Disclaimer

The information provided here is for general guidance purposes only. It is a combination of manufacturer guidance, first- and second-hand experience, and personal opinion. It may me inaccurate, incomplete, or outdated.

Questions and complaints about the V8 Vantage’s lack of power and sluggish engine response come up fairly often, especially when they center on the earlier cars with 4.3L engines. When the 4.3L V8 was first made, the power it made was competitive with other cars in its market. However, it was still decried as being too slow. The issue wasn’t that the engine didn’t make enough power, it’s that the engine revved so slowly that it took forever to get to the power it did produce. With forced induction engines becoming incredibly commonplace in the years following the V8 Vantage’s release, the 380 bhp that first engine produced was quickly left in the dust. But the key issue with the 4.3L V8 engine was and still is actually the throttle response.

To get everyone on the same page, there are multiple factors at play and I’ll walk through them in a logical progression to make it easy to digest everything. However, I won’t be going into the “why?” of the matter. I’ve heard plenty of speculation including that it was due to cost reduction for manufacturing the cars (particularly the clutch and flywheel, which I’ll touch upon later), to improve reliability of the engines due to an issue they had early in development (related to the first 1000 engines having better internals), or to sandbag the car so it wouldn’t outperform the higher-positioned and much more expensive DB9 (which had been released the year prior) - or all the above. But since I haven’t been able to verify things for sure, I’ll leave that speculation there to consider however as you will.

When asked how to improve throttle response in a V8 Vantage (or any manual-transmission car), my immediate response is always to get an engine tune and clutch package. The former represents the electrical side of the equation, and the latter is the mechanical side.

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General Information

Electronic Controls

Mechanical Restrictions

Change Concerns

When I press the gas pedal, I expect the engine to respond accordingly. If the engine doesn’t respond the way I expect, it distracts me from my driving and can disrupt my driving performance. If I’m on a track and the engine isn’t doing what I’m telling it to do, I’m spending my mental energy trying to predict what will happen rather than know what will happen, and that takes me away from minding my driving lines, and can make me take worse lines to correct for the engine performance not being where I’d wanted it.

We’re going to go over things both electronic and mechanical in nature. It’d be worth going over some of the basics before going to those sections to get an idea of why each matters.

Electrical vs Mechanical

Modern cars are heavily dependent on computers. Any driver input can be changed based on pre-determined parameters (“tuning”), and that’s especially true for throttle inputs. That means how much a driver presses the gas pedal isn’t actually how the engine will be told to behave. Rather, the driver is telling the engine’s controlling computer (usually called an ECU - Electronic Control Unit - but Aston Martin fucked that up by calling their glass key fob “ECU” - Emotional Control Unit, which is fucking stupid). Anyway, the driver tells the computer what they want, and the computer then tells the car what to do. What the computer does with driver inputs is based on how it’s programmed to react to those inputs in any given situation. All of this falls under the electrical side of things.

Changing how a computer calculates driver inputs is basically what engine tuning is, and it encompasses far more than just how much a driver presses the gas pedal - especially as modern cars get more and more advanced and complicated.

The other major aspect is the mechanical side and the core of understanding it is understanding momentum.

Simply put, momentum is resistance to change. If an object has a lot of momentum, it will continue as it is longer/further and it will take more energy/force to change that momentum (slow it down or speed it up). Here are a couple extreme examples to help that make sense:

• A yoga ball has extremely little momentum. It takes very little energy to move it and very little to stop it.

• A round boulder has extremely high momentum. It takes a lot of energy to move it and a lot to stop it.

The momentum of mechanical components has a major impact on how an engine behaves. It takes energy to get the engine internals spinning, and energy to get the clutch and flywheel spinning, and energy to get the gears in the transmission spinning, and energy to get the wheels and tires spinning… the energy it takes to spin all of those things is why a BHP (brake horsepower) rating will always be different and higher than a WHP (wheel horsepower) rating.

The difference between the two is called "drivetrain loss" and typically reduces the amount of power from the engine to the wheels by 15-25% (measuring exact drivetrain loss is nearly impossible due to the variability of chassis dynos, but that’s a whole other can o’ worms). Drivetrain loss in itself is another topic but it's good to know here because improving the efficiency of the drivetrain reduces drivetrain loss, which equates to more power getting from the engine to the ground - and it can also affect how quickly the engine responds to throttle inputs because the less power lost in the drivetrain, the more power can be used to change the momentum of the drivetrain components (quicker engine response) and the car itself (quicker acceleration).

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Electronic controls change how the engine responds by taking driver input and then changing it based on various parameters.

Gas Pedal vs Throttle Body

The gas pedal isn't actually a gas pedal - it's an air pedal. Yes, it's semantics but I'm gonna be petty about it. This is my website and I'll do what I want. The gas pedal can also be called the throttle. Anyway, let’s move on.

You press the "gas" pedal and the throttle body opens to allow more air into the intake manifold (thus, air pedal). More fuel is then added to compensate for the extra air going into the engine. Squish, bang, blow, et voila, you've got more power.

It's simple enough in concept, but the amount you press the gas pedal isn't the same amount that the throttle body opens - at least, not on modern cars. There are two basic systems that determine how a throttle body reacts when the gas pedal is pressed: Drive-by-cable and drive-by-wire.

Drive-By-Cable vs Drive-By-Wire

Up until sometime in the 90s, cars used drive-by-cable systems. That means a metal cable physically connected the gas pedal and throttle body. When you pressed the gas pedal, the cable would physically pull open the throttle body, allowing more air into the intake manifold. Sensors in the intake system would read the amount of air coming in and adjust fuel accordingly. (Prior to the sensors, carburetors would add fuel based on the physical movement of air.) These were direct-input systems as the gas pedal physically moved the throttle body’s butterfly valve. How much you press the gas pedal dictated how much the throttle body would open.

Here’s a pic of my dad’s 1965 Pontiac GTO, which is carbureted and has a drive-by-cable system.

The cable in the top half of the circled area is the cable that opens the throttle valves (of the carburetor in this case) - it’s connected directly to the gas pedal. The spring below it in the bottom half of the circled area is a return spring to make sure the throttle valves close as the gas pedal is released.

Modern cars use what's called drive-by-wire systems which control the throttle body electronically. You press the gas pedal, sensors in the pedal send electric signals through wires to the engine’s control computer, the computer reads that input and calculates new values based on other parameters (the “tune”), and then the computer sends signals through wires to the throttle body telling it to open based on the driver’s throttle input and in accordance with how the computer is programmed.

You can see the wires in the pic below, which give the design its name.

Inside the throttle body are the electronic controls that take the signals sent to the throttle body and interpret those into the physical action of moving the throttle body’s butterfly valve. The movement is done by an electric motor attached to gearing inside the throttle body.

So, although the concepts are basically the same - you press the “gas” pedal and the throttle body opens to let more air through, they do function completely differently.

Our cars use drive-by-wire systems, and that’s the first problem we have when it comes to the factory setup of our cars and how that affects throttle response.

Drive-By-Wire vs Throttle Response

The relationship between how much you press the gas pedal and how much the throttle body opens is usually not linear for drive-by-wire systems. Here’s an example of that.

Here’s how that looks when graphed out.

You can see that not only is there a complete lack of linearity on the graph, it’s also a 3D mapping - not a simple X:Y axis. So, let's put this concept into very round, fictional numbers to make this easy to understand. Keep in mind, actual throttle mapping is a lot more complicated than the simple examples we’ll use, as seen in the images above. Case in point, that chart and graph mapping show torque figures, not throttle body valve positioning - output targets aren’t even throttle body valve positions at all. It’s a quick reminder that it’s a very different system than the direct-input drive-by-cable setup.

Moving on…

Say you press the gas pedal 25% of the way. The computer might tell the throttle body to open only 15% of the way. This is done for a number of reasons: improved fuel efficiency, better emissions, smoother acceleration, reduced drivetrain component shock, maintaining traction control, and so on. Regardless of the reason, the throttle body will open based on an expected resulting torque output from the engine, and it may not be the best for outright performance. There’s almost always a “curve” that changes driver input into a different value.

The factory drive-by-wire system in the V8 Vantage is not very linear and it’s a major factor that keeps the engine from revving as quickly as it could. It prevents the engine from behaving the way we expect, and it holds back the power the engine does have. The point is that I want throttle response and the factory tune basically "numbs" the signal going from gas pedal to the throttle body at low RPMs.

Throttle Signal Override vs Engine Tuning

Changing how a drive-by-wire system behaves means changing the signals that are sent from the computer to the throttle body. There are two primary ways to do this: an engine tune and a throttle signal override.

Note: I sometimes get asked about a product called a "Pedal Commander" so that's going to be the term I use. There are many products like it on the market. I've never used a Pedal Commander so I can't comment on it as a product, or compared to other similar products. I use it as a generic term for the sake of comparison between that type of product and an engine tune. It's like saying "Kleenex" for facial tissue, even if it isn't the Kleenex brand.

A Pedal Commander (and other products like it) change the signal being sent from the gas pedal to the computer to make it seem like the pedal is being pushed more than it is, making the computer tell the throttle body to open more for low-input pedal movement. Obviously, this isn’t an engine tune or tuning at all. It’s just making it so you press your gas pedal less to get the same throttle input, and the throttle body keeps doing what it would usually do. Basically it just means you can be lazy with your gas pedal, but you also have to be more careful with your gas pedal as the throttle will open more for the same pedal movement and that can make it feel twitchy.

An engine tune, like that available from VelocityAP, goes through the actual engine tune programming on the car’s computer and changes it so the throttle body opens more quickly for a given throttle amount to make the relationship more linear, while also changing how everything else in the engine reacts to that increased air - it optimizes the tune itself for more efficiency and better performance.

The optimization is done by getting rid of the concessions of the factory tune, which are required for a variety of reasons like emissions. That may seem like a small thing, but tuning to meet global emissions restrictions alone is a major performance handicap. Aston Martin makes very little changes to their cars depending on which market they’re sold in. The drivetrains are essentially the same globally, so a car sold new in lawless Florida will have the same performance-sapping emissions compliance as a car sold new in very-strict Singapore.

Lots of power is picked up just by tuning out the super-conservative “test spots” where emissions override all other considerations. When added to the quicker and more predictable throttle response, and engine tune is definitely worthwhile on these cars.

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While there are many things that can affect throttle response mechanically, the two key players for the sake of this Article are the clutch and flywheel. Generally, lightweight components will allow the engine to rev up more quickly but the engine will lose revs more quickly when the throttle is released as well, and heavier components will rev up more slowly but maintain revs longer when the throttle is released. More on all that later, but what’s important to know here is that weight reduction in the clutch and flywheel will reduce their momentum and thereby improve throttle response.

Standard vs Lightweight

The flywheel is attached to the backside of the engine and spins with the crankshaft of the engine. The clutch is attached to the flywheel and is the coupling that connects (or disconnects) the engine from the rest of the drivetrain. Since they spin on an axis, the further out the weight is located, the more it affects momentum. Here are the weights of the OEM single-plate clutch and flywheel that came on my 2007 V8 Vantage.

I replaced those with the twin-plate clutch and lightweight flywheel package from VelocityAP, which made a very noticeable improvement on engine response.

Even lighter still is the twin-plate clutch and lightweight flywheel package from AMR.

A couple notes about the weights shown above:

• The VelocityAP flywheel design changed sometime after I got mine so the weight of the one shown above may be different than others from the same company. Also, as of this writing (April 17, 2022), VelocityAP are producing their own clutch and flywheel so the weights of each may have changed again.

• The AMR clutch weighs slightly less than the weight shown due to the paper packaging that is still on it. The actual weight is likely only an ounce or so lighter than shown, but it’s worth mentioning for consistency’s sake.

I didn’t weigh it myself so I can’t verify how exact the weights are, but another person posted that the 4.7L clutch weighs 21 lbs 4 oz, and its flywheel weighs 15 lbs 14.5 oz. Aston Martin did advertise a lighter flywheel being used in the 4.7L cars for improved throttle response, but based on these specs it’s less than a pound difference and the weight reduction wasn’t focused on the outer area of the flywheel so its effect on throttle response will be minimal.

The AMR clutch package is, as of this writing, the lightest package available. The difference between it and the VelocityAP kit is that VAP uses the V12’s clutch, which is a super-beefy unit when mated to the V8, while the AMR kit uses a similar design but not quite as robust. To be clear: both are fantastic upgrades over the original single-plate clutch. I will always recommend one of these twin-plate clutch packages over the original single-plate setup, and both have their advantages over each other as well as a couple drawbacks vs each other. Either way, you’ll be happy.

I just wanted to make that last part clear (and in bold italics) because people ask me what the difference is between the two very often. Here’s some copy pasta of stuff I’ve already written:

My recommendation for which way to go depends on each person’s requirements. Is the customer okay with aftermarket or do they strictly want OEM? Is one priced better than the other? Are you supercharging your car? Which one is available?

Those last two are odd but important. If you’re supercharging your car, like I’ve done with my 2007 V8 Vantage, then I’d recommend the most robust clutch you can get, which means the VelocityAP kit. That’s an incredibly small percentage of my customers, so its importance outweighs its relevance. But the last bit about availability has been a key issue during the COVID-19 pandemic. So its importance is a bit inflated more than it would be at any other time.

Bottom line is, unless you have a specific reason to use one over the other, both are great. That’s all.

Other Mechanical Things

As I mentioned earlier on, the rest of the drivetrain can affect how quickly the engine can rev up. Reducing mass in various areas can help with this - and help with performance overall - and are absolutely worth doing, but some things affect performance more than others depending on the situation. This falls under weight loss, and it’s something I can (and often do) talk about ad nauseum.

Engine internals can be swapped out for stronger and lighter versions, but this tends to be a very high cost so the “man maths” can get skewed pretty quickly. It’s something I’d generally only recommend for someone that already needs to replace them and is looking at upgrades happening during an engine build that’s happening anyway, or for customers with super-deep pockets and aren’t as concerned about budget.

But when looking at easy mechanical targets specifically, the clutch and flywheel are the key things that can be changed for the greatest impact.

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Sluggish vs Twitchy

The key to throttle response is finding a balance between response being sluggish or twitchy and, in my opinion, Aston Martin missed the mark. Badly.

Generally speaking, linear is predictable and predictable is good. I know that when I do something, the result will be consistent based on what I do and I can drive without worrying about it. Even though the engine may feel like it responds somewhat linearly, it isn’t (as we covered in the previous sections above). More importantly, even if it was linear, the engine is still extremely sluggish to rev up, and that’s the root of the issue.

Making throttle response too reactive can make it twitchy, which is what happens when a small amount of input creates an outsized reaction. This can make the car more difficult to drive as you’re constantly concerned about accidentally giving it too much throttle when only a small amount is needed, like when parking. Trying to compensate for this is usually done by riding the clutch or just stalling the car - neither of which is a good thing (and rather embarrassing to do when others are around).

Maintaining drivability (read: not making the throttle twitchy) is important because the last thing you want to do is spend a whole bunch of money to modify your Aston Martin just to find out you’ve made it worse. I’m speaking from experience here as I’d previously over-modified a 1993 Mazda RX-7 (FD3S) I used to have and ended up hating to drive it. My young n’ dumb self thought it’d be a good idea to remove the power steering and air conditioning from the car and only afterwards did I realize that air conditioning is kind of a big deal during the summer - and I was living in Georgia at the time. Not having power steering wasn’t as big of a deal in that car, but combined with the lack of A/C, I ended up ruining a car that I had originally loved.

The lesson I learned with my RX-7 has stuck with me ever since and I try to help spare others from making the same mistake of over-doing things for the sake of potential performance gains. It’s why I try to explain the pros and cons of any parts I sell or modifications I demonstrate.

The good news here is that there are so few options available for our cars that nothing crazy is even available to affect throttle response so much as to ruin it. The closest I’ve come was with GMR… twice.

Let me explain.

The first time was when I visited England and drove GMR’s supercharged demo car - I was a little worried about stalling it because it had a GT4 racing clutch in it. Racing clutches are notoriously easy to stall for an uninitiated driver and I had never driven that specific clutch before. Turns out, it felt perfectly fine and I didn’t have to think about it a single time.

The second time was when I supercharged my 2007 V8 Vantage. I’d gone from a custom VelocityAP engine tune to the one included with (and required for) GMR’s supercharger kit and I immediately noticed a difference in throttle response. I called them up and they explained that they kept throttle response the same as stock for the sake of safety. Obviously, that was not a concern of mine, so I asked them to revise the tune to give me the quicker throttle response that I wanted. I understand their concern as having so much torque from the supercharger can lead to some hairy situations with a snappy throttle, but I absolutely prefer quicker throttle response over the sluggish factory throttle mapping. The updated tune was far better and I’ve been happy ever since.

Okay, maybe I was being a wee-bit very kinda super dramatic and stretching things by leading in with a comment that GMR nearly ruined throttle response for me. I’ve gotta keep these topics at least somewhat interesting and entertaining enough to hold my readers’ attention, right? Anyway, neither situation was actually an issue.

My point is that there really isn’t a serious concern about making a Gaydon-era Aston Martin’s throttle response twitchy or too reactive with products currently on the market, and I doubt any will be developed given how incredibly niche the product would be. Of course, anything can happen, but that’s how things are in April 2022.

Cost vs Performance

There are two main options for improving throttle response in an Aston Martin: engine tuning and a clutch/flywheel package. If you just skipped over the huge amount I’ve said about these, scroll back up because I’m not rehashing it. I am mentioning them again because now we’re talking about change concerns and with that comes pricing.

An engine tune is not terribly expensive, especially when you consider there’s zero labor cost for installation. A clutch package is, and you also have to figure in a lot of labor time for installation on top of that. Generally speaking, a clutch job is going to cost $5000-8000 including both parts and labor. It’s a lot of money and is a major factor that people figure in when considering buying a V8 Vantage.

Each of these things improves the car on their own, and their effects compound when done together. So although they add up to quite the cost, they’re absolutely worth doing. What I recommend to the majority of my customers is to get the engine tune at your convenience, and then upgrade to a twin-plate clutch and lightweight flywheel when it comes time to replace the original factory units - what I call doing a “maintenance upgrade.” You have to replace the parts anyway, so improve them while you’re at it!

When the question comes up as to whether or not the extra expense for a twin-plate clutch and lightweight flywheel is worth it, my answer is always a simple, yes. Why? Because it’s better in every way.

One of the biggest and most frequent complaints about these cars is rooted in their sluggish throttle response. Fix that and you’re fall in love even more with a car that already holds your heart.

That’s it. Simple.

Thanks to Stuart, Chris, Deano, Colin, and Marcus for help with this info!

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