Ok, so after seeing several new fords with tubos, and pictures of the turbos, im wondering about their turbo design. I thought the idea of the plumbing between the two turbos was to optimize the off the line, to pull ratio. The fords are back to back with no plumbing killing the way i thought twins ran. anyone clear this up to me?

Mike

 

I'm not sure and want to hear something about this as well. It's kinda pointless, I've heard there's a big deal about the emissions on it, and this was a way to pass on it...or something like that. Check out these posts, I was browsing them lastnight...might help a bit, but still want to hear more.

https://www.dieseltruckresource.com/...ferrerid=51194

 

I was just getting ready to say...the twin turbos is a MUST with them because Navistar can't figure out how to meet emissions/make enough power with the new EGRs they have on that new motor, etc etc...believe it or not JTheissen, those twin turbos are actually the cause of a pretty heated disagreement, if you will, between Ford and Navistar right now. It is going to push back production and cost the consumer more and Ford is pretty upset to say the least. (they are talking about SUING Navistar over this twins ordeal)...but all the luck to em' I say...I think it's embarrassing to HAVE to implement twins to be competitive with a single turbo Cummins, quite frankly. Both are rated at 350/650 if I'm not mistaken, so why all the "extras" under the hood of the Ferd?

Derek

 

That last one is copied from someone else in those posts.

 

In compounds, the exhaust gases pass through the secondary (smaller) turbo first, then drive the primary (bigger) turbine. The intake air first goes through the primary (bigger) compressor and is compressed, then the compressed air is fed through the secondary (smaller) compressor. This allows you to get high pressure ratios fairly efficiently; very few single turbos can run 60psi efficiently.

A turbo is driven by hot exhaust gases. The less plumbing between the secondary and primary turbines, the less heat loss, meaning more available power to drive the primary turbine. Ford's design builds the output of the secondary turbine directly into the primary turbine's housing. The lack of plumbing reduces heat loss and makes more heat energy available to drive their primary turbine.


Feel free to correct me if I got anything wrong; I'm not an engineer yet

 

so then my whole idea of the twins is off?

 

I've heard that this new set-up has just as much lag as the 6.0...

 

The twin turbo setup up can be parallel or compound, more than likely its compound. They aren''t really doiing this for all the hp and torque they get to give the customer, its being done to help with emissions. Some of the emissions laws are measured in PPM, (parts per million) One way to fool that number in the exhaust is to shove extra boost thru the engine throughout its RPM range, now, where did they learn that trick?.. Cat-ACERT! Lets see if they can make it work!!!...

 

Twin turbos are a compound system the turbo that takes the air in from the air cleaner is the low presure turbo witch then compresess the air to the second turbo witch is the high presure then it gos to the intake manafold I have worked on alot of industrial cummins the largest is a 78 Liter and it has 12 turbos each set of two turbos feed 3 cylenders

 

ahh, so the back to back plumbing does nothign to give more or less power. i understand that there just for emmisions

 

Fellers - I'm no expert on this. But I do have a Mazda RX-7 with twin turbos. I think its what you guys are calling a compound turbo set-up. I would call it a series or sequential. And the other set-up I would call a parallel.

Anywho - The turbos being sequential in my Mazda are extremely complex. In my Mazda, I can see the point. The rpm range is extreme. Redline is like 8,000 rpm or something. The engine is a 1.3L Wankel (rotary). At low rpm it uses only the primary turbo. But at a set rpm and boost level, the secondary turbo kicks in to add all the necessary air that the primary can't make by itself. The primary comes on quick at low rpm, and uses some of its waste-energy to pre-spool the secondary. Anyway, its complex. If this is the way Navistar is doing, holy cow ... stay away from that.

BMW's M3 (or whatever it is) uses a parallel turbo system. 2 turbos. Each one blows 3 cylinders, I think it works. Much simpler.

I can't see why a low revving diesel engine would need sequential turbos, unless for like the emissions that's been stated. I don't know anything about that.

 

Ford refers to the 2 turbos as " Dual Turbo " . Hence 6.4L DT PSD .

 

Jyro, in the gasoline world, I think youre right... If i'm not mistaken, the old 3000GT VR-4 what a sequential parallel setup (actually had 4 turbos on it).. Its just terminology differences between the gasoline world and the diesel world. Why they are called pushrods on a 350 chevy and push tubes on a 3406 Cat.....??? Who knows? Some engineer thought they had to be different???.. hahaha... I know that Caterpillar uses both setups.
On the PSD, the twin setup is for emissions, if there is a HP gain, thats just a side benefit to the engineers that designed it.