The Best Twin Turbo setup

[Jim Fulmer]

Jim, if anyone can do it Brent can.

The reason I ask is when I'm on boost(15-20) mine spools to 80 so quick it's sick and I have blown a 40 yet.



Jim

 

[AK RAM]

If you want the cleanest set up... ... .

How is this for clean ... .....

 

[Yooper1]

AK Ram your set up is very nice and clean! No question. . I wish it too could show mine, looks about the same. I will say your engine area is cleaner then mine. But the points of both sides is well taken. My point is only this, I spent a year looking at everything till I went with poole. And I have seen a lot of stuff that is crap. Were all trying to help everyone on here from buying bad stuff. Again, Nice looking Rig!

 

[JR2]

I don't have twins but I have some experience with them and a couple of the guys mentioned in this thred. If it where my $$ I would go with Piers or Poole.



As far as how twins look on the truck, does it really matter to the guys building comp trucks. I understand why myself or AKRam would want a good looking shiny set of twins, but if I where building a set for pulling or racing all i would want is them to work fantastic, who cares what they look like.



Good luck

 

[Morse]

JR2, I used to feel the same way until I started dumping the cash to the old truck. . Now, I would like everything to look decent as well as make crazy power... Althought the sleeper effect is pretty cool... Hmm. .

 

[Bpostel]

Jim,

The top turbo was an HY-9, need I say more :-laf

 

[Diesel Freak]

If you really want to get a handle on how sequential turbos are supposed to work, Borg Warner has a great paper on it.



It's a little long and dry, but it illustrates the principles very well.





http://www.nwbombers.com/membersites/diesel_freak/bwts_library_106_107.pdf

 

[CRoth - BD-Power]

DF, we built something like that with BorgWarners help, the problem was the control of the diverter valves and cost. But still peak torque was just below 1700 RPM and peak HP was at 2900 RPM.



It was pretty crazy to look at, I suspect the next generations of engines will have that design. I know the now cancelled Ford V6 diesel engine had this design.

 

[Diesel Freak]

Yep, cost is a factor, but it sure is one cool system.



What diverter valve? are you talking about the pilot controlled valve between turbine stages in figure 1?



To me that is just a wastgate to bypass un-needed exhaust gas around the seccondary.

 

[CRoth - BD-Power]

Your right a wate is all that is need but the valve needs to be quite large as you need to re-route quite a bit of exhaust with out disturbing flow.



The other problem is peak power, the small turbo is so small that it hurts power on the top end, hence is why you regulate around it. But for big top end power you need to compound to get your pressure higher. It just can't be done as efficiently with a single as with two turbos.



We've seen some pretty efficient wheels from Garrett but still nothing is as efficient as two turbos at their peak. Not yet anyway.

 

[Diesel Freak]

just speculating here, but I think the main limit for high pressure ratio capable wheels is the material.



You can only go so far with aluminum, then titanium takes over. After that everything is just too heavy for a decent spooling turbo.

 

[AK RAM]

... ... then titanium takes over... ...

Seems I read somewhere recently that BorgWarner not long ago produced a series of turbos that used titanium wheels. Whatcha reckon the price tag on something like that would be? :--)

 

[Diesel Freak]

dont want to know

 

[CRoth - BD-Power]

The price is actually not that bad as we can get them for our Duramax turbo. But your right the increase in weight does hurt its accleration. But at the same time they have reduce some of the material thickness due to the increase in strength of the Ti.



The best system I have seen is a dual compound single turbo, the compressor wheel was double sided.

 

[Hohn]

So, this is like having two compressors driven by a single turbine?



This is almost close to a jet engine, with multiple compression stages driven by multile turbine stages-- all on the same shaft.

 

[CRoth - BD-Power]

Yup it was prety neat, the seoncd compressor wheel was made from Ti. The only problem is that turbine needed to generate huge amount of HP to turn the two compressors.

 

[Diesel Freak]

now back to the topic at hand.



I would have to say that the "best" twin turbo setup would give the widest possible powerband and supply enough air to burn a given ammount of fuel without exceeding the current federal limits for Soot and NOx which are 4. 0g/BHPxHR and . 1g/BHPxHR respectively while at the same time keeping EGT at a "usefull" level.



NOx is the toughn one!!!!

 

[Hohn]

Yup it was prety neat, the seoncd compressor wheel was made from Ti. The only problem is that turbine needed to generate huge amount of HP to turn the two compressors.

Yes, but isn't the total turbine power LESS than it is in a twins setup with two turbines driving their own compressors?

 

[Hohn]

now back to the topic at hand.



I would have to say that the "best" twin turbo setup would give the widest possible powerband and supply enough air to burn a given ammount of fuel without exceeding the current federal limits for Soot and NOx which are 4. 0g/BHPxHR and . 1g/BHPxHR respectively while at the same time keeping EGT at a "usefull" level.



NOx is the toughn one!!!!

Well, yes, because everything we do to increase power and/or mpg increases peak combustion temp, and therefore NOx as well.



I say give up on the NOx, and focus on particulates-- PM10 and such.

 

[CRoth - BD-Power]

Yes, but isn't the total turbine power LESS than it is in a twins setup with two turbines driving their own compressors?

True but can imagine a single turbine wheel generating well inexcess of 300HP.