007 you should really try the cats.

 

Funny you mention that Stuart. The V12 is much quieter than the V8 with the sport cats and I miss the more aggressive sound. I promised myself I wouldn't mod the V12, but we'll see . . .

 

I'm unclear about whether getting to the "correct" A/F ratio is actually a good thing given what AM Dragon Maker said here and elsewhere earlier about the reasoning for what it is stock. As he said, they had a reason for doing it, so, while I'm as hopeful as everyone else that this is all perfectly safe (I'd also love to have a 450 horsepower NA engine), I'd like to understand why, if it's as simple as a retune, it wasn't done that way originally.

Mike, if you're still reading this thread, any comments on any short or long term effects you imagine this might have on the engines/other parts?

 

Guys-

The link below has been posted before on this forum, and you all might find this thread interesting, as it is the primer for everything that MikeBamford has written on PistonHeads regarding the V8V.

http://www.pistonheads.com/gassing/t...m+Bamford+Rose

 

Thanks for posting. Lots of good info there.

 

Hi 007, do you have the references numbers for the carbotech (rear and front)?
Thanks

 

Call me naive, but I'm hesitant to think the company that makes the cars we all obviously like so much would take self destructive measures just to keep performance down. I'm reluctant to believe it just because it's convenient. Mike wrote a number of things based on engineering, not just profit, that drive me to want to get an opinion on this specific thing (pardon the pun).

No offense intended, and I want it to be true, too. We have a resource here who knows more about these engines than any of us or Eurocharged; I'd just like to hear (read?) his educated take on this as well. I know your opinion (and I hope you're right).

 

I have to agree. And I don't think there was any real concern about the V8 outshining the V12. As Mike said, "there is no replacement for displacement." If you read Mike's posts and consider them together, it's clear that his recommendation to increase performance is to increase the displacement from 4.3 to a 4.7. That way the car gets more power (torque) at lower rpms where 90% of all driving occurs.

 

I still believe the reduction in performance was intentional, that is my belief and I am sticking to it ...

With that said, it is quite common practice in the industry to sandbag lower models not to interfere with the sales of the higher models (M3 vs. M5, C63 vs. other 63s, etc etc). Whether they do it by adding more weight, or reducing potential power depends on the manufacturer.

Another point which hasn't been brought up is costs to the manufacturer. I'm sure they could pick up alot more power if they invested more $$ into the car, but ultimately they have to make a profit on every car they sell so they definitely cut corners.

Emissions and upcoming regulations are also putting more pressure on OEMs to reduce their carbon foot print. The stock cats are surely restrictive for this very reason.

Newer cars are being built better than before and its very rare for manufacturers to leave that much power on the table anymore. I find it very hard to believe the manufacturers left 70-90HP on the table by accident, or by sheer incompetence. It was obviously intentional, but we probably will never know 100% why.


One thing I have learned by modding the 4.3L (and I will agree with you on), trying to make low end torque on this 4.3L is near impossible haha. I do see the benefits of the 4.7L. Although the HP I have been able to extract has been impressive, I just cannot make any more torque below 3500rpm. I obviously still have many mods up my sleeve so the battle for more HP is far from over, but so far nothing I have done has worked in this regard. The combination of small displacement, and absurdly aggressive cams has made my quest for low end grunt be frustrating to say the least. Its funny, I started out the project trying to make a bunch of torque, and all I have gotten is a bunch of HP...

C'est la vie
________
WEB SHOWS

 

If you really had read the whole overview of the engine/car on PH, you would realize that it is possible, but not without a fair expense spent on pieces that are designed to get torque. You have chosen to put your money into components that are designed to get more horsepower.

I hope that your mods work out for you, I really do. But it is the height of arrogance to believe that the guy who helped design and test the Vantage engines is less knowledgeable than you. My money is on him....

 

I have to agree with 007 on this one. Since the Vantage has come out, the DB9 has gone from 440hp to 470...and 490 from the Virage and 510 from the DBS. AM could have easily jumped from 440 to 510 and beyond, but they choose to increase it incrementally in order to keep people coming back to upgrade to the next big thing. Good from a business perspective but annoying for a buyer.

If you don't think the V8 could be made to threaten the V12, just look how close the performance numbers of the 4.7 are to the V12 Vantage...in some cases the 4.7 was tested to be faster. Displacement certainly is great for low-end torque and a good power band, but the V12 isn't exactly a high-tech engine. At 470hp (or even 510) it's not even close to maxed out...no DI, low rpm, no variable valve timing, etc. Look at the engine from the 599 for comparison...same displacement with 612-661 hp. That's where AM could and should be with that engine to allow the V8 to move up into the 500 hp range where it could easily be if they uncorked it.

 

Yeah, I'm not saying that it's impossible to get 500 hp from a V8 with approx. 4.3L of displacement. However, to do so, as someone noted above, comes at a high price. You mentioned the Ferrari 599. That's a $315K car! That's what, about twice the cost of a Vantage?

As for the 4.7L, I could be biased, but I find it hard to believe that the performance numbers for the 4.7L are close to those of the 6.0L. I realize that there may be some outlier data out there somewhere (I recall a test of the 4.3 with a 0-60 time of 4.2 seconds!), but after driving both cars, there's just no comparison. The cars weigh nearly the same but the V12 has much more power, a tighter suspension, better brakes, etc.

 

Well the V12 also comes in the DBS, which is a $300k car. So it really should be competitive in that market. Last time it was tested, the performance came way short.

http://www.caranddriver.com/reviews/...mparison_tests

As for the 4.7 vs the V12...I'm sure the V12 is faster, although this hasn't really tested out well in the magazines. I've seen the 4.7 get as low as 4.1 in the 0-60 and 12.5 in the 1/4, vs 4.2 and 12.4 for the V12. Likely more of a traction issue. The rolling numbers show an advantage for the V12...60-100 of 5 seconds vs 5.9 for the V8 (or 4.0 for my car). Given enough road, the V12 will definitely beat the 4.7 V8, but in short runs and off the line it will be surprisingly close.

 

Yes, the DBS is up there in cost too, but we're talking about the "entry level" Aston Martin, the Vantage, not the top of the line DBS.

As for the test data, I don't know what to tell you. As I said earlier, there is always anomalous data out there. Again, there was one test in which they said the 4.3L did 0-60 in 4.1 or 4.2 seconds and there was a quote from the test driver that he thought it could do it in "under 4 seconds." I owned a 4.3L for two years and there is simply no way it could do 0-60 in around 4 seconds. Therefore, I don't buy it. I also don't buy a 0-60 time of the 4.7L of 4.1s. Aston Martin's 0-60 times for the 4.3 and 4.7 were 5.0 and 4.7, respectively. If the cars could do 0-60 in around 4 seconds, trust me, they would have advertised it that way.

So, I don't put much stock in all these tests. I don't know why such odd results are reached (or if they are even reached in reality). All I know is what I have observed myself, and the difference between the V8 and V12 Vantage is night and day. If you drove the V12 for a few days I think you'd agree.

Getting back to my original point, I agree with Mike that, if you really want to make a difference with the 4.3, you need to increase the displacement, or go to forced induction. Although a gain of 30-40 hp is great, it doesn't really mean that much if you only get those horses at or near the red line. I don't know about others, but I don't spend a whole lot of time in the 6000-7300 rpm range when just driving around.

 

I agree with you on the problem of only having improvements at or near redline.

On the car test results, you are confusing tests. The one with a 4.1 second time where they said it could go under 4 seconds was on an '09 4.7L car. The published tests of the 4.3 that I know of got 4.7-5.3 for 0-60.

AMs published numbers were 4.8 seconds for 0-60 for the 4.3 L if I remember correctly and 4.7 seconds for the 4.7 L.

By the way Car and Driver has the 0-60 for the Vantage S at 4.0 seconds.

And I agree with you that the 4.3 to V12 is night and day. That goes back to what we said about AM sandbagging the car so as not to compete with the V12 models. But the 4.7 is closer than you think to the performance of the V12. And they could do more with it if they wanted.

None of this is meant to take anything away from the awesomeness of the V12 model. It's just that I think AM could do more, and that engine which is shared with the higher-priced DBS, should be making numbers to allow it to compete with the Ferraris.