Diesel - Warm or Cold?

[arcosine]

I went to bed perplexed and woke up with the answer. It is not more air for efficient combustion as Jyden has said, this is a wrong conclusion.

http://www.oricpub.com/SE-1-1-2-3.pdf

The answer can be found by looking at the bsfc curves for different intake temperatures. See how the curves steepen downward at cold temperatures. Now imaging putting liquid nitrogen in the engine, it would run without any fuel. The gain in bsfc is due to the cold air expanding by heat transfer from the warm engine. This goes along with Nightking in that the engine needs to be kept hot in winter. The logic should follow on a otto cycle too, except for pumping losses may exceed the gain of expanding cool air in the cylinder.

[PAFirefighter11]

Originally Posted by TexasCotton

cold air intake is way way over sold. Ebay has plenty of them. The benefit is marginal if not nothing on some vehicles

I'm picking mine up from eBay for $24.99. I'd like to hear the turbo more, so that's a cheap way to do that. Mufflerectomy is next.

[Jyden]

Originally Posted by arcosine

So you are saying that more air in the engine the better the mpg, well then why not have a big engine that sucks a lot of air in and that should get better mpg than a small engine that sucks less air in at a given output. I still don't follow the logic, since at partial throttle there is more excess air in a Diesel and less fuel but yet the sbfc is not better.

In the report that you site, they don't mention changing the injection timing for optimum torque at the different temperatures tested.

Why do you think they make and mount intercoolers om diesel engines?
To cool the intake air!

The reason for the WAI on a gas/petrol car is to make the throttle plate open more to lover intake resistance. Diesels donset have throttelplates, but rund wide open all the time, so as cold air as possible and as little restriction in the air intake on a diesel is the best both for FE and HP.

[PAFirefighter11]

Any of you TDI forum guys.. check out the thread over here: Cold or Warm? - TDIClub Forums

[NachtRitter]

You might have gotten better information if posting in the Fuel Economy section: TDI Fuel Economy - TDIClub Forums. I do agree that any aftermarket intake on the stock engine is not worth the money.

Mufflerectomy is not going to help FE either, but it sure does make the TD sound a lot better!

Grill block & Frostheater will help get the engine up to temp and keep it there. Also Scangauge II, of course, so you can keep tabs on the temp and other things.

[PAFirefighter11]

Originally Posted by NachtRitter

You might have gotten better information if posting in the Fuel Economy section: TDI Fuel Economy - TDIClub Forums. I do agree that any aftermarket intake on the stock engine is not worth the money.

Mufflerectomy is not going to help FE either, but it sure does make the TD sound a lot better!

Grill block & Frostheater will help get the engine up to temp and keep it there. Also Scangauge II, of course, so you can keep tabs on the temp and other things.

The intake and mufflerectomy are just for personal purposes (the turbo whine). Not too concerned about FE improvement with those. I just love the sound of a turbo spooling, even at idle.

Thanks for the other info, I do need to look into an engine block heater and grill block ASAP!

[Diesel_Dave]

I made my own CAI. See here:
http://ecomodder.com/forum/showthrea...ctd-22770.html

We got into some of the efficiency details too. The effect is fairly small, but basically a diesel like colder air for better efficiency up until the point the combustion gets significantly retarded due to the longer ignition delay. i, personally wouldn't get too concerned until ambient temps get at least below 20 deg F. We recently had temperature dip below zero here, so I temporarily plugged mine. I was getting some white smoke of start ups without my grid heater.

[NachtRitter]

Yep, that's the same reason I did the mufflerectomy... I love the sound.

My grill block, along with a receptacle for the Frostheater where the VW badge used to be. The PO had already smashed the badge, and since I kept (unintentionally) dragging the plug on the ground, that seemed like a good place to put the receptacle: