Building Surface Tension

[silverghost]

If we can get the SS 2.5 to work several challenges will be solved and several more presented. The weight of the powerhead will be 5" lower and that should help a LOT with stability. The mid range acceleration should be VERY impressive as compared to the Promax option. Better hold on to that wheel tight These motors also came standard with the Offshore midsection to let the hamsters sing. Sounds kinda like a ..............

On the downside you must use high test gas and these motors require rebuild at 200 hours max as compared to the Promax at 600 hours. This is what you get if you want to run 8200RPM versus 6500. Overall, the 2.5 EFI is a great, albeit touchy, little powerhouse. I'm looking forward to getting back at it provided my cajones are still there and my insurance riders are all updated LOL.

You had wondred why I have never been a big outboard fan~~~
When I look at the 200 & 600 hour rebuild times you mention above it just scares me away from using any high-peformance outboard.
Heck I put about 150 hours on my Cevy BB 454 Ho MK IV in my skiboat almost each and every season since I owned it since new .
I now have 1500 hours on this original engine and it's still going strong. It is quite quiet with great oil pressure & like new compression.
Now all those hours were NOT high speed hours.
BUT~~~
No high-performance outboard would last that long the way I would run it .

[silverghost]

You had wondred why I have never been a big outboard fan~~~
When I look at the 200 & 600 hour rebuild times you mention above it just scares me away from using any high-peformance outboard.
Heck I put about 150 hours on my Cevy BB 454 Ho MK IV in my skiboat almost each and every season since I owned it since new .
I now have 1500 hours on this original engine and it's still going strong. It is quite quiet with great oil pressure & like new compression.
Now all those hours were NOT high speed hours.
BUT~~~
No high-performance outboard would last that long the way I would run it .

Greg:
What is the typical required re-build time on a non high-performance outboard in hours ?
I assume the newer four strokes are better than the older two strokes.

In it's early life my ski-boat was only used 10-20 hours a year for the first ten years or so.
Since then about 150 hours per year.
I was running my BB TRS Formula 27 as well as several other boats at this time period each year.
I once had four power boats in the water every season, all season long, in those days, The Formula 27, American Skier 24' Eagle ,
Several old Mahogany Classics, along with two PWCs & a lightning & a star sailboat I used to race offshore.

[Tidbart]

Greg,

I finished your tank calcs. Actually, they were done some time ago and I just never got back to them to double check my figures.

From my calcs, you have 59.45g. tank. This is derived from the drawing that you sent me. Although, that drawing said 51g. at the top. This is also, not corrected for the volume of alum used for the tank. I use the OD's.

Attached is an illustration of the error that a float sender or even a non-corrected centroid would give you with that tank. Due to the odd shape of the tank, a float sender would be accurate at 3 points, instead of the normal 2. The flat line would be a corrected sender.

Now, obviously, this is a one-off. So, it is a bit more expensive. I will PM you a quote.

Bob

[Tidbart]

Good talking with you Greg.

I will wait for you updated print of the tank and re-do the calcs.

B

[Greg Guimond]

"Greg: What is the typical required re-build time on a non high-performance outboard in hours? I assume the newer four strokes are better than the older two strokes?"


silverghost, It's tough to compare any OB to a well maintained 454 package for useful hours but the ETECs have been logging 1000 hours with no problem and the Yamaha Ox66 250's would do more but neither are as fun as the high strung 2.5 Merc stuff. Some think the 2.5 was the best consumer/race motor that Merc ever built. The calcs say I will need 9HP for each 1MPH gained so there you go.

I've never seen a 2.5 mounted on a 16 Baby so I'd suspect it will be "interesting". May not end up being useful but certainly interesting.

[Greg Guimond]

Bob, nice talking with you. I will get a precise set of measurements for the tank, as we now actually have it in hand. Here is a pic of the tank, are these the dimensions you would need?

[Tidbart]

Bob, nice talking with you. I will get a precise set of measurements for the tank, as we now actually have it in hand. Here is a pic of the tank, are these the dimensions you would need?

Looks great Greg. Ignore what I said about the vent and fill, I thought they were on the lower portion.

B

[Greg Guimond]

Should have the full dimensions for the fuel tank tomorrow.......

[Greg Guimond]

Here is another picture of the tank along with the needed dimensions. As you can see it rises a bit from rear to front in terms of total height.

[Tidbart]

Here is another picture of the tank along with the needed dimensions. As you can see it rises a bit from rear to front in terms of total height.

Greg,

I need the dimensions of the other end of the tank. Without them, I have having a hard time visualizing the tank.

Bob

[Tidbart]

Also,

I'll need the depth of tank, inside dimension, at the sender mounting point.

B

[Greg Guimond]

Bob,
The tank is 22" wide for the entire 68" length. I will get you what you asked for shown in red in the pic as I, II, and III with II being sticking the tape inside the tank to get the exact height.
Thanks

[Tidbart]

Greg,

Do you have the A and B dimensions swapped?

I know there is an angle on the photo, but my eye says they are.

Bob

[Greg Guimond]

Optical illusion. Here is the new photo with what I owe you in red - I, II, III

[Tidbart]

III = 8x22 with 11" bottom and 5" sides. I have all of that end's dimensions.
I >> End height is 9, width is 22, need any other dimensions from that end, unless it is a rectangle??
II, yes, need depth.

Bob