Evaluating the possibility of AWD in the C7... discuss!
12-29-2012, 04:53 PM
#21
Le Mans Master
No Thanks
12-29-2012, 05:04 PM
#22
The only reason the FF's AWD system works and is as light as it is, is because the engine has two output shafts, one in the front and one in the rear. So the front transmission is fed power directly from the front of the engine, therefore negating the need to have drive shafts connecting to the rear transaxle. Are you suggesting that the LT1 could be modified to have an output shaft coming out of the front of it? If not, then all the issues I have mentioned earlier are still valid and would need to be overcome if AWD were to be added to the C7.
Frankly, I think that if Ferrari can do it, so can Corvette. Obviously, it would also cost a lot more than the base Vette but so did the ZR1.
You are asking if it could be done and I am saying a resounding YES. Is it happening? I doubt it. I really suggest you look around the web at the FF AWD system as there are a lot of write ups about it.
Corvette has said "Nothing will be the same!". What that means to them and to us remains to be seen.
12-29-2012, 05:06 PM
#23
Well, since we don't know much about the C7's chassis yet, a real technical discussion is pretty hard to have. I'm not any kind of engineer or mechanic to compare what the FF's chassis is like comparatively.
I view a system like this mostly as a marketing tool to expand the brand to better compete with the likes of Porsche/GTR/etc.
I view a system like this mostly as a marketing tool to expand the brand to better compete with the likes of Porsche/GTR/etc.
From a technical perspective, I think I have raised some valid points regarding adding AWD on the C7 would be very difficult based on those issues that need to be overcome.
One such solution to the issue I pointed out about getting power past the engine to the front axle was your FF suggestion to make the engine with two output shafts, which I believe is a very innovative and novel solution for a Ferrari but it doesn't seem very practical on a Corvette, do you disagree? It would require significant modifications to what we already know of the LT1 to make this happen.
So barring a version of the LT1 engine with two output shafts, all my previous issues that I mentioned are still valid and need to be overcome to make AWD a reality in the C7.
12-29-2012, 05:06 PM
#24
12-29-2012, 05:19 PM
#25
Well, this discussion was well before we knew the LT1 was the engine. I have never suggested that ALL C7's would or should be AWD so it would take a specific design (both engine and chassis) that would allow it to be done, wouldn't it? Again, we don't know if the C7 chassis has any allowance for that or not.
Frankly, I think that if Ferrari can do it, so can Corvette. Obviously, it would also cost a lot more than the base Vette but so did the ZR1.
You are asking if it could be done and I am saying a resounding YES. Is it happening? I doubt it. I really suggest you look around the web at the FF AWD system as there are a lot of write ups about it.
Corvette has said "Nothing will be the same!". What that means to them and to us remains to be seen.
Frankly, I think that if Ferrari can do it, so can Corvette. Obviously, it would also cost a lot more than the base Vette but so did the ZR1.
You are asking if it could be done and I am saying a resounding YES. Is it happening? I doubt it. I really suggest you look around the web at the FF AWD system as there are a lot of write ups about it.
Corvette has said "Nothing will be the same!". What that means to them and to us remains to be seen.
I would like to believe that I have a decent understanding of the FF's AWD system, as it relates to this AWD C7 discussion. So what should I be reading about?
I did not mean to say that Ferrari can do things that GM cannot but we do have to consider the price points and intended purpose of their respective products. Can GM create a C7 with Ferrari levels of luxury? Sure it can be done but it is not realistic at the C7 price point.
So back to my point about the FF's AWD system, while I don't doubt that GM can modify the LT1 to include a front output shaft, I think we can agree that it is not realistic since this engine needs to be flexible and used in various platforms. Since the C7 is the only FMR platform, the front output shaft would be completely useless in all other FR platforms where the front mounted transmission could easily power the front axle.
12-29-2012, 05:22 PM
#26
Well no one knows anything about the C7 chassis yet but that hasn't stopped everyone from saying definitively that it cannot accommodate back seats. In any case, the point of this thread was just to have a technical discussion on what it would take to make AWD possible on the C7. Since no one knows for sure what this chassis will be like, all we can do is speculate, which is what I have done in my original post with what I consider educated guesses (as educated as I can be without being an engineer, just a car enthusiast).
From a technical perspective, I think I have raised some valid points regarding adding AWD on the C7 would be very difficult based on those issues that need to be overcome.
One such solution to the issue I pointed out about getting power past the engine to the front axle was your FF suggestion to make the engine with two output shafts, which I believe is a very innovative and novel solution for a Ferrari but it doesn't seem very practical on a Corvette, do you disagree? It would require significant modifications to what we already know of the LT1 to make this happen.
So barring a version of the LT1 engine with two output shafts, all my previous issues that I mentioned are still valid and need to be overcome to make AWD a reality in the C7.
From a technical perspective, I think I have raised some valid points regarding adding AWD on the C7 would be very difficult based on those issues that need to be overcome.
One such solution to the issue I pointed out about getting power past the engine to the front axle was your FF suggestion to make the engine with two output shafts, which I believe is a very innovative and novel solution for a Ferrari but it doesn't seem very practical on a Corvette, do you disagree? It would require significant modifications to what we already know of the LT1 to make this happen.
So barring a version of the LT1 engine with two output shafts, all my previous issues that I mentioned are still valid and need to be overcome to make AWD a reality in the C7.
I stand by my suggestion that the FF is the best model since it adds less weight, less complexity, and the FF also works off a similar torque tube design.
12-29-2012, 05:36 PM
#27
It would take a lot less screwing around to replicate the FF's system than to replicate the GTR's system. Not to mention the much more additional weight it would add.
I stand by my suggestion that the FF is the best model since it adds less weight, less complexity, and the FF also works off a similar torque tube design.
I stand by my suggestion that the FF is the best model since it adds less weight, less complexity, and the FF also works off a similar torque tube design.
The GTR's AWD system is awfully convoluted and is the reason why it is such an overweight pig.
The FF's AWD system is very clever but I just don't think it is practical or feasible in the C7 based on my reasons I noted earlier. It really makes zero sense for GM to make a special version of the LT1 with a front output shaft just for the AWD C7. Even versions of the LS7, LS9 and LSA engines have been used on various GM vehicles, this LT1 variant with a front output shaft could not be used in any other car besides the AWD C7 so I cannot imagine GM going this route. Again, I agree that the FF's AWD is an innovated solution that works well for Ferrari but I can't imagine it applied to the C7.
So while it is technically possible for the C7 to adapt the FF method, I don't think it is realistic at all.
Any other ideas that would be more realistic?
12-29-2012, 05:46 PM
#28
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Agreed, which was the point of my thread but for some reason, some folks still believe AWD is possible. There are many who are quick to point out that back seats are impossible given the layout of the chassis and space limitations but I have yet to hear anyone else make the same argument debunking the possibility of AWD.
12-29-2012, 05:50 PM
#29
Le Mans Master
Yuck to AWD is all I have to say. Just Yuck. Weight, cost, lost mpg, less driver involvement
12-29-2012, 05:52 PM
#30
Yeah I thought about this picture before I started this thread. Just to play devil's advocate, some might argue that the picture depicts the base RWD model and the AWD model is not yet available or not depicted in this manual. Regardless, just because the picture depicts a RWD C7 doesn't mean an AWD C7 isn't possible or available in the future.
12-29-2012, 05:53 PM
#31
12-29-2012, 05:58 PM
#32
*As long as the availability of AWD does not negatively impact the RWD models as well. For example, if the engine had to be mounted higher up for both AWD and RWD models to accommodate the AWD components.
12-29-2012, 05:59 PM
#33
However, here is a different write up about it with a different approach to how it works.
Power goes to the front wheels by way of a power take off, similar to the way the hydraulic pump in a garbage truck or on farm machinery gets power from the engine. The difference here is that the power take off is also a gearbox which attaches to each front wheel via a haldex-type clutch pack. By regulating how much these clutches slip, the system can regulate how much power goes to each of the front wheels. But there are limits, a maximum of just 20 percent of the engine's power can be sent to the front at any given time. The system is also only active in first through fourth gears, and then only when the car is in "comfort" or "snow" modes.The result is an AWD system that you almost don't realize is there. The car drives like it's RWD most of the time, until you push in too hard into a corner, and then the back end doesn't step out like you'd expect it to. But at the same time, there's none of the understeer normally associated with AWD cars. It's not a system which will handle dirt or snow quite as well as others do, but it is a very good method for a more controllable application of power. The engine is similar in many ways to the one found in the Enzo and the 599, but it has been largely redesigned and now displaces 6.3 liters.
This displacement, along with very high compression ratio of 12.3:1, means that the FF produces 651 horsepower. Ferrari claims that this makes it the fastest four-seat car in the world. This power goes through a 7-speed dual-clutch transmission, similar to the one found in the 458. This allows for the launch control which allows the FF to hit 60mph in 3.5 seconds. Despite the slightly odd proportions, the FF has a 47/53 weight distribution. This might be just average for a pure sports car, but it's one of the better splits you'll find on a GT car. With the FF, cargo capacity became something which people talked seriously about for the first time with a Ferrari.
This displacement, along with very high compression ratio of 12.3:1, means that the FF produces 651 horsepower. Ferrari claims that this makes it the fastest four-seat car in the world. This power goes through a 7-speed dual-clutch transmission, similar to the one found in the 458. This allows for the launch control which allows the FF to hit 60mph in 3.5 seconds. Despite the slightly odd proportions, the FF has a 47/53 weight distribution. This might be just average for a pure sports car, but it's one of the better splits you'll find on a GT car. With the FF, cargo capacity became something which people talked seriously about for the first time with a Ferrari.
Last edited by BlueOx; 12-29-2012 at 06:02 PM.
12-29-2012, 06:18 PM
#34
Interestingly, the Haldex AWD system is used in the new Caddys.
12-29-2012, 06:49 PM
#35
Le Mans Master
An LT1 variant for a front transmission doesn't seem such a reach.
The transmission itself is a different story, but who knows, maybe Ferrari would get a kick out of licensing it to GM.
I wonder how this permanent slippage would impact wear on the clutch, I cannot imagine this being very reliable over time and with higher mileage (again okay in a Ferrari but not feasible in a Corvette). Granted, the front transmission would not be activated all the time but it is intended (or at least marketed) as a viable solution for driving on snow. Can you imagine taking the FF on few hundred mile ski trip with the front clutch slipping the entire time? Even with wet clutches and transmission coolers, it should still generate a bunch of heat and wear...
but seriously... longevity and maintenance costs are big question marks for this transmission. Ferraris aren't known for their million mile club members. Still, it is a very limited-situation component, and it's hardly the only use of slipping clutches in the market. Ask yourself how often your Honda CR-V is actually powering all four wheels and how it's doing it... No, I wouldn't expect the quarter-mile brigade to be singing this design's praises after a year or two, but the folks wishing they didn't have to park their Corvette four months out of the year might be quite pleased with its performance. Big unknown, though.I applaud Ferrari for trying something radical. But I sure wouldn't point to it as fait accompli for an AWD Corvette.
.Jinx
12-29-2012, 07:22 PM
#37
12-29-2012, 07:22 PM
#38
What other production vehicles was the LS7 used in? It's essentially a hand-built engine. Sure, the engineering is based on the Chevy smallblock but the whole thing is essentially custom parts, built in low volumes, for a special Corvette that was never going to be anything but low-volume.
An LT1 variant for a front transmission doesn't seem such a reach.
The transmission itself is a different story, but who knows, maybe Ferrari would get a kick out of licensing it to GM.
An LT1 variant for a front transmission doesn't seem such a reach.
The transmission itself is a different story, but who knows, maybe Ferrari would get a kick out of licensing it to GM.
Sure, it is just a rumor and it might never happen but technically-speaking, there is absolutely no reason why the LS7 cannot be used in any number of applications. In fact, historically GM has trickled down Corvette engines to other Pontiac, Holden and Cadillac cars in the past so this shouldn't be a surprise to anyone.
This special version of the LT1 with a front output shaft would be completely useless in anything except an AWD C7 and cannot be used in any other application, that is the difference.
Heat buildup in the snow but seriously... longevity and maintenance costs are big question marks for this transmission. Ferraris aren't known for their million mile club members. Still, it is a very limited-situation component, and it's hardly the only use of slipping clutches in the market. Ask yourself how often your Honda CR-V is actually powering all four wheels and how it's doing it... No, I wouldn't expect the quarter-mile brigade to be singing this design's praises after a year or two, but the folks wishing they didn't have to park their Corvette four months out of the year might be quite pleased with its performance. Big unknown, though.
I applaud Ferrari for trying something radical. But I sure wouldn't point to it as fait accompli for an AWD Corvette.
.Jinx
but seriously... longevity and maintenance costs are big question marks for this transmission. Ferraris aren't known for their million mile club members. Still, it is a very limited-situation component, and it's hardly the only use of slipping clutches in the market. Ask yourself how often your Honda CR-V is actually powering all four wheels and how it's doing it... No, I wouldn't expect the quarter-mile brigade to be singing this design's praises after a year or two, but the folks wishing they didn't have to park their Corvette four months out of the year might be quite pleased with its performance. Big unknown, though.I applaud Ferrari for trying something radical. But I sure wouldn't point to it as fait accompli for an AWD Corvette.
.Jinx
So while you are right about clutch slippage occurring in other AWD system, they still have the ability to lock up in most scenarios, whereas the FF system can never lock due to its different gear ratios front to back and therefore is in a permanent state of slippage.
In a low mileage FF, that amount of slippage might be acceptable for reliability but is that also true for a 100k mile Corvette?
Finally, why is heat build up in the snow funny? Never seen a car overheat in the winter?
12-29-2012, 07:27 PM
#39
The GTR is an AWD car, all the time.
The FF is a RWD car with a limited ability to send power to the front (up to only 20%) and only for limited period of time (only in gears 1-4 and also in Snow/Comfort modes).
12-29-2012, 07:27 PM
#40
the new gtr's with the new transmission are pushing well over 800awhp without any mods, few aftermarket upgrades ad they hold over 1400 crank hp, 1200 at the wheels......