Astons V8 is a Jaguar engine - or is it?
Discussion
I keep seeing this banded around so I thought I do a bit of digging!
So far I've discovered the following;
1) It was originally developed as Jaguar code - AJ37 for the Gaydon era Vantage, the project was owned & managed by Jag
2) AM changed the code to - AM5 to prevent confusion
3) It is derived from the Jaguar AJV8 Gen2 engine and was developed from a high performance higher revving R&D version of the 4.4 AJ26
4) The firing order is different to the other AJV8 engines, very few parts are interchangeable
5) The block, heads, crankshaft, con rods, pistons, camshafts, inlet and exhaust manifolds, lubrication system and engine management are all unique to AM
6) it has a "dry" sump to allow it to me mounted lower and further back for better weight distribution/handling
7) It is not a true dry sump system as Jaguar didn't have the required expertise
8) The block & head castings are jaguar
9) The 4.7 evolution was all done by Aston
10) The 5.0 AJ37 variant didn't meet EU5 & 6 emissions so Ford canned it
11) Jaguar went on to develop the AJV8 Gen3 at 5.0 for their needs coinciding with Ford selling AM
ETA - more detail from a reliable source
So far I've discovered the following;
1) It was originally developed as Jaguar code - AJ37 for the Gaydon era Vantage, the project was owned & managed by Jag
2) AM changed the code to - AM5 to prevent confusion
3) It is derived from the Jaguar AJV8 Gen2 engine and was developed from a high performance higher revving R&D version of the 4.4 AJ26
4) The firing order is different to the other AJV8 engines, very few parts are interchangeable
5) The block, heads, crankshaft, con rods, pistons, camshafts, inlet and exhaust manifolds, lubrication system and engine management are all unique to AM
6) it has a "dry" sump to allow it to me mounted lower and further back for better weight distribution/handling
7) It is not a true dry sump system as Jaguar didn't have the required expertise
8) The block & head castings are jaguar
9) The 4.7 evolution was all done by Aston
10) The 5.0 AJ37 variant didn't meet EU5 & 6 emissions so Ford canned it
11) Jaguar went on to develop the AJV8 Gen3 at 5.0 for their needs coinciding with Ford selling AM
ETA - more detail from a reliable source
Edited by mikey k on Thursday 27th November 17:12
http://www.pistonheads.com/gassing/post.asp?h=0&am...
Speedrasers post!
Speedrasers post!
Edited by cayman-black on Thursday 27th November 16:24
A bit of history/family tree, wiki-style: http://en.wikipedia.org/wiki/Jaguar_AJ-V8_engine
SFO said:
I thought it has a separate oil tank?
the car has a dry sump system in name and components, however, in many eyes to be successful dry sump system the engine needs to lose no power from crankshaft windage from interaction with oil / have no parasitic loss. I think from motorsport world the reports came that unlike a successful dry sump system, the system on V8 did have some not insignificant power loss from windage, due to there being an amount of oil always in the sump. Simply put, there isn't a whirlwind going on in the sump to scavenge all the oil out hence becoming know as 'damp sump'. But it does tick the box of another requirement of dry sump, which is to lower bonnet line from shorter engine height. Perhaps because the engine met is power target, and the 'damp' system lowered the bonnet line it was left alone. Good thing knowing this, is there is some free horsepower to exploit should a system that does scavenge sufficiently be implemented by somebody.BamfordMike said:
SFO said:
I thought it has a separate oil tank?
the car has a dry sump system in name and components, however, in many eyes to be successful dry sump system the engine needs to lose no power from crankshaft windage from interaction with oil / have no parasitic loss. I think from motorsport world the reports came that unlike a successful dry sump system, the system on V8 did have some not insignificant power loss from windage, due to there being an amount of oil always in the sump. Simply put, there isn't a whirlwind going on in the sump to scavenge all the oil out hence becoming know as 'damp sump'. But it does tick the box of another requirement of dry sump, which is to lower bonnet line from shorter engine height. Perhaps because the engine met is power target, and the 'damp' system lowered the bonnet line it was left alone. Good thing knowing this, is there is some free horsepower to exploit should a system that does scavenge sufficiently be implemented by somebody.Does it have a separate scavenge pump, or does the system just provide an additional 'buffer' oil reserve in the tank?
simonpa said:
I've not looked into this (yet).
Does it have a separate scavenge pump, or does the system just provide an additional 'buffer' oil reserve in the tank?
the system has all parts of conventional dry sump system. To have a look is engine out of car and complete strip down as all parts internal to sump / front cover. Spinning the scavenge pump faster with different pulley and the like has already been looked into and failed, requires a deeper engineering fix than the simple stuff. Such as grafting on a system similar to one-77, but that's one hell of an engineering job and probably easier and cheaper to get better power gain from gas exchange than relieving parasitic loss. I'm sure there is one in their for jockman, but go easy on me, i have only just recovered from rolling on the floor with laughter after the first.Does it have a separate scavenge pump, or does the system just provide an additional 'buffer' oil reserve in the tank?
BamfordMike said:
SFO said:
I thought it has a separate oil tank?
the car has a dry sump system in name and components, however, in many eyes to be successful dry sump system the engine needs to lose no power from crankshaft windage from interaction with oil / have no parasitic loss. I think from motorsport world the reports came that unlike a successful dry sump system, the system on V8 did have some not insignificant power loss from windage, due to there being an amount of oil always in the sump. Simply put, there isn't a whirlwind going on in the sump to scavenge all the oil out hence becoming know as 'damp sump'. But it does tick the box of another requirement of dry sump, which is to lower bonnet line from shorter engine height. Perhaps because the engine met is power target, and the 'damp' system lowered the bonnet line it was left alone. Good thing knowing this, is there is some free horsepower to exploit should a system that does scavenge sufficiently be implemented by somebody.so a true dry sump system has no oil at the bottom of the engine when engine is running?
serious question, what is 'crankshaft windage' and why does it lead to power loss?
Is a mezger engine from Porsche a true dry sump?
SFO said:
thanks.
so a true dry sump system has no oil at the bottom of the engine when engine is running?
serious question, what is 'crankshaft windage' and why does it lead to power loss?
Is a mezger engine from Porsche a true dry sump?
crankshaft windage is the term used to define the power draining forces the crank has to work against whilst it tries to spin. Just imagine an engine without a sump / oil system - the crank and its large surface area / counterweight webs could spin in free / fresh air - no negative forces to overcome. Now imagine a sump enclosing the crank and full of oil thrashing around. The crank has to now spin but it has oil trying to slow it down and breathing gas which gets passed from block bay to block bay as counterweights open and close passages. This negative / power reducing aspect is one part of the make up of friction mean effective pressure (fmep), another negative part of the cycle / parasitic loss the engine has to overcome is pumping mean effective pressure (pmep), suck / squeeze part of cycle. The v8 engine consumes about 150 bhp at 7500 rpm just to turn itself over. Pmep can be reduced by no real way, it is what it is. Fmep is stuff like ancillary components and any drag, like piston rings in liners. So great effort is made to reduce fmep to return more flywheel power without anything different going on above the piston / combustion. If you run the theoretical sump on / sump off test on v8, the fmep (crank windage) is reduced by about 20bhp sump off compared dry sump fitted. If the sump was wet, then ok - fair game. But a dry sump causing a negative drain goes against mainly why dry sump was created - for the motorsport world so that engine power could be the maximum possible. For the v8 the dry sump achieved its main objective - lower the bonnet line to get the looks, but from perspective of achieving its other objective - reduce to as close as zero crankcase fmep, its not scored so well. But, if the power of the engine is so great it can live with throwing away what is in effect free bhp (free because nothing above the piston changed to get the power) then fine. Problem is that the car could have benefitted from what should have been easy power to exploit.so a true dry sump system has no oil at the bottom of the engine when engine is running?
serious question, what is 'crankshaft windage' and why does it lead to power loss?
Is a mezger engine from Porsche a true dry sump?
i dont know what constitutes a true dry sump system, but in my score book it would be one that has as close to zero crankcase / crankshaft windage fmep. Of course, a dry sump is adding fmep via pumps compared to overall gain over wet sump with no pumps. Meaning if the crankcase / crankshaft windage of a dry system is a disappointment (20 bhp is hugely disappointing), the dry system in absolute reality aides engine performance no better than conventional wet sump. Meaning the sole reason for its existence is to lower the bonnet line but im sure marketing uses the fact the architecture is dry as an allure, despite perhaps it not being too advantageous.
i have no clue about the Porsche engine, but if its sump creates losses, like the v8, then it is not as good as it perhaps can be. But same as v8, whoever was holding scorecard, if it achieved what they needed even though it failed other criteria, which perhaps didn't matter - its fit for production too. But seeing as Porsche worry if the dash binnacle is 4 gramms overweight, i cant believe they would be as comfortable with 20 bhp sitting in an inefficient sump
PiloteAM said:
I though another motivation for dry dump motors was something to do with cornering and oil starvation?
I've heard claim from Porsche people that some of their flat 6s aren't "true" dry dump either, not sure which ones.
yep, that is a benefit too. It took V12 engine car a few goes to complete nurburgring 24hr, failures were due to wet sump and starvation. But decent design wet sump can prevent starvation (as was done in the end for v12) meaning it isn't an aspect a dry sump will always win over a wet sump.I've heard claim from Porsche people that some of their flat 6s aren't "true" dry dump either, not sure which ones.
a dry sump system that ticks all boxes is very difficult thing to implement, the knowledge holders will be motorsport consultancies not road car oem.
MrOrange said:
Great explanation Mike (I'm wiser now). As I understood it, for race cars benefits also include a lower centre of gravity and less worry about G force effecting oil distribution and therefore cooling/lubrication.
yep, another great benefit, the oil bulk / weight is where you want it / wherever the dry tank is situated.BamfordMike said:
crankshaft windage is the term used to define the power draining forces the crank has to work against whilst it tries to spin. Just imagine an engine without a sump / oil system - the crank and its large surface area / counterweight webs could spin in free / fresh air - no negative forces to overcome. Now imagine a sump enclosing the crank and full of oil thrashing around. The crank has to now spin but it has oil trying to slow it down and breathing gas which gets passed from block bay to block bay as counterweights open and close passages. This negative / power reducing aspect is one part of the make up of friction mean effective pressure (fmep), another negative part of the cycle / parasitic loss the engine has to overcome is pumping mean effective pressure (pmep), suck / squeeze part of cycle. The v8 engine consumes about 150 bhp at 7500 rpm just to turn itself over. Pmep can be reduced by no real way, it is what it is. Fmep is stuff like ancillary components and any drag, like piston rings in liners. So great effort is made to reduce fmep to return more flywheel power without anything different going on above the piston / combustion. If you run the theoretical sump on / sump off test on v8, the fmep (crank windage) is reduced by about 20bhp sump off compared dry sump fitted. If the sump was wet, then ok - fair game. But a dry sump causing a negative drain goes against mainly why dry sump was created - for the motorsport world so that engine power could be the maximum possible. For the v8 the dry sump achieved its main objective - lower the bonnet line to get the looks, but from perspective of achieving its other objective - reduce to as close as zero crankcase fmep, its not scored so well. But, if the power of the engine is so great it can live with throwing away what is in effect free bhp (free because nothing above the piston changed to get the power) then fine. Problem is that the car could have benefitted from what should have been easy power to exploit.
very interesting.no doubt a wet sump system also creates fmep and pmep .. would a wet sump on the V8 result in power loss of more or less than 20bhp re fmep? any difference on pmep?
On the subject of V8 blocks, I understand that Aston Martin Racing build their 4.7 engines, by starting with a 4.3 block.
If this is so, I presume that there must be a significant difference, between the 4.3 and 4.7 blocks.
Can anyone explain the background to this, including the reason for not using a standard 4.7 block, when that is the engine capacity required?
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