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Cheadder 
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Joined: August-27-2024 Location: Discovery bay Status: Offline Points: 9 |
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 Topic: Gt40Posted: August-28-2024 at 9:36pm |
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Has anyone reported a “2001” with a gt40 specifically a 1989? I
Just acquired the running gear from a 2000 air and wanted to Know how straight forward it is and if there’s anything I should expect? |
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TRBenj
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Joined: June-29-2005 Location: NWCT Status: Online Points: 21186 |
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Posted: August-29-2024 at 7:01am |
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89 should be easy, the boat should already be set up with a 1.23 and the larger motorbox. Other than a fuel return line, should be pretty close to plug and play.
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Cheadder
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Posted: August-29-2024 at 11:28am |
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So I have to drill and tap my gas tank? Also I’m more concerned with the wiring hoping someone has done it before. The harness has whips And haven’t dove into it yet but that’s going to be the harder part I think
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KENO
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Joined: June-06-2004 Location: United States Status: Offline Points: 11125 |
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Posted: August-29-2024 at 8:37pm |
If you look at your 8 plug connector on the 89 engine and look at your 8 plug connector on the gt40, you should be able to see that the wire colors and wire locations are the same, so the gt40 will plug right into the boat side connector. Assuming you want to use the key on the 89 dash to start the engine and not the keypad from the Air Nautique, then it's all compatible. If you want to use the keypad, change your mind right now  If you want the slow mode warning light you'll have to run a wire to the dash and use a light and or horn to make that functional. All the gt40 fuel injection wiring is on the engine side of things and it'll get power thru the the 8 plug connector Here's a gt40 wiring diagram from PCM for power to the engine thru the 8 plug connector and like mentioned, when this is hooked up you'll have power to the injection related stuff when the key is ON.  |
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Cheadder
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Posted: August-29-2024 at 11:15pm |
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No way! It’s that easy!? I haven’t even dig into it yet was going to start tomorrow. But that’s great news! The return line? Any advice on best way to do it?
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KENO
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Posted: August-30-2024 at 7:14am |
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As long as everything is there on the gt40, you'll find it pretty straightforward.
It'll be a little crowded around the 89's muffler but it'll fit and clear the ECM on the back of the engine. The return line.....a tee in the fill hose or the vent hose works without getting into gas tank modifications, here's one example of a vent line adapter with 5/8 fittings and a 3/8 fitting for the return line in the link. A little pricey but it gives you an idea of what can be done. Time to start diggin' and comparing stuff
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Cheadder
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Posted: August-30-2024 at 8:26am |
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The 2000 exhaust work
And or a better option? Straight pipe it? |
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KENO
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Posted: August-30-2024 at 1:50pm |
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I'd probably use the 89 setup for the muffler/exhaust.
You'd need to use the 89 risers that have 3 inch outlets, the 2000 would have 3 1/2 inch outlets.
It would be the easiest route to go.
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Cheadder
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Posted: August-30-2024 at 5:32pm |
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Thanks Leno I really appreciate the info. I couldn’t find a write ups on it anywhere. Any reason for the 89 exhaust? Does the other not fit well? You think straight pipe would be abnoxious?
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MrMcD
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Joined: January-28-2014 Location: Folsom, CA Status: Offline Points: 3750 |
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Posted: August-30-2024 at 7:05pm |
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I think he was pointing out which would be easier. Your boat is set up to use the early 3" exhaust. The newer engine uses the 3.5" exhaust. The old system bolts right up, no modifications needed. To use the new system you would need to study your boat and see exactly what needs to be converted. The dual straight pipes have a great sound, traditional Nautique sound. You can run that system like factor with mufflers in the straight pipe or run without them. Without the mufflers the rear seat passengers hear a lot of exhaust noise while boating.
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KENO
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Posted: August-31-2024 at 5:34pm |
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Here's a picture from somebody's ad for a 91 with a gt40 transplanted into it.
 Same muffler as your 89 and it's close to the ECM but fits. So 91 ....different hull, but same running gear Now as far as noise levels, that's up to you |
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TRBenj
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Posted: September-01-2024 at 6:15am |
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‘95’s would have been sold with that muffler on a GT40 from the factory and the same motorbox, so not surprising that it fits fine.
I’d keep the 3” risers to match the muffler inlets and keep the swap as simple as possible. |
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Cheadder
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Posted: September-01-2024 at 10:39am |
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Agreed. My 89 muffler I had to sikaflex a small spot that’s why I was wondering. I guess I’ll sell the 2000’s exhaust
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KENO
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Posted: September-01-2024 at 8:42pm |
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Something I hadn't really thought about until TRB mentioned the 95 boats, but from 89 through 94 the single exhaust outlet was on the right side of the boats centerline and in 95 when they started with the gt40 the exhaust outlet moved to the left of the centerline for some reason.
Only thing I can come up with is that on the gt40 there's a fair amount of stuff on the right rear that maybe the downpipe got in the way of easily accessing. Things like the remote solenoid for the starter, the 2 relays for the ECM and fuel pump and a couple of test connections. I'd figure it'll still fit and just make life a little more difficult. Maybe there was a different reason for the switch of outlet locations.
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Fl Inboards
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Posted: September-02-2024 at 7:02am |
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Hull huger muffler is why we went to the other side. 95 will be the last year that an invertaflow was on the ski boats. space saver transmission mounts was next as water valves and other components were rather tight. I am doing a repower on a 1995 sport, 6.0 non cat and having to come up with a custom exhaust because the outlet port is opposite of what is now a day's normal side. Those of you maybe looking for a GT engine i am pulling a high hour out and is for sale, running complete with series 40 123-1.
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Hobby Boats can be expensive when the hobbyist is limited on their own skill and expertise.
1993 Shamrock "fat" 20. 2008 Nautique 196 5.0 |
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KENO
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Posted: September-02-2024 at 8:00am |
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That still leaves me confused.....89 thru 94 invertaflow exhaust on right.
95 first year of gt40...... exhaust was moved to the left, it was an invertaflow that year. There must have been a reason for the change in 95 that coincided with the gt40 engine being used? 96 hull hugger exhaust on left for quite a few years. And they keep changing sides thru the years to make your swap life hard |
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Cheadder wrote: