Aston MartinDB7, DB9, Vantage, V8 and Classic models
Welcome to 6SpeedOnline.com!
Welcome to 6SpeedOnline.com.
You are currently viewing our forum as a guest, which gives you limited access to view most discussions and access our other features. By joining our community, at no cost, you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is free, fast and simple, join 6SpeedOnline.com today!
Morning/Afternoon/Evening (delete where applicable) Everyone,
At the request of a couple of Vantage-owning 6speeders, I thought I would start this thread. We have done some preliminary work looking at the feasibility of a Crown Wheel & Pinion kit (CWP) for the Vantage. Although RSC will be offering a Supercharger package later this year there seem to be a number of people who are interested in sticking with NA mods and looking at ways to improve acceleration. With a 3.9:1 diff as standard and a tall 6 speed box the Vantage is potentially geared a little bit long for a car which needs to be kept on the boil to maximise it's power.
We need to have pre-sold 5 units in order to rationalize the development cost for this project and at the request of a couple of interested 6speeders I am starting this thread with the intention of garnering enough interest to make the project viable. We will be producing the kit in conjunction with a UK-based professional racing team that is currently developing our uprated clutch and expect it to be of higher quality than the OE unit.
I am hesitant to mention pricing because while we believe we have a firm handle on the cost I know from experience that there are sometimes unforseen expenses which add to the total. Having said that, since I know a lot of people will ask, we are aiming for a cost of $6500.00 USD. I know that is probably a lot higher than Ford Mustang/Subaru Impreza etc. examples but we are talking about a very small initial production run and all the associated tooling setup.
Where I need your help and input is, in addition to registering interest, we also need to determine what final drive ratio people would prefer to see as I don't think we will make more than one variant at this point. I have attached a gearing chart below which shows engine speeds in 5th & 6th gear respectively for 3 ratios which will give an idea of both cruising RPMs as well as theoretical top speed and engine speed. Obviously the higher the ratio the better the acceleration is going to be.
Thoughts/Input very welcome.
EDIT - Have tried to insert the chart directly into this post but proving to be a b**ch so have attached the file instead.
I am interested Stuart. I'm sure someone will ask if I don't, so: Do you know what the torque increase at the wheels would be for each option?
These aren't exact down to the last decimal place but you just need to look at the relative differences in ratios. So from 3.9 to 4.1 is roughly a 5 percent difference to the final drive, 4.3 is 10 percent and 4.55 is 15 percent. I only really listed 4.55 for reference, in my opinion it is going to be too short for most people. 4.1 would be the conservative option but I would also be tempted to go for the 4.3 to se a really noticeable difference.
__________________
"If everything seems under control you're just not going fast enough" - Mario Andretti
I'd be interested in the 4.33:1. The increased torque to the road is substantial, and the revs aren't all that much higher. The car likes higher revs anyway. Also, I don't see myself driving over 175 mph very often.
I admire your efforts! ... but outside of the 4:55 option, it would probably be down to who ate the lighter lunch - in a drag race against a car with the stock ring and pinion. You could come really close to the actual drive ratios of a 4:11 set by simply installing lower profile (-1 series) tires. It might look a little strange, but it would accelerate exactly the same.
I think the idea is a good one, the car is geared pretty tall. I wonder if an off-the-shelf item (a lot of this car is parts bin) could be used or modified instead of doing the whole thing custom. If so several options might be available.
__________________
07 Vantage, AM suspension upgrade kit, AM power upgrade kit, Quicksilver Supersport cat back exhaust, Brembo 6 piston front brakes.
Dunno about the lunch theory , but I agree that you get the same result with small wheels/tires. Then again, I doubt anyone would actually consider that as an option. Remember the Audi 5000s from the '80s?
Dunno about the lunch theory , but I agree that you get the same result with small wheels/tires. Then again, I doubt anyone would actually consider that as an option. Remember the Audi 5000s from the '80s?
Why disgrace that beautiful home with that car?
__________________ 2008 BMW X5 4.8i - Space gray/black 2007 Aston Martin V8 Vantage - Onyx Black/Black 2001 BMW M3 - Imola red/black
I think the gear set is a good idea...and the 4.33 seems to make the most sense. I don't know why AM geared this car so tall...it doesn't have the low-end grunt that a Chevy V8 has. This should help keep it in the power band during normal driving.
Even a 599 GTB has much shorter gearing...of course it helps to have an 8400 rpm redline.
__________________ 2008 BMW X5 4.8i - Space gray/black 2007 Aston Martin V8 Vantage - Onyx Black/Black 2001 BMW M3 - Imola red/black
Is this an option with the sportsshift? Oh and by the way, what kind of supercharger are you working on, what is your projection in terms of power and performance and what is taking so long? If the price is right(ie 10-12K), I think a lot of us would be interested.
Is there anyone else interested in changing their final drive ratio? It seems to me that this mod would likely do more to address the lack of low-end torque and its effect on acceleration than many of the other mods discussed on this forum. Am I missing something here? I'm surprised by the apparent lack of interest.
BTW, I found this in an old post by another one of our fellow Sixspeeders (Tahoe M3), and it sounds pretty on point to me:
"So in my quest to explain why the Vantage is slower than other cars with higher (worse) weight/power ratios, the easy explanation was that the engine was making less than stated horsepower. Dynos show around 300-305 at the wheels, which if using a 20% drivetrain loss, does roughly come out to 380. There might be a bit of a difference, but it's not huge.
Then I looked at the gearing. Compared to many other cars with inferior weight/power ratios that are faster, the gearing of the Vantage is pretty tall.
Here are the multipliers for the gears for the Vantage:
This is consistently 20% taller than the gearing on the R8, which may explain some of the difference in performance. Other cars I checked on that have shorter gearing included the naturally aspirated cars: 370Z, M3 (6speed and DCT), and 911/911 S (6speed).
Ones that didn't have shorter gearing included the turbos and big V8s: 911 turbo, 135i, Mustang GT, Dodge Challenger SRT-8, Corvette. All cars I looked at had similar or worse power-to-weight ratios but similar or better performance.
The point of this is that Aston Martin didn't just leave horsepower on the table, they left performance from more aggressive gearing. This was probably done to make the car smoother, but at the sake of significant performance losses."
My thought is that a wheel/pinion change would go a long way to compensate for the tall gearing. I'm no expert though, and would love to hear other opinions. Thanks.
Is this an option with the sportsshift? Oh and by the way, what kind of supercharger are you working on, what is your projection in terms of power and performance and what is taking so long? If the price is right(ie 10-12K), I think a lot of us would be interested.
Yup, sportshift and manual would both be fine.
__________________
"If everything seems under control you're just not going fast enough" - Mario Andretti
Sounds like a few people are interested. What I really need at this point is to get 5 people who are interested in putting down a deposit. I'm my opinion (and it seems there's some concensus on this) the 4.33:1 is the ideal setup for this car so I'm inclined to go with this ratio.
Once we achieve that level of committment we need to then source a transaxle to serve as the prototype for development. This is probable a 6-8 week process.
As far as the performance benefits are concerned I think there's an important distintion to be made between numbers and real world power. Let's face it, in an outright drag race the Vantage isn't that slow. Not brilliant but not exactly a slouch either. While the CWP conversion would undoubtedly improve it's outright figures like 0-60 & 1/4 mile times, I think the most significant benefit you're going to see is in terms of real world applications. In gear acceleration is going to be much better, in large part because it will be a lot easier to keep the engine in the power band, but you will also find that a lot of the difference will be improved acceleration in 4th, 5th, 6th gear from low-mid RPMs rather than shaving a tenth or two when you're ragging it's arse off in 2nd.
To put that in perspective or a different context that might make it understandable. I recently swapped the diff in my Vintage race car from a 3.9 to a 4.1. In terms of outright test numbers, it is not that much quicker because once it is in the power band in a 1/4 mile or 0-60 the difference between the two isn't that big. On track however it makes a big difference because coming into/out of corners you aren't always able to keep the RPMs int he optimum range. So if you were to drag race an OE Vantage vs. one with a 4.33 diff you might not see a massive difference. Lap times on the other hand would probably show a huge difference!
__________________
"If everything seems under control you're just not going fast enough" - Mario Andretti
Let's face it, in an outright drag race the Vantage isn't that slow. Not brilliant but not exactly a slouch either.
No argument there. It's definitely not "slow." However, I wish the car were a bit more responsive when you stomp on it. As Jeremy Clarkson put it on Top Gear when discussing the 4.3L:
You get 380 brake horse power so you can go 0-60 in under 5 seconds, then on to a top speed of 186. Problem is though . . . it doesn’t feel that fast. You drop a cog on the big, heavy, manly gearbox, put your foot down, the noise comes, and you’re expecting Armageddon . . . but it never really comes. I’m not going to call it slow. That would be ridiculous, but it’s not . . . it’s not as fast as I was hoping it would be. That means that this car has to wade into battle with slightly damped powder . . . which is a problem because for the same money, look what you can now buy . . . (segue to BMW M6 and Porsche Carrera S).
Linear Mode
