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Compound turbos

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I have a 86 Mack with the 350 and was wondering if anyone had tried putting compound turbos on one. I'm not trying to make more boost or sup up the engine, just a quicker spool by putting a small turbo with my stock one, any suggestions would be helpful, Thanks

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My suggestion is why would two turbos spool up faster than one.Same drive pressure going thru two instead of one.You can put a turbo on from a smaller HP engine and it will spool faster and boost maybe more till it blows or has too much drive pressure build up and will not be able to over come the advantage of fast spool up.

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I understand how the smaller turbo spools up and makes boost until the exhaust pressure come up enough to have the larger turbo make the power.They take out the low rpm lag. Fabricating the plumbing fabrication is intense. What happens with the fuel delivery with the added low speed boost? I know it works fine with a gas engines. You can use a laptop to reprogram ECM's fuel curve. Question is what system its there for the diesel?

The system for the 6.7 Dodge-Cummins has a piggy back controller and a Fast Tune port for your laptop. Think doing a MACK, Cummins or other is un charted territory.

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E.J. Utley had compounds on his e6 4valve in GATR racing back in the day .

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There is an E-9 Puller on here running a twin compound set up. But the fuel management is way different for a street driven truck.

I would look into a Garrett Variable Vane Turbo Diesel as a possible alternative the the compound set up. Does basically the same thing as a compound turbo in a single unit. Might be better and simpler in the long run. Less plumbing and no real heavy injection mods. Paul

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staxx, do you know more about E.J. Utley? I found a few pictures of his yellow superliner but not much. cool ride for sure

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It has a mechanical pump, would u have to have wiring to tell the VGT what position to be in?

VGT units the intake aperture not the vanes are controlled by a one of the following. A vacuum actuator, electric servo actuation, 3-phase electric actuation, hydraulic actuator or air actuator using air-brake system pressure.

A few years ago Suprock Technologies released a VGT turbocharger controller that is capable of actuating any variable geometry turbocharger based on sensor parameters including pressures, temperatures, and shaft speed. This controller enables vehicles that aren't originally equipped with a VGT to make use of the technology for increased performance and efficiency. The controller is capable of calculating turbo performance based on engine and exhaust temperatures, exhaust pressure, air flow, and compressor behavior. The turbo compressor efficiency among other parameters that are displayed on a gauge pod located in the dash board.

The Garrett Variable Vane uses both rotating vanes of their design or the Cummins patented Sliding vane mechanical technology depending on application.

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Ford Powerstroke had a variable vane turbo at one time? Maybe still does?

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They call them VGT's variable geometry turbos. The vanes are partialy open for greater air flow velocity on acceleration. When the vanes are full open you get max air flow

at higher power levels. On my 6.0 the max boost (vanes wide open) is about 40 psi. Being that its a 6.0 I never go over 20 psi. 6.0's like to be worked easy if you want them to last.

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Ford seems to have the best success with the VGT units both on Diesels and the Eco Boosted gas engines.

Getting a smaller turbo from a salvage yard is possible if you do a "compressor map" to match the boost verses rpm and Power bands. With out that the turbos will end up "fighting" each other and you'll lose power, economy and have emissions issues.

I gained most of the knowledge working with Ohio George Montgomery setting up my SVT Mustang. Went through the compound turbo verses twin Garrett Eco Boost style turbos verses turbo and an axial blower combo.

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Could I just figure up what turbo would go with a 056AP, and then look up what vehicles would have that turbo size?

Don't see why not. You could also call Garrett and see what VGT is a direct replacement for the stock one on your engine.

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It involves about 6 different algebraic formulas with this info plus more needed. Engine cubic inch. RPM, CFM, #PM, Ambient Air temp, Altitude, Barometric pressure, Flow loss through Air Filter, Exhaust temp, Exhaust pressure and Fuel use per hour, Air inlet temp, Air outlet temp and Power band desired.

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I know what your saying, but I think it would be wasted on this type of set up. For instance, your engine should have a multi speed gearbox to keep you in the right hp/rpm band. I know in my truck, if I change up at say 1700, next gear I'll start at around 1400 and I'm making plenty of boost already.

But I'm not trying to talk you out of it, it would be cool to see something like that. And I'm always thinking of things I'd like to try, but I don't think you'd see much benifits.

P.S. Hope you prove me wrong.

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So I am in the process of building a compound setup for my 2v E6 Mack I believe there much tougher then given credit.... just gotta keep it up in rpm and not lug it ..... so I’m going to use a k31 as my high pressure turbo comes off a Detroit series 60 and a s480 as my low pressure turbo I have my fuel setup figured Out so my plan is run it till it quits if it does quit then swap out for a e7 mech engine. Mack truck are what I love but!!! Coming from building quite a few performance Diesel engines I can tell you this Mack’s air flow research has always been behind a k31 will much more air and move it much more Efficiently aka faster spook up  so it should be much more snappier and cooler running and and on the big end the s480 will take care I will take pictures when I start and give you a update how it performs 

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10 hours ago, Mack Technician said:

I'm in the hater category when it comes to compounding turbos. They are engine killers. We lost a Liehberr at 4,800 hours because the secondary turbo blew and the operator ran right through it till the engine literally exploded. The sister turbo will make up for the second while its failing so it robs the operator of sensing the catastrophe onset. If you have a DPF your really in trouble, it will not even smoke before it explodes.

In your case you would see some smoke. When/If your secondary turbo goes it may start to ingest engine oil and your first turbo will give her lots of extra air so if it blows it may be quite an impressive show. Crowd pleaser at a truck pull.  

 

 

  

 

NICE! Probably  not  doing an inframe on that puppy! oops

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1 hour ago, fjh said:

NICE! Probably  not  doing an inframe on that puppy! oops

Nothing left but the crying on that unit. Liehberr abandoned that engine and went back to one turbo now.

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