RE: Aston Martin V8 Vantage GMR Supercharged
Discussion
k-ink said:
That layout must give the car a lovely balance.
er, nearly.Let me qualify that:
The larger polar moment of inertia as a result of the CofG of the engine and transmission being separated by about 1.5m does make the car quite stable. Unfortunately, it also slightly compromises the rear suspension geometry and applies quite high loads to that rear suspension. As a result, the VH cars, particularly the early ones where the damping was softer and the geo not as well optimised, didn't have a nice, progressive break away at the rear, particularly over crests or lumpy road surfaces. As the lateral load at the point of breakaway are high, that breakaway is sudden and as a result often causes over correction by the driver. imo, only with the latest cars has AML got the limit handling to an acceptable point.
That breakaway behavior in early cars was also negatively emphasized by the differential locking settings, where the cross axle diff was set up to lock quite heavily on a trailing throttle but not on a positive one. As a result, the car feels like it pushes on when you lift, resulting in the driver imputing perhaps too large a handwheel input, and then when they re-apply the accelerator a little timidly, the diff unlocks and the yaw rate builds suddenly.
For the Rally GT, we had great success in "turning the diff upside down" which gave a 60% locking value on positive torque! (because the insides of the diff are vertically symmetrical, inverting the core results in the positive ramps becoming negative ones and vise versa. (Later rear diff settings from the factory, post MY07 pretty much did exactly this)
Max_Torque said:
er, nearly.
Let me qualify that:
The larger polar moment of inertia as a result of the CofG of the engine and transmission being separated by about 1.5m does make the car quite stable. Unfortunately, it also slightly compromises the rear suspension geometry and applies quite high loads to that rear suspension. As a result, the VH cars, particularly the early ones where the damping was softer and the geo not as well optimised, didn't have a nice, progressive break away at the rear, particularly over crests or lumpy road surfaces. As the lateral load at the point of breakaway are high, that breakaway is sudden and as a result often causes over correction by the driver. imo, only with the latest cars has AML got the limit handling to an acceptable point.
That breakaway behavior in early cars was also negatively emphasized by the differential locking settings, where the cross axle diff was set up to lock quite heavily on a trailing throttle but not on a positive one. As a result, the car feels like it pushes on when you lift, resulting in the driver imputing perhaps too large a handwheel input, and then when they re-apply the accelerator a little timidly, the diff unlocks and the yaw rate builds suddenly.
For the Rally GT, we had great success in "turning the diff upside down" which gave a 60% locking value on positive torque! (because the insides of the diff are vertically symmetrical, inverting the core results in the positive ramps becoming negative ones and vise versa. (Later rear diff settings from the factory, post MY07 pretty much did exactly this)
Very interesting stuff - thanks.Let me qualify that:
The larger polar moment of inertia as a result of the CofG of the engine and transmission being separated by about 1.5m does make the car quite stable. Unfortunately, it also slightly compromises the rear suspension geometry and applies quite high loads to that rear suspension. As a result, the VH cars, particularly the early ones where the damping was softer and the geo not as well optimised, didn't have a nice, progressive break away at the rear, particularly over crests or lumpy road surfaces. As the lateral load at the point of breakaway are high, that breakaway is sudden and as a result often causes over correction by the driver. imo, only with the latest cars has AML got the limit handling to an acceptable point.
That breakaway behavior in early cars was also negatively emphasized by the differential locking settings, where the cross axle diff was set up to lock quite heavily on a trailing throttle but not on a positive one. As a result, the car feels like it pushes on when you lift, resulting in the driver imputing perhaps too large a handwheel input, and then when they re-apply the accelerator a little timidly, the diff unlocks and the yaw rate builds suddenly.
For the Rally GT, we had great success in "turning the diff upside down" which gave a 60% locking value on positive torque! (because the insides of the diff are vertically symmetrical, inverting the core results in the positive ramps becoming negative ones and vise versa. (Later rear diff settings from the factory, post MY07 pretty much did exactly this)
Also, I particularly liked "handwheel input" as a turn of phrase
Max_Torque said:
For the Rally GT, we had great success in "turning the diff upside down" which gave a 60% locking value on positive torque! (because the insides of the diff are vertically symmetrical, inverting the core results in the positive ramps becoming negative ones and vise versa. (Later rear diff settings from the factory, post MY07 pretty much did exactly this)
Great info snippet there.The demonstrator and some of our customers cars have done 80k miles already with the GMR Supercharger with NO clutch problems / gearbox problems. All the questions have already been answered and if JohnG1 took the time to read the facts he would have little else to say but we do admire him for his loyalty towards Bamford Rose.
Interestingly, we held an event here on Saturday for V8V owners interested in the GMR Supercharger and we ran 2 GMR supercharged V8V's here all day literally non stop doing standing starts, flat out on our runway and then drove them all the way back to Dorset at the end of the day ON TOP of the 80k miles already done! All the V8V owners that drove the car on Saturday were asked to give us feedback on what they thought and they were ALL overwhelmed by its performance and driveability. We have permission to publish these and will do so shortly. With regards to tough testing Aaron Perrott won the hill climb at the weekend (that's 2 on the trot now since installing the supercharger for the start of this season) in his GMR Supercharged V8V and he is totally delighted with it. http://gmr-uk.co.uk/archives/1201
This has been debated constantly but the facts remain the same. Anyone that genuinely wants to know the facts will take the time as these V8V owners did on Saturday while Graham took the time to show them.
Interestingly, we held an event here on Saturday for V8V owners interested in the GMR Supercharger and we ran 2 GMR supercharged V8V's here all day literally non stop doing standing starts, flat out on our runway and then drove them all the way back to Dorset at the end of the day ON TOP of the 80k miles already done! All the V8V owners that drove the car on Saturday were asked to give us feedback on what they thought and they were ALL overwhelmed by its performance and driveability. We have permission to publish these and will do so shortly. With regards to tough testing Aaron Perrott won the hill climb at the weekend (that's 2 on the trot now since installing the supercharger for the start of this season) in his GMR Supercharged V8V and he is totally delighted with it. http://gmr-uk.co.uk/archives/1201
This has been debated constantly but the facts remain the same. Anyone that genuinely wants to know the facts will take the time as these V8V owners did on Saturday while Graham took the time to show them.
JohnG1 said:
Not this again!
This has been done to death over on the Aston Martin forum.
I have offered £50 to Help for Heroes if anyone who was responsible for this will take a few hours to debate this with BamfordMike from Bamford Rose. The offer still stands. And if anyone is serious about this, I can show evidence of what I have raised for H4H in the past.
If you buy this "package" and drive it you'll end up with some pretty serious problems:
(1) The clutch in a 4.3 V8 will not handle the torque. It's a weak link. Even with a standard 4.3 the clutch gets smelly in reverse gear. The V12V has a twin plate part that's more expensive but can handle the extra torque. Labour plus part via AML main dealer for V12V clutch supply and fit is about £4000.
(2) The gearbox is the same as the V12V but the V12 has a gearbox oil cooler - the 4.3 V8 does not. Why do you think AML fitted a gearbox oil cooler to the V12V? And what will happen if you overheat the gearbox? £15,000 for a reconditioned gearbox from Aston Martin. Plus labour...
(3) Would love to see what endurance testing they have done. Such as driving round Millbrook in 4th gear at the redline for a few hours, the sort of thing an OEM does.
(4) Compression ratios. Without changing any parts the supercharged V8V will have the same compression ratio as standard. In the OEM world forced induction involves reduction of compression ratio. What do these folks know what AML don't??
(5) A supercharger pushes more air into the engine. The engine is effectively an air pump. No mention of any assistance with the exhaust system - how is that going to work?
Wonder if these folks offer a real warranty that includes the downstream parts that the extra torque generated will damage? Or do they warranty their parts only and so if you overheat the gearbox then it's on your head?
This has been done to death over on the Aston Martin forum.
I have offered £50 to Help for Heroes if anyone who was responsible for this will take a few hours to debate this with BamfordMike from Bamford Rose. The offer still stands. And if anyone is serious about this, I can show evidence of what I have raised for H4H in the past.
If you buy this "package" and drive it you'll end up with some pretty serious problems:
(1) The clutch in a 4.3 V8 will not handle the torque. It's a weak link. Even with a standard 4.3 the clutch gets smelly in reverse gear. The V12V has a twin plate part that's more expensive but can handle the extra torque. Labour plus part via AML main dealer for V12V clutch supply and fit is about £4000.
(2) The gearbox is the same as the V12V but the V12 has a gearbox oil cooler - the 4.3 V8 does not. Why do you think AML fitted a gearbox oil cooler to the V12V? And what will happen if you overheat the gearbox? £15,000 for a reconditioned gearbox from Aston Martin. Plus labour...
(3) Would love to see what endurance testing they have done. Such as driving round Millbrook in 4th gear at the redline for a few hours, the sort of thing an OEM does.
(4) Compression ratios. Without changing any parts the supercharged V8V will have the same compression ratio as standard. In the OEM world forced induction involves reduction of compression ratio. What do these folks know what AML don't??
(5) A supercharger pushes more air into the engine. The engine is effectively an air pump. No mention of any assistance with the exhaust system - how is that going to work?
Wonder if these folks offer a real warranty that includes the downstream parts that the extra torque generated will damage? Or do they warranty their parts only and so if you overheat the gearbox then it's on your head?
Edited by wassa on Monday 27th June 14:29
The idea is this competes with the V12V, for less outlay than a used V12V - sounds good.
So, for clarity - GMR have multiple cars that have had the conversion, have done 80k miles post conversion and are on the original, OEM clutch?
Aaron Perrott's car has a GT4 clutch which is very different from the OEM V8V unit and would be very harsh for road usage for regular users.
You've not explicitly answered the question about warranty John raised, without stating the "facts" you allude to but don't mention. Fundementally, if the gearbox gets cooked, it's on the owner. It doesn't mean it will get cooked, but more power / torque = more heat / wear / strain. It needs acknowledgement.
GMR only takes responsibility for it's own components, not even those it installs as part of the package that aren't manufactured by GMR - if they fail, you have to go whom? From GMR's website:
"Our guarantee is a simple one:
The GMR-originated parts are guaranteed for 12 months. If they fail, we will replace them at no cost. All that we ask is that you deliver the car to our installation centre (or one of our registered installers) and collect it again when the replacement installation is complete.
The non-GMR parts are guaranteed by their respective manufacturers."
To paraphrase, if it isn't a manufacturing defect, not made by GMR (even if installed as part of package the wording suggests), or happens after 12 months, you're on your own.
To be compelling to me to compete with a V12V (which I guess is the idea), it would need to be backed with a rock-solid warranty that covered downstream components which are subject to the additional performance this package brings.
If that raises the price, so be it - but without the back-up, to me it's just a huge risk (potentially +75% of conversion cost) that simply makes the V12 look better value. With rock solid backing however, it would be very compelling indeed.
So, for clarity - GMR have multiple cars that have had the conversion, have done 80k miles post conversion and are on the original, OEM clutch?
Aaron Perrott's car has a GT4 clutch which is very different from the OEM V8V unit and would be very harsh for road usage for regular users.
You've not explicitly answered the question about warranty John raised, without stating the "facts" you allude to but don't mention. Fundementally, if the gearbox gets cooked, it's on the owner. It doesn't mean it will get cooked, but more power / torque = more heat / wear / strain. It needs acknowledgement.
GMR only takes responsibility for it's own components, not even those it installs as part of the package that aren't manufactured by GMR - if they fail, you have to go whom? From GMR's website:
"Our guarantee is a simple one:
The GMR-originated parts are guaranteed for 12 months. If they fail, we will replace them at no cost. All that we ask is that you deliver the car to our installation centre (or one of our registered installers) and collect it again when the replacement installation is complete.
The non-GMR parts are guaranteed by their respective manufacturers."
To paraphrase, if it isn't a manufacturing defect, not made by GMR (even if installed as part of package the wording suggests), or happens after 12 months, you're on your own.
To be compelling to me to compete with a V12V (which I guess is the idea), it would need to be backed with a rock-solid warranty that covered downstream components which are subject to the additional performance this package brings.
If that raises the price, so be it - but without the back-up, to me it's just a huge risk (potentially +75% of conversion cost) that simply makes the V12 look better value. With rock solid backing however, it would be very compelling indeed.
Impasse said:
I think you've just described most used cars. If the gearbox on my V8V went pop I would have to pay for it myself, so I'm not sure what point you're trying to make.
The standard car is very robust and not prone to major engine or gearbox issues. My point is that they will be under significantly more strain with an additional 200hp. Were the V8 clutch / gearbox were over-engineered +50% for ongoing use? The additional cooling for the V12 gearbox suggests not, likewise the different clutch AM fitted. It seems odd to put all that development into FI for the engine and then not uprate anything downstream for longevity.
For me, it makes the standard V12 more enticing, rather than less so as it's the complete package for the power under the bonnet.
krisdelta said:
To be compelling to me to compete with a V12V (which I guess is the idea), it would need to be backed with a rock-solid warranty that covered downstream components which are subject to the additional performance this package brings.
If that raises the price, so be it - but without the back-up, to me it's just a huge risk (potentially +75% of conversion cost) that simply makes the V12 look better value. With rock solid backing however, it would be very compelling indeed.
Not to mention that the V12V (manuals) are appreciating, modded V8V's will drop in value faster than the £If that raises the price, so be it - but without the back-up, to me it's just a huge risk (potentially +75% of conversion cost) that simply makes the V12 look better value. With rock solid backing however, it would be very compelling indeed.
Gearboxes, diffs, clutches, engines can all fail for whatever reason. HOWEVER, not one of the 17 supercharger installations have experienced any failures since installing them over the last 3-4 years. I have a question also. Do those who specialise in tuned AM engines offer to guarantee all other components on the car?
wassa said:
Gearboxes, diffs, clutches, engines can all fail for whatever reason. HOWEVER, not one of the 17 supercharger installations have experienced any failures since installing them over the last 3-4 years. I have a question also. Do those who specialise in tuned AM engines offer to guarantee all other components on the car?
And these 17 installations that have had no failures are all running via the original, OEM clutch to 80k plus? You've not addresses a single question...If you want to find out other companies warranties, ask them
I'm not aware of any other companies suggesting you can make make V12 power whilst not considering breathing and the clutch. I'm advocating just buying the real deal as its engineered bumper to bumper to deal with the power / torque and will retain its value better.
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