View Poll Results: which is faster in stock form, be honest.
Rx-7 FD
283
41.13%
Supra TT
323
46.95%
300ZX TT
23
3.34%
3000GT VR4
59
8.58%
Voters: 688. You may not vote on this poll
Are 3mm apex seals better than 2mm?
05-11-02, 01:18 AM
#27
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Anybody here see the Scoot FD? The one in the Option video that breaks 200mph in New Zealand. The one that hits like 710ps on the dyno with four guys sitting on the back. That one had 2mm seals. 'nuff said. No wait, not 'nuff said. If detonation is an issue and you are not over 700hp, then get your car on a dyno and spend some money to tune it right. 3mm seals will not make an engine "bulletproof" or even more durable. Something will give if there's detonation.
jerk_racer@hotmail.com
jerk_racer@hotmail.com
05-11-02, 10:16 PM
#28
rx7
Originally posted by Mid_KnightFD
That's the first time I've ever heard that. Supra's suck off the line, the only thing there good at is makeing big HP easly. They do handle ok for a big car, but they dont have that go kart feal like a real sport's car.
As far as the apex seal's go, if you dont have 3mm seals then of course your going to come up with all sorts of justification's why you dont need them
Better safe than sorry
That's the first time I've ever heard that. Supra's suck off the line, the only thing there good at is makeing big HP easly. They do handle ok for a big car, but they dont have that go kart feal like a real sport's car.
As far as the apex seal's go, if you dont have 3mm seals then of course your going to come up with all sorts of justification's why you dont need them
Better safe than sorry
05-12-02, 10:41 PM
#29
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Originally posted by Jerk_Racer
Anybody here see the Scoot FD? The one in the Option video that breaks 200mph in New Zealand. The one that hits like 710ps on the dyno with four guys sitting on the back. That one had 2mm seals. 'nuff said. No wait, not 'nuff said. If detonation is an issue and you are not over 700hp, then get your car on a dyno and spend some money to tune it right. 3mm seals will not make an engine "bulletproof" or even more durable. Something will give if there's detonation.
jerk_racer@hotmail.com
Anybody here see the Scoot FD? The one in the Option video that breaks 200mph in New Zealand. The one that hits like 710ps on the dyno with four guys sitting on the back. That one had 2mm seals. 'nuff said. No wait, not 'nuff said. If detonation is an issue and you are not over 700hp, then get your car on a dyno and spend some money to tune it right. 3mm seals will not make an engine "bulletproof" or even more durable. Something will give if there's detonation.
jerk_racer@hotmail.com
sweet, I would just lose the wheel covers in the back.
05-23-02, 01:46 AM
#32
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According to Rotary Power, 3 mm seals work best. Jeff has built over 1000 engines, and he uses 3 mm. He says it's not a coinsidense that the up to '85 the rx-7 was so reliable. He says that Mazda had no problems...since then it's gone south. He says the 3 mm will handle that split second of detonation just enough for you to get off the throttle...that split second can save you an engine. Better safe than sorry...oh and he says the difference isn't THAT big where it would rough up the housing.
05-24-02, 05:17 PM
#33
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To those who have the Motor Trend articles- could you post the actual times they got at Willow Springs? I assume they were all with the same driver? Just curious, I go there a lot.
05-24-02, 08:56 PM
#34
Lives on the Forum
Originally posted by 93TTRX7
According to Rotary Power, 3 mm seals work best. Jeff has built over 1000 engines, and he uses 3 mm.
According to Rotary Power, 3 mm seals work best. Jeff has built over 1000 engines, and he uses 3 mm.
He says it's not a coinsidense that the up to '85 the rx-7 was so reliable.
He says that Mazda had no problems...since then it's gone south.
He says the 3 mm will handle that split second of detonation just enough for you to get off the throttle...that split second can save you an engine. Better safe than sorry...oh and he says the difference isn't THAT big where it would rough up the housing.
I doubt you could react fast enough to lift off.  Detonation is a progressive condition which starts off inaudible to the human ear - this is why we use pieze microphones to detect low levels of detonation.  You are implying about audible detonation, right?  Most humans can react at 0.2 seconds - is this your "split second"?  At 6,000RPM, the rotary engine would've spun a whole revolution in 0.01 seconds; this means by the time you react, the e-shaft would've spun at least 20 revolutions, or the rotors spun almost 7 times around.  Or are you an F1 driver level type reflexes, which get cut down in half - which means your down to 10 revolutions of the engine?  I believe the magic number was 217% stronger across the thickness of the seal moving up from 2mm to 3mm.  Detonation pushed normal combustion pressures from an average of 1,000psi to over 10 times that.  Yes, 3mm seals will give you another margin of safety, but somehow I doubt your reflexes are fast enough to save almost 10,000psi of force against a 3mm cast steel apex seal.
My experience - I use stock 2mm, 3-piece Mazda stock OEM apex seals in my car.  The engine has been rebuild (3 times) over the past 30k miles or so.  In between then, I've done some "bone-head" things like:  run with no trailings, run with no leadings, crossed trailing spark plugs wires.  These lead to elevated EGT's, and the crossed T spark plugs leads will reward you with a nice TINK under heavy boost (14psi).  I've gotten the hard TINK at least half a dozen times...on purpose.  My engine is still intact, and the stock apex seals show no signs of obvious damage.  If you're wondering why the engine was rebuilt so many times within a short amount of time, it was due to oil lubrication problems that killed the oil control o-rings.  The engine has seen numerous inaudible signs of detonation (I run a J&S Safeguard) which you would never hear.  I don't count my fast reflexes to a living engine; I put the laurels squarely on the "new" stock OEM Mazda apex seals for that one.
-Ted
05-24-02, 10:02 PM
#35
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Originally posted by RETed
Define "split second"...
I doubt you could react fast enough to lift off.  Detonation is a progressive condition which starts off inaudible to the human ear - this is why we use pieze microphones to detect low levels of detonation.  You are implying about audible detonation, right?  Most humans can react at 0.2 seconds - is this your "split second"?  At 6,000RPM, the rotary engine would've spun a whole revolution in 0.01 seconds; this means by the time you react, the e-shaft would've spun at least 20 revolutions, or the rotors spun almost 7 times around.  Or are you an F1 driver level type reflexes, which get cut down in half - which means your down to 10 revolutions of the engine?  I believe the magic number was 217% stronger across the thickness of the seal moving up from 2mm to 3mm.  Detonation pushed normal combustion pressures from an average of 1,000psi to over 10 times that.  Yes, 3mm seals will give you another margin of safety, but somehow I doubt your reflexes are fast enough to save almost 10,000psi of force against a 3mm cast steel apex seal.
My experience - I use stock 2mm, 3-piece Mazda stock OEM apex seals in my car.  The engine has been rebuild (3 times) over the past 30k miles or so.  In between then, I've done some "bone-head" things like:  run with no trailings, run with no leadings, crossed trailing spark plugs wires.  These lead to elevated EGT's, and the crossed T spark plugs leads will reward you with a nice TINK under heavy boost (14psi).  I've gotten the hard TINK at least half a dozen times...on purpose.  My engine is still intact, and the stock apex seals show no signs of obvious damage.  If you're wondering why the engine was rebuilt so many times within a short amount of time, it was due to oil lubrication problems that killed the oil control o-rings.  The engine has seen numerous inaudible signs of detonation (I run a J&S Safeguard) which you would never hear.  I don't count my fast reflexes to a living engine; I put the laurels squarely on the "new" stock OEM Mazda apex seals for that one.
-Ted
Define "split second"...
I doubt you could react fast enough to lift off.  Detonation is a progressive condition which starts off inaudible to the human ear - this is why we use pieze microphones to detect low levels of detonation.  You are implying about audible detonation, right?  Most humans can react at 0.2 seconds - is this your "split second"?  At 6,000RPM, the rotary engine would've spun a whole revolution in 0.01 seconds; this means by the time you react, the e-shaft would've spun at least 20 revolutions, or the rotors spun almost 7 times around.  Or are you an F1 driver level type reflexes, which get cut down in half - which means your down to 10 revolutions of the engine?  I believe the magic number was 217% stronger across the thickness of the seal moving up from 2mm to 3mm.  Detonation pushed normal combustion pressures from an average of 1,000psi to over 10 times that.  Yes, 3mm seals will give you another margin of safety, but somehow I doubt your reflexes are fast enough to save almost 10,000psi of force against a 3mm cast steel apex seal.
My experience - I use stock 2mm, 3-piece Mazda stock OEM apex seals in my car.  The engine has been rebuild (3 times) over the past 30k miles or so.  In between then, I've done some "bone-head" things like:  run with no trailings, run with no leadings, crossed trailing spark plugs wires.  These lead to elevated EGT's, and the crossed T spark plugs leads will reward you with a nice TINK under heavy boost (14psi).  I've gotten the hard TINK at least half a dozen times...on purpose.  My engine is still intact, and the stock apex seals show no signs of obvious damage.  If you're wondering why the engine was rebuilt so many times within a short amount of time, it was due to oil lubrication problems that killed the oil control o-rings.  The engine has seen numerous inaudible signs of detonation (I run a J&S Safeguard) which you would never hear.  I don't count my fast reflexes to a living engine; I put the laurels squarely on the "new" stock OEM Mazda apex seals for that one.
-Ted
05-28-02, 03:59 AM
#36
Banned. I got OWNED!!!
I can back ted 100%, I had a T2 detonate so hard that it sound like a machine gun going off, and the fucked thing is we did this three times !
pulled up in the drive and noticed a drip of oil from the rear of the engine, cracked rear plate.
Stripped the motor, checked the seals under a microscope (yes I am a freak!) No Problem, re used them ! Engine is still going strong to this day on 2mm stock seals.
I will never use 3mm unless the rotors have alot invested in them (ie snap rings and race cleranced) and the customer cannot afford new units, then and ONLY then will I machine the slots to take the inferior 3mm seals.
PS. Only my opinions here so do not get to excited, but I have used all types of seals (from std to Iannetti) including ones I have made my self and find the std 2mm three piece design to be excellent.
Do a search on this topic to see all my reasons why and what the limitations are of these as I have gone into great length on this subject before, suffice to say if you respect the "thermal" limits of the stock seal you will never need to think of another type.
pulled up in the drive and noticed a drip of oil from the rear of the engine, cracked rear plate.
Stripped the motor, checked the seals under a microscope (yes I am a freak!) No Problem, re used them ! Engine is still going strong to this day on 2mm stock seals.
I will never use 3mm unless the rotors have alot invested in them (ie snap rings and race cleranced) and the customer cannot afford new units, then and ONLY then will I machine the slots to take the inferior 3mm seals.
PS. Only my opinions here so do not get to excited, but I have used all types of seals (from std to Iannetti) including ones I have made my self and find the std 2mm three piece design to be excellent.
Do a search on this topic to see all my reasons why and what the limitations are of these as I have gone into great length on this subject before, suffice to say if you respect the "thermal" limits of the stock seal you will never need to think of another type.
05-28-02, 08:00 AM
#37
In my opinion!
2mm always out perform 3mm in many areas!
They handle more heat may it be from rotor housing temperature, a/f mixture or advanced ignition timing!
They can operate at higher rpms due to lower mass!
They require less lubrication!
Most of all you'll always make more HP due to them conforming to housing ware etc. and less friction thus leading to better sealing.
This is not saying that 3mm apex seals can't operate at the same conditions as above.
They do offer some greater detonation protection over 2mm's but how much depends on power output and most of all your right foot! That added safety margin do come with a cost though. You might not crack a 3mm apex seal but the chattering marks left inside the housing from detonation would decrease service life. Also in continous high rpm use their performance is less than desired. Let's say a 3mm would always float at a lower rpm than a 2mm would.
In elevated temperature use they also tend to fail much easier than the 2mm's. I've never seen a 2mm seal warped! The single spring design of the 3mm also tend to flatten out easier after use.
All things being equal the 3mm would perform on par with the 2mm most of the time but in the same working enviroment when operating at peak levels(heat,rpm etc.) the 3mm would require a richer a/f mixture, more lubrication, cooler rotor and rotor housing operating temperatures etc. to enjoy a healthy life.
They both can do the job. Both have their superior and inferior qualities. It's up to you to meet the requirements of each to perform at it's best!
crispeed
87 Rx-7 TII
9.204@150.47mph
2600lbs
un-tubbed
2mm always out perform 3mm in many areas!
They handle more heat may it be from rotor housing temperature, a/f mixture or advanced ignition timing!
They can operate at higher rpms due to lower mass!
They require less lubrication!
Most of all you'll always make more HP due to them conforming to housing ware etc. and less friction thus leading to better sealing.
This is not saying that 3mm apex seals can't operate at the same conditions as above.
They do offer some greater detonation protection over 2mm's but how much depends on power output and most of all your right foot!
That added safety margin do come with a cost though. You might not crack a 3mm apex seal but the chattering marks left inside the housing from detonation would decrease service life. Also in continous high rpm use their performance is less than desired. Let's say a 3mm would always float at a lower rpm than a 2mm would.In elevated temperature use they also tend to fail much easier than the 2mm's. I've never seen a 2mm seal warped!
The single spring design of the 3mm also tend to flatten out easier after use.All things being equal the 3mm would perform on par with the 2mm most of the time but in the same working enviroment when operating at peak levels(heat,rpm etc.) the 3mm would require a richer a/f mixture, more lubrication, cooler rotor and rotor housing operating temperatures etc. to enjoy a healthy life.
They both can do the job. Both have their superior and inferior qualities. It's up to you to meet the requirements of each to perform at it's best!
crispeed
87 Rx-7 TII
9.204@150.47mph
2600lbs
un-tubbed
05-28-02, 12:12 PM
#38
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Not once have I ever seen a Bone Stock Supra run better than a 13.7 stock and I've seen alot of supras run....
My STOCK 93 RX7 ran a 13.4 @102 bone stock with a 2.0 60 foot......... 13.9 stock my *** !!!!maybe automatic
My STOCK 93 RX7 ran a 13.4 @102 bone stock with a 2.0 60 foot......... 13.9 stock my *** !!!!maybe automatic
05-30-02, 08:51 PM
#39
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i know this thread has to be old cause i dont remeber it and it says i already voted on the poll..hahah..way to bring it back form the dead...i swore this subject has been highly debated on several different occasions..but maybe its just me?
06-04-02, 12:49 PM
#40
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There was a thread about this a year ago and I said STOCK 2mm are best. This is the only time I have ever disagreed with Jeff MCaul at Rotary Power. Most of the reasons have been adressed by Peter, Ted and Chris...
06-15-02, 10:07 AM
#41
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If you want reliablity, go with what you had; 2mm. If your THAT far out of tolerance to where you HAVE to use the 3mm then, IMHO, you are only trying to polish a turd, **** is very very hard to do 
!
!
06-16-02, 03:44 AM
#42
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Sorry guys havent read the whole thread, 2mm seals were developed by Mazda to be an improvement, I ran 8.18@164mph in a 2270lb car which needed around 800hp to do. I consistently turned the engine to 12K and ran 2mm apex seals straight from my local Mazda dealer. Yes that had over 30lb boost and a shot of Nitrous. We have never fitted 3mm seals int a turbo at Maztech and do not find a need for them. I would prefer to utilise their efficiency and run less boost.
My two cents!
Anthony
My two cents!
Anthony
06-28-02, 07:50 AM
#45
Rotary Freak
Originally posted by Anthony Rodrigues
Street Port at that time.
Street Port at that time.
06-28-02, 10:31 AM
#46
BDC Motorsports
I have an engine I'm about to port and rebuild for a buddy of mine but I've been wrestling with whether or not I should go ahead and modify his rotors to 3mm or convince him to stick w/ 2mm. After reading this thread, I'm leaning towards the 2mm.
B
B
06-28-02, 08:02 PM
#47
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Also, what about the springs for the stock apex seals. Are they strong enough for high horsepower/ high rpm applications? Would the Hurley 2mm race seals be a better option than the stock?
06-29-02, 08:33 PM
#48
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Just on a side not, which is fairly irrelevent to the debate, what type of seals are the big drag racers like Abel Ibarra, Rafaelitto, Siguel, and Marcos Acosta using? What type of seals were used in the 787b's R26B engine?
06-30-02, 12:24 AM
#49
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Originally posted by fdracer
Also, what about the springs for the stock apex seals. Are they strong enough for high horsepower/ high rpm applications? Would the Hurley 2mm race seals be a better option than the stock?
Also, what about the springs for the stock apex seals. Are they strong enough for high horsepower/ high rpm applications? Would the Hurley 2mm race seals be a better option than the stock?
07-01-02, 08:07 AM
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Hey Judge,
You wouldnt be edging me on would you buddy? There is something in the pipeline that I will speak to you about this month when I'm over. I hope that the accident hasnt hurt my chances of racing over there with you guys. I know that it has set me back financially though. My involvement with some of the top guys will make sure that I stay in touch with the big boys.
Thanks-Anthony
You wouldnt be edging me on would you buddy? There is something in the pipeline that I will speak to you about this month when I'm over. I hope that the accident hasnt hurt my chances of racing over there with you guys. I know that it has set me back financially though. My involvement with some of the top guys will make sure that I stay in touch with the big boys.
Thanks-Anthony