3.09 ring & pinon???
05-05-2010, 03:30 PM
#16
Rennlist Member
Regards, Hammer
05-05-2010, 05:00 PM
#17
Rennlist Member
doing a 3.09 for an automatic, for what reason? Have you penciled out the final ratios? what do you have in the automatic 928 now? 2.2? if so, the change to the rear end of 3.09, might only shift all the gears down one gear, if you get what I mean. 3.09 to 2.2 isa 71% rpm drop. manual gear spacings are just around there, (i.e. around 72%) . So, even with the automatic, you might only loose 4th (?) and then gain a "super" 1st. 
05-07-2010, 09:24 AM
#18
Nordschleife Master
I still have that calculator. Put in the car specs (gearing, weight, Cd, dyno chart, shift points) and it spits out acceleration and speeds.
I should have mentioned that a 2.2 will keep me off the rev limiter in twistier parts so I may make up the 0.1 on the back side.
And that's the reason race teams have multiple gearboxes: to maximize applied force all around the track. Ya want to come out of a corner as strongly as possible and not have to shift right before the next one.
(yes, yes, maximizing applied torque is the same as applied power, just working a different equation. Ain't life beeyuteefull?)
I should have mentioned that a 2.2 will keep me off the rev limiter in twistier parts so I may make up the 0.1 on the back side.
And that's the reason race teams have multiple gearboxes: to maximize applied force all around the track. Ya want to come out of a corner as strongly as possible and not have to shift right before the next one.
(yes, yes, maximizing applied torque is the same as applied power, just working a different equation. Ain't life beeyuteefull?)
05-07-2010, 09:57 AM
#19
Nordschleife Master
Can you run me a fun experiment, please?
Stock US model 1987 S4 and it's original G28.13 transmission with the original 2.20 final drive ratio. Car basically stock with the following mods:
- About 600 rwhp max at 6,500 rpm
- About flat torque curve from 4,000-6,500, say 484 ft-lbf
- 3750 lbs weight
- Cd marginally worse because of the intercooler vents, can't quantify
I don't know the shift points, but I wouldn't rev it past 6500 rpm.
If your software takes it into account, the tires will be sticky street tires.
Stock US model 1987 S4 and it's original G28.13 transmission with the original 2.20 final drive ratio. Car basically stock with the following mods:
- About 600 rwhp max at 6,500 rpm
- About flat torque curve from 4,000-6,500, say 484 ft-lbf
- 3750 lbs weight
- Cd marginally worse because of the intercooler vents, can't quantify
I don't know the shift points, but I wouldn't rev it past 6500 rpm.
If your software takes it into account, the tires will be sticky street tires.
I still have that calculator. Put in the car specs (gearing, weight, Cd, dyno chart, shift points) and it spits out acceleration and speeds.
I should have mentioned that a 2.2 will keep me off the rev limiter in twistier parts so I may make up the 0.1 on the back side.
And that's the reason race teams have multiple gearboxes: to maximize applied force all around the track. Ya want to come out of a corner as strongly as possible and not have to shift right before the next one.
(yes, yes, maximizing applied torque is the same as applied power, just working a different equation. Ain't life beeyuteefull?)
I should have mentioned that a 2.2 will keep me off the rev limiter in twistier parts so I may make up the 0.1 on the back side.
And that's the reason race teams have multiple gearboxes: to maximize applied force all around the track. Ya want to come out of a corner as strongly as possible and not have to shift right before the next one.
(yes, yes, maximizing applied torque is the same as applied power, just working a different equation. Ain't life beeyuteefull?)
05-07-2010, 10:23 AM
#20
Addict
Rennlist Member
Rennlist Member
05-07-2010, 11:16 AM
#22
Rennlist Member
Guys, forget about this "flat" torque concept! Its a misnomer, and confusing.
flat HP yes, flat torque, not usually seen. torque, even in the torquey-est motors, falls from max torque to max HP. (just look at the diesel engine specs, especially the Audi race diesel engine specs)
Unless you are limited by the values of the experiement, it would be better to have less HP and more torque, with a flat HP curve. However, you may have something with the limitations and values you have described. iIn which case, Glens program can tell you of the raw performance predictions.
Yes, Glens program takes it alll into account, because you input the torque values at all speeds. for example, if you wanted to use the limitations below, then you would have an extremely peaky hp curve and would want to shift at well past 6500rpm. . A flat HP curve would alow you to shift at 6500rpm and maximize available HP
flat HP yes, flat torque, not usually seen. torque, even in the torquey-est motors, falls from max torque to max HP. (just look at the diesel engine specs, especially the Audi race diesel engine specs)
Unless you are limited by the values of the experiement, it would be better to have less HP and more torque, with a flat HP curve. However, you may have something with the limitations and values you have described. iIn which case, Glens program can tell you of the raw performance predictions.
Yes, Glens program takes it alll into account, because you input the torque values at all speeds. for example, if you wanted to use the limitations below, then you would have an extremely peaky hp curve and would want to shift at well past 6500rpm.
. A flat HP curve would alow you to shift at 6500rpm and maximize available HPCan you run me a fun experiment, please?
Stock US model 1987 S4 and it's original G28.13 transmission with the original 2.20 final drive ratio. Car basically stock with the following mods:
- About 600 rwhp max at 6,500 rpm
- About flat torque curve from 4,000-6,500, say 484 ft-lbf
- 3750 lbs weight
- Cd marginally worse because of the intercooler vents, can't quantify
I don't know the shift points, but I wouldn't rev it past 6500 rpm.
If your software takes it into account, the tires will be sticky street tires.
Stock US model 1987 S4 and it's original G28.13 transmission with the original 2.20 final drive ratio. Car basically stock with the following mods:
- About 600 rwhp max at 6,500 rpm
- About flat torque curve from 4,000-6,500, say 484 ft-lbf
- 3750 lbs weight
- Cd marginally worse because of the intercooler vents, can't quantify
I don't know the shift points, but I wouldn't rev it past 6500 rpm.
If your software takes it into account, the tires will be sticky street tires.
05-07-2010, 11:26 AM
#23
Rennlist Member
thats why gearing changes with the race teams generally dont give much time, but do allow them to make sure they have enough top end gear to reach top speed without running out of gear, and allow them to optimize HP throughout the majority of the track. all trade offs that they consider. you come out and race with me at laguna with a 2.75 and the same HP , you will be at a distinct disadvantage at 2 of the 3 tracks we visit, and will have more equipment wear as well.
I still have that calculator. Put in the car specs (gearing, weight, Cd, dyno chart, shift points) and it spits out acceleration and speeds.
I should have mentioned that a 2.2 will keep me off the rev limiter in twistier parts so I may make up the 0.1 on the back side.
And that's the reason race teams have multiple gearboxes: to maximize applied force all around the track. Ya want to come out of a corner as strongly as possible and not have to shift right before the next one.
(yes, yes, maximizing applied torque is the same as applied power, just working a different equation. Ain't life beeyuteefull?)
I should have mentioned that a 2.2 will keep me off the rev limiter in twistier parts so I may make up the 0.1 on the back side.
And that's the reason race teams have multiple gearboxes: to maximize applied force all around the track. Ya want to come out of a corner as strongly as possible and not have to shift right before the next one.
(yes, yes, maximizing applied torque is the same as applied power, just working a different equation. Ain't life beeyuteefull?)
05-07-2010, 01:32 PM
#24
Nordschleife Master
The right gear ratios could mean the difference between being able to pass in a certain location or not, or going back and forth between two gears without a lot of speed change.
What even modestly improved hp 928 doesn't spin the tires in first? Whats the idea, spin them faster? Spin and hook up like on a drag strip is what breaks parts, so gets a lot more expensive than tires pretty soon.
What even modestly improved hp 928 doesn't spin the tires in first? Whats the idea, spin them faster? Spin and hook up like on a drag strip is what breaks parts, so gets a lot more expensive than tires pretty soon.
05-07-2010, 01:32 PM
#25
Nordschleife Master
I don't understand much about this stuff, admittedly, but I do understand the basic definitions of torque and horsepower. When I said a flat torque curve, I meant flat torque curve. I didn't mean flat hp curve. I understand that this means an increasing hp curve. So what's your beef with this?
My ideal torque curve would be something like this:
That's the new BMW V12 twin turbo.
Since I have a rpm-specific boost controller and large turbos, after 4,000 rpm I can choose pretty much any torque value, provided that the components hold up. That's a big "provided," of course. What could break? Everything, but specifically:
- Transmission. Solution: limit max torque with a flat torque curve.
- Cylinder towers. Solution: limit max torque with a flat torque curve.
- Detonation. Solution: limit max torque with a flat torque curve and control the charge temperature.
- Traction. Solution: limit max torque with a flat torque curve, to a gear-specific value.
All of this points to engineering a flat torque curve. I think (but do not know) that I could go pretty much flat at 500 lbft to 6,000 rpm, and then with a flat hp curve from 6,000 rpm to 7,000 rpm. At 7,000 rpm the engine is at risk of giving up the ghost just for the revs.
For readers: Caveat lector. I am not an expert on the topic, just a random guy writing on the internet. I haven't done this yet, so take this as day dreaming and speculation. I hope to do this, but "hope" is not an engineering process. So those new to this forum, don't rely on my writings for anything, never, I don't know enough about what I am writing, ever.
My ideal torque curve would be something like this:
That's the new BMW V12 twin turbo.
Since I have a rpm-specific boost controller and large turbos, after 4,000 rpm I can choose pretty much any torque value, provided that the components hold up. That's a big "provided," of course. What could break? Everything, but specifically:
- Transmission. Solution: limit max torque with a flat torque curve.
- Cylinder towers. Solution: limit max torque with a flat torque curve.
- Detonation. Solution: limit max torque with a flat torque curve and control the charge temperature.
- Traction. Solution: limit max torque with a flat torque curve, to a gear-specific value.
All of this points to engineering a flat torque curve. I think (but do not know) that I could go pretty much flat at 500 lbft to 6,000 rpm, and then with a flat hp curve from 6,000 rpm to 7,000 rpm. At 7,000 rpm the engine is at risk of giving up the ghost just for the revs.
For readers: Caveat lector. I am not an expert on the topic, just a random guy writing on the internet. I haven't done this yet, so take this as day dreaming and speculation. I hope to do this, but "hope" is not an engineering process. So those new to this forum, don't rely on my writings for anything, never, I don't know enough about what I am writing, ever.
Guys, forget about this "flat" torque concept! Its a misnomer, and confusing.
flat HP yes, flat torque, not usually seen. torque, even in the torquey-est motors, falls from max torque to max HP. (just look at the diesel engine specs, especially the Audi race diesel engine specs)
Unless you are limited by the values of the experiement, it would be better to have less HP and more torque, with a flat HP curve. However, you may have something with the limitations and values you have described. iIn which case, Glens program can tell you of the raw performance predictions.
Yes, Glens program takes it alll into account, because you input the torque values at all speeds. for example, if you wanted to use the limitations below, then you would have an extremely peaky hp curve and would want to shift at well past 6500rpm. . A flat HP curve would alow you to shift at 6500rpm and maximize available HP
flat HP yes, flat torque, not usually seen. torque, even in the torquey-est motors, falls from max torque to max HP. (just look at the diesel engine specs, especially the Audi race diesel engine specs)
Unless you are limited by the values of the experiement, it would be better to have less HP and more torque, with a flat HP curve. However, you may have something with the limitations and values you have described. iIn which case, Glens program can tell you of the raw performance predictions.
Yes, Glens program takes it alll into account, because you input the torque values at all speeds. for example, if you wanted to use the limitations below, then you would have an extremely peaky hp curve and would want to shift at well past 6500rpm.
. A flat HP curve would alow you to shift at 6500rpm and maximize available HP
05-07-2010, 03:41 PM
#27
Rennlist Member
thats not a flat hp curve, it has a flat spot, but its not flat to 6500rpm. if it was flat, it would be incredibly peaky. sharp peak, not the rounded top you see with the bmw curve. the point is, if you have stress limited components, sure, its a great idea. acuatlly, your useable HP will be much much lower, unless you can employ a close ratio gear box. its one of the reasons I had my way with the 2600lb S2000 with 410rwhp (supercharger) vs my 370rwhp. flat HP curve, not flat torque curve. this allows for a reduction in engine RPM and maximized HP, for acceleration (as you know, acceleration is directly proportional to HP at any given road speed). but, if you wanted to have, not 600ave hp , but 500ave hp, and not the torque issues on the gear box or clutch, then your "ideal " curves would be valid. Lots of trade offs.
the reason your "flat "curve doesnt work too well, is because in actuality, you only use the last 20% of the flat part ,and then it falls off a cliff 4500 to 6500pm. so, you end up with a type of slanted, "r" HP curve.
mk
the reason your "flat "curve doesnt work too well, is because in actuality, you only use the last 20% of the flat part ,and then it falls off a cliff
4500 to 6500pm. so, you end up with a type of slanted, "r" HP curve. mk
I don't understand much about this stuff, admittedly, but I do understand the basic definitions of torque and horsepower. When I said a flat torque curve, I meant flat torque curve. I didn't mean flat hp curve. I understand that this means an increasing hp curve. So what's your beef with this?
My ideal torque curve would be something like this:
That's the new BMW V12 twin turbo.
Since I have a rpm-specific boost controller and large turbos, after 4,000 rpm I can choose pretty much any torque value, provided that the components hold up. That's a big "provided," of course. What could break? Everything, but specifically:
- Transmission. Solution: limit max torque with a flat torque curve.
- Cylinder towers. Solution: limit max torque with a flat torque curve.
- Detonation. Solution: limit max torque with a flat torque curve and control the charge temperature.
- Traction. Solution: limit max torque with a flat torque curve, to a gear-specific value.
All of this points to engineering a flat torque curve. I think (but do not know) that I could go pretty much flat at 500 lbft to 6,000 rpm, and then with a flat hp curve from 6,000 rpm to 7,000 rpm. At 7,000 rpm the engine is at risk of giving up the ghost just for the revs.
For readers: Caveat lector. I am not an expert on the topic, just a random guy writing on the internet. I haven't done this yet, so take this as day dreaming and speculation. I hope to do this, but "hope" is not an engineering process. So those new to this forum, don't rely on my writings for anything, never, I don't know enough about what I am writing, ever.
My ideal torque curve would be something like this:
That's the new BMW V12 twin turbo.
Since I have a rpm-specific boost controller and large turbos, after 4,000 rpm I can choose pretty much any torque value, provided that the components hold up. That's a big "provided," of course. What could break? Everything, but specifically:
- Transmission. Solution: limit max torque with a flat torque curve.
- Cylinder towers. Solution: limit max torque with a flat torque curve.
- Detonation. Solution: limit max torque with a flat torque curve and control the charge temperature.
- Traction. Solution: limit max torque with a flat torque curve, to a gear-specific value.
All of this points to engineering a flat torque curve. I think (but do not know) that I could go pretty much flat at 500 lbft to 6,000 rpm, and then with a flat hp curve from 6,000 rpm to 7,000 rpm. At 7,000 rpm the engine is at risk of giving up the ghost just for the revs.
For readers: Caveat lector. I am not an expert on the topic, just a random guy writing on the internet. I haven't done this yet, so take this as day dreaming and speculation. I hope to do this, but "hope" is not an engineering process. So those new to this forum, don't rely on my writings for anything, never, I don't know enough about what I am writing, ever.
Last edited by mark kibort; 05-07-2010 at 04:01 PM.
05-07-2010, 03:50 PM
#28
Nordschleife Master
thats not a flat hp curve, it has a flat spot, but its not flat to 6500rpm. if it was flat, it would be incredibly peaky. sharp peak, not the rounded top you see with the bmw curve. the point is, if you have stress limited components, sure, its a great idea. acuatlly, your useable HP will be much much lower, unless you can employ a close ratio gear box. its one of the reasons I had my way with the 2600lb S2000 with 410rwhp (supercharger) vs my 370rwhp. flat HP curve, not flat torque curve. this allows for a reduction in engine RPM and maximized HP, for acceleration (as you know, acceleration is directly proportional to HP at any given road speed). but, if you wanted to have, not 600ave hp , but 500ave hp, and not the torque issues on the gear box or clutch, then your "ideal " curves would be valid. Lots of trade offs. mk
05-07-2010, 04:09 PM
#29
Rennlist Member
with a big V8, we are only talking about the 1st stage of the powertrain,that should be able to be beefed up. in the end, the HP level at the rear wheels will dictate the actual torque on the CV joints and that cant change. in otherwords, they might snap, and having a lower torque engine, with lots of HP might kill the final stage components, where if the hp was lower to get a better average due to higher engine torque, the CV joint torque would have less force on it, not more. so , yes, it is about trade offs. It always is.
Remember, we are talking "ideal " here. sure, given what we have as far as stock or near stock, sure, I agree. keep the torque and RPM down,so we wont break things and that will yeild some fraction of the peak HP for useable.
Remember, we are talking "ideal " here. sure, given what we have as far as stock or near stock, sure, I agree. keep the torque and RPM down,so we wont break things and that will yeild some fraction of the peak HP for useable.
I don't think there are a lot of trade offs here, given that we're talking about a 32v 5.0L V8 with two gt3071s. I think the issue is in fact really simple. Detonation destroys the engine. Too much torque destroys the transmission. Too much torque to the rear wheels means losing traction. Too much cylinder pressure breaks the cylinder tower. The answer to all these questions is to use rpm and gear specific boost control to produce a flat torque curve per gear at the maximum safe torque that the tires can handle on that gear.
05-07-2010, 05:18 PM
#30
Race Director
Thread Starter
Guys I think we are getting a bit off topic....since I started this thread my reasoning behind the LOWER gears is to give the automatic race car 1 more usable gear.....right now at my on track speeds between 45-120mph I only have 2nd (85mph) and 3rd (139mph) that I can use....if I drop to the 3.09 then I gain 4th gear...with a 65mph 2nd, 100mph 3rd and 142mph 4th.....which is my reasoning behind it.....
So back to the original ? Does anyone know of anyone who could make a new ring-pinon for an automatic 928?
So back to the original ? Does anyone know of anyone who could make a new ring-pinon for an automatic 928?