pdm
|
| posted on 1/6/10 at 04:24 PM |
|
|
Aftermarket turbos and emissions
Hi
I wanted to check my understanding of what happens if you turbocharge an engine when it comes to emissions. Might seem like a daft question but
I've no experience of this. I ask in all seriousness and off the back of the RV8 carbs or EFI thread earlier....
To me you get a stock engine and it has emissions based on its air/fuel mix - set up all ok and dandy to pass it's MOT by you're trusty
major manufacturer.
Now assuming you can map it/piggy back ECU and you have the funds to build it, you strap on a turbo - nothing too fancy, stock injectors, small/no
intercooler and you up the power by say 35hp or so.
Presumably your ECU compensates for more air with more fuel and so you're emissions stay the same proportionally (CO being measured as % and HC
as ppm).
Is that right so far ?
Then say you get really adventurous - add a bigger intercooler, new ECU, bigger injectors and really ramp up that boost.
Presumably the same applies - at its simplest you're now sending even more air in so you have to send more fuel in as well - so you're
emissions still stay same even though you're power output is now a lot higher ?
In other words - if you built say a MX5/Zetec/Duratec with EFI and then turbo it are you likely to run into emissions issues ?
thanks all
|
|
|
|
|
CNHSS1
|
| posted on 1/6/10 at 04:37 PM |
|
|
not if mapped properly.
depending on your ecu, if it has swictahble maps or if it hasnt and you can download/upload easily enough, then id have two maps, a rip snorting fuel
guzzling flower unfriendly map for max power and a road map with decent emissions based on good economy and MOT friendly.
I use an Emerald K3 ecu which will switch maps from the dash (up to 3) and when using the MOT map, only perfume comes out of the exhaust 
"Racing is life, everything else, before or after, is just waiting"---Steve McQueen
|
|
|
hobbsy
|
| posted on 1/6/10 at 04:38 PM |
|
|
MOT emissions are only checked at idle and fast idle when the engine is under no load and so the turbo won't be making any meaningful boost so
the fact its running forced induction shouldn't make any different in itself.
|
|
|
alistairolsen
|
| posted on 1/6/10 at 04:46 PM |
|
|
Wont make any difference where the MOT meaures it, but yeah, on extreme power levels when youre dipping the AFR's into the 10s to keep it from
melting it will show rich.
My Build Thread
|
|
|
turbodisplay
|
| posted on 1/6/10 at 05:31 PM |
|
|
most cars are fitted with a maf sensor, which measures mass air flow. The more air flowing, the more fuel added, up to a certain point.
The ecu on some cars map to 14.7 afr (closed loop) even at WOT. when boosting you want to run rich, at low boost (3 - 5 psi) it will probally be
ok.
Darren
|
NOTE:This user is registered as a LocostBuilders trader and may offer commercial services to other users
|
pdm
|
| posted on 1/6/10 at 07:00 PM |
|
|
Thanks everyone - lot to learn here !!!
|
|
|
