how much HP stock 20B shaft could handle?
10-12-05, 11:22 PM
#4
T-von, wouldn't a more accurate answer depend on what setup you're running? If you're running the stock (or upgraded) sequential twins, it's in teh 400hp range IIRC (the whole deal w/ the e-shaft snapping w/ the stockers). IIRC, they addressed this w/ the upgraded e-shafts in the later (C & D) series motors, but it should be mentioned nonetheless, no? Don't think he specified whether he's running a large single or not.
~Ramy
~Ramy
10-13-05, 12:22 AM
#6
kill it with BOOMSTICK!
That is because with the stock twins the boost pressure is gradually increased to max boost and max power. With a big single, the power spikes once the turbo spools, making the power more of a shock to the E-shaft, as well as a way to force the shaft to flex from dramatically increased pressures and stresses.
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10-13-05, 02:23 AM
#8
Originally Posted by Falcoms
That is because with the stock twins the boost pressure is gradually increased to max boost and max power. With a big single, the power spikes once the turbo spools, making the power more of a shock to the E-shaft, as well as a way to force the shaft to flex from dramatically increased pressures and stresses.
Here's what Dave Morris (DMRH) said with regards to a question about early series 20B motors:
As you have a first batch run engine, you may have issues with the shaft run-out depending on the engine KM. They where prone to flexing due to the "snap torque" of the twin turbo's around the 2000rpm area when the engine is under high lateral load.
If you are going to use the twin turbo's in a sequential operation then be aware of this factor.
If you intend to use the engine with a large single turbo (suspected) then this problem may never arise. The high load of the shaft will not cause a proble at high RPM were the single turbo is making power as the rotating inertia will counter any lateral forces.
All this is true as long as the shaft is perfect to start with. If the shaft is already out of spec, then you will destroy the engine every time you try to make power no matter how many times you rebuild with the same shaft.
If you are going to use the twin turbo's in a sequential operation then be aware of this factor.
If you intend to use the engine with a large single turbo (suspected) then this problem may never arise. The high load of the shaft will not cause a proble at high RPM were the single turbo is making power as the rotating inertia will counter any lateral forces.
All this is true as long as the shaft is perfect to start with. If the shaft is already out of spec, then you will destroy the engine every time you try to make power no matter how many times you rebuild with the same shaft.
The reason for the failures at low RPM under what the Japanese term "snap torque" is due to the higher "lateral" loading of the engine at this RPM. When the shaft goes from no load to 80-90% max torque within 1-second at this RPM it creates this situation. At a higher RPM, centrifical force reduces the lateral loading
Originally Posted by sillbeer
The upgraded e-shafts where in all the letter series motors. The original ones in the number only engines where the ones prone to failure.
-Destin
-Destin
~Ramy
10-13-05, 02:30 AM
#10
Some of the top racers have found the limit of the stock shaft. I've been told just over 1000 rwhp. Although there are some that claim they still use the stock shaft in very high output situations.
Only one way too tell I guess. Good old trial and error.
Only one way too tell I guess. Good old trial and error.
10-13-05, 02:43 AM
#11
That, and again, since I def. trust Dave Morris (DMRH), who's a 20B guru, I think the limit of the e-shaft is dependent on your setup, namely b/c of the higher "lateral" loading of the engine at low RPMs, which only occurs w/ the twin turbo setup, and not a large single setup. A large single makes power at higher RPMs, where rotating inertia will counter any lateral forces.
So again, I think to accurately answer the question, you gotta specificy what setup
~Ramy
PS: Ivan, does it really matter? I'm sure you and I both know you're gonna find out the answer to your question the hard way hehe. Tranny: check. E-shaft: pending...
(For those of you who don't know, he's straight broken TWO tranny's...the stock 13B w/ straight cut gears 1 - 3, in which he lost 4th gear on the dyno at 780rwhp LOL, and he broke the 13B 1200hp Acosta tranny...)
So again, I think to accurately answer the question, you gotta specificy what setup
~Ramy
PS: Ivan, does it really matter? I'm sure you and I both know you're gonna find out the answer to your question the hard way hehe. Tranny: check. E-shaft: pending...
(For those of you who don't know, he's straight broken TWO tranny's...the stock 13B w/ straight cut gears 1 - 3, in which he lost 4th gear on the dyno at 780rwhp LOL, and he broke the 13B 1200hp Acosta tranny...)
Last edited by FDNewbie; 10-13-05 at 02:46 AM.
10-13-05, 04:29 AM
#12
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Originally Posted by FDNewbie
That, and again, since I def. trust Dave Morris (DMRH), who's a 20B guru, I think the limit of the e-shaft is dependent on your setup, namely b/c of the higher "lateral" loading of the engine at low RPMs, which only occurs w/ the twin turbo setup, and not a large single setup. A large single makes power at higher RPMs, where rotating inertia will counter any lateral forces.
So again, I think to accurately answer the question, you gotta specificy what setup
~Ramy
PS: Ivan, does it really matter? I'm sure you and I both know you're gonna find out the answer to your question the hard way hehe. Tranny: check. E-shaft: pending... (For those of you who don't know, he's straight broken TWO tranny's...the stock 13B w/ straight cut gears 1 - 3, in which he lost 4th gear on the dyno at 780rwhp LOL, and he broke the 13B 1200hp Acosta tranny...)
So again, I think to accurately answer the question, you gotta specificy what setup
~Ramy
PS: Ivan, does it really matter? I'm sure you and I both know you're gonna find out the answer to your question the hard way hehe. Tranny: check. E-shaft: pending...
(For those of you who don't know, he's straight broken TWO tranny's...the stock 13B w/ straight cut gears 1 - 3, in which he lost 4th gear on the dyno at 780rwhp LOL, and he broke the 13B 1200hp Acosta tranny...)well, season is over here and I am planing to rebuild my engine and be ready for the next summer. Main reason why I want to do it is because I have some carter gases going out more than ususally. I think some of the o-rings were overheated. I used viton seals, are there any better seals available??
Also I am going to switch to ethanol, throw away my big intercooler and fit a little larger turbo ( it is ITS GT80R now). I used RA 2mm apex seals, their first release! many people claimed that they are bad but hopefully I had no issues even after 30+ races (maybe more). Bruce ( manufacturer of the seals) said that they might not handle high temperatures but my EGT never shown more than 780deg C so I guess its alright. But anyway I am going to switch to NRS 2mm ceramics.
Acosta also adviced that 1000whp is a limit for the stock shaft, so now I am curious if I need to invest into upgraded shaft or not...its not cheap!
As for tranny, then Acosta just shipped me new "improved" parts. I have not got it yet. Hope it will work better now! But this is not for my car but for customers car. I am using th350 and going to switch to th400.
10-13-05, 04:59 PM
#13
Originally Posted by 20bfd3s
Acosta also adviced that 1000whp is a limit for the stock shaft, so now I am curious if I need to invest into upgraded shaft or not...its not cheap!
Check with these guys here. They have a 20b e-shaft with center bearing that they have fabricated in their own shop. It's rated up to 14k rpms.
https://www.rx7club.com/20b-forum-95/mechanical-power-systems-3-rotor-fc-469177/
10-13-05, 08:48 PM
#14
InsaneRotaries.com
friend of mine told me that Pepe loco mx6 uses the stock shaft at about 1025hp on c16 and they dont rev pass 8k rpm.....pepe tried running a custom guru shaft but it broke....one time i ask abel which shaft is better, the stocker or the custom shaft made for him by mike long at gforce transmissions....he showed me a few stock shafts in this trailer and he said thats what he uses.....1400hp on a stock eshaft is hard to swallow
10-13-05, 08:55 PM
#15
t-von, thanks for that thread. I just posted in it, hoping to see if we can get a price on that e-shaft.
RoTaRyBoYz, can your friend verify this info? I'm not big on heresay. It would make sense that they don't rev past 8K rpm, b/c that's when you'll prob see the stock e-shaft flexing. I think that's what it's really all about...flexing at higher rpms. Keep 'em low, you got nothing to worry about.
He said he broke the guru e-shaft? That the custom 2-piece one? I hear they're coming out w/ a 3-piece shaft. I'd appreciate it if you could verify which shaft he broke from Guru. That's a lot of money to dump into something that may break...
RoTaRyBoYz, can your friend verify this info? I'm not big on heresay. It would make sense that they don't rev past 8K rpm, b/c that's when you'll prob see the stock e-shaft flexing. I think that's what it's really all about...flexing at higher rpms. Keep 'em low, you got nothing to worry about.
He said he broke the guru e-shaft? That the custom 2-piece one? I hear they're coming out w/ a 3-piece shaft. I'd appreciate it if you could verify which shaft he broke from Guru. That's a lot of money to dump into something that may break...
10-14-05, 09:05 PM
#16
InsaneRotaries.com
called my friend Roy today and he told me that a NA 20b will flex its eshaft about 20 thousant of an inch @ 10K rpm.....he said that Pepe dont rev his motor pass 7400 rpm because the motor was built to run at a lower rpm to avoid shaft flex....thats why we dont see alot of PP turbo 20bs in Pro class (abel,Pepe) because with the pport motor u'll have to rev it pass 10K rpm to make the power ....so they rather run a side port motor (street or bridge) to 8K rpm with higer boost than a Pport motor with a lower boost level at 10K rpm....so it looks like RPM is a MAJOR problem with the 20b's,so thats the reason these guys keep the side port...i've herd (rumor) that Abel used 5different shafts but ended up with the factory one because it worked best....alot of these 20b race cars make about the same power (1000-1150) with the exception of Abel and Major league...as of right now it seems like the only way to go for big HP is to get a custom short crank 3rotor...shorter eshaft = less flex
10-15-05, 01:11 AM
#17
RoTaRyBoYz, thanks for getting back to me. I was pretty sure they don't go past 8K rpm b/c of the e-shaft flex.
Did your friend Roy tell you what e-shaft it was? Ie, was it in fact the Guru e-shaft they broke? (one of the 5). And was it a one or two piece e-shaft?
Also, how would you accomplish making a custom short crank 3rotor? I would think a multi-piece e-shaft (like the one Guru's coming out w/...the 3 piece one) would solve the issue w/ e-shaft flexing @ higher rpms? Here's what they say on their website (re: the 13B 2-piece e-shaft, but I'm sure the same applies to the 2 and 3 piece 20B shaft they're working on):
GURU Racing can supply a two piece eccentric shaft for a 13B engine that substantially reduces eccentric shaft flex as well as providing extra bearing surface area. The end result is increased horsepower with substantially increased reliability!
The unit is especially designed for exceptionally high horse-powered and high revving engines, where bearing fatigue and crank flex is detrimental to engine reliability.
Did your friend Roy tell you what e-shaft it was? Ie, was it in fact the Guru e-shaft they broke? (one of the 5). And was it a one or two piece e-shaft?
Also, how would you accomplish making a custom short crank 3rotor? I would think a multi-piece e-shaft (like the one Guru's coming out w/...the 3 piece one) would solve the issue w/ e-shaft flexing @ higher rpms? Here's what they say on their website (re: the 13B 2-piece e-shaft, but I'm sure the same applies to the 2 and 3 piece 20B shaft they're working on):
GURU Racing can supply a two piece eccentric shaft for a 13B engine that substantially reduces eccentric shaft flex as well as providing extra bearing surface area. The end result is increased horsepower with substantially increased reliability!
The unit is especially designed for exceptionally high horse-powered and high revving engines, where bearing fatigue and crank flex is detrimental to engine reliability.
- 30% more bearing surface area than a standard 13B Shaft
- Helps reduce bearing failure & fatigue on high boosted turbo engines
- Helps eliminate crankshaft flex at high rpms
- Reduces crankshaft flex therefore rotor clearance can be set to a minimum and seal clearances can be set tighter for increased horsepower
- Stronger
- 1.2kg lighter than a "standard" eccentric shaft
- Kit supplied with all components (including needle roller bearing) and specifications for centre housing machining to fit the centre bearing.
Last edited by FDNewbie; 10-15-05 at 01:14 AM.
10-16-05, 12:21 PM
#19
InsaneRotaries.com
Originally Posted by t-von
Hmmm makes me wonder what kind of e-shaft the NA PP 13G had?
10-16-05, 12:37 PM
#20
InsaneRotaries.com
Originally Posted by FDNewbie
RoTaRyBoYz, how would you accomplish making a custom short crank 3rotor?
another fella in NZ can build u a 1400hp short crank 3rotor, peri port with tripple turbos and motec for about $120k US...
10-16-05, 04:11 PM
#21
Originally Posted by RoTaRyBoYz
a guy in New Zealand makes a cutom 3rotor kit that uses all 13b parts and its a little shorter than a factory 20b...because it uses a shorter eshaft it has less flex than the 20b....i think the kits come with a new eshaft and new modify cast iron plates for about $7000
another fella in NZ can build u a 1400hp short crank 3rotor, peri port with tripple turbos and motec for about $120k US...
another fella in NZ can build u a 1400hp short crank 3rotor, peri port with tripple turbos and motec for about $120k US...
10-17-05, 09:04 PM
#23
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Originally Posted by RoTaRyBoYz
....Abel... showed me a few stock shafts in this trailer and he said thats what he uses.....1400hp on a stock eshaft is hard to swallow
Hard to swallow, but true! Flaco uses a stock 20B e-shaft... ok that being said, it's never as easy as it sounds.
One needs to begin with a quality rotating assembly. Flaco has been using Racing Beat balanced and lightened rotating assemblies, and we feel there are none better... these things are a work of art.
After delivery of the assembly from Racing Beat, Flaco Racing uses a 8-step proprietary process on the e-shaft, and a 3-step process on the Rotors, to make the whole thing live happly ever after. Flaco has been using the same OEM e-shaft in the 20B now for two years, and he revs the motor to 10k. This set-up is so nice that no break-in is needed at all... it's ready to run out of the box! This thing is not only rock solid, but it makes power!
The drawback... about $10K+ per rotating assembly. Slightly less for 13B set-ups.
If anyone is intrested in a complete assembly, just contact me.
to answer question.... 1300-1400hp no issues.
-Bern
10-17-05, 09:07 PM
#24
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Originally Posted by RoTaRyBoYz
...a fella in NZ can build u a 1400hp short crank 3rotor, peri port with tripple turbos and motec for about $120k US...
be careful when you throw #'s like this around...
-Bern
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