twin engine rpm sync in a boat

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phughes69
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twin engine rpm sync in a boat

Post by phughes69 »

Im installing a MS3's in my boat this summer. The engines are twin turbo BBC with dual throttle bodies. The throttle bodies will be cable operated. Most boats with twin engines have a sync gauge that shows how much one engine is differing in rpm than the other engine. some of the gauges are not very accurate and most people listen to the tone of the engine. What I am wondering is if it is possible to have the MS3 adjust the rpm's of the engines thru the IAC valve to bring the engines more in sync than your ear can detect?
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Re: twin engine rpm sync in a boat

Post by jsmcortina »

There's no feature for dual engine sync, but if you use closed loop idle with the same parameters, both engines will be aiming for the same RPMs.

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phughes69
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Re: twin engine rpm sync in a boat

Post by phughes69 »

Can the closed loop idle be turned on and off with a analog input? Can the closed loop idle feature be extended in the upper RPM range (3000-6000 rpm)?
Yves
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Re: twin engine rpm sync in a boat

Post by Yves »

I'm wondering if you make some sort of cross over tube between the plenums, thereby making the map equal would achieve exactly that: a synchronized set of engines. Reason why I'm thinking this is that on an engine with ITB's you also make the individual amount of map equal from one running to the other. What remains is making sure the throttle plates open equally.
billr
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Re: twin engine rpm sync in a boat

Post by billr »

Are there no modern sync gauges/controllers, that have reasonable accuracy? I expect you really want sync to be "automatic", but just looking at the rpm from each engine's ECU would be more accurate than listening for the sound; that should be easy to do.
phughes69
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Re: twin engine rpm sync in a boat

Post by phughes69 »

Mercury (the outboard motor company) has a product called Smartcraft and DTS (digital throttle system). It connects to the engine via a CAN bus and is used a lot on their new outboards and sterndrive engines. The DTS has a engine sync function. "DTS has an automatic synchronization function. As long as the throttle handles are within 5-degrees of being aligned, and the engine speed is above 1,500-RPM, the DTS system will try to synchronize the engine speed of the starboard engine to match the port engine." "However, if you push the SYNC button, you can shut this feature off." I know that all the new outboards and sterndrive engines have fly by wire throttle bodies which hakes this possible. SO for my application I would have to install electronic throttle bodies, but does the MS3 support that?
phughes69
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Posts: 16
Joined: Wed Aug 17, 2011 8:42 pm

Re: twin engine rpm sync in a boat

Post by phughes69 »

Yves wrote:I'm wondering if you make some sort of cross over tube between the plenums, thereby making the map equal would achieve exactly that: a synchronized set of engines. Reason why I'm thinking this is that on an engine with ITB's you also make the individual amount of map equal from one running to the other. What remains is making sure the throttle plates open equally.
I like your thought Yves, but in a marine application it would be better to sync off rpm than MAP. You could have both engines running at the same RPM but different trim angles and the load on each would be different.
billr
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Re: twin engine rpm sync in a boat

Post by billr »

I don't think MS supports electronic throttle in it's standard form. I'm guessing that with all the versatility in MS a clever person could do some mods that would give you what you want. It would probably have to be a simplified version of E-throttle, but I think could be OK for your purposes, since marine engines aren't (usually) subject to as frequent or rapid throttle changes as an auto.
Yves
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Re: twin engine rpm sync in a boat

Post by Yves »

phughes69 wrote:
Yves wrote:I'm wondering if you make some sort of cross over tube between the plenums, thereby making the map equal would achieve exactly that: a synchronized set of engines. Reason why I'm thinking this is that on an engine with ITB's you also make the individual amount of map equal from one running to the other. What remains is making sure the throttle plates open equally.
I like your thought Yves, but in a marine application it would be better to sync off rpm than MAP. You could have both engines running at the same RPM but different trim angles and the load on each would be different.
Ok, I'm not familiar with marine engines. Didn't know they were running at different loads.
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