240D Turbo? Is there such a thing? - PeachParts Mercedes-Benz Forum

#1 12-11-2002, 11:32 PM

Obviously, I'm new to MB, as you can tell by the question.
I thought all 240D were non-turbo. Am I wrong?

#2 12-12-2002, 12:22 AM

No and yes, they didn't come from the factory with turbo's, but there are some aftermarket turbo kits people put onto their 240D's.

omegabenz · #3 12-12-2002, 01:41 AM

my friend said a long time ago, they had a kit for them, but it actually made them slower. Hes a benz mechanic.

73MB280SEL · #4 12-12-2002, 06:34 AM

A turbo only adds more air to the engine, you also have to add more fuel to take advantage of the additional air. Does the 240d engine come with an ALDA boost enrichment device? How much additional fuel could a 240d injection pump supply at maximum enrichment?

leathermang · #5 12-12-2002, 10:40 AM

The 240 engine is not designed to withstand a turbocharger... when they were added to the five cylinder they also put oil nozzels into the block which directs cooling oil to the base of the pistons to keep them from melting... in addition to increasing the bearing capabilities....and the cut the compression down just a tad also...

#6 12-12-2002, 10:50 AM

Greg,

Don't you mean they raised the compression UP just a tad also? My manual shows (for the 83) that the 240 has 21-1 and the 300d is 21.5-1

wheelguru · #7 12-12-2002, 11:38 AM

I have read that in general when a manufacturer goes to a turbo on an engine they lower the compression and beef up the block/head, whatever. Under load, the turbo adds back the compression that the non-turbo had to start with and then some.
Maybe mercedes just beefed everything up a lot to withstand the extra compression.

leathermang · #8 12-12-2002, 12:59 PM

I was saying that they lowered the compression between a non turbo 5 cyl and the turbo model...I can't find it in my book right now... but it appears they decided/found that packing extra air into the 21.5 to 1 compression cylinder developed too much pressure on the bearings...or connecting rod...

#9 12-12-2002, 01:11 PM

Ok. Was going 240-300d, not non-T to T 300d. I don't know for what it is on the non 300d.

psfred · #10 12-12-2002, 11:03 PM

All US 240 models are naturally aspirated. I know there was a W123 200 Turbo and maybe 240 Turbo in Europe. I'd suspect the engine was modified as the 300 Turbo was.

Peter

samiam4 · #11 12-13-2002, 12:25 AM

I seem to remember Dave at ASAP had a employee that was converting 240's. He would get everything off a dead 300-turbo motor and cut-off and weld up the intake.
Less boost and he said they ran strong for 50,000 miles. Suppose to get good mileage too(?).

Michael

#12 12-13-2002, 11:38 AM

.

73MB280SEL · #13 12-13-2002, 12:36 PM

It's not the size of the dog in the fight but the size of the fight in the dog.

Seriously though, how does an aftermarket Diesel turbo kit add more fuel to the engine? On a gas engine, either (1) you let the existing EFI computer compensate or (2) restrict the return line so the fuel rail runs at a higher pressure or (3) add supplimentary injectors.

Sholin

leathermang · #14 12-13-2002, 01:53 PM

Sholin, " Seriously though " ? LOL... don't let those little smiley faces misslead you ... each question on this forum is taken seriously by at least one person.. not the same person... different questions , different persons...
This was the same question I kept posing when Ridge was talking about adding the intercooler to his 300 .... If a significant increase in air was available due to the cooling would the stock system react with proper additional fuel ?
I don't know.. and did not recognize an answer to this within that thread , if it was there...

73MB280SEL · #15 12-13-2002, 06:52 PM

leathermang, I hope it my smilie comment wasn't taken to disrespect the original question nor did I intend to hijack the thread, I was just commenting on Jim's comment, which I found funny.

As far as turbos and superchargers are concerned, I think people don't think of them correctly. Most think a turbo's role in life it to provide more air. While this is true, one should think of it as a license to burn more fuel (hopefully efficiently). Without more fuel being burnt, there isn't more power developed.

GLAinc, As far as turbo 240's are concerned, While I am absolutely no expert on MB Diesels, I believe the confusion arises with the naming convention of MB wagon models. Mercedes will name the sedan a 300D or 240D, but the wagon version is 240TD or 300TD. Some might mistake this for 'turbo', but it only means "touring" (or something to that affect) which stands for the wagon version of the sedan car. The turbo would be like 300D turbo. A wagon turbo would be 300TD turbo which is abbreviated as 300TDT around here.

You might want to pick up a book "Mercedes Benz Production Models Book 1946 - 1995" byRobert Nitske. Good book, a few errors, but really informative about the models MB produced.

etc.... I once called on a 200D turbo that was being sold on collectorcartraderonline.com in LA. It looked OK and was in my price range, so I thought I'd inquire (figuring the owner was mistaken about the turbo). Turns out the guy selling it really did put a turbo on it and put the boost guage right smack in the middle of the dash (big hole cut there). I passed on it.

As far as boost in general is concerned (though I'm no expert), Diesel engines are really benefitted by turbocharging. When you turbo/supercharge a gas engine, the limit to the boost you can apply is when the engine starts to knock. The solution for boost knock is to retard the ignition under boost and lower the compression ratio. Both of these lower the efficiency of the gas engine. Diesel engines, on the other hand, do not have a knock limit to boost. They can take as much boost as the mechanical limits of the engine can handle (as long as you can supply additional fuel to take advantage of the extra air).

N/A Diesel engines also suffer a performance penalty over their gas counterparts. Gas engines acutally have better volumetric efficiency due to the evaporation of gasoline as the fuel is injected. This cools the intake charge, making more fit in the cylinder during the intake stroke. This affect can be pretty significant and is also one of the side benefits of using Nitros Oxide (NOS) in a gas engine. (NOS also is an oxidizer so even more fuel can be injected and burnt resulting in more power.) Diesel engines only take in outside temperature air without this precooling. Thus, they take in less air. For that matter, propane fueled "gas" engines do not benefit from the intake charge cooling affect because the propane is heated prior to mixing with air in order to prevent freezup of the propane regulator. They also suffer a performance penalty over gasoline engines. (Propane is also a gas, which displaces some air as opposed to gasoline. This means less air in the cylinder so less power.)

Turbo's rectify this by adding whatever air the engine can "handle". For a Diesel, I believe the exhaust gas temperature is used to set the limit of how much boost (and extra fuel) the engine can safely handle. Of course, this still depends on the bottom end of the engine being strong enough to handle the additional power being generated.

Well, that's about all I (think I) know. Most of this comes from when I was into Chevrolet performance engines (LT1). Most people who bought superchargers for their Camaro's ended up blowing up their engines, but a properly engineered system can be very reliable.

Sholin