Tohatsu 70hp Engine Swap

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Ormonddude
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Tohatsu 70hp Engine Swap

Post by Ormonddude »

Hi everyone, This is the follow up story to (the Good the Bad and the Ugly) I will try to load it with good information and tips so as not to waste anyone's time. First was to harvest the engine after removing my 40hp Yamaha now for previous installations and removals I used a come along attached to a eye screwed into a roof rafter this was simply to big a job and on rough terrain so I purchased a engine hoist on craigslist for $90.00 however if this is not a option they are available at Harborfreight for under $200.00 next I bought 2 pieces of standard 1/2" plywood so the hoist could roll and the plywood be step moved so I could manipulate the engines for the needed distances.
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With healthy doses of 5200 I commenced installation the bolt holes lined right up and large washers were used on the fiberglass contact sides again with healthy doses of 5200 Cut Large washers where used in the splash well (compliments of ugly it had a similar situation). The bear as always was the engine power cables however they did actually snap on to the Yamaha cable so I used electrical tape to secure the connection and also affixed the tachometer cable (with tape) and then used a dremel to ever so carefully cut a small slot in the cable opening making sure not to effect the the water lip so I/we (you need a really good friend for this part) could tuck the steering cable a bit out of the way into the slot and proceed to pull and run the large cable.
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With the engine installed and the cables ran next I needed to align the engine to the rudders (see picture) I had just broken a large tape measure as I am thinking about a new trailer next when I noticed the center line (smooth part) etched in the gelcoat, By aligning the center line to the rudder bolt to the engine bolt I was confident I was at least in tolerance (actually I detected no problem at all water testing) and moved on to the new helm now removing the old Yamaha throttle had left a large hole and it needed to be covered so Again poor ugly was called upon as I cut the patch from the only glass on it a generic helm cowl (the mac helm is sloped on both sides to make this look very good I folded a sheet of paper to match the contours and cover the hole then used it as a template) I then used a variation on Tkanzler's Mod http://www.macgregorsailors.com/modt/in ... ?view=1714 Thank you Tkanzler and re routed my old controls and the engines cables.
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and there ya go a fresh engine and helm. Um did I mention I sold ugly for $500.00 and that it had a inflatable tow behind toy worth about $100.00 I have yet to sell and I still need to sell the Yamaha first I am going to build a test stand you always get a couple hundred more if they can hear it run and test the compression. THANK YOU to Everyone that gave me ideas and encouragement and information for this Project especially Crabman and Tkanzler
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Ormonddude
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Re: Tohatsu 70hp Engine Swap

Post by Ormonddude »

Really I got nothing? I was expecting a few performance questions or at least a Good Luck LOL
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Tomfoolery
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Re: Tohatsu 70hp Engine Swap

Post by Tomfoolery »

:D

I like the look of the engine control. Mine's higher than the helm, but that's a personal choice, of course.

Nice being able to actually see where to put the key, and the lights, and to not be bumping the tilt/trim button by accident all the time, isn't it. :wink:

Is it in the water and running?
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Ormonddude
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Re: Tohatsu 70hp Engine Swap

Post by Ormonddude »

Yes its up and running and had some sea trials, I took her about 20miles down the ICW to the inlet and I was very impressed the boat has a cruise speed of about 14knots @ 4500rpm with full ballast I topped out at only about 17 knots WOT but honestly the prop feels wrong I have the 14x11 and I think it would be great for a Much heavier Load than i typically have on board but I am looking at a 13.75x13 on craigslist I think I should Pick up My WOT RPM was just under 6000 and the engine specs say 5850 Max so I would like to bring them down to around 5500 or so and get the 18 knots I am supposed to achieve. Gas consumption was actually better than the 40hp had at slower speeds but of course greater at higher speeds. The biggest noticeable difference was in handling when my :macx: truly achieved plane as compared to semi-plane it had at 7-8 knots the boats handling smoothed right out and it handled much more like a giant speed boat (a experience I had not had before) Now NOTE: It was extremely choppy that day and wind was extremely variable I think this explains the lower than expected top speed. The Ocean was almost a foolish maneuver on my part the swells were supposed to be 3' with 8 second intervals by the time I made the inlet it had built to 4-5' and choppy. Still She handled very well and was solid as a rock even when I did the turn to come back in after a very short time. Surfing in the inlet my speed would fluctuate from motor only of about 10 knots to 14 knots as I shot down the waves yelling "Cowabunga" Over all the upgrade has made me very happy and I would recommend it to anyone with a Mac.
vitger
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Re: Tohatsu 70hp Engine Swap

Post by vitger »

Great work! I have been toying with the idea of a similar upgrade from my 50 HP Tohatsu, mainly what bothers me is the exhaust fumes coming over into the cockpit nearly at all times. Annoying! Plus the kids would prolly enjoy tubing a lot more with a larger engine. I am keeping my eyes open for a 90HP E-tec....
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Seapup
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Re: Tohatsu 70hp Engine Swap

Post by Seapup »

Cool!

So how long until you are poking ebay for a 90hp ecm :evil: :evil: :evil:
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Ormonddude
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Re: Tohatsu 70hp Engine Swap

Post by Ormonddude »

No 90hp I am staying with BWY/Mac Suggested power - By the way to turn a 70hp to a 90hp you simply flash the computer chip after some research I learned people hack these engines all the time its just like adding larger carbs to a old Merc Instant power upgrade.
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Ormonddude
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Re: Tohatsu 70hp Engine Swap

Post by Ormonddude »

Update I sold the 96Yamaha C40 for $950.00 + $500.00 for the Ugly Boat. So I got my new engine for $175.00 plus gas for 300 miles
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Catigale
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Re: Tohatsu 70hp Engine Swap

Post by Catigale »

File this one under deal of the decade

:D :D :D
bahama bound
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Re: Tohatsu 70hp Engine Swap

Post by bahama bound »

have you run the boat yet ????? just curious about how it performed ??? curious about fuel consumption and speed ?
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Ormonddude
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Re: Tohatsu 70hp Engine Swap

Post by Ormonddude »

bahama bound wrote:have you run the boat yet ????? just curious about how it performed ??? curious about fuel consumption and speed ?
Yes but I just got a 14x12 stainless prop I need to test next like I said in the above post fuel consumption at slower speeds was about the same as the ~Yamaha C40 at WOT I got 17knots per gps with full ballast and I used about 10gallons total in 3 hours in a variety of speeds and conditions I did shoot the inlet into open ocean in very bad conditions but hey I was testing LOL The Engine clears the seat when trimmed up and I can see why BWY recommends them it sort of fits like a glove. Now my engine was running rather high RPM its rated Max 5850 and I was right there Hence the 14x12 Which I think will get me a extra knot and bring that down to around 5500. I love this engine and I got a super deal on the new prop on Ebay. So in a variety of speeds and a lot playing with the throttle and boat in choppy conditions on ICW and really bad in the Ocean I averaged 4 miles to the gallon 20 miles out and 20 back 10 gallons gone and all in about 4 hours that day. Now weather has been awful lately but is starting to break I cant wait to get back out there.
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