08-01-2013, 11:19 PM
Why would you want a cold air feed when the HDi already has a ram air cold air feed? IAT's on the HDi are always at ambient or just 1 or 2 deg higher even in the height of summer.
It also has a ram air system which means that even though it's not a cool looking cone filter, it probably has less overall restriction post-cone in normal driving conditions than NO filter at all.
MAF is small, but you'd want to check a 123d or something with 2.0 and a lot of bhp and see how big their MAF is. If it's the same size then that is a good indicator that isn't a problem.
MAF on the HDi should be good for metering nicely to 180bhp at 4000rpm, and if you simply run a bit leaner at peak and have a dip to stoich (as an example), then 200bhp and nice clean running should easily be possible.
I'd say the biggest single cost to a HDi intake is the gauss on the MAF (not really needed if you are happy to run a perfectly good paper filter imo), and that weird bendy flexy pipe just after the MAF which probably causes a lot of turbulent flow too.
After that I'd say it's all good again right to the compressor, which is where your biggest single 'intake' bottle neck right up to about 200bhp sits... maybe even 250bhp, who knows
I agree, too much testing and you will spend a lot of money and maybe get not very far. There is a compromise.
But if you don't even know what you have and why it has merits before you start hacking it up there is every chance you will spend money and have a compromised car, which is just as bad as spending money and having tested a lot and not made any changes hehe.
Chances are that even if the HDi90 compressor feed is only 'good' to 120bhp or something, you won't suffer from it's issues from a cost effectiveness point of view till 180bhp+ any way... and even at that point you might be hard pressed to spend £200 or so making/fitting one vs the cost of some other mod that you know will be a better idea at that level.
It is all about the efficiencies, you don't want to run over-rated on too many things. But until you know which things are out of efficient range it's hard to justify spending money on a hunch for most people.
Most people ARE tuning a cheap car and want to do it cheaply, so £££ on a hunch inefficiency vs a known power boosting mod is a hard call I guess.
If someone said a new off the shelf £150 replacement pipe added 0% at 90bhp and 20% at 200bhp, then you'd buy one after stage 2 without a doubt.
If it were £150 and 5% at 200bhp, would you bother?
Dave
It also has a ram air system which means that even though it's not a cool looking cone filter, it probably has less overall restriction post-cone in normal driving conditions than NO filter at all.
MAF is small, but you'd want to check a 123d or something with 2.0 and a lot of bhp and see how big their MAF is. If it's the same size then that is a good indicator that isn't a problem.
MAF on the HDi should be good for metering nicely to 180bhp at 4000rpm, and if you simply run a bit leaner at peak and have a dip to stoich (as an example), then 200bhp and nice clean running should easily be possible.
I'd say the biggest single cost to a HDi intake is the gauss on the MAF (not really needed if you are happy to run a perfectly good paper filter imo), and that weird bendy flexy pipe just after the MAF which probably causes a lot of turbulent flow too.
After that I'd say it's all good again right to the compressor, which is where your biggest single 'intake' bottle neck right up to about 200bhp sits... maybe even 250bhp, who knows
I agree, too much testing and you will spend a lot of money and maybe get not very far. There is a compromise.
But if you don't even know what you have and why it has merits before you start hacking it up there is every chance you will spend money and have a compromised car, which is just as bad as spending money and having tested a lot and not made any changes hehe.
Chances are that even if the HDi90 compressor feed is only 'good' to 120bhp or something, you won't suffer from it's issues from a cost effectiveness point of view till 180bhp+ any way... and even at that point you might be hard pressed to spend £200 or so making/fitting one vs the cost of some other mod that you know will be a better idea at that level.
It is all about the efficiencies, you don't want to run over-rated on too many things. But until you know which things are out of efficient range it's hard to justify spending money on a hunch for most people.
Most people ARE tuning a cheap car and want to do it cheaply, so £££ on a hunch inefficiency vs a known power boosting mod is a hard call I guess.
If someone said a new off the shelf £150 replacement pipe added 0% at 90bhp and 20% at 200bhp, then you'd buy one after stage 2 without a doubt.
If it were £150 and 5% at 200bhp, would you bother?
Dave
