make more power this way. However you can't do it at an optimal afr without detonating so you do it overly rich. That's fine. It's done all the time. People that run water injection can get away with leaner afr's. This is because the water is doing the same job that the extra fuel was doing and notice that typically the cars with richer mixtures aren't making any more power. This is because added fuel after a certain point isn't going to contribute except to absorb heat. Gasoline can't absorb as much heat as water though.
11.5:1 is safe as long as you don't detonate. That's the key. Technically speaking, the best afr is the leanest you can get away with without detonation. However we don't want to tell people that as that's a pretty risky area to hit. It's far easier to tell them to tune overly rich. It uses extra fuel and still makes good power but it probably won't die as easily. Keep in mind that most rotary people have a tendency to try to push their engines a bit far for street use. The sister forum is full of examples of wasting too much effort on a street car for the sake of hitting a high power number on paper. As cool and impressive as those engines can be, there is a limit to practicality not to mention traction. You only need so much and I'd argue that the limit can easily be hit with stock porting.
The RX-8 ignition system isn't terribly strong compared to the older RX-7 ignition systems. You will completely blow out spark well before you ever hit 400 hp and you'll start seeing the first signs of ignition breakup somewhere after about 300 hp or so. A richer afr isn't going to make this issue any better. In fact that opposite would be true.
Now saying this, it doesn't mean it is safe to run leaner even though on paper it would technically make the most power. At the very least it wouldn't make appreciably less. The reason people need to run overly rich is to make up for something they are lacking. It could be poor tuning. It could be an overly high compression ratio. If you need to tune the afr's into the 10's, there is one common issue that will always apply. You are trying to push your boost limits too far for the octane level of fuel you are using with your setup. If you can't improve efficiency elsewhere, use a better fuel.
Sure you can make more power this way. However you can't do it at an optimal afr without detonating so you do it overly rich. That's fine. It's done all the time. People that run water injection can get away with leaner afr's. This is because the water is doing the same job that the extra fuel was doing and notice that typically the cars with richer mixtures aren't making any more power. This is because added fuel after a certain point isn't going to contribute except to absorb heat. Gasoline can't absorb as much heat as water though.
11.5:1 is safe as long as you don't detonate. That's the key. Technically speaking, the best afr is the leanest you can get away with without detonation. However we don't want to tell people that as that's a pretty risky area to hit. It's far easier to tell them to tune overly rich. It uses extra fuel and still makes good power but it probably won't die as easily. Keep in mind that most rotary people have a tendency to try to push their engines a bit far for street use. The sister forum is full of examples of wasting too much effort on a street car for the sake of hitting a high power number on paper. As cool and impressive as those engines can be, there is a limit to practicality not to mention traction. You only need so much and I'd argue that the limit can easily be hit with stock porting.
The RX-8 ignition system isn't terribly strong compared to the older RX-7 ignition systems. You will completely blow out spark well before you ever hit 400 hp and you'll start seeing the first signs of ignition breakup somewhere after about 300 hp or so. A richer afr isn't going to make this issue any better. In fact that opposite would be true.
07-06-2007, 09:02 PM
#61
Without pointing the finger at any one poster in particular as to avoid mods getting butthurt, I would like to pose a question to the "forum elite" here. Why do you guys think everything can only be your way or the highway? There are OTHER WAYS to do things in the world, versus the "set path" that most people follow.
There are quite a few folks, like yourself, that think that applying old, standard techniques in the regular way are the best way to go.
Then there are those that have spent quite a bit of time actually re-engineering from a clean slat with no expectations of what the "proper" way to do things are.
I'm not sure that I want to venture into the area of "keyboard tuners" that you seem to fear so greatly, but nearly all of the posts on this forum that contain actual techniques and numbers that are specific to the RX-8 are derived from real experience with the real machine, not mantra-like repetition of RX-7 mythology.
Really, with your impressive collection of loaded vocabulary and pejorative double-talk, I'd suggest posting less and reading more.
07-06-2007, 09:16 PM
#62
Registered
This forum is very nice from the standpoint that we have many people that actually get out there and try things for themselves regardless of what the general opinion is. We are also more open about sharing our results with others so that they won't waste their time trying the same things over again. That's how it should be. You'll find that the people that give the most advice will probably have practical real world experience to back it up too. What's really cool is that half the time it goes against what was always thought as traditional. I like that.
When you hit the 7 guys up, you have people telling you not to try something. If you don't give them one, they say you're full of crap. When you do give them one, they ask you for dyno charts to back it up. When you give them one, they say you faked it. You can't win. Most of them don't understand that a dyno chart is only a 2D representation of a 3D powerband anyways. Then you have the people that spout off plain old bad advice after it's been proven not to work. Just because you and six million other people couldn't make it work doesn't mean I can't! Nevermind the fact that I don't have any of the proper tuning aids or skills neceesary to make it work. That's a prevalent attitude in the 7 community yet people encourage them to try the same crap that's been proven not to work all over again. How about encouraging them to try something else for once! Take that bs auxiliary bridgeporting crap that gets tried over and over again with the same crap results. Give it up people. It doesn't work! Those that have tried it and say not to waste their time are typically the ones that are flamed. Why are the smart people not listened to more over there? Then the idiots become the forum experts and now everyone listens to their techno flotsam babbling and believe it to work that way. Not so here. We share for the betterment of the community. A very smart and respected rotary person said at Sevenstock last year that the worst thing to happen to the RX-7 was the 7 forum! I'm not going to name him but most know who he is. So if we seem different over here, don't think we take that as an insult. It's a compliment.
When you hit the 7 guys up, you have people telling you not to try something. If you don't give them one, they say you're full of crap. When you do give them one, they ask you for dyno charts to back it up. When you give them one, they say you faked it. You can't win. Most of them don't understand that a dyno chart is only a 2D representation of a 3D powerband anyways. Then you have the people that spout off plain old bad advice after it's been proven not to work. Just because you and six million other people couldn't make it work doesn't mean I can't! Nevermind the fact that I don't have any of the proper tuning aids or skills neceesary to make it work. That's a prevalent attitude in the 7 community yet people encourage them to try the same crap that's been proven not to work all over again. How about encouraging them to try something else for once! Take that bs auxiliary bridgeporting crap that gets tried over and over again with the same crap results. Give it up people. It doesn't work! Those that have tried it and say not to waste their time are typically the ones that are flamed. Why are the smart people not listened to more over there? Then the idiots become the forum experts and now everyone listens to their techno flotsam babbling and believe it to work that way. Not so here. We share for the betterment of the community. A very smart and respected rotary person said at Sevenstock last year that the worst thing to happen to the RX-7 was the 7 forum! I'm not going to name him but most know who he is. So if we seem different over here, don't think we take that as an insult. It's a compliment.
07-06-2007, 09:17 PM
#63
kevin@rotaryresurrection
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I've also had cars come through here from shops such as PFS, Rotary Performance, and Judge Ito, and a few notable drag racers who build and tune on the side, all of which were tuned at-or-sub 11.0AFR.
I am just giddy with anticipation for one of you to say that those guys don't know what they are doing, especially when I doubt that any of the "forum elite" here have matched or exceeded the performance those guys have attained from their setups...all while "choking the ignition:.
<sarcasm>But, rx-7 engines are absolutely irrelevant to, and totally different from rx-8 engines in every way, and the rx-8 guys are able to make 400-600rwhp just as easily as those older rotaries who came before them. It's clear that they don't need to regard any of the rx-7 racers/tuners with any respect, and can disregard any information relating to successful rx-7 setups.</sarcasm>
Last edited by RotaryResurrection; 07-06-2007 at 09:22 PM.
07-06-2007, 09:25 PM
#64
Registered
Brian will tune that rich. He also experiments with AI alot and has had some neat results in leaning out the mixture when used in conjuction with alcohol. He's definitely one of the smartest guys out there. He's creative and learns by doing. I respect him probably more than anyone out there as a result. He's also hated by many on the 7 forum so he must be good! Steve is a fantastic tuner. He's a great guy. I need to get up to Dallas again to see both of those guys. It's been too long. He does tune rich too but again it's for a margin of safety. Rarely do we see either of them tuning cars under 400 hp and often much higher. An afr in the 10's just isn't always necessary. On a 300hp car it most likely isn't. We rarely see that here. It's usually in the 200's somewhere so there really isn't much of an issue with afr's well into the 11's. It all really needs to be put into power context. After a certain point, if you aren't going to use some crazy fuel, you need to run overly rich or use AI to help out. If the only penalty to controlling detonation is running pig rich and wasting a little bit more fuel, it's pretty easy to see why it's done. Power isn't greater down there though. If you don't need to go that rich to control detonation, there's really no reason to tune it that way. MM has spent lots of time on his car. He knows what works on it.
:
07-06-2007, 09:55 PM
#70
kevin@rotaryresurrection
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Regardless of whether I agree with your statements or your attitude, you have just lost ALL credibility of anything you say now or in the future, in my eyes (and likely in lots of other readers' as well).
So let me get this straight. You, a dude on an internet forum who works on your own car, probably making somewhere in the 250-300rwhp output range (correct me if I am wrong), has just "corrected" the work of a longtime veteran builder and tuner who has HUNDREDS of 400-600rwhp rotaries under his belt?
FUT THE WUCK?!?!
I think you just proved everything I have said about you to this point. Thanks, you make it easy for me.
07-06-2007, 10:02 PM
#71
07-06-2007, 11:16 PM
#73
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As I said in the other thread, no non renesis rotors in the renesis. The ports and seals relate to each other in a unique way. Also be careful with your porting since there is much to consider there.
07-07-2007, 03:09 AM
#75
It needs some design revision before it is ready for the "main stream", but nothing a few minutes of detail attention cant fix.The EMS was a bit rough, though.
I guess you need to read up a bit.
The tune was screwed. Sorry if Steve is you idol. I don't know the guy and I'm sure he's the ****. He certainly has a reputation that precedes him (in a good way, unlike you). I have nothing against him and, as noted, I don't know if there was any meddling between what he did and what I got.
But, the tune was screwed.
I'm not even talking about "finesse" things like injector PW or timing (though that was an abortion).
I mean things like having the WOT map engage at -15" and setting the cruise map to -20" with PW modifiers that put the A/F randomly in the 17:1 range.
Dumbfounded and speechless? We should be so lucky.
Hopefully, we will get a chance in the near future to discuss all of this in Socratic fashion so that I can benefit from your boundless wisdom.
Last edited by MazdaManiac; 07-07-2007 at 03:15 AM.