Was testing this weekend with the turbine engines and one Mercury M8 drive on test stands (counter rotating). I only tested the counter rotating drive and it seemed warm to the touch after running appox 30 minutes. Using infrared temp gun I read about 150F degrees. Not warm enough to burn your hand but warm enough to raise an eyebrow to ask if this is normal. I asked a Mercury rep in Key West because i had noticed this when running them in a previous test but he didnt know many specifics when it comes to drive temps. Anyone have any knowledge of acceptable temp parameters?

I know on my Weismann's when running on the hose out of the water they were hot enough after 5-10 minutes in gear that you couldnt even touch them. The water flowing past them in the water has a huge cooling effect vs out of the water.

yes that seems normal especially outside the water.
keep in mind that if your n2 at idle is running at 60-70 percent no load out of a 1.1scs crashbox that is roughly 4500 rpm going into the m8 input shaft.
my sixes on the trailer you could barely touch after running 10 min.
hope that helps!

Good to hear that. Ive got my Idle down to the bare minimum according to the manual at 50-51% and N2 is rotating around 3250rpm and when I shift to be in forward or reverse im getting N2 down to about 2850-2900 rpm. So the drag of the crash box and drives are enough to scrub off a few hundred rpm. How much does the prop in the water reduce your idle rpm in gear while you are in the water ? Im a little concerned the props wont pull the engines idle rpm down much more and ill give anybody around a shower while taking off from a docks... Ive heard quite a bit about your setup and it looks like you have done a great job setting it up.

are you running t53s? If so we normally wire the N2 quadrant wide open and throttle N1. What are your ratios in the m8s and what propeller pitch are you running?
my guess when u put it in the water its gonna pull that rpm way down.
when i ran ssm sixes i had a 1.35 ratio which with a 37 pitch propeller turns around 800 rpm in the water. Both drives in forward gear.
Note : The scs gearbox has a reduction only in reverse.

Not T53's, I am using Turbomeca Turmo C6 engines. I am throttling N1 as well.. N2 is free to rotate using the gas generator. I have 1.40 gears in the M8 and i have a set of 17.5X 40 six blade herrings

oh i found you! your running Turbomeca s that run on French cognac
So what is the final reduction rpm at full power?
The T53 is reduced to 6600rpm at 105percent n2

thats gonna be so sick!!!
Hot shaft engine which makes exhaust away from soft tissue!
its a free turbine obviously you can stop n2.
back to t53 at ground idle the t53 produces roughly 25-25 hp so when your idling around the docks
n2 is barley spinning with n1 at or around 50pecent in gear.
in neutral it will go up and hang around n1 at like 50-60 percent. with the reduction that's around 3300-4000 rpm.
i look forward to the seeing this !!!

Yes! Final reduction for N2 @100% is 6300 in the turbomeca. Ive read the heli had an emergency mode at 125% for 5 min max but I dont plan on testing that right from the start. The power graph in the manual for the turbomeca shows around 93hp at 50%. And it seems like it does have quite a bit of low end torque. finding the right brake setup was a challenge but i think i am close now. I wonder what makes the engines so different in output shaft power at idle? both are two stage power turbines... That why im a little concerned the water might not pull them down as much as the t53 around the docks. Might be a good water show though. Ill tell you one thing different for sure is the sound of the turbomeca is deafening. if you are within 100ft of the intake you will need hearing protection. its ungodly loud!

I partnered up with Raymarine to put a full auto pilot system in the boat that uses their flir cameras and augmented reality to race next year in Ocean Cup series. They are the major sponsor for the team and we will be testing all their latest equipment in the boat, This boat will be closer to an attack helicopter than a race boat before its ready next spring. I am super excited!