planing problem

[ruf1967]

Re: planing problem

The altitude you are operating at plays a big factor in your engines inability to perform well. Do you have a carb or fuel injection? FI adjust better to altitude changes. If you've bought the boat new and followed the break-in correctly, and winterized it properly, there are probably no mechanical issues. Ferrying 10 people around, all their crap, watertoys, all the beer and then trying to pull a boarder is going to stress out any engine. You're going to have to play around with some different prop configuations and see what happens. Also, your dealer's claim about the engine operating range being 4800 to 5000 rpm is correct. That's where it needs to be otherwise the engine will suffer damage, either with overloading (too much prop) or over revving (too little prop).

 

[QC]

Re: planing problem

A GI is EFI, so it should not need any recalibration or rejetting. 4500 ft. is significant regardless though. I lose 200 RPM at 3000 ft. . . . Also if the most you have ever seen at WOT is 4400 it has never been propped right unless it has always had an engine problem. Is that what you saw new? 4400? I think you need to get 5000 RPM with a normal load if you expect heavier loads frequently. There may in fact be something wrong with the engine, but 4500 ft. and 4400 RPM are not going to live well together if the engine is right . . .

Trim tabs always help with boats that struggle to plane. With your heavy boat you 're going to need helm adjustables like Bennett's or Lenco's.

Edit: Sorry ruf1967, we were probably posting at the same time, I'll leave my comments to underscore yours, I almost totally agree. I think it may be more clear to say that EFI adjusts for altitude instead of adjusts "better". Carbs don't adjust period, they must be adjusted. OEM EFI's adjust completely and automatically to Barometric Pressure.

For others that may not understand this as well as ruf, these engines cannot make air, they must reduce the amount of fuel to equal the available air at any given altitude, so there has to be less power. This is true for ALL naturally aspirated engines. Only those engines with some kind of forced induction, a turbo or a supercharger, can compensate completely for altitude. . . . I need to look into Verados . . . it is possible that they can maintain power say to 7000 feet or so. I haven't heard that, but theoretically it is possible if they have excess air at sea level.

I agree that this engine is probably right, they (Electronic) are very rarely wrong anymore if they are maintained properly.

 

[ruf1967]

Re: planing problem

Yeah, I was pretty vague with the "adjust better" statement. There is something wrong however. That engine should definitely be revving higher than 2900 rpms. Is there anyone else who has a similiar engine/boat set up and live in a similar altitude?

 

[QC]

Re: planing problem

My favorite recomendation is to verify the tach. 2900? How fast GPS?

 

[zack]

Re: planing problem

thanks for all of your input guys. My sister has the same engine with a different boat and an aluminum prop but she can reach 5000 rpm. I agree that I may need to change the current prop But according to Volvo there isnt a smaller pitched prop avail for this engine. btw, I dont know the pitch of the cuurent F4 prop bc Volvo guards that knowledge for some reason.

The engine temp and oil pressure are all normal. I often boat at 7000ft above sea level, so that probably has a lot to do w it. I just dont know how to prop down to reach 5000 rpm when Volvo says it is not avail.

i went boating on Sunday and I was able to reach 4200 rpm at 7000ft.

 

[QC]

Re: planing problem

7000ft.

May be the entire issue!!!! 2900 is still a very low number, but you had said 4500 ft. By chance was the 2900 figure at 7000?

Also, I don't think I would be too concerned about Volvo saying that propset is not available, probably just not a common need. However, we do need DonS from the I/O section to chime in . . . I'll PM him and see if he'll grace our presence . . .

 

[zack]

Re: planing problem

Yes, it was at 7000 ft when I could only get it to 2900 rpm. I also went boating yesterday at 7000ft and was able to reach 4200 rpms. The only difference being 4 less people in the boat than the time I only got to 2900 rpm. Could 4 people really make a 1300 rpm difference?

Volvo does make an F3 prop but Volvo says it is not available for the 5.7 GI engine. Apparantly, my boat has never been propped correctly since I bought it new last year. Should the dealer trade me my F4 prop for an F3 if it will fit?

Thanks again for your help guys.

 

[Don S]

Re: planing problem

I had everybody in the bow and i still could only reach 2900 rpms

Well DUH, spread them out equally around the boat. If you have all the weight in the bow, you never will get the bow up enough to plane. Trim tabs will only push the bow down, not up. All you are doing is plowing thru the water which is why you only get 2900 rpm.

You may also need the F3 set, maybe lower for 10 people. The WOT test is for your NORMAL load and is not good for all loads and conditions.

 

[QC]

Re: planing problem

My guess is that you had to put them in the bow to get her to plane and then it would probably have helped your top speed if you had moved them back after she got going. Did yoy try that? Moving them around after you got on plane?

7000 ft. is very significant.