Hot diesels or cold diesels
 

I am really confused with all the talk of cooler air for the intake. This is my first diesel and am not a mechanic but will tinker with a motor from time to time. When I was younger I always hear d that a diesle ran better as it got hotter. The 18 wheelers would have covers over there grills to stop the flow of air to the motor. But now I read all the info about the cold air flow. Am I missing something? Am about to build my own cool air intake.

Diesel engines run better hot, but colder air coming into the engine is denser giving more oxygen for the fuel to ignite. The grille covers are used to keep the engine at operating temperature, many of the semis have those big round chrome canisters on the outboard side of their hoods, those are the air filters. drawing in colder, denser air than the hot stuff under the hood. Hope this helps, but if not, I'm sure to be followed by better responses.

As I understand it the engine needs to be hot to perform better but the cold air packs a denser air charge into the cylinder and thus gives you more power.

Those that know will correct me if I am wrong.

I think both of your posts sound reasonable to me. Thanks for your help. Now I can continue with my cold air project.

bearwhiz

BTW what is the optimal operating temps for these engines, mine rarely gets above 160 in the summer (170-180 while pulling a Jeep up a grade in OD in the summer with the AC on was the highest that I have seen it hit...)

As posted above, all info is correct as far as I know. The motor needs to be warm so that the oil gets in all the cracks and crevices to lubricate, but cooler air is more dense, dense air=more oxygen=more efficent=lower egt's=longer engine life. Plus, if the engine is not at operating temp, then the diesel does not get burned, causing *cylinder wash*? (don't know if that's the correct term) where the unburnt fuel washes the oil off the cylinder walls, and that's bad ju-ju.
Just my $0.02...

These engines came with an oversized cooling system to keep the engine cool under extreme conditions. Your temps. sound reasonable.

optimal temp would be right around 200 degrees. so cycling between 195 and 205 works for me

What's your cold-air project, BearWhiz?

I have a cold air intake 9 months out of the year[laugh] ...no moding involved.

I got the same cold air setup as you AkTallPaul. Not working as well recently as it made it up to -10* and near 0* the last couple of days.

I just like piddling with stuff like this so I am designing and attempting to build one off of what I have seen other people do. You know, kind of like re-inventing the wheel.

bearwhiz