Twin screw kit questions
02-23-2005, 09:20 PM
#121
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mspiegle - that is where you are right. We will never know unless you yank the motor after a dyno run and put it on an engine dyno.
But again, one of the mathmatical methods validates against the Porsche factory numbers, the other does not. They ARE the only published numbers for crank HP of our motors that we have, after all.
But again, one of the mathmatical methods validates against the Porsche factory numbers, the other does not. They ARE the only published numbers for crank HP of our motors that we have, after all.
02-23-2005, 09:26 PM
#122
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Carl,
One more point.. The factory had a tolerance level or "acceptance spread".. This is the reason that you can have 2 identical models dyno different amounts and in similar condition...
The factory published numbers are MARKETING BASED...
Method of calculation has nothing to do with this..... You should expect to be deviated from the published number. In any event, the published number will most likely be an average if it is indeed a scientific chart, and not a Marketing chart...
One more point.. The factory had a tolerance level or "acceptance spread".. This is the reason that you can have 2 identical models dyno different amounts and in similar condition...
The factory published numbers are MARKETING BASED...
Method of calculation has nothing to do with this..... You should expect to be deviated from the published number. In any event, the published number will most likely be an average if it is indeed a scientific chart, and not a Marketing chart...
02-23-2005, 10:19 PM
#123
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Carl said:
Yep. You were calculating a markup (gain) versus a discount (loss), hence, my comment earlier. The statistic, be it 15, 18, 20 or 25% is stated as a LOSS due to drivetrain friction and slippage. Yes, certainly, a 25% loss from a higher number to a lower number equates to a 20% gain from the lower number. It would be best if we just agreed to do it one way, so we don't get confused.
You wouldn't confuse a markup with a discount in business, so let's not do the same here.
Oh, and I really want to make it very clear how much I appreciate all you are doing for us, offering special tools and SC kits, etc. I don't want this little technical issue to get blown out of proportion and appear to overshadow my appreciation. We were just coming at the same problem from the other side. Admittedly, the drivetrain loss is largely a guestimate anyway.
The difference between the methods is whether you are starting at the rear tire number and looking for the GAIN at the motor (my method); or starting at the motor and looking at the LOSS to the tire (your method).
You wouldn't confuse a markup with a discount in business, so let's not do the same here.
Oh, and I really want to make it very clear how much I appreciate all you are doing for us, offering special tools and SC kits, etc. I don't want this little technical issue to get blown out of proportion and appear to overshadow my appreciation. We were just coming at the same problem from the other side. Admittedly, the drivetrain loss is largely a guestimate anyway.
02-24-2005, 12:40 AM
#124
Originally Posted by GoRideSno
Dave,
Sounds like a plan to me. The only thing that would make it better is if all 3 GTs got Twin-Screwed.
Brian,
The Jag/Eaton M112 is 1.835 liters while the Autorotors are over 2 liters.
This accounts for part of the Autorotor's higher and extremely high thermal efficency and low drive power. The shape of the rotors and optimized intake port account for the rest of it's efficency.
The Jag/Eaton M112 is a cast and machined unit with cast intake port.
The Autorotor is CNC machined from a solid block of aluminum with optimized CNCmachined intake port.
The Jag/Eaton M112 will probably Max out at 10-12psi on the 32v 928 and 550-575CHP (after other mods).
The Autorotor will make over 700CHP on the 32v engine (with other mods) and will make up to 20 psi on the 32V engine, and that would be well over 700chp.
The Autorotor requires low drive power and is commonly held as the most efficient type of SC of any kind available.
Basically if you think you'll be happy with about 500 HP the the Jag/Eaton M112 setup is a good buy. If you think you want more then you'll want to go with the Autorotor.
HTH,
Andy
Sounds like a plan to me. The only thing that would make it better is if all 3 GTs got Twin-Screwed.
Brian,
The Jag/Eaton M112 is 1.835 liters while the Autorotors are over 2 liters.
This accounts for part of the Autorotor's higher and extremely high thermal efficency and low drive power. The shape of the rotors and optimized intake port account for the rest of it's efficency.
The Jag/Eaton M112 is a cast and machined unit with cast intake port.
The Autorotor is CNC machined from a solid block of aluminum with optimized CNCmachined intake port.
The Jag/Eaton M112 will probably Max out at 10-12psi on the 32v 928 and 550-575CHP (after other mods).
The Autorotor will make over 700CHP on the 32v engine (with other mods) and will make up to 20 psi on the 32V engine, and that would be well over 700chp.
The Autorotor requires low drive power and is commonly held as the most efficient type of SC of any kind available.
Basically if you think you'll be happy with about 500 HP the the Jag/Eaton M112 setup is a good buy. If you think you want more then you'll want to go with the Autorotor.
HTH,
Andy
Andy,
I am very interested in this for my '85 when time and money permit. I was looking at getting the Stage 2 kit, and basically just having fun. Any chance you have any numbers on cars with the Stage 2 kit? I'm looking at your having your supercharger as well as full exhaust and head work. Just wondering what kind of numbers I might expect.
Thanks,
Jon
02-24-2005, 01:24 PM
#125
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Originally Posted by Jon B.
Andy,
I am very interested in this for my '85 when time and money permit. I was looking at getting the Stage 2 kit, and basically just having fun. Any chance you have any numbers on cars with the Stage 2 kit? I'm looking at your having your supercharger as well as full exhaust and head work. Just wondering what kind of numbers I might expect.
Thanks,
Jon
I am very interested in this for my '85 when time and money permit. I was looking at getting the Stage 2 kit, and basically just having fun. Any chance you have any numbers on cars with the Stage 2 kit? I'm looking at your having your supercharger as well as full exhaust and head work. Just wondering what kind of numbers I might expect.
Thanks,
Jon
02-24-2005, 05:06 PM
#126
Originally Posted by Shane
Jon, You would be right around 400rwhp with your '85 depending on what boost level you went with. HTH
Jon
02-24-2005, 06:55 PM
#127
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Jon, if you checkout some of the dyno charts andy posted, and compare them to the twinscrew charts, you'll see what the differences are.
hmm... maybe i should make an overlay...
hmm... maybe i should make an overlay...
02-25-2005, 04:33 AM
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Andy.
"The Jag/Eaton M112 is 1.835 liters while the Autorotors are over 2 liters."
I assume this is the 2.3l Autorotor You are talking about.
Looking at the numbers of req. liter.pr.min, screw rpm and max pressure. Wouldt the Lysholmers 3.3 liter Screw be a better option for 4.5- 5l engines with a max rpm of app. 6000?
Not that I know offcourse, but i'm trying to learn as much as possible about the system before I put it in.
Geir
"The Jag/Eaton M112 is 1.835 liters while the Autorotors are over 2 liters."
I assume this is the 2.3l Autorotor You are talking about.
Looking at the numbers of req. liter.pr.min, screw rpm and max pressure. Wouldt the Lysholmers 3.3 liter Screw be a better option for 4.5- 5l engines with a max rpm of app. 6000?
Not that I know offcourse, but i'm trying to learn as much as possible about the system before I put it in.
Geir