I know the power difference is about 40HP (380 vs 420), but I'm more interested in the mechanical specs and differences.

Are both DOHC with chain-driven cams?
Do both have hydraulic valve tappets (no adjustments)?
I know the 4.3 has port FI. Is the 4.7 direct-injected?
Do they have a single or dual throttle valve?
What kind of variable valve timing do they have (cam phasing and/or valve lift), and on intake or both?
Is the 4.7 a stoked-out version of the 4.3, a bored-out version, or both?
Is the tranny and clutch beefier, or the same?
What are the typical problems on each engine? Read about oil leaks on the 4.3 but no specifics. I'd like to learn more on that (where, how easy to fix, if a recall or TSB, years affected, etc). Any links?

And I'd also like confirmation these engines are Ferrari-sourced, but with a cross-plane crankshaft (thankfully!), and a much milder state of tune with a lower redline, for better reliability and comfort. I'm not a Ferrari fan at all, but I think their engines in Maseratis (also with a cross-plane crank and mildly tuned) are considered fairly reliable.

I don't want to spend on an '09, but want to consider everything . I basically want the least complex drivetrain, to minimize future problems. Although I like high-tech engines, now that I'm considering to own an expensive car out of warranty for the first time in my life, suddenly the double VANOS with 8 freaking TBs driven by complex valves on my M3 doesn't sound that appealing anymore . That's one huge advantage the Vette has that I never saw before: can't get any simpler than 1 cam, 16 valves, and no variable timing of any kind. Plus how easy it's to work on them, but man, are those cars built cheap. I'd like something in the middle . Thanks folks.

 

I can tell you that the engine is NOT a Ferrari motor, it's a modified version of the Jaguar AJ V8. Smooth motor that sounds FANTASTIC

 

The Aston V8 is based on the Jaguar V8, with some modifications--not sure just what. Aston V8 is hand assembled (I think by one guy) in their engine assembly plant in Cologne, Germany. They did something to the cylinder sleeves to make them thinner in the 4.7L.

 

That's great news. So only Maseratis have a Ferrari engine then. I trust Ford MUCH more (who's behind the AJV8, I believe) than Ferrari in the reliability department, especially if built by hand. So guess it has both chain-driven cams and hydraulic valve tappets, like Jags. It must also have at least cam phasing on the intake valves, but need to do more research to see how it works (the ones that work with oil pressure are pretty reliable). Thanks.

 

There are very few differences between the 4.7 & 4.3. Aston changed over from cast cylinder liners to pressed-in which mean the liners could be thinner. Increased the bore and displacement.

They also lightened and beefed up the clutch/flywheel assembly by a small amount. (dropped 0.5kg I think)

Also, worth remembering guys, that the AM 4.3 is not really a derivative of the 4.2L AJV8. The AJ was used as a 'starting point' in that they wanted to use a similar bore, stroke, firing order, crank plane and so on. However, the actual engine is a completely new animal. Block and head castings right through to all the moving parts, all are totally discrete items. It's a common misconception that it is basically the same engine with a couple of minor changes and a dry-sump!

 

The motor is really not the same as the Jag. This is not being a snob, it is just the facts. Stuart is dead on.

 

Actually there are a lot more differences in the 4.7 vs the 4.3. AM highlighted them all when they introduced the upgrade, but from what I remember...

Increased bore and stroke
Larger valves
Redesigned chambers
Lighter pistons and crankshaft
Redesigned chain
Different profiles for the cams
Lighter flywheel

There might be more, but thats what I remember

 

Very interesting findings. So the engine is basically built in-house then. Even better. And both are dry-sump; that's a nice surprise. And it only makes sense with such a low hood line. I bet the next iteration will have to be much taller due to that crazy pedestrian regulation in Europe, no?

Does anybody here recall what was the problem with the oil leaks? The '08 convertible I was researching for my brother had the problem fixed by a dealer when new, but I never knew what/where it was. Curious how big of a deal the problem is.

Finally, with a larger stroke, did the redline decrease on the 4.7, or the weight reduction offset the increased piston speed? Interesting subject. Thanks again for all the contributions.

 

Thanks for the info on the AM's vs Jag's AJ V8. I stand corrected.

No wonder I almost fell asleep when I drove the Jag XK (no offense to the XK, just a different car)

 

Cut & pasted from an AM promotional piece called "Revised V8 Vantage Key Facts"

New Parts
• Pistons
• Inlet valves
• Oil sump
• Cylinder liners (push-fit rather than cast-in)
• Crankshaft
• Head gasket

Modified Parts
• Cylinder head
• Cylinder block
o Boremovesfrom89mmto91mm
o Strokemovesfrom86mmto91mm
• Piston rings
• Inlet manifold
• Tappets
• Camshafts
• Front chain drive and sprockets
• Connecting rods
• Electrical harness
• Oil pipes
• Water Pump
• Alternator
Other Revisions
• Oil water cooling (in place of oil air cooling)
• Revised cooling pack

Inlet Manifolds
The profiles of the inlet manifolds have been modified, to improve the flow of air into the combustion chamber.

Inlet Ports and Inlet Valves
The valves have been increased in diameter by 1mm and the profile of the port modified to increase the airflow into the combustion chambers.

Variable Camshaft Drive Chain and Sprockets
To enable the V8 engine to cope with the additional power and torque, the chain drive which takes power to the Variable Camshaft Drive sprocket has been increased in width from a 9 plate design to an 11 plate design. (This refers to the number of plates, or ‘links’, that go across the width of the chain – the higher the number, the wider the chain).

Cylinder Block
The cylinder block’s bore, (the diameter of the cylinders), moves from the 4.3 V8’s 89mm to 91mm, which in conjunction with the increased stroke, provides the engine with a capacity of 4.7 litres. Quite simply, the increased capacity of each cylinder allows the engine to draw in more air so that more fuel can be burnt and more power can be produced.

Push-in Cylinder liners
A key change is the inclusion of cylinder liners, which are pushed into the cylinder bores rather than being included in the block as a part of the casting process. The benefit here is that the cylinder bores can be produced with greater accuracy and the bores themselves can be taken out to their maximum capacity.

Pistons
Just as the cylinder bores increase in size from 89mm to 91mm for the 4.7 V8, the cast pistons also increase in diameter. Despite the increase in size, the weight of each piston is reduced by 10g due to a more efficient design. This reduces the amount of moving masses within the engine, increasing its responsiveness.

Crankshaft
The crankshaft stroke has been modified, from 86mm to 91mm. The crank also incorporates new holes in the counter-rotating masses. These holes reduce the weight of the crankshaft, reducing the amount of rotating masses in particular, which increases the engine’s responsiveness. The holes in the counter-rotating masses, along with a larger hole in the centre of the crankshaft, also improve the ‘inter-bay breathing’ capabilities of the engine.

Below each cylinder there is a volume of air. As the piston moves down the cylinder it compresses the air. This pressure build-up begins to resist the downward movement of the piston, soaking-up the power that is being produced. Inter-bay breathing holes allow the air to move from below each cylinder into a neighbouring cylinder instead of being compressed. The effect is to reduce the amount of air compression that takes place, and reduce the amount of power that would otherwise be lost.

Revised Oil Sump
The design of the oil sump has also been revised. Here the oil pick-up points have been moved from the front and rear of the sump to the side of the sump. This allows the volume of the oil sump’s ‘basin’ to be increased, which in turn allows the air to flow more freely around the inside of the sump. Again, this reduces the effects of the pistons compressing the air in the sump as they move up and down, reducing the corresponding power losses which would otherwise take place. This revised sump design accounts for a power increase of approximately 5 bhp.