Well it appears that I came to the right board to get the information that I need. You guys are great! From what I understand from waternwaves (I'm not the technical type, so please correct me if I misunderstood something) Evinrude etec 90 HP has enough power to pull a slalom skiier, is lighter weight and has computerized adjustment for altitude. (Although Moe doubts that this would work). Since the X is faster for motoring and the M is faster for sailing and the MacGregor warranty doesn't cover motors in excess of 60 HP (?), is the recommendation to get a used X with the 90 HP Anyone out there that has this set-up that could confirm this does work? How would I go about getting a demo?
Catigale - Thanks for the welcome! Don & I have a newer Jeep Grand Cherokee so power is not an issue. But pulling the old trailer we currently have, was terrible going no more than 45 MPH, not something that you' want to drive very far at all.
Thanks for all the help! Don is chomping at the bit to go ahead and order a 2005, but I am still not convinced. Are all the modifications on the 2005 really make it all that much better than prior years? Thanks, Elle
Ellen Bailey wrote:Evinrude etec 90 HP has enough power to pull a slalom skiier, is lighter weight and has computerized adjustment for altitude. (Although Moe doubts that this would work).
Let me clarify that for you. As you go up in altitude, the air your engine is breathing is thinner, so you're going to make less power. You can also lose additional power if the thinner air makes the air/fuel ratio richer (i.e. if the motor feeds the same amount of fuel for less oxygen). Most fuel injection systems can compensate for the lesser oxygen at higher altitude by feeding less fuel and keeping the air/fuel ratio where it should be, avoiding the "additional" loss. While the Tohatsu can't, the E-Tec can do this. However, less air and less fuel equals less power, and that's what you'll have with a naturally aspirated (not turbocharged) engine, regardless of the EFI system.
Ellen Bailey wrote:Since the X is faster for motoring
Hi Ellen.
People,
Is this true? I haven't seen any empirical to back this up; however, it stands to reason with the deeper V hull of the M. To date, what is the largest motor installed on an M and how fast will she go.
My '98X with Nissan 2stroke (Tohatsu) 50 had a top speed of about 19 knots lightly loaded with ballast dumped at about 6000 rpm. My '04M with Suzuki 70 has a top speed of about 18 knots with same load conditions, but it is only turning 5150 rpm. I believe I am a bit over propped.
BWY has a test sheet in their office showing the Suzi 70 achieving 24 mph at 6000 rpm. Prop. size and pitch not stated. I asked Todd if I should re-prop to less pitch, but he sez for most cruising the 13.5 X 13 is ideal, and the torquey Suzi is happy at those engine speeds.
The most noticeable difference between my boats at top speed is the M with the Suzi is much quieter, with more torque, with less vibration, and much more comfortable in the waves, being able to cut through them better than the X boat. I suspect an X with a modern engine would be a lot more comfortable than mine was.
In reality we tend ot cruise in the 10-15 knot range unless in a nasty sea state so top speed is interesting, but not very important. How does she feel at your normal cruising speeds is more important.
I can easily tow both of my two kids (6&7) on a ski tube with my honda 50. Now I don't think there is a chance in hades that my mac could pull me out of the water at 215lbs.
Moe,
Good point in trying to explain the effects of pressure altitude.
But I would like to add,,
This is another point where specsmanship is rampant....
dynos, and standardization , not everyone tests their engines for sea level standard temp and pressure....29.92 inches and 77 deg. f.
In fact, american outboard manufacturers are the only ones I know of that rate their power heads on the water (with the corresponding effects of humidity/slight tho it may be ) already incorporated into the curves.
Honda and Yamaha both preferring to do brake horspoower measurements in the lab, on a fixed dyno.
For and engine speced in the lab, and assumming a perfect stochiometric mixture ratio for maximum prefomance (disregarding artificial temperature increase techiques to obtain more energy from the mix with timing and mulitple spark firings, sources etc..)then there would be a theoretical decrease in available air for combustion of approximately 23%, based only on pressure altitude difference. resulting in approximately 70 hp at 7,000 standard pressure. ( a 20 hp decrease)
But the an engine optimized and designed for 90 hp at 2,000 ft of pressure altitude, results in a decrease of 15 hp.
Furthermore.....depending on the measurement device....as you note, making peak horsepower/ vs. peak torque is still going to be a matter of experimentation..., and without supercharging 90hp will not be obtained..
You are also right , that I should have noted Rolfs top speeds were at sea level.... I was remiss.
I should have also noted that improving airflow to outboards is the single greatest improvement in performance at altitude.
In my attempt to espouse the advantages of altitude compensation, I assumed that others were familiar with density altitude effects, other than mixture control.
All in all, a compensated 90 will deliver 10 to 20 more horsepower at a 7,000 ft altitude than a non compensated engine. Hence the reason I discussed the carbed version.....The DF Nissans (carbed) could be jetted for high altitude
Many years ago in the 70's .....when I had my 1972 VW van... 1.7 liter.. I experienced this first hand on a trip from seattle to durango colorado.. After and engine tune up and rejetting of carbs, and my poor old overloaded van which I swore was a beast and incredibly underpowered, actually ran better and better the closer and higher and colder I got to the continental divide.....
Till finally I was cruising up those mountain passes at 70 -75 on stretches of road that I was lucky to make 45 to 50 in the summer... Leaned out the jets on those dellortos a little too much for my native seattle I think......lol. The pressure altitiude effects mitigated by the density altitude of the cold day slightly.....lol
All in all....a true 75 hp ( obtained from a 90 hp rated and compensated engine) delivered on the propshaft ( transom) of a lightly loaded X should hit 25-26 and hold her up. if it is tuned well.....and assuming it is not 95 degree air on the lake surface.....
JMHO
Last edited by waternwaves on Wed May 18, 2005 10:40 am, edited 1 time in total.
Wow hold on here, First off I cant even breath at 7000 feet and that water has to be very cold. I wouldnt even stick my feet in it, let alone ski.
I cant see putting out that much exertion, your lungs must be huge compared to mine. Forget the outboard breathing how do you do it.
Look buy a ski boat even my boston whaler at 13 feet with a small prop and 50 hp will not pull me up on a single ski at sea level. Now if I start with two and drop one it works fine. There is no law says you cant own two boats.
aya16 said: Wow hold on here, First off I cant even breath at 7000 feet and that water has to be very cold. I wouldnt even stick my feet in it, let alone ski.
I cant see putting out that much exertion, your lungs must be huge compared to mine. Forget the outboard breathing how do you do it.
I'm originally from Michigan and we start skiing as soon as the ice breaks there. LOL In Colorado, the lakes are from mountain snow melt so yes it is cold, use a wet suit in the early season. But summers are hot and it feels great to get in & great to get up. Used to be able to ski much longer in the flatlands 20 or more miles, but now I do have to drop and catch my breath after 10, hiking in the mountains builds up the lungs, but you have to get used to it. Ellen
Just ordered our 2005 26M from the Anchorage today. Looks like we are going with the Evinrude E-tec 90. If it pulls me up, great! If it don't - I'll hitch a tow with some of our friends that have ski boats. I like to kneeboard but I could learn how to wakeboard. Thanks again for all the great info you guys! Catch ya later. Ellen
Real time experience with our 40 horse is my daughters have ski'd behind the boat at 90 # 100# and 115#, I have wakeboaded but not enough ponies to do anything but go straight.
I hate to rehash this but Im of the opinion that the mac transom isnt meant for the thrashing providied by a super huge motor. There is many threads discussing this and if my recolection is up to par, the owners with the 70-80+ hp blenders are always discussing the transom beef up mods.
Ellen,
We have a 26M. We've sailed at Granby, Pueblo and Chatfield. The 50 hp injected Tohatsu did not work well at all at those altitudes. We switched to a 40hp carburated Tohatsu. We've been working with Fred at "The Boat Shop" in Commerce City on getting the proper prop. The one we started with would only let the motor get to 4200. He set us up with a different prop that now gets us to 5200 on Chatfield. Unfortunately I didn't have my GPS so I don't know how fast we were going. With the old prop we were hitting 14 mph. I don't know much about the X so I can't comment on speed comparisons.
We tow ours with a Suburban no problem. Haven't tried towing with anything else. We have surge brakes on the trailer.
You're welcome to come see our boat if you like. It's in our driveway here in Evergreen now and we'll be slipping at Granby in a week or two. I was thinking about racing on Chatfield in the Luekemia Regatta this weekend but I'm not sure now. My wife broke her finger due to an ornery horse and won't be able to crew.
Actually just $1,000 deposit to order, $30K+ upon delivery (gulp!). I was thinking that I might not be able to get up on a slalom even with 90HP but I bet I could get up on two and drop one.
Can you tell me the name of the thread that speaks to modifications to the transom for the higher HP motor, any other modifications needed besides a proper prop? Any prop recommendations?
I have a Suzuki 115hp on my 96X. The transom cracked when the motor hit a rock. Here are some photos. Pictures 12, 13, 14 and 15 show how Billy with his 140 Suzuki reinforced his transom. Picture 16 shows a stiff sharp edged reinforcement I originally had improperly installed. Installing this piece was probably a major factor in my transom damage. Pictures 6 and 7 show how my transom is reinforced now. Picture 6 shows a fiberglass reinforcing knee inside the transom. I have two of them. These knees are made of a closely celled light composite material covered with fiberglass and are exceptionally strong.
Anyone out there that has this set-up that could confirm this does work? How would I go about getting a demo? 
Ellen
