+- 306oc - Peugeot 306 Owners Club & Forum (https://www.306oc.co.uk/forum)
+-- Forum: Engines (https://www.306oc.co.uk/forum/forumdisplay.php?fid=16)
+--- Forum: DW10 HDi section (https://www.306oc.co.uk/forum/forumdisplay.php?fid=10)
+--- Thread: The effects of intake temperatures (/showthread.php?tid=30818)
The effects of intake temperatures - lolsteve - 11-06-2015
Now I'm no turbo yoda (Ruan) but I've been doing some reading recently about this and that trying to learn more about spark advance, octane etc and I came across a article about intake temperatures and diesels so thought I'd write up a summary for you guys . now take from this what you will but thought it might help with the cone/airbox arguments
I'm including it in the HDi section because it's about direct injection and HDi owners tend to be smarter
The engine that was tested is a 6 cylinder turbocharged direct injection with a 5.9L displacement and 16.3 compression ratio. So a bit different from the DW10 .
All tests were done at a steady state rpm of 1408rpm
Inlet manifold temperature was manipulated to vary between 30 and 60 degrees ( we could assume the 30 is stock box with decent intercooler setup and 60 is open cone with a not so good setup)
Fuel used was ultra low sulfur BP15
First up is needle lift duration. Imagine a tap that you turn on and off, the longer it's open the more fuel that is injected/water comes out
![[Image: snhwxs.png]](http://i62.tinypic.com/snhwxs.png)
Figure 2 shows the overal action of the needle during the injection cycle with Figure 3 being a close up of the EOI (end of injection)
As we can see the hotter the intake air temperature the longer the needle stays open suggesting increased fuel consumption.
The article does not specify why the injection cycle is extended, however going off my own knowledge I would say that perhaps its done to aid in the cooling of the air temps and reduce the chance of knock from the increased temperature of the mix during the compression cycle which could cause the mixture to ignite before optimal angle.
Next up is cylinder pressure
![[Image: 2co0ilx.png]](http://i61.tinypic.com/2co0ilx.png)
If you look closely you'll see the 60 degree air temperature has a lower peak pressure than the others although the angle they peak is roughly the same. As a rough rule of thumb you want more compression (at the right time) . Therefore by solely reducing the compression we can effectively loose performance. How much is hard to say but a loss is a loss right?
Next is rate of heat release
![[Image: 2duimtd.png]](http://i61.tinypic.com/2duimtd.png)
The combustion cycle is located at the point where the lines crosses from the negative to positive values. If you look closley you'll see that with increased temperatures comes an earlier start of combustion. Which works with what was mentioned earlier about the cooling off the air to prevent too early a combustion or "knock"
The burning peaks are also smaller on the premixed and diffusions stages resulting in less energy or KJ being emitted from the combustion cycle (i think)
Next is cylinder temperature
![[Image: 2q2lnpf.png]](http://i61.tinypic.com/2q2lnpf.png)
Although this test only ranges the inlet temperature from 30 to 60 degrees we see the internal temperature rise 150 kelvin or 150 degrees Celsius which is quite the increase and shows that it can have quite the effect. Perhaps keeping intake temperatures down will aid in keeping your engines cooler during those hot summer months when you're stuff in traffic
Figure 8 ,
![[Image: 20h80o1.png]](http://i60.tinypic.com/20h80o1.png)
Pretty self explanatory and summarises some of the previous points and common knowledge. Increasing the intake temperature reduces the density of the air which limits the power output, no air to burn no powerrr. It also shows the fuel use increase that we saw in action with the increased needle duration
Nine!
![[Image: 2a82nph.png]](http://i57.tinypic.com/2a82nph.png)
Decreased air fuel ratio, making the car run richer. Probably resulting in more smoke from the unburnt fuel and dturbo boys shouting "reeeeeek"
Running richer sound boast worthy but if it's running rich from a lack of air rather than an excess of fuel then that's not ideal
Now one that might get your attention, exhaust temperatures
![[Image: 2ebrdw4.png]](http://i60.tinypic.com/2ebrdw4.png)
Like with the cylinder temperatures the exhaust temperatures unsurprisingly rise too. Now I'm not clued up on how close to the limit the stock turbo is on the HDi when mapping etc but doesn't take a genius to gather than a hotter turbo is not going to last as long. A temp increase of 30 degrees has increased the exhaust temperature by 50.
After this it's exhaust emissions and I think I'll save both our time here and no one is working for emissions now are they .
So in summary
Cone filter might sound better but unless setup with a decent cold air intake system you could end up sapping engine power, decreasing MPG and adding additonal wear to the engine/turbo. A concept that is pretty well known anyway but it's always nice to have some graphs to back you up
RE: The effects of intake temperatures - Poodle - 11-06-2015
Great post mate, thanks.
RE: The effects of intake temperatures - Ruan - 12-06-2015
Really interesting stuff!
Monitoring your air inlet temperatures is key to making decent power with any engine! But there's a bit of confusion between SI (spark ignition) engines with CI (compression ignition) engines - their limiting factors are quite different!
Quote:The article does not specify why the injection cycle is extended, however going off my own knowledge I would say that perhaps its done to aid in the cooling of the air temps and reduce the chance of knock from the increased temperature of the mix during the compression cycle which could cause the mixture to ignite before optimal angle.
Petrol motors "knock" because their fuel (generally...) is mixed with the air as it enters the cylinder via the injector in the inlet manifold, this means that the fuel gets heated significantly by the compression of the engine and certainly the inlet temperatures!
Diesels can't "knock" or "pre-ignite" - by the fact they're Direct Injection - there is no fuel mixed with the air before top dead centre, therefore it can't accidentally ignite it. The diesel will ignite shortly after you inject it - in the HDi engine, this is calibrated inside the ECU, it's calculated by factoring in mainly the amount to be injected and the engine speed, but also all sorts of other variables like air temperature and coolant temperature to ensure that it's correct for the operating condition of the engine.
However Diesels are limited by their ignition delay, which inlet, cylinder and fuel temperature do affect - it's by no means a simple factor!
If anyone is interested in Diesels and stuff about injection timing, which is also closely related to inlet temperatures - here's a cracking article about it:
http://killerbeeperformance.com/download/tuning/Timing%20the%20Diesel.pdf
RE: The effects of intake temperatures - lolsteve - 12-06-2015
Interesting to know, can tell im more of a petrol person
There was a bit on injection delay although I forgot to include it, will edit it in later
Been trying to read into it more after FCS and the effectively cone filter i was running in the bay which got to chronic temperatures (what with it being right next to the exhaust manifold)
Also found a good article on the effects of running a higher octane fuel than the car was meant for
RE: The effects of intake temperatures - Poodle - 13-06-2015
Cheers Ru, can haz moar plz?
RE: The effects of intake temperatures - Dum-Dum - 13-06-2015
I need to read this when I'm not sleep deprived.