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Old 21 November 2015, 07:32   #1
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PAC 22 acceleration problem

Hi everyone,

hope somebody can point me in the right direction as im stumped at the moment,
My boss just bought a pac22 sight unseen and not tested, apparently it has only done 1000hrs from new,
The boat accelerates very slowly up to 1700rpm with a bit of black smoke and as soon as it gets up to this speed just suddenly accelerates away, the turbo was quite sticky and loads of play in the shaft, fitted brand new turbo and it has the same problem.
The engine is a 4lha stp, with borg warmer 72 gearbox and a 100 series sterndrive, no info came with this boat so unsure of gearset or prop
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Old 21 November 2015, 07:45   #2
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Those yanmars are quite prone to turbo lag.
First thing is the hull clean?
What rpm is the engine making at wot I think they should make just over 3400 with a clean hull
If it doesn't then it's possibly over propped or dirty
The intercooler can coke up on both the air & water side which reduces power too
Also is the exhaust system free from obstructions
Need more info to narrow down the possible causes
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Old 21 November 2015, 17:27   #3
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That sounds about right for P22 with a standard 160hp engine. Should manage about 26 knots flat out at about 2600 revs. Make sure the weight is kept forward (people) if it struggles to get on the plane but it does take time compared to an outboard rib.

I added a set of foils to the rear chines which helped provide lift to the stern.

Lots of posts on here about Pacific 22s, worth doing a search back over 12 years.

Worth a read:

http://www.northernexposurerescue.or...s/Pac%2022.pdf
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Old 21 November 2015, 17:31   #4
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Isn't the 4lha stp the 240hp one?

What rpm and boat speed are you getting?
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Old 21 November 2015, 17:37   #5
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Quote:
Originally Posted by Searider View Post
Isn't the 4lha stp the 240hp one?

What rpm and boat speed are you getting?
Ah good point, what is the number on the boat plate 8110 would be the 10th boat in 1981 so should give you an idea of its age.
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Old 21 November 2015, 17:54   #6
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[QUOTE=Pete7;700360]That sounds about right for P22 with a standard 160hp engine. Should manage about 26 knots flat out at about 2600 revs. Quote

I assume you mean 3600rpm?
Won't last very long if it's only making 2600rpm at wot!
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Old 21 November 2015, 18:14   #7
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[QUOTE=beamishken;700366]
Quote:
Originally Posted by Pete7 View Post
That sounds about right for P22 with a standard 160hp engine. Should manage about 26 knots flat out at about 2600 revs. Quote

I assume you mean 3600rpm?
Won't last very long if it's only making 2600rpm at wot!
I posted that before Sea Rider pointed out it has a Yanmar in it. The quote was for the older Ford Dover 4.2 engine.

Pete
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Old 21 November 2015, 18:40   #8
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[QUOTE=Pete7;700370]
Quote:
Originally Posted by beamishken View Post

I posted that before Sea Rider pointed out it has a Yanmar in it. The quote was for the older Ford Dover 4.2 engine.

Pete
Says in his first post it's a 4lh stp
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Old 21 November 2015, 18:44   #9
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[QUOTE=beamishken;700372]
Quote:
Originally Posted by Pete7 View Post

Says in his first post it's a 4lh stp
Which I overlooked because he also mentioned the Borg Warner 72 box and stern drive 100. Would be interesting matching the Yanmar to the Borg Warner, wonder why they didn't use a Yanmar box and alter the jack shaft if the engine position is slightly different, still lets see what his answers to this thread are.

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Old 21 November 2015, 19:09   #10
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Isn't that a standard set up in the later pac's? The yanmar usually comes with a zf/ hurth box but the military spec some strange stuff or possibly buy the engines bobtail & fit the origional box during re powers
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