Winter fuel economy tip

GreenDieselEngineering · **Joined:** Sun Jun 07, 2009 5:10 pm **Posts:** 1111

During the winter months the KJ CRD will get slightly better fuel economy if it can breathe warmer air in the intake. It is fairly easy to remove the snorkel on the front of the air box and just let the airbox pull warmer fresh air from inside the engine compartment. You may also want to tape up the snorkel opening to the grill to minimize the cold air coming in. During the summer months it is more efficient to run the engine with the snorkel in place to keep the intake temps lower.

We also removed the mechanical fan for the winter (as long as you are not towing) and it seems to be worth at least 1 mpg after continued testing. However, this can be a pain to remove and much more time consuming than the snorkel mod.

ATXKJ · **Posted:** Fri Mar 05, 2010 8:13 pm

I appreciate the suggestion - but it's March, March - a month after the Groundhog - couldn't you have mentioned this in November or December??

CRD Joe · **Posted:** Fri Mar 05, 2010 8:49 pm

I dont get it. Why wouldnt the intake be the same temperature with the snorkle in place? The outside air is the outside air.

mikey1273 · **Posted:** Sat Mar 06, 2010 9:49 am

yeah air outside is air outside but under the hood of a warn engine he is saying its just a bit warmer cus the engine is warming it.

DynoPax · **Posted:** Sat Mar 06, 2010 1:08 pm

I recall doing just that with my previous vehicle (Chevy Tracker), and it did alleviate the lower mpg rating I was getting, compared to summer. I'll keep this in mind next winter, then!

Compared to a gasser, how does breathing warmer air affects performance on a diesel? It does have an impact on gas engines...

BVCRD · **Posted:** Sat Mar 06, 2010 1:57 pm

DynoPax wrote:

I recall doing just that with my previous vehicle (Chevy Tracker), and it did alleviate the lower mpg rating I was getting, compared to summer. I'll keep this in mind next winter, then!

Compared to a gasser, how does breathing warmer air affects performance on a diesel? It does have an impact on gas engines...

Up to a certain temp, diesel engines actually like it warm. Hot, not so much, but warm is better than cold.

GreenDieselEngineering · **Joined:** Sun Jun 07, 2009 5:10 pm **Posts:** 1111

The KJ CRD is most efficient with the intake manifold temps in the range of 90-150 F. The variance depends on the boost level and load. The cooler air combined with low coolant temps can take a few percentage points off the fuel economyduring the winter. At very high intake temps there are protection algorithms built in to minmize the potential to go above 175 F. Above 200 F for an extended period of time will not have a positive effect on liner durability or the turbo for that matter. With the built in safeties there is no risk on this engine for liner damage unless the turbo has failed.

BVCRD · **Posted:** Sat Mar 06, 2010 2:57 pm

GreenDieselEngineering wrote:

The KJ CRD is most efficient with the intake manifold temps in the range of 90-150 F. The variance depends on the boost level and load. The cooler air combined with low coolant temps can take a few percentage points off the fuel economyduring the winter. At very high intake temps there are protection algorithms built in to minmize the potential to go above 175 F. Above 200 F for an extended period of time will not have a positive effect on liner durability or the turbo for that matter. With the built in safeties there is no risk on this engine for liner damage unless the turbo has failed.

Thanks for the logistics, but what would you say is the optimum ambient air temp for best fuel economy?

geordi · **Posted:** Sat Mar 06, 2010 3:01 pm

Probably in the 70s-80s. I got the best economy out of my CRD down in the Savannah Ga area, where it is RARELY much below that, except for a few weeks in February.

Summer temps got above that solidly... Into triple digits a few times. Economy didn't seem to suffer, but I sure was!

RAF 3829 · **Posted:** Sat Mar 13, 2010 11:04 am

I've seen a definite MPG pick up since the weather's turned warmer here.

LibertyCRD · **Posted:** Sat Mar 13, 2010 2:02 pm

I removed that small section of the intake tract between the filter box and the grille on my previousCRD 5 years ago. I did this one as soon as I got it too. I've seen no difference really but it can't hurt so i leave them off.

BBB · **Posted:** Sat Mar 13, 2010 3:36 pm

Makes thermal sense. Some cover the grill intakes or radiator like the big rigs in really cold weather. I disconnected the viscus heater and had to re-connect it after the Miss's said :furious:

it was taking way too long to get cabin heat. I can't imagine the efficiancy with the viscus heater running is better than not with the radiator air flow reduced to increase operating temps. I might try the radiator cover next winter with the viscus heater off. I'd be curious if the tranny cooler is the entire height of the radiator area or does it only take up a few inches of the bottom. I'm thinking you may not want to cover the radiator all the way if the tranny cooler section is in the bottom rows.

We run with the insulated factory skid plate, insulated engine cover and hood insulation in the winter (stock) Since the Miss's doesn't off road we pull ALL of that heat retaining stuff off for the summer. Amazing how much heat all that sound insulation causes the engine to retain. Sounds better with it gone too :wink:

05infernoCRDL · **Posted:** Mon Mar 15, 2010 5:15 pm

BBB wrote:

I'd be curious if the tranny cooler is the entire height of the radiator area or does it only take up a few inches of the bottom. I'm thinking you may not want to cover the radiator all the way if the tranny cooler section is in the bottom rows.

don't think it would matter much... my trans temp doesn't move over 100* in temps lower than about 40*... this is in the pan temp

Winter fuel economy tip

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