FI Discussion Thread for the Boost Atheists
i just started reading Maximum Boost and Street Turbocharging tonight. What bits i have skimmed so far have re-enforced my understanding of the physics involved with turbo/super chargers.
I think he should DO IT!! spin/ or try to spin it up to 14PSI, just stand behind a blast door. As funny as it would be in some ways if you didnt......, losing life or limb is a bit much just to prove physics owns your *** and there is nothing you can ever do about that.
I think he should DO IT!! spin/ or try to spin it up to 14PSI, just stand behind a blast door. As funny as it would be in some ways if you didnt......, losing life or limb is a bit much just to prove physics owns your *** and there is nothing you can ever do about that.
I just dont understand "why" someone would want to do this---but then again more than one of my family think i am crazy just installing a s.c.to begin with. I totally agree with RG--i dislike high rpm in cars.
oldscdragger
oldscdragger
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What more do you want? Why would you expect Lysholm to release the findings of their internal testing? Maybe you should write to them yourself and talk to their engineers.
And outside of "some guy I know once did it" you have yet to produce a single piece of emperical evidance to say any of us is wrong. And even in your "some guy" story all your facts were wrong. So why would I think anything else was correct?
I don't really know what else to tell you. If you think the OEM's of this machinery are just yanking your chain with their numbers then go prove them wrong.
And outside of "some guy I know once did it" you have yet to produce a single piece of emperical evidance to say any of us is wrong. And even in your "some guy" story all your facts were wrong. So why would I think anything else was correct?
I don't really know what else to tell you. If you think the OEM's of this machinery are just yanking your chain with their numbers then go prove them wrong.
Outside of Lysholm's charts, where is your "single piece of emperical evidance" to say I am wrong.
It's easy not to believe someone when you don't want to. If you choose to believe the propaganda on the history of the twin-screw that has been posted here I will not try to persuade you otherwise.
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From: Away from the fruits of my labor
There is nothing to interpret here. Its not a question of "Can you spin this blower to 15k and have it survive?". Its just the question "Why?".
If you are just looking to say it can be done, I'll save you the effort: Probably.
But you have accomplished nothing.
If you are just looking to say it can be done, I'll save you the effort: Probably.
But you have accomplished nothing.
And you are also right that I have accomplished nothing. But I never believed for one second that I would convince anyone here to change their mind as that was not my intent.
As to the why, I don't intend to push my blower to 25k rpms; Not because i'm afraid of it blowing up, but because I do agree with you, RG, and others in regards to longevity. Not only for the blower, but my motor as well.
Last edited by morkusyambo; Jan 5, 2008 at 12:24 PM.
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Spinning a supercharger past it's rated speed is no different than spinning an engine past it's rated speed. In the case of a rotary you have 2 problems with this. The first is internal clearances between the sides of the rotors and the housings. This is an issue because the long distance between the front and rear bearings is unsupported. At high speeds the eccentric shaft flexes. Actually it always does but above a certain point it does so bad enough that the rotors actually hit the housings. The rotors on a supercharger would experience the same thing. They too run minimal clearance between rotors but at high speeds the flex will cause them to contact each other at some point. When this happens you'll be lucky if the only thing to break is the supercharger.
The other problem with revving a rotary real high is with the bearings. They don't live long as they spin faster and faster. As I said, bearing stresses go up with the square of the rpm. That means above a certain point, a few more rpm is a ton more stress and it only gets worse for every rising rpm. This is again the same thing that happens with the rotors in a supercharger. The question is will the bearings seize before the rotors contact each other or the casing around them?
This isn't even talking about efficiency as far as compression is concerned. There are ways to modify roots blowers that make them more efficient past the rated max blower speed. That is from the standpoint of compression. However in order to accomplish this, people take them apart, install tougher bearings and increase the clearances. This allows them to spin them faster to get more out of them. The downside is a loss down low from added clearance.
There's far more to it than jut spinning it faster because you think it can do it. Can it? Yes. How long? Maybe a minute. Maybe an hour. Maybe a day. Maybe more. There is one absolute fact that doesn't need any documentation and that is you are drastically going to shorten the lifespan of the blower. You can not change that fact. Keep in mind that at any blower, turbo, etc rated max speed and load rating, you are already losing efficiency compared to it's peak spot. Again this doesn't need written verification. That's how they are designed.
If you want to take a blower past it's rated speed limit and not risk hurting it, you have to modify it for this application. If you don't it's like taking a rotary to 16,000 rpm because you think it can.
There is no more documentation needed to show this is a bad idea. It's already been shown and the trend applies to every other blower out there. If you do it and get an engine failure from it, don't blame it on the supercharger manufacturer. I'd actually go a long way out of my way just to tell them about this thread if that ever happened. It's a bad idea and if your opinion says otherwise, you're wrong!
The other problem with revving a rotary real high is with the bearings. They don't live long as they spin faster and faster. As I said, bearing stresses go up with the square of the rpm. That means above a certain point, a few more rpm is a ton more stress and it only gets worse for every rising rpm. This is again the same thing that happens with the rotors in a supercharger. The question is will the bearings seize before the rotors contact each other or the casing around them?
This isn't even talking about efficiency as far as compression is concerned. There are ways to modify roots blowers that make them more efficient past the rated max blower speed. That is from the standpoint of compression. However in order to accomplish this, people take them apart, install tougher bearings and increase the clearances. This allows them to spin them faster to get more out of them. The downside is a loss down low from added clearance.
There's far more to it than jut spinning it faster because you think it can do it. Can it? Yes. How long? Maybe a minute. Maybe an hour. Maybe a day. Maybe more. There is one absolute fact that doesn't need any documentation and that is you are drastically going to shorten the lifespan of the blower. You can not change that fact. Keep in mind that at any blower, turbo, etc rated max speed and load rating, you are already losing efficiency compared to it's peak spot. Again this doesn't need written verification. That's how they are designed.
If you want to take a blower past it's rated speed limit and not risk hurting it, you have to modify it for this application. If you don't it's like taking a rotary to 16,000 rpm because you think it can.
There is no more documentation needed to show this is a bad idea. It's already been shown and the trend applies to every other blower out there. If you do it and get an engine failure from it, don't blame it on the supercharger manufacturer. I'd actually go a long way out of my way just to tell them about this thread if that ever happened. It's a bad idea and if your opinion says otherwise, you're wrong!
It's great that you are willing to stick up for the blower manufacturers, but as I have said more than once allready I never had any intentions of doing this. I only wanted to discuss the possibility, which we certainly have.
I want to thank those who participated in this conversation for keeping it civil, not attempting to shoot holes in each others credibility as opposed to the original idea, and not taking any of this personally.
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Understanding it doesn't make the WTF go away...still don't know what all the D**K waving was all about.......Kinda reminds me of the " fighting with a handicapped person" kinda thing 
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yep i thought so- i wondered about your use of the word "indoctrination" .. if you have a different history to relate that counters what i posted please do. show where what i have posted is wrong. thats how i understand the history to be , if its wrong i would like to know. you are making insinuations while asking others to provide proof of physics. show me your proof.
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OHHHH....wait a minute...both you numb nuts are wrong.
Rotary Crawfish
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From: Da swamps of La.
I mostly understand the topic but was wtf on the why can't I turn my blower XXXX speed and not have a grenade for like 3 pages.
I hoped this would be a clean thread without the need for hipboots and safety goggles.
I hoped this would be a clean thread without the need for hipboots and safety goggles.
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From: Away from the fruits of my labor
yep i thought so- i wondered about your use of the word "indoctrination" .. if you have a different history to relate that counters what i posted please do. show where what i have posted is wrong. thats how i understand the history to be , if its wrong i would like to know. you are making insinuations while asking others to provide proof of physics. show me your proof.
All I am willing to say is that I was not insinuating you made that up, as I am sure you received that history from someone/somewhere that you know personally in the engineering community.
I never claimed to be an authority on the subject, but the man I trust the most has a slightly different take than you guys on the history/engineering of superchargers. He takes the occasional look at this forum when I forward him the links, but he's only interested in making sure I am not led astray, not to mention there is no way for him to profit from it or make himself credible as he has nothing to prove to me.
He's not going to post on here, and the bottom line(for me) is his integrity, not to mention i've seen and "felt" the application of twin-screws that I have "talked" about here on multiple daily-driven vehicles.
If that is not enough for some of you, then there is nothing more I can offer.
Furthermore, if your concern is for others not trying something you believe to be dangerous(including myself), I respect that.
Last edited by morkusyambo; Jan 7, 2008 at 05:25 PM.
morkusyambo - have you ever read "Maximum Boost" by Corky Bell? All the "proof" you need is in there, plus the compressor map posted above.
If someone else does the math for you, you're still not going to be convinced.
Read the book and plug in the numbers, you will see why MM is telling you this is a bad idea.
If someone else does the math for you, you're still not going to be convinced.
Read the book and plug in the numbers, you will see why MM is telling you this is a bad idea.
I just got back from my trip from Macon Ga to Pettit last night. The final "tuning for my S.C. install.
For those in the know--I now have no cel and i have a tail. I also have a grin on my face about 2 miles wide. Gas mileage is about 20mpg now! Idle is better than stock. Power......welll maybe a little bit?
Cam's business is sure growing. Says he is shipping 2 kits out to Australia. Got his shop air installed.
I help him assess problems on a sweet 2nd gen 3 rotor (needed some heatshielding and i saw that the front pulley had a wobble(NOT GOOD) that a guy with an Australian accent brought in on a truck He wouldnt pay me a consultation fee however.......hehehehe.
He gave my install " thumbs up".
I saw the value of having the car for the flash rather than just sending in the ecu. There was about 4 RX8's there with the kit and we where taking all of them out to monitor the car's response---diag one with a leaking vacuum line(guy didnt have a clue he had a leak) that was causing the car to add too much fuel to compensate.
I can say with certainty now that ECU tuning is no longer a problem for any kind of kit. Cam and his "tuner" (Bill) have it figured out. End of story.
Car is MUCH more drivable. the int x wasnt bad now and i am not knocking it at all---that unit that Scott built started this entire thing and we couldnt be where we are today without it. But, now the car has a smoother throttle response in acceleration partial and full, and it idles steady at 1.1K---even with air on! stft, ltft barometric sensors, start up(cranks like a oem car now) all fully functional.
At the end of the day i took Bill back to his little shop and HOLY BE JESUS! Not only does he have Formula cars around(plus the one he owns and drives---would you believe a 1.2 min at Road Atlanta--4 G's in the corner and over 2400 lbs of downforce on a 1400lb car with approx 720 hp!! He had some track data and showed me a part of it and where in my na rx8 i was running maybe 128--- he was hitting 180!! he was going faster through some turns than I am going on the straights! 180mph in an open cockpit car---wooooo.
Plus---would you believe a 1 rotor---thats right a one rotor--- shifter cart that is air cooled?
All in all --when it gets to the point in which you think you know a little you meet guys like this that show you exactly how much you do know.
oldscdragger
For those in the know--I now have no cel and i have a tail. I also have a grin on my face about 2 miles wide. Gas mileage is about 20mpg now! Idle is better than stock. Power......welll maybe a little bit?
Cam's business is sure growing. Says he is shipping 2 kits out to Australia. Got his shop air installed.
I help him assess problems on a sweet 2nd gen 3 rotor (needed some heatshielding and i saw that the front pulley had a wobble(NOT GOOD) that a guy with an Australian accent brought in on a truck He wouldnt pay me a consultation fee however.......hehehehe.
He gave my install " thumbs up".
I saw the value of having the car for the flash rather than just sending in the ecu. There was about 4 RX8's there with the kit and we where taking all of them out to monitor the car's response---diag one with a leaking vacuum line(guy didnt have a clue he had a leak) that was causing the car to add too much fuel to compensate.
I can say with certainty now that ECU tuning is no longer a problem for any kind of kit. Cam and his "tuner" (Bill) have it figured out. End of story.
Car is MUCH more drivable. the int x wasnt bad now and i am not knocking it at all---that unit that Scott built started this entire thing and we couldnt be where we are today without it. But, now the car has a smoother throttle response in acceleration partial and full, and it idles steady at 1.1K---even with air on! stft, ltft barometric sensors, start up(cranks like a oem car now) all fully functional.
At the end of the day i took Bill back to his little shop and HOLY BE JESUS! Not only does he have Formula cars around(plus the one he owns and drives---would you believe a 1.2 min at Road Atlanta--4 G's in the corner and over 2400 lbs of downforce on a 1400lb car with approx 720 hp!! He had some track data and showed me a part of it and where in my na rx8 i was running maybe 128--- he was hitting 180!! he was going faster through some turns than I am going on the straights! 180mph in an open cockpit car---wooooo.
Plus---would you believe a 1 rotor---thats right a one rotor--- shifter cart that is air cooled?
All in all --when it gets to the point in which you think you know a little you meet guys like this that show you exactly how much you do know.
oldscdragger
Yes i do--i have always felt the idle was too slow from the factory---earlier on in the forum (maybe a year ago?) there was even a small discussion on how to get a faster idle---utilizing the neutral switch, drilling the TB butterfly, etc. The idle speed is by design, not because they had too.
Interesting observation--as most know I originally installed the INT x with the kit. I have no c/o with it. Scott had installed a base map for me designed for the s.c. It ran very good. it ran strong. I did have some idle tweaking to do and that is all.
What was interesting was once I got to Florida , about 500 miles further south--the car ran better, the idle was better, etc. Climate and altitude changes. I knew the car would run different with the climate and altitude change. but, it is one thing to know this, it is another to experience it.
Now with the flash--as expected--- my car runs the same in Ga as it did in Florida.
As far as a/f's and timing-- the flash is not anywhere near the "edge". Very safe settings.
Bill even tweaked my TPS settings to make the car respond in the way i wanted it too.
oldscdragger
Interesting observation--as most know I originally installed the INT x with the kit. I have no c/o with it. Scott had installed a base map for me designed for the s.c. It ran very good. it ran strong. I did have some idle tweaking to do and that is all.
What was interesting was once I got to Florida , about 500 miles further south--the car ran better, the idle was better, etc. Climate and altitude changes. I knew the car would run different with the climate and altitude change. but, it is one thing to know this, it is another to experience it.
Now with the flash--as expected--- my car runs the same in Ga as it did in Florida.
As far as a/f's and timing-- the flash is not anywhere near the "edge". Very safe settings.
Bill even tweaked my TPS settings to make the car respond in the way i wanted it too.
oldscdragger
Yeah, the Int-X's Achilles Heel is its inability to react to density changes.
Changes in altitude, humidity and temperature make its handling of low airflow very touchy.
The idle speed issue was a point of contention for a while, mostly because it was so unstable. Now that Mazda got that worked out with the last flash, I don't think it affects people the same way.
A flat 850 RPM is perfect. Even 900 would be pushing it.
1100 RPM is just to high for a street car.
Changes in altitude, humidity and temperature make its handling of low airflow very touchy.
The idle speed issue was a point of contention for a while, mostly because it was so unstable. Now that Mazda got that worked out with the last flash, I don't think it affects people the same way.
A flat 850 RPM is perfect. Even 900 would be pushing it.
1100 RPM is just to high for a street car.
Did i mention my idle does not change when i kick in the a/c?
Jeff, what are the numbers that show the negative affects in regard to that 200rpm difference at idle ? I'm curious.
oscd
Jeff, what are the numbers that show the negative affects in regard to that 200rpm difference at idle ? I'm curious.
oscd
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From: Misinformation Director - Evolv Chicago
Anybody experiment with this, or discuss the option with Scott?
Since the Ve of the motor at 1000 RPM is only something like 50%, fuel used down there is already going out the tail pipe. Multiply that by 1.30 and you have that much more waste.
However, my issue with a high idle is simply drivability and poor comparison to OE.
My idle doesn't move when my A/C comes on, either.
Microtech has an option to add a temp sensor to compensate for this...doesn't come with the Int-X, but I can't see why it can't be incorporated into the Mazsport setup...that written, from Microtech's manual it appears to be a blanket +/- % for both fueling and ignition.
Anybody experiment with this, or discuss the option with Scott?
Anybody experiment with this, or discuss the option with Scott?
The problem is that it is too granular.
Last edited by MazdaManiac; Jan 8, 2008 at 04:11 PM.
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From: Misinformation Director - Evolv Chicago