Exhaust Options - 300 Tdi

I wouldn't hesitate to use a 3" exhaust on a 300Tdi. If I could fit a 4" (which I can't) I would use 4" from the turbo on my Isuzu, but it flows a lot more air than a 300Tdi.

I have never seen a reputable explanation for better performance from increased back pressure in the exhaust system of a turbo diesel engine. Only on internet discussions like this.

I stand to be corrected, but I can not recall reading such in any of the books I have and I trust the authors far more than 2nd or 3rd hand reports from the likes of someone working for and exhaust place.

It may well be that the average 300Tdi owner will not notice much difference between a 2-1/2" and 3" system on an otherwise stock engine.

But the original poster has fitted a larger turbo that flows much more than stock. IMHO he will see the benefit from a 3" system.

Hi All

Gale Banks says that for power a turbo motor should have a 20 degree ever increasing cone and thats from hundreds of hours of dyno testing.

Personally I believe that mufflers on diesels are exhaust brakes and havent seen an exhaust upgrade in size that wasn't beneficial to some varying degree.

The turbo is a very expensive muffler and usually all that most vehicles need :Dunless you do deep water crossings and would like to slow water from entering the turbo via the exhaust:eek:

If fitting bigger turbo and exhaust then it might be a good idea to get the injection pump tuned to the new mechanicals as it may be possible to lean the motor out.

Regards Mark

I ended up fitting the 3", it seems to have opened it right up

I can now hit 100 in 4th if need be :twisted: and it's not overly loud with the muffler on

Although when the turbo loads up is does get a noisy

Quote:

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Originally Posted by marko66

Hi All

Gale Banks says that for power a turbo motor should have a 20 degree ever increasing cone and thats from hundreds of hours of dyno testing.

Personally I believe that mufflers on diesels are exhaust brakes and havent seen an exhaust upgrade in size that wasn't beneficial to some varying degree.

The turbo is a very expensive muffler and usually all that most vehicles need :Dunless you do deep water crossings and would like to slow water from entering the turbo via the exhaust:eek:

If fitting bigger turbo and exhaust then it might be a good idea to get the injection pump tuned to the new mechanicals as it may be possible to lean the motor out.

Regards Mark

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All that EXCEPT, you don;t lean out a diesel.......unless your talking about depriving it of oxygen( lean of air:p) by adding to much fuel and melting the pistons;)

I'm guessing Mark has fallen into the common trap of assuming issues with petrol engines might apply to diesel engines.

Your diesel engine will love you more, the leaner you run it.

Quote:

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Originally Posted by Bush65

I'm guessing Mark has fallen into the common trap of assuming issues with petrol engines might apply to diesel engines.

Your diesel engine will love you more, the leaner you run it.

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Yep, very common misconception, with those that haven't been around desiesal engines:D

Quote:

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Originally Posted by marko66

Hi All

Gale Banks says that for power a turbo motor should have a 20 degree ever increasing cone and thats from hundreds of hours of dyno testing.

...

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A turbo needs a diffuser immediately after the turbine exducer (where the gas exits from the impeller). A 20 degree included angle cone makes for an excellent diffuser, particularly with axial flow turbines, fans and compressor.

The turbines used with small turbos are radial inflow - a type for which has received virtually no treatment in classical or any other texts on the subject of turbines etc.

The turbine on Jock's new turbo has an exducer diameter of approximately 44mm. The diffuser in his turbine housing is not conical, but rather more complex, which makes me believe that Garrett have carried out comprehensive computer modelling using computational fluid dynamics (CFD) software to arrive at the shapes used (mad if they didn't, if they want to stay competitive).

One million hours of dyno testing will not reveal the complex behaviour that good computational fluid dynamics modelling will show.

The exit of this diffuser where the dump pipe connects is 70mm inside diameter (for everyone claiming the exhaust shouldn't be greater than 2-1/2", should know that 2-1/2" is 63.5mm).

This exhaust was with the VNT fitted?.I think most people though it was with the OME model. Pat

Yes that is with the VNT fitted

Hi All

Rovercare asked me to post again so I will:D

Rovercare said you don't lean out a diesel but you can over fuel it.:eek:
Bush 65 said that your diesel engine will love more the leaner you run it:eek:

I will agree that for small simple upgrades the chances are that the original fuel parameters and boost compensator will cope - probably wont be ideal but will cope.

So if you can't lean out a diesel we get a diesel engine say a 300 tdi and compound boost it to 65psi and leave the pump standard and while money is no object and flights of fantasy are catered for we make a new dual 3 inch intake manifold:D and dual four inch exhaust and because you cant lean out a diesel all cylinder head temps and exhaust gas temps will be perfect:D:D I believe not.:o

Regards Mark