4.3 or 4.7 AM V8 Throttle body size?
Discussion
Hi, I am building a Jag 4.4 engine for racing and in my application my engine tuner has discovered that at the last 1000rpm to maximum revs the manifold pressure is negative. i.e there is not enough air.
It has been cured in one case by another competitor by fitting another throttle body on the other end of the Jag plastic plenum as there is a flange. It looks messy as its hard to package in the engine bay, etc and if the AM intake plenum would fit (and does indeed have a bigger throttle body, which i suspect it may) this would not only look better but would package better as well.
So my question is.. how big is the throttle body orifice on the AM engine variant, (I am assuming that the heads are the same and the plenums are interchangeable?)
Can anyone help?
Thanks
Ben
It has been cured in one case by another competitor by fitting another throttle body on the other end of the Jag plastic plenum as there is a flange. It looks messy as its hard to package in the engine bay, etc and if the AM intake plenum would fit (and does indeed have a bigger throttle body, which i suspect it may) this would not only look better but would package better as well.
So my question is.. how big is the throttle body orifice on the AM engine variant, (I am assuming that the heads are the same and the plenums are interchangeable?)
Can anyone help?
Thanks
Ben
Hello Ben, you are way advanced past anything I have ever done, so not sure I can help at all, or indeed even close. Can you clarify the measurement you are after and I'll see if I can help, because my V12 is partly disassembled, unless the V12 is no good to you and you need a V8 dimension, in which case I can't help at all. Sorry. 
bjd7326 said:
So my question is.. how big is the throttle body orifice on the AM engine variant, (I am assuming that the heads are the same and the plenums are interchangeable?)
No idea on the throttle body size Bamford Rose guy would know off the top of their headThey do race work as well so may be able to offer a bit of advice.
Not sure the heads and intakes are interchangeable either.
that's what's going on Johnny 550 
as to what you're talking about ......Well, by letting it have more air (that it is asking for, as the plenum pressure is sort of going into a negative pressure, i.e less than atmospheric) there is the possibility of more power. My engine tuner fitted another throttle body to another cars engine on the back of the plenum and got an easy 15hp without trying to hard with the tune, so there you go, just a bit more HP,
Ben
Ben
Simple fluid dynamics/combustion
The engine requires more air as you increase the power, this peaks at the red line.
A race engine spends A LOT more time high in the rev range
So the stock throttle body diameter and plenum chamber struggles to deliver enough air on the OP's engine
The solution is to get more air in - either with a bigger throttle or a throttle body for each bank of 4 cylinders
Many in line race engines take this further and have one throttle body per cylinder
The engine requires more air as you increase the power, this peaks at the red line.
A race engine spends A LOT more time high in the rev range
So the stock throttle body diameter and plenum chamber struggles to deliver enough air on the OP's engine
The solution is to get more air in - either with a bigger throttle or a throttle body for each bank of 4 cylinders
Many in line race engines take this further and have one throttle body per cylinder
They are both derived from the Jaguar AJ-V8, however the Aston version is much modified
wikipedia said said:
Aston Martin hand-assembles a special version of the AJ-V8 for the 2005 V8 Vantage. This engine is unique to Aston Martin and features race-style dry-sump lubrication. The cylinder block, cylinder heads, crankshaft, connecting rods, pistons, camshafts, inlet and exhaust manifolds, lubrication system and engine management are all unique to the Aston Martin version.
On the basis of those changes I'd suspect they are not a direct swapMmmm you might be right but I would be amazed if they have modified the heads as such that the port locations and fixings are different. I could do with someone who has some experience of this to add their 'input'.
I would guess, but may be wrong, that the cam profiles will be different and maybe the valves would be different but cast a new head? - I doubt that?
I rang BR today and spoke to a very pleasant chap who suggested i put it in an email and send it in for their engineers to comment on. I have not done this as yet as I feel guilty as I 'may not' be spending any £ with them.
I would guess, but may be wrong, that the cam profiles will be different and maybe the valves would be different but cast a new head? - I doubt that?
I rang BR today and spoke to a very pleasant chap who suggested i put it in an email and send it in for their engineers to comment on. I have not done this as yet as I feel guilty as I 'may not' be spending any £ with them.
bjd7326 said:
Mmmm you might be right but I would be amazed if they have modified the heads as such that the port locations and fixings are different. I could do with someone who has some experience of this to add their 'input'.
I would guess, but may be wrong, that the cam profiles will be different and maybe the valves would be different but cast a new head? - I doubt that?
I rang BR today and spoke to a very pleasant chap who suggested i put it in an email and send it in for their engineers to comment on. I have not done this as yet as I feel guilty as I 'may not' be spending any £ with them.
Bruce or Mike @ BR "love" questions like this I would guess, but may be wrong, that the cam profiles will be different and maybe the valves would be different but cast a new head? - I doubt that?
I rang BR today and spoke to a very pleasant chap who suggested i put it in an email and send it in for their engineers to comment on. I have not done this as yet as I feel guilty as I 'may not' be spending any £ with them.
Drop them an email
Personally I have found that getting info on stuff at places such as this forum is very good, I have no experience of BR, but they seem to have a very following here, so I am guessing that they would be helpful. However, at the end of the day, I have found that the best way is to physically do it yourself. When you pull something apart and try and fit it back together, its a great learning curve. Obvioulsy sometimes it's not always that good and things do go wrong. Sometimes you wonder what the hell you're doing as half you car is laid out on the floor.
However there have been a few examples where someone has said, "it cannot be done", found that I pulled it apart and it can be done, or you should, "do this", and find you don't have to. I think the best examples of this, are if you phone up Aston Martin directly, you can't so much as cough without AM saying, "its not in the manual, you can't do it", I bet if you phone up AM with this question, the answer would be a direct, "NO", but mostly you can do things.
I still don't fully understand what you guys are doing, but I would suggest that you find someone with a V8V, someone who is friendly and easy going, and whom will allow you to prod and poke his car. Or look on eBay and see if you can buy the part as an individual part and see if it fits. I think you are looking at a throttle body? are they expensive? I'd love to help you with this sort of problem, but I'd help because I'd like to learn, however with an engine that is totally different, I'm sorry ......
Know anyone with a V8 ..... ?
However there have been a few examples where someone has said, "it cannot be done", found that I pulled it apart and it can be done, or you should, "do this", and find you don't have to. I think the best examples of this, are if you phone up Aston Martin directly, you can't so much as cough without AM saying, "its not in the manual, you can't do it", I bet if you phone up AM with this question, the answer would be a direct, "NO", but mostly you can do things.
I still don't fully understand what you guys are doing, but I would suggest that you find someone with a V8V, someone who is friendly and easy going, and whom will allow you to prod and poke his car. Or look on eBay and see if you can buy the part as an individual part and see if it fits. I think you are looking at a throttle body? are they expensive? I'd love to help you with this sort of problem, but I'd help because I'd like to learn, however with an engine that is totally different, I'm sorry ......
Know anyone with a V8 ..... ?
Gassing Station | Aston Martin | Top of Page | What's New | My Stuff