KAD32's problem

[dfleminguk]

KAD32\'s problem

Recently got a Fairline Targa 29 with twin KAD32's

I am not particulalry mechanically minded so bare with me! I noticed that when you open up the throttles fully the revs pick up but then there is a 3 or 4 second delay before the engines fully open up. (both engines behaved the same.)

Towards the end of this weekend however both engines seemed to stop picking up to full speed, again though both engines seemed to behave the same, but there seemed to be a loss of top end power.

Anyone any ideas?

 

[crazy4557]

Re: KAD32\'s problem

As they both show the same symptons it's more than likely a fuel flow issue. Maybe a blocked fuel vent?

 

[[2068]]

Re: KAD32\'s problem

What RPM do they get "stuck" at ?

I'm asking because KAD32's have two means of propelling you forwards at high speeds:
1.) Superchargers that work between 1600rpm and 2500rpm
2.) Turbochargers that work from 2500rpm to 3900rpm

dv.

 

[dfleminguk]

Re: KAD32\'s problem

thanks for your replies, its around the 2300 to 2500 that it 'gets stuck'. The engines did however eventually get to full throttle until the end of this weekend when neither engine got to full revs.

 

[[2068]]

Re: KAD32\'s problem

It could be many many things. Is there smoke at the same time?

e.g.

- Fuel restriction - tank pickup blocked / primary filters blocked / secondary filters blocked
- Air restriction - blocked air filter?
- Old oil / sticky turbos - when was the oil last changed?
- Fouling on hull or props - you'd be shocked how a few barnacles and weeds can ruin your day

dv.

 

[dfleminguk]

Re: KAD32\'s problem

Thanks for those replies, It must be something that has happened fairly suddenly as opposed to say fouling on the hull. The boat reached full revs on saturday and today just wasnt getting there, revs got to about 2800 then they just werent getting any further. thanks again will check the above.

 

[[2068]]

Re: KAD32\'s problem

I'd start with the fuel filters.

dv.

 

[davedpc]

Re: KAD32\'s problem

Try the air filters. If clean try running with the engine hatch ajar. If one engine is down on power its going to affect the other.

 

[Peanuts]

Re: KAD32\'s problem

Hi
Although I have read your post and some of the replies you have been given I have some questions for you regarding your engine problem.
I assume that this is the first time you have noticed any sort of problem?.
When were the engines last serviced? (including all the fuel filters)
Have the main circulation belts on the engine been correctly torque loaded? I myself would check this first of all apart from being the easiest one to do. It has been known in the past for a person to incorrectly fit (torque load) these belts and to have exactly the same problem to both engines, one example of this was found out after the compressors had their clutches removed, checked and re-fitted, all because the belts were incorrectly torqued up by a trained technician I must add!!. A simple torque check and every thing was OK.
When you open the throttles up are you doing so gradually or slamming them open?
I hope this may be of some help.

 

[Pendana]

Re: KAD32\'s problem

Just a thought. Sometimes the problem is in just one engine which means the other has to do all the work and thus doesnt acheive full normal revs. It will take the other engine along for the ride so to speak so they both appear to be under performing.
Try opening up with one engine at a time and establish that theyare both perfoming equally or show that one is under performing.

Good luck

Eddie

 

[Peanuts]

Re: KAD32\'s problem

I agree with your theory but how can you open up one engine at a time and expect it to reach max RPM, is that not the same situation as one engine not reaching max RPM and dragging the other engine down? Or am I just having one of those days??

 

[DavidJ]

Re: KAD32\'s problem

Pendana is taking a problem solving approach rather than brainstorming causes. The BIG clue is that it happens (or appears to happen!) to both engines. Once we have this BIG clue either proved or disproved the solution will just drop out I'm sure.
Maybe hold one engine at say 2000rpm then take the other up, see what happens, then vice versa. Record the results exactly (maybe even with a stopwatch)
If both engines are exhibiting the same problem there are very very few things both engines have in common. eg Air filters won't both block exactly at the same time, nor will fuel filters, nor will belt tensions both be exactly the same degree of overtightness.
Need more performance data!

 

[Peanuts]

Re: KAD32\'s problem

I do agree need some more data, that is why I asked some questions,however I did state as an example that if some one has worked on his engines, carrying out exactly the same job on both of them then a problem could arise both exhibiting the same systems as previously experienced. The belts are a good example and would both be at the same tightness/slackness, therefore would give equal results because it was the same person who tighten them, that is one (of many) reasons for using a torque wrench so it does not matter who does the job it will always be the same correct loading. (Sorry if that sounded patronizing)

 

[DavidJ]

Re: KAD32\'s problem

[ QUOTE ]
(Sorry if that sounded patronizing)

[/ QUOTE ]
Not at all.

Taking your example of the belts, there are so many variables involved incl variability in belt manufacture, variability in pulley friction and even variability in the torque device that the chances of two failures or effects happening equally and at exactly the same time are thousands (maybe millions to one) so the conclusion is that a failure will not be the effect of two identical things going wrong at the same time.
More like it will be something that both systems share, hull friction being a good example (but discounted in this case). But first we need to prove/disprove whether the problem is a shared or individual system problem.
Pheeew, I need a rest now. /forums/images/graemlins/grin.gif

 

[Peanuts]

Re: KAD32\'s problem

"and even variability in the torque device"

That is why we have to check our torque wrenches against a calibrated torque analsyer every time we use one and record the torque wrench serial number and the calibrator used on the job card in the Engine Bay that I am in charge of.
I think I will have a rest now as well, especially as we seem to be deviating away from the original post.

 

[Pendana]

Re: KAD32\'s problem

You are right that one engine not acheiving max revs will bring the other one down too, so no, you're not having one of those days. But we are using that principle to establish which, if any, engine is not performing as it should. For example, a pair of kad 32'S should both acheive about 3800RPM at WOT. Opening up each engine individually, the boat won't climb out the hole and the engine may achieve about 2600RPM but individually they should both achieve the same revs. If one is substantially lower than the other then you will have established which is under performing.

Eddie

 

[Vagabond]

Re: KAD32\'s problem

Could be that the superchargers are kicking out too early. 2,500 revs is a bit low and the turbo has not spun up to speed enough to give proper boost.

Open up the box of tricks and adjust that screw so the kick out at 2,800

 

[enterprise]

Re: KAD32\'s problem

Is that really possible, If so I might look to do that too, mine seams to stick at around 2500rpm, thought it maybe all the junk we loaded aboard! /forums/images/graemlins/ooo.gif

 

[Peanuts]

Re: KAD32\'s problem

Although I agree 2500 RPM is low, it should be 2600+/-50 RPM, 2800 is too high. I would not alter the settings at the moment as it worked OK earlier in the weekend therefore I doubt if it is the cut out speed that is causing the problem, all IMHO of cause.
Just for the record the cut in RPM for a KAD32 is 1700RPM and as above cut out at 2600RPM+/-50 and if you do decide it requires adjusting then 1 revolution of the adjusting screw equals 48RPM.
Hope this is of some help.

 

[Vagabond]

Re: KAD32\'s problem

Interesting ...

Mine cut in at 1,400 and out at 2,700.

Any idea where the recommended settings are? In the book it doesn't mention anything about cut in/out.

Any idea what controls the cut in?