What do you think about this porting?
10-04-06, 04:50 PM
#76
Originally Posted by rotarygod
He too will admit that just strapping a housing on a bench and flowing it as is, is a futile thing. There's no refuting that. That's no more different than flowing a cylinder head with no valves in it. That's worthless. He uses it as a tool but not as an absolute be all end all to determine ultimate power production. It's for that last few percent and when you are building a race engine, every little bit counts. I think that's where many people get confused when it comes to using them. Too many out there (not implying you guys!) just assume that you do strap on a housing and flow it and port it until your numbers go up and up as high as they can. Rick will also flow test intake manifolds and other components that are a functional part of the engine to look for improvements there.
Rob is correct in that any added power from flow testing might only be a small amount. Flow testing a port with a rotor in front of it in various stages of rotation will allow a person to see how well their closing edge shape or opening edge shape flows but as you've pointed out doesn't tell everything. These are only showing us what happens at these points as the rotor is at these spots but this is important to know. It does allow a person to see what may or may not work well though. I have no doubt that over time a person can learn what shapes work the best and not need to constantly use a flowbench over and over again. You have lots of experience with porting and have seen firsthand what works and what doesn't and you know how to blend port shapes into runners. Many others don't though. A porting template shows a person a port's total size and timing but it't the work underneath, how well it is blended with the intake runner that matters the most. A flowbench can show you what works best but it's only if you have a rotor in front of it in various stages of rotation. If your intake port closes at 70 degrees and you have a rotor in front of it covering the port up to 55 degrees, you know good and well the shape of the transition from the top of the port from the runner underneath can affect how well air continues to flow into the engine. This makes a difference but of course it will show up as far less flow than a fully opened port. A port is only open all the way for a very short time and this isn't the most crucial aspect anyways. Enlargening a port runner based on flowbench numbers is also worthless. Thes best thing about the flowbench is being able to tell if you've gotten your ports flowing all the same as the rotor passes it. That is also important.
After you've worked on engines for as long as Rob has, I'm sure you can just port by hand well enough to get very close to what you could do with a flowbench. That is a knowledge and skill that he has acquired over the years. Consistency is a skill. Last year when talking about the flowbench with Rob at Sevenstock, he pretty much said he learned what he needed to years ago and no longer needs it as he can pretty much do it over and over again. That's a good thing but it's not to say that the flowbench was worthless. It had it's value at some point in the game. It's just another tool in a sea of useful tools. No one tool can be used to absolutely tell you everything. It's just like relying on a dyno chart telling you everything about your powerband. A full throttle run doesn't really tell you crap but using a dyno propely at different loads can tell you a lot. How many people here put all of their faith on a mod's benefit based solely on a full throttle run dyno chart? You guys know this though and I'm just preaching to the choir.
Rob is correct in that any added power from flow testing might only be a small amount. Flow testing a port with a rotor in front of it in various stages of rotation will allow a person to see how well their closing edge shape or opening edge shape flows but as you've pointed out doesn't tell everything. These are only showing us what happens at these points as the rotor is at these spots but this is important to know. It does allow a person to see what may or may not work well though. I have no doubt that over time a person can learn what shapes work the best and not need to constantly use a flowbench over and over again. You have lots of experience with porting and have seen firsthand what works and what doesn't and you know how to blend port shapes into runners. Many others don't though. A porting template shows a person a port's total size and timing but it't the work underneath, how well it is blended with the intake runner that matters the most. A flowbench can show you what works best but it's only if you have a rotor in front of it in various stages of rotation. If your intake port closes at 70 degrees and you have a rotor in front of it covering the port up to 55 degrees, you know good and well the shape of the transition from the top of the port from the runner underneath can affect how well air continues to flow into the engine. This makes a difference but of course it will show up as far less flow than a fully opened port. A port is only open all the way for a very short time and this isn't the most crucial aspect anyways. Enlargening a port runner based on flowbench numbers is also worthless. Thes best thing about the flowbench is being able to tell if you've gotten your ports flowing all the same as the rotor passes it. That is also important.
After you've worked on engines for as long as Rob has, I'm sure you can just port by hand well enough to get very close to what you could do with a flowbench. That is a knowledge and skill that he has acquired over the years. Consistency is a skill. Last year when talking about the flowbench with Rob at Sevenstock, he pretty much said he learned what he needed to years ago and no longer needs it as he can pretty much do it over and over again. That's a good thing but it's not to say that the flowbench was worthless. It had it's value at some point in the game. It's just another tool in a sea of useful tools. No one tool can be used to absolutely tell you everything. It's just like relying on a dyno chart telling you everything about your powerband. A full throttle run doesn't really tell you crap but using a dyno propely at different loads can tell you a lot. How many people here put all of their faith on a mod's benefit based solely on a full throttle run dyno chart? You guys know this though and I'm just preaching to the choir.
10-04-06, 07:45 PM
#77
7 Rx-7s since 1980
Thread Starter
Did I test the oil for fuel dilution? Don't take this the wrong way either but I'll cut to the chase before you reprimand me for not sending out oil out to lab I'll tell you that even by casual inspection it was evident that fuel was in the oil. Besides, it's hard to discount filling the oil catch can every three pulls when near 20psi. Other threads in other places show that I cut that blow-by down but never got rid of it and could not maintain consistent boost 20psi or above.
Don't bother going into all the different causes and contributing factors in this thread. I have covered them from the turbo seals being bad (ending up having the turbo rebuilt) drain being to small or kinked (went to AN-10 then AN-12 with no 90 degrees and smooth flow) to opening up the rear plate oil return port into the catch for more release of oil pan pressure, too boost controller, or other issues. Does Rob know about the blow-by issue? I called him and asked for his help on it. He offered to tear the engine apart to diagnose it for me. I have not called him recently and plan to soon.
Again, this is the third time and hopefully the last time, 99.99% of the life of that engine was logged and run with great care to avoid unplanned detonation. The only contributing factors to it's breaking the corner seal in the last hours of it's life is my frustration and lack of care on an empty tank of gas. Lost compression after that while no log. There is not another detonation problem...or bigger problems around unplanned detonation. You don't know me from Adam but rest assured that this is true.
Here is how you can contribute to this thread:
1) is it okay, normal, best case to use rotors in a rebuild that are dented in a rebuild? Do you see engines coming out of Pineapple that way?
2) is it common practice to mark the rotor faces with a letter or number punch?
3) would Pineapple mark a dented rotor face and re-use it in a rebuild?
I have asked others and have their opinions already. I need this information in guidance on what to do with the parts I have right now. Thanks and appreciate your time on this thread.
Like this:
Don't bother going into all the different causes and contributing factors in this thread. I have covered them from the turbo seals being bad (ending up having the turbo rebuilt) drain being to small or kinked (went to AN-10 then AN-12 with no 90 degrees and smooth flow) to opening up the rear plate oil return port into the catch for more release of oil pan pressure, too boost controller, or other issues. Does Rob know about the blow-by issue? I called him and asked for his help on it. He offered to tear the engine apart to diagnose it for me. I have not called him recently and plan to soon.
Again, this is the third time and hopefully the last time, 99.99% of the life of that engine was logged and run with great care to avoid unplanned detonation. The only contributing factors to it's breaking the corner seal in the last hours of it's life is my frustration and lack of care on an empty tank of gas. Lost compression after that while no log. There is not another detonation problem...or bigger problems around unplanned detonation. You don't know me from Adam but rest assured that this is true.
Here is how you can contribute to this thread:
1) is it okay, normal, best case to use rotors in a rebuild that are dented in a rebuild? Do you see engines coming out of Pineapple that way?
2) is it common practice to mark the rotor faces with a letter or number punch?
3) would Pineapple mark a dented rotor face and re-use it in a rebuild?
I have asked others and have their opinions already. I need this information in guidance on what to do with the parts I have right now. Thanks and appreciate your time on this thread.
Like this:
Originally Posted by Blake
I'm viewing them at full resolution. I need somthing much closer and sharper (the focus is kind of soft). If you have a flat bed scanner, you can just put the plate directly on the bed and scan it at high resolution. I've had a lot of success doing that.
You'll have to ask Rob, but it was approximately 3 years ago.
Just email them to me, if you can. Did you ever talk to Rob about the issue? How do you know it was blow-by? Did you test the oil for fuel dilution? And don't take this the wrong way but considering the detonation damage, you seemed to have bigger problems than blow-by.
Earlier in the thread, someone commented that the exhaust ports were huge. Appearances are a bit deceiving. Part of the reason is because they are squared-off for rapid opening and closing (not ideal for all applications, of course). Here is a picture showing before and after. Notice the chamfer on the closing edge. Like I said before, the chamfer is not necessary in ideal circumstances but it is good insurance if your oil temps spike and the apex seals warp as a result. A non-warped seal cannot catch, unless the port is too wide. As you can see in the picture, the scribed lines are the same width as the widest part of the stock port.
You'll have to ask Rob, but it was approximately 3 years ago.
Just email them to me, if you can. Did you ever talk to Rob about the issue? How do you know it was blow-by? Did you test the oil for fuel dilution? And don't take this the wrong way but considering the detonation damage, you seemed to have bigger problems than blow-by.
Earlier in the thread, someone commented that the exhaust ports were huge. Appearances are a bit deceiving. Part of the reason is because they are squared-off for rapid opening and closing (not ideal for all applications, of course). Here is a picture showing before and after. Notice the chamfer on the closing edge. Like I said before, the chamfer is not necessary in ideal circumstances but it is good insurance if your oil temps spike and the apex seals warp as a result. A non-warped seal cannot catch, unless the port is too wide. As you can see in the picture, the scribed lines are the same width as the widest part of the stock port.
10-04-06, 09:02 PM
#78
Originally Posted by Asleep
1) is it okay, normal, best case to use rotors in a rebuild that are dented in a rebuild? Do you see engines coming out of Pineapple that way?
2) is it common practice to mark the rotor faces with a letter or number punch?
3) would Pineapple mark a dented rotor face and re-use it in a rebuild?
I have asked others and have their opinions already. I need this information in guidance on what to do with the parts I have right now. Thanks and appreciate your time on this thread.
2) is it common practice to mark the rotor faces with a letter or number punch?
3) would Pineapple mark a dented rotor face and re-use it in a rebuild?
I have asked others and have their opinions already. I need this information in guidance on what to do with the parts I have right now. Thanks and appreciate your time on this thread.
Last edited by Blake; 10-04-06 at 09:24 PM.
10-05-06, 01:18 PM
#80
Notice the chamfer on the closing edge. Like I said before, the chamfer is not necessary in ideal circumstances but it is good insurance if your oil temps spike and the apex seals warp as a result. A non-warped seal cannot catch, unless the port is too wide. As you can see in the picture, the scribed lines are the same width as the widest part of the stock port.
10-05-06, 02:49 PM
#81
7 Rx-7s since 1980
Thread Starter
Originally Posted by Blake
No, we never use dented rotors like that and no, we do not stamp the faces. Some Mazdacomp rotors come stamped, but those are 4-digit numbers. No idea what that stamp was for, but someone else put it there. Dents like that are typically caused by coil crossfire or other *severe* ignition mis-timing. If you look at your trailing coils you may find carbon tracks. Every time we've seen dented rotors like that, replacing the trailing coils was the cure to avoiding a repeat incident. Now, we recommend new trailing coils to all our customers. Pricing is $160 each for the trailings and $170 for the leading. Cheap insurance.
See if I can work through the logic of it.
I have dent in the rotor.
I have a stamped number 3 on that rotor face.
Mazda does not build engines with dents in the rotor.
Mazda does not build engines with stamped numbers in the rotor faces.
This is the second time the engine has been apart.
First time was by an engine builder.
Second time by me now.
Denting is caused by pre/post detonation.
Marking is caused by a tool operated by a human.
The denting and marking is on the front rotor, gear side is to the left.
I did not mark the rotor with a number 3.
Here is the missing data.
Who marked the rotor when it was apart the first time?
When did the detonation occur: After the first build? Before the first build and marking?
The second question above really isn't important since either way the rotor was dented. Since it has been established that it would not be common to reuse a rotor dented in this fashion, there is probably a higher realistic probability that it detonated after the first build. So why is the rotor marked and who marked it?
I am at a "?"
Last edited by Asleep; 10-05-06 at 02:56 PM.
10-05-06, 02:50 PM
#82
7 Rx-7s since 1980
Thread Starter
No carbon tracks, tracks or markings, excessive dirt, with wire boots on or off, look pretty clean.
What about 4 of these coils (D580) out of the vette?
What about 4 of these coils (D580) out of the vette?
10-05-06, 02:52 PM
#83
7 Rx-7s since 1980
Thread Starter
Originally Posted by Zero R
I have seen quite a few with stamped numbers never quite sure what they were there for.
-S-
-S-
10-05-06, 03:22 PM
#84
All were used and out of various motors. So I have no history of what the rotors lives were. I have yet to come across a one owner first build type scenerio they all have remans or were built by someone previous. The number on the face wont hurt a thing but then you have a nice dent in the way.
-S-
-S-
10-05-06, 03:40 PM
#85
The marking and the dent are just coincidental. There are all sorts of cases of weird marks like that, but it has nothing to do with the dent. It's possible it was done at the factory or during a previous rebuild...I don't know. But even if it were a mark in the shape of the Virging Mary, I would say it's not a sign of anything. Correlation does not mean causation. This is a coincidence and no more.
Dents like those are not what I would call "common" (we see about 5 a year) but they are not all that uncommon either and the cause has always been tracked down to extreme pre-ignition, where the cylinder pressure more than doubles as the combustion tries to force the rotor backwards. Some people in the past have spectulated overheating can do that too, but that is not something our experience validates.
One of our customers is dyno-tuner Ralph Friend, who has two 670+ RWHP FDs. On the dyno, he actually witnessed a coil cross-fire incident that, upon breaking down the motor, revealed a dented rotor face. Interestingly, the apex seals remained in-tact, because while the pressure was very high, the seals were not shocked like a typical detonation incident. More commonly, however, we find some apex seal damage. In Ralph's case, as is pretty common, the trailing coils showed carbon tracking. The cross-fire was caused by voltage finding its way back to the harness and fooling the other trailing coil to fire simultaneously...kind of like a trailing ignition version of a wasted spark setup, but due to the rotor position, the ignition took place in the next chamber, which was still in the compression stroke. Replacing the coils appears to be the solution, even where there is no obvious carbon tracking. Bad wiring could also cause it.
The dented rotor was obviously a recent occurance; nobody would put it back in the engine like that and it's impossible to miss when cleaning the rotor.
Dents like those are not what I would call "common" (we see about 5 a year) but they are not all that uncommon either and the cause has always been tracked down to extreme pre-ignition, where the cylinder pressure more than doubles as the combustion tries to force the rotor backwards. Some people in the past have spectulated overheating can do that too, but that is not something our experience validates.
One of our customers is dyno-tuner Ralph Friend, who has two 670+ RWHP FDs. On the dyno, he actually witnessed a coil cross-fire incident that, upon breaking down the motor, revealed a dented rotor face. Interestingly, the apex seals remained in-tact, because while the pressure was very high, the seals were not shocked like a typical detonation incident. More commonly, however, we find some apex seal damage. In Ralph's case, as is pretty common, the trailing coils showed carbon tracking. The cross-fire was caused by voltage finding its way back to the harness and fooling the other trailing coil to fire simultaneously...kind of like a trailing ignition version of a wasted spark setup, but due to the rotor position, the ignition took place in the next chamber, which was still in the compression stroke. Replacing the coils appears to be the solution, even where there is no obvious carbon tracking. Bad wiring could also cause it.
The dented rotor was obviously a recent occurance; nobody would put it back in the engine like that and it's impossible to miss when cleaning the rotor.
10-05-06, 03:53 PM
#86
Originally Posted by Asleep
No carbon tracks, tracks or markings, excessive dirt, with wire boots on or off, look pretty clean.
What about 4 of these coils (D580) out of the vette?
10-05-06, 06:13 PM
#87
7 Rx-7s since 1980
Thread Starter
Originally Posted by Blake
Well, that doesn't mean it wasn't happening, we just don't have the most obvious outward manifestation of the occurance. It could also have happended elsewhere in the system, like plug wire to plug wire, or even perhaps as a result of RF interference. I believe you said you were running 20 PSI. At those pressures it becomes a challenge to make a spark in the chamber, so the voltage will try to find any more convenient path to ground. Like a chain, only the weakest link needs to fail.
What about them? Were you running them at the time or are you asking if you should do so in the future?
What about them? Were you running them at the time or are you asking if you should do so in the future?
Your statement on the coils and the replacement costs was only one option. There are other options out there. I WAS running the the stock coils, new wires (when the engine went in) and the HKS Twinpower CDI amp. You have a negative experience about the setup I ran or running those alternative coils, let me know.
10-05-06, 07:25 PM
#88
Originally Posted by Asleep
Have to start somewhere and start with the obvious and work into the oblvious. Visible inspection is the most common first step into any type of testing. You can discount the lack of visible evidence, but it is what it is.
Your statement on the coils and the replacement costs was only one option. There are other options out there. I WAS running the the stock coils, new wires (when the engine went in) and the HKS Twinpower CDI amp. You have a negative experience about the setup I ran or running those alternative coils, let me know.
10-08-06, 07:48 PM
#89
Originally Posted by Asleep
No carbon tracks, tracks or markings, excessive dirt, with wire boots on or off, look pretty clean.
What about 4 of these coils (D580) out of the vette?
What about 4 of these coils (D580) out of the vette?
10-09-06, 12:47 PM
#90
multipersonality disorder
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Originally Posted by Blake
Those Corvette coils may or may not be suitable...I have no direct experience with them and don't have the specs handy to review.
the ls1/2 coils need too high a charge time to be effective in wasted leading spark mode, but they work fine for one coil-per-plug, direct fire applications, like the e8 and 11's.
10-11-06, 01:55 AM
#92
Senior Member
Interesting thread! I have use a Flowquick bench since 1997 and it's my companion since 1987 Mikael that done all the porting and flowing. I can say the flowbench is a great tool when you use it with a rotor and suck air over the trailing plug. On a typical stage 1 streetport we gain 20 % more flow when raising (later closing) the streetport from 51mm to 57mm and no more duration. We have no exact figures on the dyno but the cars are always faster on 1)4 mile speed when doing the stage 1 port. Stage 2 a Monsterport gives almost 30% more intake flow than stock. Stage 1 exhaust port is stock shape but a little more overlap and stage 2 has just as Rick's square ports. Just my 2 cents of opinion.
/Lasse
/Lasse
10-11-06, 04:55 AM
#93
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Originally Posted by Lasse wankel
On a typical stage 1 streetport we gain 20 % more flow when raising (later closing) the streetport from 51mm to 57mm and no more duration...
this seems to be an oxymoron. can you clarify how you close the port later without adding duration?
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