Joe Ewen wrote:

Steve, Dave, or anyone else using the stock turbo(s)

 

On my 20B installation I am considering using the stock turbo system.  I would only be using low boost levels.  I have a couple of questions for anyone who is using the stock turbos.  Were your systems twins turbos?  Did you leave both turbos in place?  Is over speeding an issue for our mode of operation?  What else should I know about using the stock turbos?

 

Thanks,

Joe

The twin turbos are a sequential affair. One for low end, the other for high end. They are not intended to be both providing large amounts of boost simultanously. I do not know of any fliers who used twin turbos.

The problem isnt so much the amount of boost, but the amount of boost over time. You need a high volume of airflow with a mild to moderate amount of boost in your application., You need to get a turbo that is intended for your mission, that will flow the cubes/pounds of air that you need without being in the surge zone or the danger zone on a compressor map.

Several people, including Dave Leonard and John Slade have had stock turbos in the 13B.. with AND without modification, that were unable to meet that task. I think John used two stock and one clipped/modified stock turbo and all failed.

Get a big turbo, with a big ratio, greater than 1. I will have to research the archives, but we hashed out how much airflow was needed, and I think John Slade has had fair experience with his current turbo.. a new device that was matched to his needs. You will be flowing up to 50% more airflow mass, so you need to plan accordingly. Do not count on a stock turbo to be able to maintain what you need for hours on end with the engine running at 75% or greater power.

Dave