Discussion
So I took the plunge on friday and took my late 4.5 block down to Andy at APM, for a set of 4.7 liners.
I now have one month to make the rest of the engine as shiny as the block I've just given Andy, and get the heads ready for replacement.
The reason for posting, apart from my excitement, is that I have a set of 4.2 inlets, and 4.5 inlets, and I can't make up my mind what will be going on the 4.7 engine.
Has anyone got any opinion on what I should do?
I now have one month to make the rest of the engine as shiny as the block I've just given Andy, and get the heads ready for replacement.
The reason for posting, apart from my excitement, is that I have a set of 4.2 inlets, and 4.5 inlets, and I can't make up my mind what will be going on the 4.7 engine.
Has anyone got any opinion on what I should do?
If you have the time then I'd be really interested if you tried both, selfish I know 
. As you'd be aware I'm a fan of the 4.2 inlets and so long as they've been worked there is no reason why they will hold the lump back. They should also give you the better throttle response associated with the 4.2 too. What does Andy recommend 
.
. As you'd be aware I'm a fan of the 4.2 inlets and so long as they've been worked there is no reason why they will hold the lump back. They should also give you the better throttle response associated with the 4.2 too. What does Andy recommend . From what Andy said, he seemed to be happy with the 4.2's.
Rather threw me a bit.
As I see it the 4.5's are large but injectors in the wrong place, has no appreciable taper, and the inlets are too short everyone tells me.
The 4.2 are a good inlet length, has the injector in the right place, but is far smaller than the 4.5.
According to the calculations I found on the internet, the 4.5's are supposed to be marginal for the engine, let alone the 4.2, but calculations don't seem to be any replacement for experience in this field.
I was hoping someone would give me the 'well actually I've tried both on a dyno talk'. Is that your experience Jools?
Rather threw me a bit.
As I see it the 4.5's are large but injectors in the wrong place, has no appreciable taper, and the inlets are too short everyone tells me.
The 4.2 are a good inlet length, has the injector in the right place, but is far smaller than the 4.5.
According to the calculations I found on the internet, the 4.5's are supposed to be marginal for the engine, let alone the 4.2, but calculations don't seem to be any replacement for experience in this field.
I was hoping someone would give me the 'well actually I've tried both on a dyno talk'. Is that your experience Jools?
Why do you not use the best of both. I've just had my 4.2 inlets bored out to 48mm which is the 4.5 size the 4.2 uses 45mm.
I used butterflies from the 48DCOE carbs (£5.00each). I had some minor flowing done around the mounting flange at the same time and also had the spindles narrowed. Total cost £200.00
I've done this for my 4.5 as I wish to fit a supercharger to my car and the 4.2 inlet system is a much better option for this (IMO) than the 4.5.
I used butterflies from the 48DCOE carbs (£5.00each). I had some minor flowing done around the mounting flange at the same time and also had the spindles narrowed. Total cost £200.00
I've done this for my 4.5 as I wish to fit a supercharger to my car and the 4.2 inlet system is a much better option for this (IMO) than the 4.5.
HarryW said:
If you have the time then I'd be really interested if you tried both, selfish I know . As you'd be aware I'm a fan of the 4.2 inlets and so long as they've been worked there is no reason why they will hold the lump back. They should also give you the better throttle response associated with the 4.2 too. What does Andy recommend .
harry will be trying both on jonnyw's racer so will let you know. As you'd be aware I'm a fan of the 4.2 inlets and so long as they've been worked there is no reason why they will hold the lump back. They should also give you the better throttle response associated with the 4.2 too. What does Andy recommend . APMAUTO said:
HarryW said:
If you have the time then I'd be really interested if you tried both, selfish I know . As you'd be aware I'm a fan of the 4.2 inlets and so long as they've been worked there is no reason why they will hold the lump back. They should also give you the better throttle response associated with the 4.2 too. What does Andy recommend .
harry will be trying both on jonnyw's racer so will let you know. As you'd be aware I'm a fan of the 4.2 inlets and so long as they've been worked there is no reason why they will hold the lump back. They should also give you the better throttle response associated with the 4.2 too. What does Andy recommend . julian64 said:
APMAUTO said:
HarryW said:
If you have the time then I'd be really interested if you tried both, selfish I know . As you'd be aware I'm a fan of the 4.2 inlets and so long as they've been worked there is no reason why they will hold the lump back. They should also give you the better throttle response associated with the 4.2 too. What does Andy recommend .
harry will be trying both on jonnyw's racer so will let you know. As you'd be aware I'm a fan of the 4.2 inlets and so long as they've been worked there is no reason why they will hold the lump back. They should also give you the better throttle response associated with the 4.2 too. What does Andy recommend . 
APMAUTO said:
julian64 said:
APMAUTO said:
HarryW said:
If you have the time then I'd be really interested if you tried both, selfish I know . As you'd be aware I'm a fan of the 4.2 inlets and so long as they've been worked there is no reason why they will hold the lump back. They should also give you the better throttle response associated with the 4.2 too. What does Andy recommend .
harry will be trying both on jonnyw's racer so will let you know. As you'd be aware I'm a fan of the 4.2 inlets and so long as they've been worked there is no reason why they will hold the lump back. They should also give you the better throttle response associated with the 4.2 too. What does Andy recommend . 
Await the outcome of this with much interest 
a1rak said:
Why do you not use the best of both. I've just had my 4.2 inlets bored out to 48mm which is the 4.5 size the 4.2 uses 45mm.
I used butterflies from the 48DCOE carbs (£5.00each). I had some minor flowing done around the mounting flange at the same time and also had the spindles narrowed. Total cost £200.00
I've done this for my 4.5 as I wish to fit a supercharger to my car and the 4.2 inlet system is a much better option for this (IMO) than the 4.5.
Did you do the flowing and porting yourself or did someone do it for you as I'd be interested in getting a 48mm set to try on my lump.I used butterflies from the 48DCOE carbs (£5.00each). I had some minor flowing done around the mounting flange at the same time and also had the spindles narrowed. Total cost £200.00
I've done this for my 4.5 as I wish to fit a supercharger to my car and the 4.2 inlet system is a much better option for this (IMO) than the 4.5.
I honestly don't know how you could flow the 4.2 inlets any more than they are.
I can see how an engineer could port what he could see, but not the actual resctiction round the bend as there isn't anything I know of that could do it. The best would be a flexible hone. fingers crossed, and some sort of xray to make sure you weren't about to breach.
Other than that porting the start and end of a 4.2 without actually attacking the restriction, which seems to be mid cruve and incidently the hardest part to get to would be a nightmare?
I wonder if a group buy shouldn't be a new set of intake castings to once and forever get the benefit of the 4.2 and the slightly wider than the 4.5.
I don't really understand why TVR didn't do it and opted for the flexi pipes
I can see how an engineer could port what he could see, but not the actual resctiction round the bend as there isn't anything I know of that could do it. The best would be a flexible hone. fingers crossed, and some sort of xray to make sure you weren't about to breach.
Other than that porting the start and end of a 4.2 without actually attacking the restriction, which seems to be mid cruve and incidently the hardest part to get to would be a nightmare?
I wonder if a group buy shouldn't be a new set of intake castings to once and forever get the benefit of the 4.2 and the slightly wider than the 4.5.
I don't really understand why TVR didn't do it and opted for the flexi pipes
julian64 said:
I honestly don't know how you could flow the 4.2 inlets any more than they are.
I can see how an engineer could port what he could see, but not the actual resctiction round the bend as there isn't anything I know of that could do it. The best would be a flexible hone. fingers crossed, and some sort of xray to make sure you weren't about to breach.
Other than that porting the start and end of a 4.2 without actually attacking the restriction, which seems to be mid cruve and incidently the hardest part to get to would be a nightmare?
I wonder if a group buy shouldn't be a new set of intake castings to once and forever get the benefit of the 4.2 and the slightly wider than the 4.5.
I don't really understand why TVR didn't do it and opted for the flexi pipes
I have looked into this in quite a lot of detail. For the cost you may aswell go for a full roler barrell set up.I can see how an engineer could port what he could see, but not the actual resctiction round the bend as there isn't anything I know of that could do it. The best would be a flexible hone. fingers crossed, and some sort of xray to make sure you weren't about to breach.
Other than that porting the start and end of a 4.2 without actually attacking the restriction, which seems to be mid cruve and incidently the hardest part to get to would be a nightmare?
I wonder if a group buy shouldn't be a new set of intake castings to once and forever get the benefit of the 4.2 and the slightly wider than the 4.5.
I don't really understand why TVR didn't do it and opted for the flexi pipes
Mike
itsallyellow said:
julian64 said:
I honestly don't know how you could flow the 4.2 inlets any more than they are.
I can see how an engineer could port what he could see, but not the actual resctiction round the bend as there isn't anything I know of that could do it. The best would be a flexible hone. fingers crossed, and some sort of xray to make sure you weren't about to breach.
Other than that porting the start and end of a 4.2 without actually attacking the restriction, which seems to be mid cruve and incidently the hardest part to get to would be a nightmare?
I wonder if a group buy shouldn't be a new set of intake castings to once and forever get the benefit of the 4.2 and the slightly wider than the 4.5.
I don't really understand why TVR didn't do it and opted for the flexi pipes
I have looked into this in quite a lot of detail. For the cost you may aswell go for a full roler barrell set up.I can see how an engineer could port what he could see, but not the actual resctiction round the bend as there isn't anything I know of that could do it. The best would be a flexible hone. fingers crossed, and some sort of xray to make sure you weren't about to breach.
Other than that porting the start and end of a 4.2 without actually attacking the restriction, which seems to be mid cruve and incidently the hardest part to get to would be a nightmare?
I wonder if a group buy shouldn't be a new set of intake castings to once and forever get the benefit of the 4.2 and the slightly wider than the 4.5.
I don't really understand why TVR didn't do it and opted for the flexi pipes
Mike
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