12v71t

[crudeoilbear]

I am looking for information on 12v71 Detroit's. Does anyone know if I can run a original turbo engine NA? What is the difference in heads between a turbo and NA? Thanks

[CoyleJR]

It has been about 35 years since I last built a DD, but I do not recall there being a difference in the heads. I do believe that there is a need to run advanced cam timing with a turbo. Additionally there are no NA, DDs they are all have a blower. Twin turbo units are the most common setups for a 12V71, DD. What are you going to put this motor in?

Good luck
John

[JRM]

Love the sound of the 12V71TT engine as it is a true 12 cylinder firing order and not just 2 318's bolted together. https://www.youtube.com/watch?v=T1XbZYJwsaA

[rustyk]

They all (DD two strokers) have roots blowers to scavenge exhaust from the cylinders, which would provide a very modest boost. IIRC, the injectors would have to be downsized.

[CoyleJR]

In my previous post I was referring to two stroke DDs only and not the newer four stroke DDs. The two stroke DDs all have blowers and they are all gear driven. The blower does not scavenge exhaust for any reason. If you install a turbo then the turbo will scavenge exhaust gasses and use it to create additional boost. You should check with a Detroit Diesel dealer to determine if you will need to change injectors or cam timing when adding a turbo. If you need to change the cam timing it will be a major project if the motor is in a vehicle.

Crudeoilbear I see you are in Pa. If they are still in business Harbaugh DD near Pittsburgh was an excellent source of information/parts on two stroke DDs in the 1970s.

John

[Liftgate]

I am looking for information on 12v71 Detroit's. Does anyone know if I can run a original turbo engine NA? What is the difference in heads between a turbo and NA? Thanks

The turbo heads had harder valves and seats. I think they were called "stellite". You could use turbo heads on a non-turbo engine. Using non-turbo heads on a turbo engine wasn't advised. Hope that helps. Greg