full blast or what?

[brettwid]

I've been engaged in a discussion lately about running an outboard wide open throttle (to reduce carbon) or 3/4 to save gas and make the motor last longer.
The motor we're talking about is a carbed F50.
I uesd to never run it full blast because I wanted it to last a LONG time and going slower was not a big deal.
So should it be run WOT?
Will running slower make the engine last longer?
Will running WOT keep carbon from building up in the motor?

thanks,
Brettw

 

[robert graham]

Re: full blast or what?

I doubt the RPM's you run the motor will have much, if any, effect on the carbon or the motor's longevity. RPM's will effect fuel economy, so go to Yamaha Outboard Performance Bulletins, plug in your boat/motor combination and it will give you a chart showing GPH, MPG, MPH at given RPM's, and you can run your boat at it's most efficient cruise RPM's, probably something in the 3500 to 4500 RPM range, or just on plane. Check it out and good luck!

 

[Woodnaut]

Re: full blast or what?

If Rodbolt weighs in on this you'll have a definitive answer. I can only add that it's important to have your rig propped out correctly. I've got an F90 and managed to over-prop it once. The unit appeared to be "making oil" so I promptly had the prop repitched so that WOT was at the top end of the recommended WOT range. End of problem.

My point in bringing this up is that it just seems that if you're producing an equivelent HP - but at a higher RPM - then it stands to reason that the internal stresses would be lower. (Lower stresses - longer fatigue life - longer engine life.) I usually run my unit around 4,500 - 5,000 RPM, but weather permitting, I take it to WOT for 15 - 30 min at the end of the trip.

 

[brettwid]

Re: full blast or what?

If Rodbolt weighs in on this you'll have a definitive answer. I can only add that it's important to have your rig propped out correctly. I've got an F90 and managed to over-prop it once. The unit appeared to be "making oil" so I quickly had the prop repitched so that WOT was at the top end of the recommended WOT range. End of problem.

My point in bringing this up is that it just seems that if you're producing an equivelent HP - but at a higher RPM - then it stands to reason that the internal stresses would be lower. (Lower stresses - longer fatigue life - longer engine life.) I usually run my unit around 4,500 - 5,000 RPM, but weather permitting, I take it to WOT for 15 - 30 min at the end of the trip.

Woodnaut,
funny you should use the "making oil" term. I checked my oil 2 days ago and was SHOCKED to find it was way above the full line on the stick. I don't think I was that negligent when I changed it. I have been running SeaFoam in the fuel and habe read that "making oil" is one possible effect it can have.
thanks

 

[Silvertip]

Re: full blast or what?

I get absolutely "nuts" when people come up with this "I heard" stuff. SeaFoam, Stabil, and any of the other fuel system treatments are the best thing you can add to the fuel to actually prevent having fuel related issues. Making oil on a four stroke is primarily due to OWNER NEGLECT. How "infrequently" have you been checking the oil??? Prop the motor correctly and run the darned thing as the manufacturer intended. It is making oil (fuel diluting the oil) due to prolonged idling/trolling, the engine not getting hot enough, and primarily "lugging" due to improper prop selection. Gas in the oil degrades the ability of the oil to lubricate. If you want the engine to last longer, stop babying it. As we tell folks, engines don't just die -- their owners kill them. OK - I've vented!

 

[gss036]

Re: full blast or what?

I have a 225 Honda and the Dealer and Honda says I should be running more at close to (WOT)100%. I occasionally will run it up to the top end, but they say I don't do it long enough. Both said not to worry about it since it under warranty.

 

[Silvertip]

Re: full blast or what?

The manufacturer specifies an upper rpm limit for a couple of reasons. It basically is maximum rpm the engine is designed to run at. Will it explode if you go over that by a little? Of course not. But engine design must take lots of things into consideration and operating RPM is just one of them. In most cases, running an engine faster than its recommended wide open throttle rpm does not produce more power so what's the use. On four strokes, unless the camshaft profiles and carburetion are changed accordingly, the engine may lose power. Cams, compression, carburetion and exhaust specs are moved around to develop the power bands for each engine. If you prop the engine wrong for wide open throttle, it will be wrong across the rpm band. So do it right and run the engine as it is designed to run.

 

[brettwid]

Re: full blast or what?

I get absolutely "nuts" when people come up with this "I heard" stuff. SeaFoam, Stabil, and any of the other fuel system treatments are the best thing you can add to the fuel to actually prevent having fuel related issues. Making oil on a four stroke is primarily due to OWNER NEGLECT. How "infrequently" have you been checking the oil??? Prop the motor correctly and run the darned thing as the manufacturer intended. It is making oil (fuel diluting the oil) due to prolonged idling/trolling, the engine not getting hot enough, and primarily "lugging" due to improper prop selection. Gas in the oil degrades the ability of the oil to lubricate. If you want the engine to last longer, stop babying it. As we tell folks, engines don't just die -- their owners kill them. OK - I've vented!

I want to vent now, but just dont see the point.

 

[rick3452]

Re: full blast or what?

Silvertip...is it a good idea to use Seafoam on a one or twice a year basis?
And just add to fuel, or oil as well...
Thanks

FYI, I was doing a search on Seafoam and came up with this thread... my application is on a 2000 5.0 Mercruiser

 

[brettwid]

Re: full blast or what?

Silvertip...is it a good idea to use Seafoam on a one or twice a year basis?
And just add to fuel, or oil as well...
Thanks

FYI, I was doing a search on Seafoam and came up with this thread... my application is on a 2000 5.0 Mercruiser

FYI, I plan on using it all the time. I had a bad carb and started using it, took it to the shop, 1100.00+ was what they wanted to clean all 4 carbs. Got it on the lake, running wide open and it sort of opened up for me. I am going back to confirm this as soon as this bad cold spell ends,
good luck
ps, put it in my oil (4 stroke) since I was told i have low compression.

 

[Silvertip]

Re: full blast or what?

Although SeaFoam and other additives can be added to the oil THAT is not required. About the only oil related additive I would ever recommend is Rislone which has been around since Hector was a pup. This is an extremely high detergency oil and would only be used to clean up an engine after a water intrusion, milky oil situation, or where sticky lifters are an issue for an improperly stored engine. I've seen this stuff work wonders on stuck rings on diesel engines, overheated engines that leave the gold varnish inside, and to clean up plain old gunky engines from years of oil change abuse (lack of it). Todays oils are such that oil additives are not needed.

As for SeaFoam in the fuel, if you tend to use your fuel rather quickly you can use small doses. If your fuel tends to be used less frequently, use it all the time in larger doses. You can't use too much of this stuff.

As for the venting post, sometimes one needs to do the equivalent of a slap in the back of the head to get someones attention and to make them think logically. As was indicated, if Pennzoil lubricants were as bad as this post makes it sound, they would have been out of business years ago. This is how unfounded rumors get spread. Pennzoil has been around since 1913 by the way, and as of 2007 the #1 selling motor oil in the country. Need I say more???? No -- I don't work for Pennzoil.

 

[99yam40]

Re: full blast or what?

FYI, I plan on using it all the time. I had a bad carb and started using it, took it to the shop, 1100.00+ was what they wanted to clean all 4 carbs. Got it on the lake, running wide open and it sort of opened up for me. I am going back to confirm this as soon as this bad cold spell ends,
good luck
ps, put it in my oil (4 stroke) since I was told i have low compression.

I would not run a sick motor wide open to see if it will get better. You can just as easily blow it up from running lean on one or more cylinders.
If it had low compression I would be doing a leak down test on it to see what the problem is. Running lean could have caused this. Just my 2 cents

I bet this is the thread were Rodbolt had his last stand and disappeared

 

[brettwid]

Re: full blast or what?

I would not run a sick motor wide open to see if it will get better. You can just as easily blow it up from running lean on one or more cylinders.
If it had low compression I would be doing a leak down test on it to see what the problem is. Running lean could have caused this. Just my 2 cents

I bet this is the thread were Rodbolt had his last stand and disappeared

I knew it was risky, but at 1100 bucks to repair the carbs, and a motor that has low compression.(so i was told and have no reason to doubt the repair guys) I was looking at a new or slightly used motor.

This weekend looks good enough weather wise to get the boat out and try it again.

 

[99yam40]

Re: full blast or what?

do a search on leakdown test and read what all Rodbolt had to say about how it will tell you what kind of problems the motor has from that simple test.
I would be looking for a different repair shop and getting a second opinion on your motor before running it till it dies

 

[mommicked]

Re: full blast or what?

Not to steal the post.someone told me recently to get a hotter thermostat for my F90 to help w makin oil.any truth to this?I also lugged my motor, slowly looking for fish/stucture on the fishfinder alot before i learned about WOT after low RPMs to help w making oil.It has seemed to work last 3 trips after changing gassy oil.(oil smells fine now) no rise on the dipstick.

 

[boobie]

Re: full blast or what?

Is Rodbolt gone? I don't visit this thread too often as I'm an Evinrude guy.He always had the best answers for the prob questions and I enjoyed them.

 

[mommicked]

Re: full blast or what?

Rodbolts replies are always as entertaining as they are informative!I look forward to meeting him one day!and thankyou Silvertip too.I hope ALL of the experts know some of us are technically/$$$$ challenged and your advice helps alot w our enjoyment/performance of our boats/motors.As a stranger and newby (4 yrs) boat owner, Im gratefull you would offer your expertise.

 

[brettwid]

Re: full blast or what?

Rodbolts replies are always as entertaining as they are informative!I look forward to meeting him one day!and thankyou Silvertip too.I hope ALL of the experts know some of us are technically/$$$$ challenged and your advice helps alot w our enjoyment/performance of our boats/motors.As a stranger and newby (4 yrs) boat owner, Im gratefull you would offer your expertise.

Indeed! I want to thank everyone that chimed in. Silvertip was most enlightening.