07-01-2013, 12:34 AM
The XUD9 306 intake is not great, so no surprises that it can be easily improved. It was bad on the 405 and it wasn't improved far on the 306 really.
The 306 HDi on the other hand has a good intake.
Now don't get me wrong, the pipe down to the turbo itself might be a problem. BUT, until someone actually logs pressure at the compressor intake in normal road driving conditions you are just wasting money doing any mods.
It's important too to see the air intake as an entire system, not just a collection of parts. The ram air effect is well embraced in the 306 HDi intake, more so than earlier cars (XUD9) and later cars with the same engine (206/307 etc)
It could probably be improved by there would be risks as there are with any direct feed ram air system.
If you get positive pressure post air filter element, and still have some positive pressure pre compressor intake then you can pretty much say it's as good as having a big K&N stuck right on the front of the compressor of the turbo!
Not really sure what is wrong with MAF here. MAF in theory responds faster than MAP because MAF is sensing air flow in kg/hr (ie, what can actually be used to burn with fuel) and that value will go up in direct proportion to the compressor speed/efficiency.
MAP lags as long as it takes the post compressor side of the intake system to reach charge pressures set.
MAF doesn't go out of range easily. There is ample range for 300lbft at 2000rpm, and then out to 4500rpm with about 190bhp, and anything under those values and you are metering perfectly.
Throw in a late C5 MAF which seems to flow nearly 25% more kg/hr range before hitting a ceiling, so about 375lbft and 240bhp?!
Maybe if people are mapping them wrong or letting the MAF let it smoke, or letting the smoke map run out of range then yes... but as said you can run the standard sensor really far.
Now, it might be a restriction at 150bhp+ through fundamental fluid dynamic issues. But the problem there is the bendy concertina pipe and then run down to the back of the engine is also small so I can't imagine a bigger maf would do anything except cost you as you'd need to step down soon after to meet up with the OEM feed pipe.
And that is all irrelevant if there really is lots of spare positive pressure in the intake system.
Totally happy to see people prove OEM weaknesses and engineer better solutions, but from my experience there is no limit to MAF and it works just fine if you use it right.
As with everything on these engines, better so spend money on mods you need. At stage 2 the turbo is by far the biggest single cost to power. Just adding a good hybrid on the same fuelling adds 20bhp right away, such is the boost in efficiency! And that is before you then remap for the better efficiency!
I remember Pete mentioning intakes as something he wanted to look at, but before he did he was running 205bhp and 325lbft iirc on a standard intake and paper filter on his 206 HDi.
He *might* have run MAP but I'm not sure why... I have a feeling why but it might not be to do with performance so much as ease of mapping. Hmmm...
Dave
The 306 HDi on the other hand has a good intake.
Now don't get me wrong, the pipe down to the turbo itself might be a problem. BUT, until someone actually logs pressure at the compressor intake in normal road driving conditions you are just wasting money doing any mods.
It's important too to see the air intake as an entire system, not just a collection of parts. The ram air effect is well embraced in the 306 HDi intake, more so than earlier cars (XUD9) and later cars with the same engine (206/307 etc)
It could probably be improved by there would be risks as there are with any direct feed ram air system.
If you get positive pressure post air filter element, and still have some positive pressure pre compressor intake then you can pretty much say it's as good as having a big K&N stuck right on the front of the compressor of the turbo!
Not really sure what is wrong with MAF here. MAF in theory responds faster than MAP because MAF is sensing air flow in kg/hr (ie, what can actually be used to burn with fuel) and that value will go up in direct proportion to the compressor speed/efficiency.
MAP lags as long as it takes the post compressor side of the intake system to reach charge pressures set.
MAF doesn't go out of range easily. There is ample range for 300lbft at 2000rpm, and then out to 4500rpm with about 190bhp, and anything under those values and you are metering perfectly.
Throw in a late C5 MAF which seems to flow nearly 25% more kg/hr range before hitting a ceiling, so about 375lbft and 240bhp?!
Maybe if people are mapping them wrong or letting the MAF let it smoke, or letting the smoke map run out of range then yes... but as said you can run the standard sensor really far.
Now, it might be a restriction at 150bhp+ through fundamental fluid dynamic issues. But the problem there is the bendy concertina pipe and then run down to the back of the engine is also small so I can't imagine a bigger maf would do anything except cost you as you'd need to step down soon after to meet up with the OEM feed pipe.
And that is all irrelevant if there really is lots of spare positive pressure in the intake system.
Totally happy to see people prove OEM weaknesses and engineer better solutions, but from my experience there is no limit to MAF and it works just fine if you use it right.
As with everything on these engines, better so spend money on mods you need. At stage 2 the turbo is by far the biggest single cost to power. Just adding a good hybrid on the same fuelling adds 20bhp right away, such is the boost in efficiency! And that is before you then remap for the better efficiency!
I remember Pete mentioning intakes as something he wanted to look at, but before he did he was running 205bhp and 325lbft iirc on a standard intake and paper filter on his 206 HDi.
He *might* have run MAP but I'm not sure why... I have a feeling why but it might not be to do with performance so much as ease of mapping. Hmmm...
Dave