I was considering adding a ATS exhaust manifold when I install my pyro probe. Can I expect to see any performance improvements by adding the exhaust manifold?
Thanks in advance,
D

 

Slightly faster spooling and slightly lower EGT's. Nothing that's gonna make it an eye opening experience, but you can expect a 25-50* drops in EGT's across the RPM range.

Best part about it is that it flows 3 - 1 on both sides, vs 2-1 on one side and 4-1 on the other side. It gets a lot better scavenging effect on each bank of cylinder.

That in turn keeps the exhaust pulses from beating each other up on one side and not having the scavening effect on the other. That's why you see the slight EGT drop and your drive pressures on the turbo are better balanced with the boost numbers, getting you closer to the 1:1 that you want.

A stock manifold puts you around a 1:1.4 of boost to drive pressure. Any of the after market ones that go a true 3-1 are gonna get you a better drive - boost ratio which is better for the engine.

 

Hey Coal Train... Not that I don't believe you, cause you know WAY more about this stuff than I do, but how come Cummins doesn't make the stock manifold do the stuff you just said the aftermarket ones do? I'm always skeptical of what the aftermarket guys say their stuff can do...

 

The all mighty dollar buddy.

Here's another reason that your run of the mill Cummins, which is only pushing 30% of it's true power capability in our trucks BTW, doesn't have all the super go fast goodies on it.

What does Cummins really sell? Do they really sell engines?

Or, do they sell HORSEPOWER and RELIABILITY?

Sure, you can get a 5.9 that is putting down a TON more power and can do it all day long. Just look in the marine market. But, you pay through the nose for that power.

Cummins hates to see all the mods and such on the aftermarket, because it eats into what they really sell.

If they were to take a marine application engine and put it into a truck for the consumer market, the price of the truck would skyrocket. Not to mention the insurance that would follow a truck making 450 HP and 1000+ lbs/ft of torque.

 

If you get a chance to, compare the manifolds next to each other. Or even just look at the stock manifold while it's in the engine bay.

Any kind of log style manifold, which the OEM part is, has serious drawbacks. Sure it evacuates the exhaust gasses, but does it do so efficiently (aiding the exhaust flow) or does if cause backpressure (like the OEM one does).

The main drawback to the OEM manifold is that it doesn't take real advantage of how a straight 6 actually works. It's like two 3 cylinder engines strapped end to end.

Cylinder 1 - 3 work together and 4 - 6 work togther. By using the exhaust pulse of them together, you get good pressure going to the turbo and the exhaust pulses aren't beating themslelves up in the manifold. As the engine rotates, cylinder 1 & 6, 2 & 5, and 3 & 4 mirror each other, they're just on different strokes in the cycle. One is on intake, one is on exhaust and one is on compression, one is on power and vice versa.

The OEM manifold has the front 4 cylinder dumping into 1 side of the flange and the back 2 dump into the other side of the flange. This completely negates the scavenging effect on #5 and #6 and by putting #4 with 1-3, you cause back pressure that hurts spooling and increases EGT's.

 

I guess this makes sense, but I still don't understand why they wouldn't make it that way in the first place. How much more could it really cost them to make it this way?

I sort of get it why they wouldn't do the intake and exhaust-- I understand they want to keep it quite for all the old farts out there. But it doesn't make sense to me why they wouldn't make something like the exhaust manifold the way you describe.

 

Thanks. I ended up ordering the ATS Manifold.

Should I be looking for any special gaskets? Is any one better or worse then the other?

I have found:
Fel-Pros for about $26 for the entire Manifold set
Commetic for about $50 for the manifold set
OEM Dodge for about $13 a piece for the manifold gasket and less than $2 for the turbo gasket
Geno's has them for $5.50 a piece for the manifold gasket and $3 for the turbo gasket
Also BD power for $57 for the whole set.

I have also read that 2004.5 and newer Cummins have multilayer gaskets, is this true? I think the only multilayer gaskets from the group I mentioned above are the Commetic, does Commetic offer a Turbo gasket?