Run in stand/dyno build.

[Terry Keeley]

Terry, do you monitor the head temperature on all dyno pulls? Wondering what it was when it was surging.

The s/w cut off the run past 20K prolly since it's messed up, maybe because of how I stopped it. Anyway here's the actual rpm plot of the first run:

CHT is too slow to pick it up but the EGT shows it, the cut off graph at 20K shows the first dip, EGT dropped from 742 to 689:

Marty was right about getting the fastest thermocouples you could find, thanks to Mike Rappold for putting me on to them. I got another thermocouple that came with an Eagle Tree module I bought, it would have never picked this up.

 

[Steve White]

I've seen it discussed before on a few threads. Optimal CHT depends upon lots of things, and of course is within a range that is dependent upon the same myriad of factors.

In the early days of piped OPS 60's was the first inkling of CHT and how it affected performance - for me. I'm probably going to setup to monitor CHT in the next nitro build. Up until then, just put a water pickup on it and maximum flow.

When the engines were over-cooled, the boat would just quit out of the blue - just stall, like the day the earth stood still. Then, warming things up came the monster performance and of course a few wasted piston/sleeve sets when it transitioned to the high side of optimal.

The drop off is something that I find very interesting. Actually, this whole thread has been real interesting - very nice of you to take the time to document and share the journey.

Another aspect that doesn't get much attention is oil. Not just the lubricating properties, but the performance. How much oil and what type. One thing I figure is the oil solution will have an effect upon exhaust gas density - it has to. Which in turn, affects the pipe. HIgh nitro pipes have a larger internal volume, due to exhaust gas volume, not sure about nitro and exhaust gas density. EGT is also a factor in the pipe performance.

There's a lot will be able to do with that little jewel.

 

[Terry Keeley]

Adding to that I don't think we burn our expensive fuel very efficiently, I've tried 80% in the boat but don't get any real increase over 60%.

I've seen magic happen over the years that guys used to call "double staging" and recently I've seen it with my Eagle Tree. The thing will hit the pipe and go to 21K or so then all of a sudden the rpm will jump to 24K+, of course the speed follows. It was thought this was caused by the waves in the pipe ganging up (and it might be) but I'm starting to think that when things are "right" the fuel is just burned more efficiently and completely before the exhaust port opens.

I think EGT will be a big part of the equation, I know drag racers use it quite a bit to tell what's going on in each cylinder.

 

[Steve White]

I've both had outriggers and witnessed others like Stu Barr's Crapshooters come out of the turn hard and climb the hill pulling all the way down the straights. Those are the select few, then there are the others that run well but seem to plateau in terms of RPM.

I know hull setup is a big part of that equation, but it's also getting the right tune in the engine setup. When the combination is right they really scream. That's what the vent or stinger does for the pipe, keeps the pressure optimal so as the RPM climbs the pressure climbs and wave speeds up. EGT & EGD will also play a factor - oil has to have an effect on the Exhaust Gas Density or EGD.

The drag guys, in addition to getting AF right, they have to watch the distribution balance between the cylinders. Austin Coil did a lot of research and development there and moved the positioning of the blower (set back blower manifold) on the intake manifold for a more balanced air flow distribution.

 

[Terry Keeley]

Finally tore the old mule down and saw it was beat up pretty bad. Rod needles were worn 1/2 thou, top bushing had 0.002" slop, bearings were toast after just a few gallons. Re-bushed the rod, put in new needles and some ceramic crank bearings.

Decided to soften the mount up a bit and my Consigliere came through again. He had some urethane they use for machine mounts that worked great, plus again provided much consultation work. It's still very stiff but I'm hoping it'll give just enough to stop beating itself up.

I'm going to try to test a bunch of glow plugs tomorrow.

 

[Steve White]

It didn't sound happy in the solid mount. Nicely engineered. Enough mass for some damping, and decoupling isolation as well. Bet it sounds different now.

 

[Terry Keeley]

It didn't sound happy in the solid mount. Nicely engineered. Enough mass for some damping, and decoupling isolation as well. Bet it sounds different now.

Ya, that's the main reason why I video the runs, you can see and hear things you don't pick up on right away.

It's always had that metal on metal clanging sound, thought it was the hard u-joint but it's still there after switching to the rubber FSR coupling. We'll soon see.

ps: engineering is all my Consigliere's, he just used this system to mount his homemade 4 cylinder in a boat.

 

[Steve White]

^^^ That's my main gripe with many of today's isolation type engine mounts. Not enough mass on the engine side to dampen much if at all. The engines almost have to be beating themselves to death.

What you have is likely in the middle, or nearing the sweet spot between not enough and too much or rigid.

I would have never thought getting a dyno dialed in would be this complex an undertaking. You're writing chapters into the book of knowledge just getting to an initial baseline setup. Which can be bit frustrating, but it will be invaluable over the long haul.

Can't wait to see the next run video and compare the sound. Who knows there could be other things affected as well.

 

[Terry Keeley]

Motor sounds completely different, no more "clanking" sound, much smoother too. I smoked the rubber coupling about 17K but it hung in so I kept going.

I'm starting to get used to the s/w and learned you havta let it run well past the peak to get good data, otherwise the curves just drop off sharply.

Something in the clutch can felt crunchy so I stopped, dumbass didn't leave any end play for the clutch bearings.

Not sure if the increase is due to letting it run on or the new bearings and rod bushing, or a little of both.

Looks like the new one-way bearing is starting to slip, I'll probably need those stronger springs after all...

 

[LohringMiller]

That's a nice improvement, especially at the higher rpms. Is it due to the ceramic bearings?

Lohring Miller

 

[Marty Davis]

I tried the FSR coupling with the needle bearing and it slipped the same.

I got my Consigliere to have a look at one of the sprag type bearings and the rpm graphs and he came up with a great idea. What if you put in stronger springs so the sprags stayed hooked up better? He also had the idea to use a bit of rubber o ring to test it. His consulting fee just went up a bunch (again).

It did slip on a few earlier runs but it was better after I leaned the needle a little and the motor smoothed out, night and day tho from other runs with the stock springs. I'm going to order some proper springs and hopefully they'll hold.

Here's an rpm plot of run D with a little slippage:

Closeup at 15K:

Here's a smooth run (F):

Anyway I'm going in the right direction I think. When they said these types of dynos were consistent they weren't kidding. I got three runs within 0.08 HP of each other with virtually the same torque.

All three together, EGT & CHT are identical:

Terry:

Why is is taking so long to do a run on your dyno? Brian Callahan sized our inertia wheels so that the run was the same as the time it took to make a saw pass "on the course" making laps. Seems that that would more accurately simulate our use.

 

[Marty Davis]

Adding to that I don't think we burn our expensive fuel very efficiently, I've tried 80% in the boat but don't get any real increase over 60%.

I've seen magic happen over the years that guys used to call "double staging" and recently I've seen it with my Eagle Tree. The thing will hit the pipe and go to 21K or so then all of a sudden the rpm will jump to 24K+, of course the speed follows. It was thought this was caused by the waves in the pipe ganging up (and it might be) but I'm starting to think that when things are "right" the fuel is just burned more efficiently and completely before the exhaust port opens.

I think EGT will be a big part of the equation, I know drag racers use it quite a bit to tell what's going on in each cylinder.

Terry:

I think this is an area that needs explored as the change in Nitro from 60% to 80% SHOULD create a ton more HP. We need find a way to get that extra HP.

 

[Marty Davis]

Terry:

Not sure why my post on the video didn't take. Anyway, why is it taking so long for a dyno run to complete. The nice thing about an inertial dyno is that you can simulate the time it takes for your boat to run a straightaway when driving on the course. Sizing the inertia wheel for your SAW runs would be slightly different. That is one of the really nice things about an inertial dyno, you can simulate exactly how you use your model.

 

[Terry Keeley]

That's a nice improvement, especially at the higher rpms. Is it due to the ceramic bearings?
Lohring Miller

Hard to say, I wouldn't doubt that a good part of it is due to the new bearings plus rod bushing. Don't know if some might be due to the new motor mount too? Could be that I just let this run go a little further?

As you can tell I'm trying to nail down as many variables as possible so I get good, consistent data. I even got a little flow meter and thermometer for the cooling system so it's consistent from run to run. I'm seeing the needle has a huge effect on output too and am still trying to find the best setting for this combination. So many variables...

Here's the best run from last time with the same conditions:

Terry:
Why is is taking so long to do a run on your dyno? Brian Callahan sized our inertia wheels so that the run was the same as the time it took to make a saw pass "on the course" making laps. Seems that that would more accurately simulate our use.

Ya, I keep hearing this, lol. I don't think I want to replicate exactly what happens on the water, I want to measure torque then calculate horsepower. Then I should tune the motor using the information to best suit what I'm trying to do with the boat. ie: running a light hydro, heavy mono, SAW, heat racing etc.

I might cut the wheel down some more but not until I get a hopped up 90 on there, that might give 10 hp and a run time of only 10 sec. The way I made the wheel with built in shafts takes a ton of machine time (plus off for balancing) and I don't want to do that again any time soon. The only drawback I see to these long runs is more wear and tear on the motor.

Terry:
I think this is an area that needs explored as the change in Nitro from 60% to 80% SHOULD create a ton more HP. We need find a way to get that extra HP.

Agreed 100%. Bigger carb, higher nitro and burning it more efficiently should get some good results.

There's so many variables with just (mostly) stock parts, finding the best combination of them has got to yield results.

 

[Marty Davis]

Hard to say, I wouldn't doubt that a good part of it is due to the new bearings plus rod bushing. Don't know if some might be due to the new motor mount too? Could be that I just let this run go a little further? (25K)

As you can tell I'm trying to nail down as many variables as possible so I get good, consistent data. I even got a little flow meter and thermometer for the cooling system so it's consistent from run to run. I'm seeing the needle has a huge effect on output too and am still trying to find the best setting for this combination. So many variables...

Here's the best run from last time with the same conditions:

Ya, I keep hearing this, lol. I don't think the purpose of an inertia dyno is to replicate exactly what happens in the boat. I think it's to measure torque by accelerating a known mass and then calculating horsepower. What you should then do is tune the engine using that information to best suit your needs depending on the boat, whether you're running a light hydro, heavy mono, running for records, heat racing etc.

I might cut the wheel down some more but not until I get a hopped up 90 motor on there, that might give 10 hp and a run time of only 10 sec. The way I made the wheel with built in shafts takes a ton of machine time and I don't want to do that again any time soon. The only drawback I see to these long runs doing is more wear and tear on the motor.




Agreed 100%. Bigger carb, higher nitro and burning it more efficiently should get some results.

There's so many variables with just (mostly) stock parts, finding the best combination of them has got to yield results.

Terry:

"I don't think the purpose of an inertia dyno is to replicate exactly what happens in the boat." I guess it is up to the individual who owns the dyno then. A load dyno would then be a better choice but much more complicated. Not sure why you wouldn't try to simulate your on water running???

As for the use of the nitro, I think it is much more complicated that that. Try to light an ash tray of straight Nitro. It won't light..... The nitro drag guys have to use twin plugs, twin mags, etc and still have trouble keeping it lit. I suspect that it will take an additive of some sort. We have worked in that area but haven't figured it out completely.

 

[Marty Davis]

Terry:

"I don't think the purpose of an inertia dyno is to replicate exactly what happens in the boat." I guess it is up to the individual who owns the dyno then. A load dyno would then be a better choice but much more complicated. Not sure why you wouldn't try to simulate your on water running???

"The only drawback I see to these long runs doing is more wear and tear on the motor." Actually I bet that there is less wear and tear with a 3 second run.

As for the use of the nitro, I think it is much more complicated that that. Try to light an ash tray of straight Nitro. It won't light..... The nitro drag guys have to use twin plugs, twin mags, etc and still have trouble keeping it lit. I suspect that it will take an additive of some sort. We have worked in that area but haven't figured it out completely.

 

[Terry Keeley]

Terry:

"I don't think the purpose of an inertia dyno is to replicate exactly what happens in the boat." I guess it is up to the individual who owns the dyno then. A load dyno would then be a better choice but much more complicated. Not sure why you wouldn't try to simulate your on water running???

As for the use of the nitro, I think it is much more complicated that that. Try to light an ash tray of straight Nitro. It won't light..... The nitro drag guys have to use twin plugs, twin mags, etc and still have trouble keeping it lit. I suspect that it will take an additive of some sort. We have worked in that area but haven't figured it out completely.

Ya, I just don't see how the two equate. An inertia dyno does the same job as an absorber dyno ( water brake, eddy current etc.) but just in a different way, no?

For instance how would I simulate what happens in heat racing? I want good acceleration from a mill, a strong pull through the corners and good top speed down the straight. What does the wheel look like to simulate that? On the other hand I could look at the curves and tune the motor to give me those traits, no? Probably a good long torque curve?

What about a SAW run? I see about 5 sec. in testing from WOT to shutdown. Do I want a wheel that only runs for 5 sec? Or do I want to again look at the curves and tune the motor for good acceleration and a high peak hp?

For sure on the nitro. I've tried running 80% with 5% prope, 3% alcohol and 12% oil and didn't see much if anything over 60%. I think the head temp, plug type and needle all have a big hand in how it works. Danny King might be on the right path with multiple plug heads?

Again, so many variables, trying to nail some of them down is why I built this thing...

 

[Steve White]

Sounds smoother even at idle. Now it's engine run noise and not the metallic shudder.

Terry:

"I don't think the purpose of an inertia dyno is to replicate exactly what happens in the boat." I guess it is up to the individual who owns the dyno then. A load dyno would then be a better choice but much more complicated. Not sure why you wouldn't try to simulate your on water running???

As for the use of the nitro, I think it is much more complicated that that. Try to light an ash tray of straight Nitro. It won't light..... The nitro drag guys have to use twin plugs, twin mags, etc and still have trouble keeping it lit. I suspect that it will take an additive of some sort. We have worked in that area but haven't figured it out completely.

The NHRA guys are running 60 lbs of manifold boost which makes it much more difficult to jump a spark in the cylinder. That being stated, our little two strokes with tuned exhaust probably get some decent boost in dynamic compression ratio as well.

It would be interesting to do some testing for sure.

 

[Wasted wages]

An inertia dyno does the same job as an absorber dyno ( water brake, eddy current etc.) but just in a different way, no?


Renault F1 engines are dynoed with data loaded in from different tracks.. including up and downshifts ... I wonder if they are using some type of hydraulic coupling to be able to vary the load ??

Turn up your speakers and enjoy !!

 

[dwilfong]

Eddy current Dyno with a load cell on the eng cradle.
The load cell gives you the torque # then a sensor for RPM is all you need to do the calculations.
Also a hydraulic pump with a shut down valve and a flow meter and a pressure gauge will give you the same calculations for HP.
Horsepower = Pressure (PSIG) x Flow (GPM)/ 1714