M1008 Aftermarket Headers

[TheControlVoice]

I've been looking for some aftermarket headers for my M1008 and I keep coming across old posts about Stan's Headers. From what I can tell, Stan's Headers went out of business. Are there any alternatives?

Thanks in advance.

 

[Keith_J]

Diesel engines cannot have any valve overlap because there is no room for either valve to be open at top dead center. In performance cam design, this is called a large separation angle. Performance engines are between 106 and 110° lobe separation angle between intake and exhaust lobes.

Why does this matter? Using tuned intake with proper headers can induce greater cylinder filling with the headers creating partial vacuum in the combustion chamber.

The tiny top dead center volume also reduces any gains with headers. Design exhaust back pressure is less than 1 PSI @ 3600 RPM. Intake restriction is even less with a dirty filter. Brake mean effective pressure is 85 PSI, this is the theoretical pressure required on the engine displacement to net identical power, taking into account the work required to intake + compress the air etc in addition to the positive work from the actual power stroke. Recall this can be as high as 1800 PSI on this engine..

Cool air intake, port matching and mandrel bend head pipes are just as effective and cheaper than Stan's when they were available.

To get more power from a diesel, you need more pressure. The J code is right at the smoke limit which is also at exhaust gas temperature of 1230°F when 48 mm^3 of diesel is injected at each stroke. To get more pressure on the power stroke you need more air density. Either keep it cool or increase the pressure. Well designed turbocharger systems do both without need for intercooling as boost pressure of 10 PSI is about the limit. This allows 20 mm^3 more fuel each stroke for about 210 HP.

 

[TheControlVoice]

Diesel engines cannot have any valve overlap because there is no room for either valve to be open at top dead center. In performance cam design, this is called a large separation angle. Performance engines are between 106 and 110° lobe separation angle between intake and exhaust lobes.

Why does this matter? Using tuned intake with proper headers can induce greater cylinder filling with the headers creating partial vacuum in the combustion chamber.

The tiny top dead center volume also reduces any gains with headers. Design exhaust back pressure is less than 1 PSI @ 3600 RPM. Intake restriction is even less with a dirty filter. Brake mean effective pressure is 85 PSI, this is the theoretical pressure required on the engine displacement to net identical power, taking into account the work required to intake + compress the air etc in addition to the positive work from the actual power stroke. Recall this can be as high as 1800 PSI on this engine..

Cool air intake, port matching and mandrel bend head pipes are just as effective and cheaper than Stan's when they were available.

To get more power from a diesel, you need more pressure. The J code is right at the smoke limit which is also at exhaust gas temperature of 1230°F when 48 mm^3 of diesel is injected at each stroke. To get more pressure on the power stroke you need more air density. Either keep it cool or increase the pressure. Well designed turbocharger systems do both without need for intercooling as boost pressure of 10 PSI is about the limit. This allows 20 mm^3 more fuel each stroke for about 210 HP.

Thanks Keith!

Got it. I was looking at some cool air intake mods and i had read something about people using Banks turbo.

Question, what do you mean by "Port Matching"?

 

[nyoffroad]

Question, what do you mean by "Port Matching"?

In a nut shell,
Some folks call it 'porting and polishing'. You'd think that the intake and exhaust passages in the head would match up closely to the manifolds , right? Well next time you have an engine apart place a intake manifold gasket on the manifold and look at how it doesn't match the ports, then take the same gasket and place it on the head (use bolt holes for locating), see how much difference there is? Think about how that restricts the air flow and if you grind and polish the openings to closely match each other the engine will run smoother and more efficiently.

 

[TheControlVoice]

In a nut shell,
Some folks call it 'porting and polishing'. You'd think that the intake and exhaust passages in the head would match up closely to the manifolds , right? Well next time you have an engine apart place a intake manifold gasket on the manifold and look at how it doesn't match the ports, then take the same gasket and place it on the head (use bolt holes for locating), see how much difference there is? Think about how that restricts the air flow and if you grind and polish the openings to closely match each other the engine will run smoother and more efficiently.

Ahh ok, I have heard of port polishing but never knew what it was for.

 

[Keith_J]

One more point. 379 cubic inches of 4 stroke has a theoretical volumetric flow rate of 395 cubic feet per minute at 3600 RPM.

Actual flow rate is 350 cubic feet per minute for a volumetric efficiency of 89%. That is impressive for 1980s technology using cast iron heads. This is from the low turbulence on the intake as the indirect injected diesel creates turbulence in combustion on compression when the air charge is forced into the Ricardo Comet type injection cavity.

Turbulence aids combustion speed, this is required for all high speed engines.

On a side note, I saw the aftermath of a shade tree mechanic with the idea of turning this engine into a more direct injection engine. This was done by cutting off the inner half of each pre combustion chamber. The engine still ran but poorly even with turbocharging. Without turbulence, the flame speed is too low and piston movement causes the flame to quench.