- The origin of the sluggish throttle response V8Vs -
#1
09-29-2011, 03:12 PM
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- The origin of the sluggish throttle response V8Vs -
Hey guys,
Been so busy as of late that I don't really frequent car forums anymore (simply don't have the time), but I have finally gotten a chance to weigh everything and take pics. I will make this one short & brief.
Rotational mass has always been a large part of the Aston V8's sluggish throttle response. Yes, you can dial out some of it with ECU modifications and air intake upgrades but ultimately there is still a significant throttle lag on these cars. Over time I started to realize that more and more it had to be rotational mass throughout the driveline. After doing the lightweight rear brembo brake rotors it became extremely obvious that mass reduction will make a substantial difference if done in key strategic areas. No one mod will eliminate all of it, but each will do its own part in improving the overall throttle response of the motor. Lightweight wheels & tires, lightweight Brake rotors and lightweight clutch & flywheel will reduce the lag but ultimately the source of the problem is at the very front of the drivetrain.
After looking closely at the engine it became obvious where the problem was. After looking at countless engine pics of all the various new generation ford engines it became obvious Aston modded made a few changes to help smoothen out the car (and make it harder to stall) but in doing so they added a significant amount of weight to the front of the crank. The real problem is the stock harmonic damper ... it is extremely heavy (actually ridiculously heavy, much more so than their ford counterparts).
Obviously, nobody was probably going to come out with pulleys for these cars, so there needed to be a relatively simple & easy OEM based solution to reduce the mass off the stock crank pulley without affecting its harmonic dampening nature or any of the crucial balancing holes. Luckily it appears Aston made that very easy as there are two parts to the pulley. The main serpentine belt groove (which houses all the necessary mounting & dampening holes), and then a totally separate unconnected mass portion (which is nothing but dead weight). This makes relatively simple to machine off (albeit you still have to pay for labor costs, and an additional stock unit if you don't want down time in your car). So I purchased a brand new damper (not cheap btw) and I searched around for a local shop to machine off the portion to very exact tolerances. Luckily I found one that would do it for a reasonable fee (I was getting some absurd quotes once people found out what car it was for, good ol' aston premium
).
Stock Pulley weight = 13.87 lbs
Lightened version = 9.37 lbs
Mass removed = 4.50 lbs
Although the total mass removed equates to roughly 33%, the location of the mass is far more important. All of the mas removed is at the very outer edge so the actual reduction in inertia is over 50% and will make a very substantial difference in the way the car accelerates. Removing 4.5lbs from the very edge of a pulley is similar to removing 7-8 lbs from the center of the pulley, so it all adds up once you do wheel, brake rotors, crank pulley, flywheel/clutch combo etc. I think of all of these mods though, the lightweight pulley will by far provide the most torque gains, 2nd followed by the brake rotors, then flywheel/clutch, then wheels.
Essentially you can unlock much of the torque & acceleration gains made from the newer lighter rotating crank assembly from the 4.7s onto the old 4.3Ls by simply removing this mass (in conjunction with the brake rotors & etc). Lighter pulleys are usually the best way to improve the torque sensation on any engine and should do wonders to wake up the 4.3L and make it much more rev-happy.
I have provided some pictures below for your reference to give you an idea of just how much different 4.5lbs looks like when removed from the outer edge. The beauty of this is any V8V owner already has the part on their car, you simply remove it, machine it and reinstall. Its that simple. (If you want to not have any down time you can buy one from the dealership and then machine the new one and remove the stock one and keep as a spare).
Hope this helps,
007
Been so busy as of late that I don't really frequent car forums anymore (simply don't have the time), but I have finally gotten a chance to weigh everything and take pics. I will make this one short & brief.
Rotational mass has always been a large part of the Aston V8's sluggish throttle response. Yes, you can dial out some of it with ECU modifications and air intake upgrades but ultimately there is still a significant throttle lag on these cars. Over time I started to realize that more and more it had to be rotational mass throughout the driveline. After doing the lightweight rear brembo brake rotors it became extremely obvious that mass reduction will make a substantial difference if done in key strategic areas. No one mod will eliminate all of it, but each will do its own part in improving the overall throttle response of the motor. Lightweight wheels & tires, lightweight Brake rotors and lightweight clutch & flywheel will reduce the lag but ultimately the source of the problem is at the very front of the drivetrain.
After looking closely at the engine it became obvious where the problem was. After looking at countless engine pics of all the various new generation ford engines it became obvious Aston modded made a few changes to help smoothen out the car (and make it harder to stall) but in doing so they added a significant amount of weight to the front of the crank. The real problem is the stock harmonic damper ... it is extremely heavy (actually ridiculously heavy, much more so than their ford counterparts).
Obviously, nobody was probably going to come out with pulleys for these cars, so there needed to be a relatively simple & easy OEM based solution to reduce the mass off the stock crank pulley without affecting its harmonic dampening nature or any of the crucial balancing holes. Luckily it appears Aston made that very easy as there are two parts to the pulley. The main serpentine belt groove (which houses all the necessary mounting & dampening holes), and then a totally separate unconnected mass portion (which is nothing but dead weight). This makes relatively simple to machine off (albeit you still have to pay for labor costs, and an additional stock unit if you don't want down time in your car). So I purchased a brand new damper (not cheap btw) and I searched around for a local shop to machine off the portion to very exact tolerances. Luckily I found one that would do it for a reasonable fee (I was getting some absurd quotes once people found out what car it was for, good ol' aston premium
). Stock Pulley weight = 13.87 lbs
Lightened version = 9.37 lbs
Mass removed = 4.50 lbs
Although the total mass removed equates to roughly 33%, the location of the mass is far more important. All of the mas removed is at the very outer edge so the actual reduction in inertia is over 50% and will make a very substantial difference in the way the car accelerates. Removing 4.5lbs from the very edge of a pulley is similar to removing 7-8 lbs from the center of the pulley, so it all adds up once you do wheel, brake rotors, crank pulley, flywheel/clutch combo etc. I think of all of these mods though, the lightweight pulley will by far provide the most torque gains, 2nd followed by the brake rotors, then flywheel/clutch, then wheels.
Essentially you can unlock much of the torque & acceleration gains made from the newer lighter rotating crank assembly from the 4.7s onto the old 4.3Ls by simply removing this mass (in conjunction with the brake rotors & etc). Lighter pulleys are usually the best way to improve the torque sensation on any engine and should do wonders to wake up the 4.3L and make it much more rev-happy.
I have provided some pictures below for your reference to give you an idea of just how much different 4.5lbs looks like when removed from the outer edge. The beauty of this is any V8V owner already has the part on their car, you simply remove it, machine it and reinstall. Its that simple. (If you want to not have any down time you can buy one from the dealership and then machine the new one and remove the stock one and keep as a spare).
Hope this helps,
007
Last edited by 007 Vantage; 11-14-2011 at 06:16 PM.
#2
09-29-2011, 08:10 PM
Interesting. This doesn't affect me because I have a different part, but I do remember Mike mentioning that they had to increase the weight of the crankshaft pulley in order to minimize vibrations that could lead to crankshaft failure. Probably worth going to the source for more info on this first.
#3
09-30-2011, 08:48 AM
Hey guys,
Been so busy as of late that I don't really frequent car forums anymore (simply don't have the time), but I have finally gotten a chance to weigh everything and take pics. I will make this one short & brief.
Rotational mass has always been a large part of the Aston V8's sluggish throttle response. Yes, you can dial out some of it with ECU modifications and air intake upgrades but ultimately there is still a significant throttle lag on these cars. Over time I started to realize that more and more it had to be rotational mass throughout the driveline. After doing the lightweight rear brembo brake rotors it became extremely obvious that mass reduction will make a substantial difference if done in key strategic areas. No one mod will eliminate all of it, but each will do its own part in improving the overall throttle response of the motor. Lightweight wheels & tires, lightweight Brake rotors and lightweight clutch & flywheel will reduce the lag but ultimately the source of the problem is at the very front of the drivetrain.
After looking closely at the engine it became obvious where the problem was. After looking at countless engine pics of all the various new generation ford engines it became obvious Aston modded made a few changes to help smoothen out the car (and make it harder to stall) but in doing so they added a significant amount of weight to the front of the crank. The real problem is the stock harmonic damper ... it is extremely heavy (actually ridiculously heavy, much more so than their ford counterparts).
Obviously, nobody was probably going to come out with pulleys for these cars, so there needed to be a relatively simple & easy OEM based solution to reduce the mass off the stock crank pulley without affecting its harmonic dampening nature or any of the crucial balancing holes. Luckily it appears Aston made that very easy as there are two parts to the pulley. The main serpentine belt groove (which houses all the necessary mounting & dampening holes), and then a totally separate unconnected mass portion (which is nothing but dead weight). This makes relatively simple to machine off (albeit you still have to pay for labor costs, and an additional stock unit if you don't want down time in your car). So I purchased a brand new damper (not cheap btw) and I searched around for a local shop to machine off the portion to very exact tolerances. Luckily I found one that would do it for a reasonable fee (I was getting some absurd quotes once people found out what car it was for, good ol' aston premium ).
Stock Pulley weight = 13.87 lbs
Lightened version = 9.37 lbs
Mass removed = 4.50 lbs
Although the total mass removed equates to roughly 33%, the location of the mass is far more important. All of the mas removed is at the very outer edge so the actual reduction in inertia is over 50% and will make a very substantial difference in the way the car accelerates. Removing 4.5lbs from the very edge of a pulley is similar to removing 7-8 lbs from the center of the pulley, so it all adds up once you do wheel, brake rotors, crank pulley, flywheel/clutch combo etc. I think of all of these mods though, the lightweight pulley will by far provide the most torque gains, 2nd followed by the brake rotors, then flywheel/clutch, then wheels.
Essentially you can unlock much of the torque & acceleration gains made from the newer lighter rotating crank assembly from the 4.7s onto the old 4.3Ls by simply removing this mass (in conjunction with the brake rotors & etc). Lighter pulleys are usually the best way to improve the torque sensation on any engine and should do wonders to wake up the 4.3L and make it much more rev-happy.
I have provided some pictures below for your reference to give you an idea of just how much different 4.5lbs looks like when removed from the outer edge. The beauty of this is any V8V owner already has the part on their car, you simply remove it, machine it and reinstall. Its that simple. (If you want to not have any down time you can buy one from the dealership and then machine the new one and remove the stock one and keep as a spare).
Hope this helps,
007
Been so busy as of late that I don't really frequent car forums anymore (simply don't have the time), but I have finally gotten a chance to weigh everything and take pics. I will make this one short & brief.
Rotational mass has always been a large part of the Aston V8's sluggish throttle response. Yes, you can dial out some of it with ECU modifications and air intake upgrades but ultimately there is still a significant throttle lag on these cars. Over time I started to realize that more and more it had to be rotational mass throughout the driveline. After doing the lightweight rear brembo brake rotors it became extremely obvious that mass reduction will make a substantial difference if done in key strategic areas. No one mod will eliminate all of it, but each will do its own part in improving the overall throttle response of the motor. Lightweight wheels & tires, lightweight Brake rotors and lightweight clutch & flywheel will reduce the lag but ultimately the source of the problem is at the very front of the drivetrain.
After looking closely at the engine it became obvious where the problem was. After looking at countless engine pics of all the various new generation ford engines it became obvious Aston modded made a few changes to help smoothen out the car (and make it harder to stall) but in doing so they added a significant amount of weight to the front of the crank. The real problem is the stock harmonic damper ... it is extremely heavy (actually ridiculously heavy, much more so than their ford counterparts).
Obviously, nobody was probably going to come out with pulleys for these cars, so there needed to be a relatively simple & easy OEM based solution to reduce the mass off the stock crank pulley without affecting its harmonic dampening nature or any of the crucial balancing holes. Luckily it appears Aston made that very easy as there are two parts to the pulley. The main serpentine belt groove (which houses all the necessary mounting & dampening holes), and then a totally separate unconnected mass portion (which is nothing but dead weight). This makes relatively simple to machine off (albeit you still have to pay for labor costs, and an additional stock unit if you don't want down time in your car). So I purchased a brand new damper (not cheap btw) and I searched around for a local shop to machine off the portion to very exact tolerances. Luckily I found one that would do it for a reasonable fee (I was getting some absurd quotes once people found out what car it was for, good ol' aston premium
). Stock Pulley weight = 13.87 lbs
Lightened version = 9.37 lbs
Mass removed = 4.50 lbs
Although the total mass removed equates to roughly 33%, the location of the mass is far more important. All of the mas removed is at the very outer edge so the actual reduction in inertia is over 50% and will make a very substantial difference in the way the car accelerates. Removing 4.5lbs from the very edge of a pulley is similar to removing 7-8 lbs from the center of the pulley, so it all adds up once you do wheel, brake rotors, crank pulley, flywheel/clutch combo etc. I think of all of these mods though, the lightweight pulley will by far provide the most torque gains, 2nd followed by the brake rotors, then flywheel/clutch, then wheels.
Essentially you can unlock much of the torque & acceleration gains made from the newer lighter rotating crank assembly from the 4.7s onto the old 4.3Ls by simply removing this mass (in conjunction with the brake rotors & etc). Lighter pulleys are usually the best way to improve the torque sensation on any engine and should do wonders to wake up the 4.3L and make it much more rev-happy.
I have provided some pictures below for your reference to give you an idea of just how much different 4.5lbs looks like when removed from the outer edge. The beauty of this is any V8V owner already has the part on their car, you simply remove it, machine it and reinstall. Its that simple. (If you want to not have any down time you can buy one from the dealership and then machine the new one and remove the stock one and keep as a spare).
Hope this helps,
007
Interesting project. Removing rotational mass does have a good effect on torque transmitted to the wheels. I'm not sure I would want to start messing around with harmonic dampers if it were my car, not without the sort of R&D capabilities that only an OEM has.
The clutch/flywheel assembly is a much easier place to remove weight, especially if you consider that this is something you're going to have to change at some point anyway.
#4
09-30-2011, 09:05 AM
Originally Posted by 007 Vantage
So I purchased a brand new damper (not cheap btw)
Originally Posted by 007 Vantage
The pulley balance was rechecked and was identical to the stock unit
#5
09-30-2011, 09:20 AM
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I would also be reluctant to do this on my car. I don't doubt that it would have a positive effect on acceleration. However, that Aston understood that the additional mass would have negative effect on performance and decided to put the mass there anyway says to me that there's a good reason for that mass being there.
#6
09-30-2011, 10:56 AM
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I remember hearing about this on a training once, Aston runs more of an aggressive tune compared to the Jag's, so to help the idle the weight was added, the weight is also used to dampen the shock felt by the A/C clutch engaging...and some other little things like user concerns ..aka vibrations
The removal of the weight can help, but is not enough alone to justify a large difference..maybe if this was a track car the difference could be compared, but for the street, this alone is not going to force much change in throttle response..but I see where your going with this, minimizing anything that you can, so eventually you will see change..good write up
Although be advised if you fit this modded pully, there is a chance you will get a check engine for random midfires P0300..this is due to the different weight of the rotating assembly. The vehicle will not misfire but the knock detection thinks it is and flags a fault. You will need to have the "MisFire Factors" cleared and "Re-Learned" correctly by doing the 36-1 relearn procedure. this will then calibrate the pcm into knowing the new adjustments needed..a simple battery disconnect(hard reset) does not do this, the dealer will need to hook up there AMDS and perform the this action..
The removal of the weight can help, but is not enough alone to justify a large difference..maybe if this was a track car the difference could be compared, but for the street, this alone is not going to force much change in throttle response..but I see where your going with this, minimizing anything that you can, so eventually you will see change..good write up
Although be advised if you fit this modded pully, there is a chance you will get a check engine for random midfires P0300..this is due to the different weight of the rotating assembly. The vehicle will not misfire but the knock detection thinks it is and flags a fault. You will need to have the "MisFire Factors" cleared and "Re-Learned" correctly by doing the 36-1 relearn procedure. this will then calibrate the pcm into knowing the new adjustments needed..a simple battery disconnect(hard reset) does not do this, the dealer will need to hook up there AMDS and perform the this action..
#7
10-04-2011, 01:53 PM
Join Date: Nov 2009
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There won't be any misfires or anything of the sort. The pulley is definitely 100% safe and was actually designed by a professional ford racing builder who has a machine shop local here in town so I trust his input 100%. I too brought of many of these concerns but he said there would be absolutely no increase in vibrations or harmonics of any kind with this type of a mild modification. He said if you want to go to a super lightweight aluminum pulley with no harmonic damper that is under driven, that would be way too aggressive for the street. The pulley still retains its stock harmonic damper and all the vital crucial components to make it completely safe. Its basically simple free HP with zero negative side effects of any kind as verified by professionals.
Now if you were to remove the harmonic damper, and try and do something out of aluminum, and underdrive the pulley on top of that ... then yes that could potentially cause problems if its improperly designed. But doing this to an OEM stock diameter unit is 100% safe and has been done for decades since the muscle car era without any negative side effects.
Remember also, the gains will be significantly greater in 1st & 2nd gear because the power out put is then multiplied by the transmission & diff gear ratios thereby amplifying the gains.
You do NOT need to upgrade displacement to 4.7L to get a lot of torque out of these cars, you just have to know what you are doing. Many engine builders would love you to think you need to spend $10k+ on a new motor (and bash all other possibilities) just to make more power but that's complete nonsense. A few simple safe both-on modifications are all you need.
Save your money and spend it on other things. Beyond a few simple bolt on mods, save your money for a V12V
Now if you were to remove the harmonic damper, and try and do something out of aluminum, and underdrive the pulley on top of that ... then yes that could potentially cause problems if its improperly designed. But doing this to an OEM stock diameter unit is 100% safe and has been done for decades since the muscle car era without any negative side effects.
Remember also, the gains will be significantly greater in 1st & 2nd gear because the power out put is then multiplied by the transmission & diff gear ratios thereby amplifying the gains.
You do NOT need to upgrade displacement to 4.7L to get a lot of torque out of these cars, you just have to know what you are doing. Many engine builders would love you to think you need to spend $10k+ on a new motor (and bash all other possibilities) just to make more power but that's complete nonsense. A few simple safe both-on modifications are all you need.
Save your money and spend it on other things. Beyond a few simple bolt on mods, save your money for a V12V
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#8
10-04-2011, 01:58 PM
If you're referring to the engine build I think you are, then it's more like £12,000 GBP (about $20,000.)
#9
10-04-2011, 02:41 PM
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I never said there would be a misfire, the vehicle pcm uses weight and speed of the flywheel along with it's 36-1 points on the flywheel to calculate the misfire factors, ..some cars are picky and some aren't. If the misfire factors that the pcm is looking for do not match because you lightened the pulley..the light will come on and the pcm will think there was a misfire(even though there wasn't), hense why they would need to be reset and relearned....like I said, some cars are picky and some aren't...some are still driving around with not even being learnt yet. I don't know how the damper will affect things but the flywheel sets things off pretty bad because of the 36-1 points...
#11
10-04-2011, 03:54 PM
Again, unless you believe in conspiracy theories that AM left free HP and torque on the table to artificially under-spec the V8 versus other cars in there lineup, there must be a sound engneering reason that AM made the design choices they made. Unless anyone else is willing to put their engine mods in a testbed for 100K miles like AM did due to Ford guidelines, I question their claims.
#12
10-04-2011, 05:03 PM
I have been following this thread with interest. I find it hard to accept that a lighter crank damper would make any significant difference in power or torque. Taking weight out of rotational mass will certainly improve responsiveness (acceleration and deceleration of the rotating parts) so it may "feel" more powerful. However, I would like to see any technical reports or reliable independent reports if any are available.
Reducing rotational mass will, as others have pointed out, make for a harder time controlling idle, and in some cases I have experienced with modified engines, adversely affected general driveability.
John
Reducing rotational mass will, as others have pointed out, make for a harder time controlling idle, and in some cases I have experienced with modified engines, adversely affected general driveability.
John
#13
10-04-2011, 05:24 PM
No disrespect, but I'm with Racer_X on this one. I'm pretty sure we all know who everyone is referring to as well. The fact is, however, that out of all the people involved in this discussion, this engine builder is the ONLY one who has the actual credentials to back up their talk. Everyone else can make any claims and say that they know a guy who knows another who says they can do this safely and without any repercussions.
Again, unless you believe in conspiracy theories that AM left free HP and torque on the table to artificially under-spec the V8 versus other cars in there lineup, there must be a sound engneering reason that AM made the design choices they made. Unless anyone else is willing to put their engine mods in a testbed for 100K miles like AM did due to Ford guidelines, I question their claims.
Again, unless you believe in conspiracy theories that AM left free HP and torque on the table to artificially under-spec the V8 versus other cars in there lineup, there must be a sound engneering reason that AM made the design choices they made. Unless anyone else is willing to put their engine mods in a testbed for 100K miles like AM did due to Ford guidelines, I question their claims.
I am constantly amazed that those who question He Who Shall Not Be Named do so without the background, pedigree or knowledge base of a design engineer of the particular engine/drive train in question. Some of you should try going to Piston Head, as the rebuilds in question have been dyno'd, and the numbers don't lie. Look at the success on the racing circuit, again, those placings don't lie.
It's one thing to sell your point of view; it is another to try to sell it based on supposition and a clear disregard for facts.
I look to this forum to educate me on the AM brand. Educate me with facts rather than personal justification. If we stick to facts, we all might learn more.
#14
10-04-2011, 05:33 PM
Should make a fine paperweight, though.
Last edited by CRVETR; 10-04-2011 at 05:45 PM.
#15
10-04-2011, 05:34 PM
No disrespect intended towards you either