How long do you hold WOT on your 787? Discussion with temperature data included.

[Krispy]

I know you looked at it some, but Exhaust gas is the way to go on most two strokes. They get the temp spikes fast enough to potentially save the motor. But it would take some machining to get one in. Not sure if there are any non-water jacketed areas around the head pipe that can be tapped for a fitting.

As far as the garmin mount, is that garmin waterproof? I would be afraid of it getting splashed.

I would say the garmin is "highly water resistant" . The 60CSx is rated to IPX-7 standards which means it can withstand immersion in 1 meter of water for up to 30 minutes. My bigger fear is losing the gps from the mount and it not floating but I can get around that.

As for EGT, I agree, it would be good for tuning purposes of a mod ski, but I am just looking for a bit of extra data, just to figure out if I have a cooling problem etc.

As the season wears on and the water eventually gets cooler I will be interested to know how the water temp changes the temp reading at the head.

I guess the basic consensus is to ride WOT as long as I can hold on and I should be fine.

 

[Matt Braley]

If your ski is bone stock with no issues then you are fine holding it WOT until your fuel runs dry.

EGT's are the way to go. I bolt anything and everything even potentially cool on my skis and would have burned up many a piston without watching it closely.

I have the GPS speedo and it's nice but loves to get wet and bead up under the glass then stop working till it dries out.

 

[Spimothy Leary]

Is that a RAM mount? I am looking at options like this for my Garmin 60CSX and RAM makes a pretty nice mount from what i hear.

yes, dual ram mounts installed on my ski one for GPS one for phone and gopro, to sum them up, they are the bomb ! Mount very securely, extremely easy to interchange units on top, and its not going anywhere. I did some shopping around and gpscity seemed to have the best selection and prices with free shipping on $50 or more. you can get a holder that is specific for your gps unit, which is what I did, along with phone holders, gopro adapters, etc. I would not hesitate to visit the website and/or make a phone call to make sure you get what you want. I have mounts specif for both models of GPS's that I own, and it was worth the investment IMO.

 

[SabrToothSqrl]

http://teespring.com/thanks01?i=PPE

i meant

http://www.waterskis.com/precision-p/mastercraft_gps_speedometer.htm

what size is the factory gauge? 3"? metric?

I'd just as soon have a factory look to it, with a GPS speedo in there... I don't care if it's a few MPH off, I care because I've spent nearly $200 getting it to work, and it DOESN'T....

I hope these 'boat' gauges are water proof enough... my ski often is upside down or on it's side... and i mean often.

 

[Krispy]

yes, dual ram mounts installed on my ski one for GPS one for phone and gopro, to sum them up, they are the bomb ! Mount very securely, extremely easy to interchange units on top, and its not going anywhere. I did some shopping around and gpscity seemed to have the best selection and prices with free shipping on $50 or more. you can get a holder that is specific for your gps unit, which is what I did, along with phone holders, gopro adapters, etc. I would not hesitate to visit the website and/or make a phone call to make sure you get what you want. I have mounts specif for both models of GPS's that I own, and it was worth the investment IMO.

I use a RAM mount for my phone in my truck, and i am very pleased with it. I just picked up a GPS specific mount and a mount to adapt my gopro. Thanks for the tip.

 

[Sportster-2001-951C-Stock]

Since you're already measuring water temp, I think I would hang a sensor on the outlet and measure that.

 

[Krispy]

Since you're already measuring water temp, I think I would hang a sensor on the outlet and measure that.

So I am measuring engine head to sparkplug interface temp, not water temp.

I decided not to measure water temp as it would vary greatly from day to day depending on the inlet water temp.

I read where someone installed a water outlet temp measure and they only saw a delta t of 8 degrees max. I was trying to avoid that if possible.

 

[Kallibrated]

I'm not overly experienced with skis, but I build turbo cars for a living. Considering the amount of 'coolant' you have at your disposal on the water, I think temps would be the last thing I would worry about on the water. One reason I want to build a turbo jet ski is because of the ability to exchange an infinant amount of heat in the water which is a huge concern on turbo engines.

 

[Krispy]

I'm not overly experienced with skis, but I build turbo cars for a living. Considering the amount of 'coolant' you have at your disposal on the water, I think temps would be the last thing I would worry about on the water. One reason I want to build a turbo jet ski is because of the ability to exchange an infinant amount of heat in the water which is a huge concern on turbo engines.

Thanks for chiming in, my riding buddy has a factory turbo ski with a water to air intercooler, even with the unlimited cooling water it still heat-soaks, and pulls boost and timing, cutting rpm and speed due to knock.

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[Sportster-2001-951C-Stock]

So I am measuring engine head to sparkplug interface temp, not water temp.

I decided not to measure water temp as it would vary greatly from day to day depending on the inlet water temp.

I read where someone installed a water outlet temp measure and they only saw a delta t of 8 degrees max. I was trying to avoid that if possible.

Yep, I agree water temp isn't the only metric but this is how I judge the cooling system function on most boats, mostly by feeling the recirculating pump hose and exhaust manifold as a first check then if that's questionable placing my thermometer on the hot side of the thermostat.
Personally, I think a pressure sensor transducer on the plug or mounted in/on the head to detect pressure spikes would be kinda neat (to detect knock).

And the DI motor uses a knock sensor but I dunno if it's possible to work that out without some sophisticated harmonics experimentation and tuning the sensor circuit. That would probably take more effort than it's worth.

On the turbo ski seems like a super charger wouldn't need time to spool and such, I've worked a lot with roots blowers so I like them of course, b/c of my familiarity (stick with what you know and keep the blinders on, right?).

 

[Sportster-2001-951C-Stock]

Thanks for chiming in, my riding buddy has a factory turbo ski with a water to air intercooler, even with the unlimited cooling water it still heat-soaks, and pulls boost and timing, cutting rpm and speed due to knock.

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Maybethere's some room to tweek the cooling system by improving the flow? Then you can run into problems with having too much pressure for the gaskets and such springing leaks, so there are risks to be assessed.

It's often not easy to improve on factory setups, usually they already optimized to improve the weak points.

I'm waiting for someone to drop a Mazda or other Wankel motor in a ski?

 

[Krispy]

Maybethere's some room to tweek the cooling system by improving the flow? Then you can run into problems with having too much pressure for the gaskets and such springing leaks, so there are risks to be assessed.

It's often not easy to improve on factory setups, usually they already optimized to improve the weak points.

I'm waiting for someone to drop a Mazda or other Wankel motor in a ski?

http://www.youtube.com/watch?v=3aSBItXzMXg&sns=em

Check this guys videos. Rotary powered doo.

In the OEM world you only need to perform as good as needed, to meet performs and cost targets. I am sure there is some improvement to be had.

On the Honda we will be looking at the effect of higher octane blends and possibly more boost.

Who knows, ultimately I want a larger ski in addition to the xp, that I won't feel I am killing to make 50 mile runs at high load.





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[Spimothy Leary]

Thanks for chiming in, my riding buddy has a factory turbo ski with a water to air intercooler, even with the unlimited cooling water it still heat-soaks, and pulls boost and timing, cutting rpm and speed due to knock.

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I have the R12X, (same engine), although its very rare that I get slowed except during long pulls, and we don't do that often, if ever as I indicated above. you can upgrade the intercooler I believe. Actually, if you do some impeller mods, intercooler, macboost, you can make that r12x a very scary machine... I rode one heavily modded R12X and i'll admit, I noticed the difference.... it was like riding a modded X4 951, pulled dam hard.

I have kept mine stock since I only have 104 hours and I hope to have 200+ by February, so I didn't feel the need to push it. Its my loaner/cruiser ski, and I take it out on my long distance river runs due to fuel economy, which is friggen awesome... Most of our run's on this machine are long distance @ around 45 mph. When i want to go faster than 60 for more than a mile or two, I bring my other ski, which can cruise comfortably at 60 and still have plenty of throttle left.

So basically if I know we're going to cruise around 45-50 I bring the 60mph ski, if I think we're going to cruise at 60, i bring the 70mph ski. If we're going to cruise at 25mph, then I find the one other guy that looks frustrated and we break away at 60 and wait for the group of turtles to catch up 15 miles up river.

I don't see a practical reason to push the engine unnecessarily.

I am very much against long WOT runs, no matter what people say, It just can't possibly be good for it . I'm of the opinion that if you need to run more than a minute or two with the Throttle pegged, then you need a faster ski.

 

[Sportster-2001-951C-Stock]

I am very much against long WOT runs, no matter what people say, It just can't possibly be good for it . I'm of the opinion that if you need to run more than a minute or two with the Throttle pegged, then you need a faster ski.

I agree with this train of thought, seen plenty of boats make it nearly to one end of the lake or part way back WOT and not complete the journey home, LOL.

 

[Sportster-2001-951C-Stock]

In the OEM world you only need to perform as good as needed, to meet performs and cost targets. I am sure there is some improvement to be had.

Yes I've seen my share of improvements as well, often a can of worms.

 

[Sportster-2001-951C-Stock]

http://www.youtube.com/watch?v=3aSBItXzMXg&sns=em

Check this guys videos. Rotary powered doo.

In the OEM world you only need to perform as good as needed, to meet performs and cost targets. I am sure there is some improvement to be had.

On the Honda we will be looking at the effect of higher octane blends and possibly more boost.

Who knows, ultimately I want a larger ski in addition to the xp, that I won't feel I am killing to make 50 mile runs at high load.





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Here's a press release from 1973, these 4-rotor outboard motors were bumping 280hp but nothing was released b/c Honda's 4-stroker bikes caused a total ban of 2-stroker bikes in California and OMC didn't want that to happen to their current outboards (so goes the story).

 

[macedonia64]

Sort of an old thread but just thinking out loud sure the under the spark plug data is cool but if you had a temp Guage under the mag plug and pto plug. Wouldn't you then see some useful data regardless of the actual number? You could see if one cylinder is running hotter than the other.

 

[Krispy]

So the general accepted way to monitor differences between cylinders is exhaust gas temp measurement. For this purpose I just wanted an idea of how hard I was pushing the engine between bursts.

Don't feel bad about bumping the thread, I think it was a fun discussion.

 

[macedonia64]

Gotcha. But egt gages are $$!

 

[spx787]

I spent A LOT of my time at WOT until I realized how much damn gas my SPX drinks! Now I try to be content to just cruise around sometimes instead. That urge to punch it always get the best of me though!

 

[Sportster-2001-951C-Stock]

I spent A LOT of my time at WOT until I realized how much damn gas my SPX drinks! Now I try to be content to just cruise around sometimes instead. That urge to punch it always get the best of me though!

All that gasoline makes plenty of heat, too.

I think if gun to head I had to chose a single sensor it would be a strain gauge on the cylinder head for detecting detonation.

 

[eddie708]

i didnt know 787s did anything but WOT:reddevil:

i try not to keep my engine at any rpm for two long and the difference between 3/4 thottle and wide open is really only few mph anyway, not really worth the stress on the engine. Then again most of the time i am wave jumping or playing around not flying across the water at wot, i mean thats the whole point in riding a x4 anyways.

 

[Krispy]

All that gasoline makes plenty of heat, too.

I think if gun to head I had to chose a single sensor it would be a strain gauge on the cylinder head for detecting detonation.

I didn't know anyone used a strain gauge for knock, microphone (accelerometer) yes, strain gauge, would have never guessed it.

Can you share more about this?


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[Sportster-2001-951C-Stock]

I didn't know anyone used a strain gauge for knock, microphone (accelerometer) yes, strain gauge, would have never guessed it.

Can you share more about this?


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I really don't know much about the application but it's my understanding OEM's use strain gauges during development for tuning and also developing their knock sensor circuits as well.

It's really not clear to me why they wouldn't actually place the strain gauge at the crank journals either, perhaps they can compensate for temp fluctuations and/or prefer to measure cylinder pressure directly.

What are the details, I couldn't really tell you b/c I don't know, perhaps EGT is more feasible for our purpose but I'd prefer to have a strain gauge somewhere if I could swing it.

Call me nuts!

 

[Matt Braley]

http://www.ebay.com/itm/Koso-Dual-E..._Watercraft_Parts&hash=item1c2ca6e234&vxp=mtr

I still run the old Racepak versions but this is a good option. I could never bolt on all the old aftermarket pipes, carbs and heads without monitoring temps. I would have burned up a bunch of engines but with this I've never even lost any compression.