Aston Martin advice from Bamford Rose independent specialist

[BamfordMike]

jonby said:

I have a question which I'm hoping you'll be able to help with Mike

I have a Vantage S which we know will only bring in tehe extra 10bhp with higher octane fuel

As higher octane is not avilable everywhere, or at least not the 98 (or is it 99) that is needed to trigger the extra last bit of power, what happens if you have say 97 RON fuel, your tank goes down to say 1/4 full, then you put in 99 or 100RON ? Another words, does every last drop need to be at the higher octane, or does it 'average out'

Because I often cannot find the higher octane, I am constantly mixing & matching & wonder what effect this has ?

Realistically, if you only put in a lower octane once in a blue moon, there will always be some in there even 5 fills later

Good question....

Different volume fills of different blends will result in an 'average' grade in the tank.

If you were to become used to the performance on 97 Octane and at half full fill up with 99 Octane, the difference might not be that noticeable. Whereas after becoming used to the performance on 95 octane and filling up with 99 Octane when at near empty - the greatest performance and driveability increase possible will be noticed.

If you had to fill with standard grade fuel and you wanted to get the biggest bang for buck out of a premium tank fill, run the lower octane tank down to the warning light as yes, a mix of a few low and high octane fuel fills when deposited at half full will result in an 'average' grade fuel in the tank which will be present for many fills.

Edited by BamfordMike on Friday 27th April 23:31

[BamfordMike]

CraigV12V said:

While on this subject I was lead to believe that my V12V will not benefit at all from using higher octane fuel, is that correct? So is the improved performance of the V8S via hi RON fuel unique to the V8S?

The absence of knock control / adaptive spark control on current V12 means V12V / DBS will not benefit from high Octane fuel.

The Valve airbox system which started life on N400 was carried across to some V12 (DBS has it Virage doesn't).

This is only a debated subject on V8 because the make-up of power from the power upgrade kit has been questioned Vs spend, it is not a debated subject or even considered on V12 as there is no power upgrade kit, meaning the make-up of performance from manufacture (whether or not a device in induction system gives 10 BHP to the total or not) is unimportant.

As a few posters on the main forum have commented, V12 DBS II looks likely to get knock control. However, knock control is probably the most difficult of any of the software functions to program correctly. When this car is released, lets see what the 0-60 or 0-100 time is on 95 Octane and empty and fill with 100 Octane and record the difference - we can then measure if the bod calibrating the system did a good job....

[jonby]

Thanks Mike. I wonder how many people (both AM & others) completely unaware fill their cars with high octane assuming it will benefit performance instead of saving a considerable amount of money ?!?

On a different subject, what are you currently offering/planning with regards to the V12V ?

Will you be offering a manifold set-up similar to that on the V8 ? Are the options you have offered on the clutch & gearchange for the V8 relevant to the V12V which I seem to recall is a slightly different set-up ? Anything else (short of major surgery) that you advise re: the engine and finally, on the suspension ?

[yeti]

jonby said:

On a different subject, what are you currently offering/planning with regards to the V12V ?

You need to have a read of my thread http://www.pistonheads.com/gassing/topic.asp?h=0&a...

Details what has been done to suspension, brakes, clutch and flywheel on a DB9, plus what is about to be done with inlet and exhaust manifolds, race cats, backboxes etc. All transferable to all V12s.

Even lots about my 6.5 litre engine...

[yeti]

jonby said:

Thanks Mike. I wonder how many people (both AM & others) completely unaware fill their cars with high octane assuming it will benefit performance instead of saving a considerable amount of money

A fiver a tank probably? Worth it for me for the detergents and engine cleaning chemicals.

It's better fuel. Do you buy the cheapest oil you can find?

Most performance cars have a knock sensor these days, the V12 is pretty old tech sadly I think almost everyone with one knows the car is mapped for 95RON or less anyway. Except mine, which is mapped for 97/98. Great unless you're in rural Wales and everyone else fills up at Asda

[jonby]

yeti said:

A fiver a tank probably? Worth it for me for the detergents and engine cleaning chemicals.

It's better fuel. Do you buy the cheapest oil you can find?

Most performance cars have a knock sensor these days, the V12 is pretty old tech sadly I think almost everyone with one knows the car is mapped for 95RON or less anyway. Except mine, which is mapped for 97/98. Great unless you're in rural Wales and everyone else fills up at Asda

I've always put the higher octane in myself for exactly those reasons, but the question was about people who put it in assuming performance will be better. However I take your point about the fact that the V12V is in the minority regarding knock sensors AND that it's possibly a niche enough car that most owners are aware of the situation

As for other benefits, I'm not saying your wrong (seriously, I'm not ! :-) ) but I'd love to see some proper testing regarding the advantages - none that i've seen have ever appeared that scientific

[jonby]

yeti said:

jonby said:

On a different subject, what are you currently offering/planning with regards to the V12V ?

You need to have a read of my thread http://www.pistonheads.com/gassing/topic.asp?h=0&a...

Details what has been done to suspension, brakes, clutch and flywheel on a DB9, plus what is about to be done with inlet and exhaust manifolds, race cats, backboxes etc. All transferable to all V12s.

Even lots about my 6.5 litre engine...

Been following your project with a lot of interest - I think it's an amazing road you're going down and great that it's on an Aston which relative to some cars, is rarely done. You will have one truly stunning car

But the reason I was specifically asking about the V12V is that for instance, I can't see there would be any point in upgrading the brakes as they are already ceramic. I don't know if the suspension would be improved over the V12V's regular suspension if one was looking at it purely from a handling point of view rather than also offering some extra ride comfort

So it was more a question of given that starting point of a V12V, if you didn't want to start enlarging the engine (there's a limit to what I'd do to a car still in warranty which most V12V's are still just about in), what upgrades both make sense from an significant improvement point of view and are possible to that particular car without going too overboard. I guess that last bit is a subjective personal opinion - I'd happily upgrade clutch or say springs on a car in warranty on the basis it would be hard for a manufacturer to argue they have an effect on other components in a warranty claim - perhaps I'm foolish in that respect......

Regarding the manifolds, I assume some sections are a different length in the shorter car. So whilst anything can be done at a price, I imagine it's a very different price if it has to be made as a one off, compared to the one offered by BR for the V8 where it's being made in some (smallish) numbers

[yeti]

Probably stuff for Mike to answer...

But you absolutely wouldn't change the CCMs for steel, the suspension... Well if you never find it harsh or wafty, you perhaps don't need that either, but switching the character of the car at the touch of a button is very useful for grand tourer like the DB9 (or V8 Vantage!). DBS of course already has it.

Manifolds will be the same as will the catalysts used, there would just be shorter sections between them as I understand it. The prototyping for my car will cover all V12 engined Gaydon cars - Mike to confirm!

The clutch and flywheel are definitely upgrades, 6kg saved. Bigger stronger clutch and lighter flywheel, engine and throttle response are markedly quicker. Then there is gearshift linkage shortening, pedal box modification, lots of little bits that add up to a big difference

[mikey k]

yeti said:

Great unless you're in rural Wales and everyone else fills up at Asda

Big T took you to the Shell I pointed out on the directions - no?

[yeti]

mikey k said:

Big T took you to the Shell I pointed out on the directions - no?

He did indeed Mikey, then Token Jock had to find me another one mid afternoon Just took our cake and tea time away at the Orme - Tony was very kind to give his time up, we were gone an hour!

I would like a switchable map in my car for the future to make life easier - BR Mike, what are the options there? Sure a lot of V12 owners would be interested, their very own personal knock sensor

Seem to remember Cerberas were fitted with them..?

[yeti]

Mike, sorry I didn't get to see you today but did hear from the guys that my new high lift camshafts have now been ground - so I have a bespoke block and cams for my 6.5 engine

I also heard that you're going to offer the high lift cams as an upgrade for the V12 cars, are they going to be the same as mine or different profiles? How much work to get them in, obviously my engine is being built from the ground up, but how easy to get them into an existing V12?

Big question... what performance do you think they'll give?

[Captain Beaky]

yeti said:

I would like a switchable map in my car for the future to make life easier - BR Mike, what are the options there? Sure a lot of V12 owners would be interested, their very own personal knock sensor

Seem to remember Cerberas were fitted with them..?

I had the ECU changed in my Cerbera to the Emerald unit which has 3 switchable maps. Mine were fast, low octane and pops'n'bangs maps (lots of gratuitous overfuelling on the over-run).

The Red Rose model had a switch from the facory for 95/98 I think.

I imagine the cost of replacing the V12 ECU would be prohibtive for solely this purpose but if the code could be cracked or piggy-backed...

[yeti]

Captain Beaky said:

I imagine the cost of replacing the V12 ECU would be prohibtive for solely this purpose but if the code could be cracked or piggy-backed...

That seems to be the position. However, even when mapped to optimise 97/98 RON fuel, it might still be OK to use 95... This is being examined as it would have made my life (and everyone else's!) much easier in North Wales

[George H]

yeti said:

That seems to be the position. However, even when mapped to optimise 97/98 RON fuel, it might still be OK to use 95... This is being examined as it would have made my life (and everyone else's!) much easier in North Wales

Where doesn't sell super unleaded now a days? The only thing I put in any car of mine

[jonby]

George H said:

yeti said:

That seems to be the position. However, even when mapped to optimise 97/98 RON fuel, it might still be OK to use 95... This is being examined as it would have made my life (and everyone else's!) much easier in North Wales

Where doesn't sell super unleaded now a days? The only thing I put in any car of mine

Of course not all super unleadeds are made equally. All this changes from time to time so I'm sure I'll be jumped on quickly if I've made a mistake, but I think the current position is:
BP ultimate is 97 RON, as with many super unleadeds
It's only Shell Vmax and Tesco momentum that are 99 RON
Not many, if any, do 98 RON anymore ?
The V8S requires 98 RON minimum (IIRC?) for the extra 10bhp, which means Tesco & Shell are the only options
I appreciate there are factors other than knock control that may dictate whether or not you put in super unleaded of course
Incidentally, I did a track day at Silverstone where they had about a 105RON option at the onsite fuel station IIRC - it was about £2.50-£3 per litre from memory..............

[mikey k]

jonby said:

Of course not all super unleadeds are made equally. All this changes from time to time so I'm sure I'll be jumped on quickly if I've made a mistake, but I think the current position is:
BP ultimate is 97 RON, as with many super unleadeds
It's only Shell Vmax and Tesco momentum that are 99 RON
Not many, if any, do 98 RON anymore ?
The V8S requires 98 RON minimum (IIRC?) for the extra 10bhp, which means Tesco & Shell are the only options
I appreciate there are factors other than knock control that may dictate whether or not you put in super unleaded of course
Incidentally, I did a track day at Silverstone where they had about a 105RON option at the onsite fuel station IIRC - it was about £2.50-£3 per litre from memory..............

The S does not need 99RON to give the 10BHP, they come from the N400 airbox valves that are now only fitted to the S & DBS.
Obviously using a lower RON will decrease the gain

[yeti]

George H said:

Where doesn't sell super unleaded now a days? The only thing I put in any car of mine

ASDA in North Wales! Fact

[jonby]

mikey k said:

The S does not need 99RON to give the 10BHP, they come from the N400 airbox valves that are now only fitted to the S & DBS.
Obviously using a lower RON will decrease the gain

Forgive my ignorance in this area - I'm not going to pretend I fully understand ! :-)

Does that mean with 95 RON you get 420 bhp and the airbox gives up to a maximum of a 10bhp gain, depending on the RON level over and above 95 ?

[mikey k]

jonby said:

mikey k said:

The S does not need 99RON to give the 10BHP, they come from the N400 airbox valves that are now only fitted to the S & DBS.
Obviously using a lower RON will decrease the gain

Forgive my ignorance in this area - I'm not going to pretend I fully understand ! :-)

Does that mean with 95 RON you get 420 bhp and the airbox gives up to a maximum of a 10bhp gain, depending on the RON level over and above 95 ?

Nope the manual states

"Recommended 98 RON Super Unleaded for optimum performance. 95 RON minimum."

Nowhere does it confirm the peak power is based on 98 RON but I can't see them missing that trick
The airbox change came in on the N400 but never made it to the 4.7's until the S, that is the major contributor to the 10 BHP (@ 98 RON) diffrence
Running on 95 RON will give less total BHP but I can't say I've noticed it in either of my roadsters.

[BamfordMike]

yeti said:

Mike, sorry I didn't get to see you today but did hear from the guys that my new high lift camshafts have now been ground - so I have a bespoke block and cams for my 6.5 engine

I also heard that you're going to offer the high lift cams as an upgrade for the V12 cars, are they going to be the same as mine or different profiles? How much work to get them in, obviously my engine is being built from the ground up, but how easy to get them into an existing V12?

Big question... what performance do you think they'll give?

Dangerous for me not to be there for even a day..... too many secrets manage to walk out the door

For our V8 improvement package 100BHP per ltr was the target as that exceeded OE effort. One reason why that was possible was because after the intake and exhaust ports had the BR GT4 porting treatment, standard valve diameter and lift can flow the demand for extra airflow. However, V12 even in standard guise is way short of the 100BHP per litre mark, one reason for that is the inability of the ports to flow the level needed to reach the 100BHP/Ltr ideal. We know this because std DB9 was 450BHP, with an inlet port mod DB9II was 470BHP and with aggressive porting mod Vanquish S was 520BHP.

Your project / engine is a no limits (ok, within reason )search for optimum and in that process high lift cams and larger diameter inlet and exhaust valves have been specified. However, when it comes to the wider V12 ownership we realised that non intrusive measures were realistically all that are possible to offer to prevent the upgrade becoming cost prohibitive. But, never satisfied with compromise, as we know from DB9/DB9II and Vanquish S, increasing airflow returns massive gains. For this reason, as an additive to the BR exhaust manifold and catalyst package for V12 we are also developing a set of high lift cams which we will fit with the engine in situ during the conversion to our improved exhaust system.

Cams on their own?? 15-20BHP although this will be dyno tested on a standard engine in isolation from any other modification - more on that point in a future post

Ease to get the cams in - we are developing our own tooling to perform the cam change with the engine in place, normally this would not be possible.