De-Rate, De-Prop or De-Throttle Detroit

They are 3 blade - and I might ask the prop shop if they have a line on some spare props - good shout on spares.

Honestly, I wouldn't keep stressing the engines. That's a meaningful overprop.

Can you get the no load RPM to equal out on both engines. Not sure which is port and stbd but at load you are down 100 rpm which is the same difference as the no load max RPM. I don't expect this to change the smoke problem but will even the load at at loaded max rpm. Would love the see the data you collected.

No load we get 2550 and 2650. To be fair, I would bet my tach's might be off a bit. I do have the data prior to having the props dialed up to 24x27/28 (current tune). Any idea how to attach a document w/out linking a URL? I can upload my previous data before we added the pitch back in,

I also reached out to Wilmington Props yesterday. Gary is a man of his word, and is going to remove an inch or so at no charge.

When you say the props are tuned to 27/28, are you saying one is 27 pitch and the other is 28? I would have though that someone would have put a digital tack on the engines to verify tach accuracy. IMHO 100 rpms is a lot.

Lol - nope they are pitched identical but around or close to 28. Probably should drop the 27/28 statement since it is confusing.

The problem is early loading of the Detroit engines and black smoke is caused by lack of turbo boost! the boost doesn't build up until about 1800 rpms. then the black smoke goes away. the black smoke is caused by too much fuel at the lower rpms and not enough air. it can be fixed but it wont be cheap.

replacing the turbos with units that build boost sooner with AR ration of .5 or .7 but you loose at higher power settings and may over boost at higher rpms. which will require waste gate controls to control over boost. go to a turbo shop and see what they recommend. Detroits are a war engine were never designed to run clean they were designed to be reliable. its a compromise.