shaft

This might be a stupid question, but I'm just curious why a set of exhaust headers is not a part of an upgrade in a Diesel. Thanks.

Lary Ellis (Top)

If this is a stupid question, then I have seen it asked many times

Actually I think it is a valid question, and the answers I have seen all point to the lack of back pressure in a diesel engine.

Unlike gas engines, they do not have the higher back pressures and thus the desire to remove it from the engine. I think going to a decent exhaust system will give you all the advantages available, that a header system might give a gas engine.

This is speaking relatively of course, as the two can not really be compared equally. If you up the fuel level then a better charger might also be needed.

This is just my uneducated take on the situation

ramguy

Lary;
I'm just curious, isn't the ATS after market manifold basically a header or is it just a higher quality, more precise exaust manifold?

ramguy

Lary Ellis (Top)

[quote author=ramguy link=board=7;threadid=18691;start=0#msg175286 date=1061488736]
Lary;
I'm just curious, isn't the ATS after market manifold basically a header or is it just a higher quality, more precise exaust manifold?

ramguy
[/quote]

There are many people here far better qualified to answer that question as I have not seen one of their manifolds in use yet .

My answer to "shaft" are strictly my observations from the conversations I have seen here. And I do not claim to be an expert on diesel exhaust systems. I too have seen the great beneifits achieved when using headers on my muscle cars back in the 70's.

But I haven't seen anything like that with the diesel engines yet. Someone using one may be able to chime in here and enlighten the both of us

dodgeman01

I have never seen a person use headers on a turbocharged engine be it gas or diesel. For one reason it might be because the air is being forced through the engine by the boost created by the charger. I don't think headers would help. I mean the way I look at it is 30psi is 30psi no matter if it is in a 1" tube of a 4"tube Not that I know a lot about engines but that is how I understaind it. If I'm wrong please correct me.
DM01

StakeMan

The cummins dragster has headers.

dodgeman01

[quote author=StakeMan link=board=7;threadid=18691;start=0#msg175321 date=1061492795]
The cummins dragster has headers.
[/quote]
why don't you buy a set and tell us what they do for you?
DM01

thecatsfan

Boost pressure is pushing air into the engine not through the engine. Your intake and exhaust valves aren't open at the same time. At least, you should hope they aren't. The 30 psi intake pressure is blocked by the closed intake valve while the exhaust valve is open; therefore it does nothing to help remove the exhaust gas from the cylinder.

dodgeman01

then how much would the headers help out in this area?
DM01

thecatsfan

I don't know. I was just clarifying one point. I have always wondered why I never heard of diesels running headers either.

I had always guessed that it was primarily because of the turbo. The longer the header tubes, the cooler and more contracted the air would be, possibly reducing boost? Perhaps it's simply the necessary airflow restriction caused by the turbo that reduces the effectiveness of the headers. Perhaps the higher compression of a diesel engine reduces the need to scavenge the gasses out of the engine cylinder.

But I really don't know why. ???

dodgeman01

what would a header look like on a diesel? how long? what tupe pipe? I would like to see one. maybe there are a few HP left we could get out of the CTDS 8)
DM01

Commatoze

This explains how headers function, and I guess why they're not used in conjunction with a turbocharger.

StakeMan

KATOOM

I think a header that replaced the manifold would have to be so much like the manifold it would not prove beneficial. The manifold is short to give the turbo as much heat as possible. As long as the runner lengths are stepped in timing with the firing cylinder then the manifold is good enough. You dont need specific runner lengths on a turbo/supercharged motor to get torque because there is no scavenging on forced induction. Thats also why their cams are so much more mellow than a naturaly aspirated engine.