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Old 06-30-2014, 09:36 PM
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Originally Posted by jeff32
how picky are these engines on fuel? I was offered on trade a twin 575 boat. was told they melt piston when using regular fuel, like 89 octane. they apparently need at least 91. True or false?

that make a long trip almost not possible, since I guess there is only or mostly 89 in different marina, right?

What about adding octane booster? would this solve the problem if any problem there is?

Not impossible at all IMO. Cruise at no boost and you won't need the octane. I have convered mine to 700hp and aometimes need to run 91 octane, much higher boost than stock. So far no issues. I had fuel pump issues and my knock sensors along with the ECM tuning the timing back made me well aware of the issue immediately, it was intermittent until I found it, but it was obvious when it happened.

7.5:1 at 3 lbs of boost is really not a big deal
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Old 07-01-2014, 07:39 AM
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They are not bad on fuel mileage when not in boost. ...but when you hear those chargers start whining, they are fast and thirsty! whoo hoo!
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Old 07-01-2014, 09:30 AM
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Originally Posted by jeff32
question for TOM A
I called a ''local'' distributor for TORCO octane booster.

I explained the case, he told me 32 onzes treats 5 gallons of fuel. each 32 onzes of torco cost 24.95$
if you multiply 24.95 x 40 (200 gallons gas tank in boat divided by 5 gallons = 40 times needed of 32 onzes) that's roughly 1000$ of cost of octane booster per gas tank !!!!

Does not make sense to me!!! is this really what you do when you need to add booster?
The math is slightly off. Each 32 oz. treats 20 gallons (to raise it 4 octane points). Assuming you get 89 octane (standard on water rating) you would need 10 quarts to be safe. That is $249.50 or roughly $1.20 per gallon.

You can also look into Boostane which raises your octane level by 15 points per 32oz bottle / 20 gallons. They are also $24.95 each and you only need 4 quarts there.

Here is a link where some of this has been discussed:

http://www.offshoreonly.com/forums/g...-1-350s-5.html
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Old 07-01-2014, 11:13 AM
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I've run hundreds of gallons of 89 octane through my tweaked 575's.
I start a trip with 200 gallons of 92 and top off each time it'll take about 100 gallons. I think the innercooler helps and I DO NOT let it get into boost.
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Old 07-04-2014, 03:20 PM
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do you have a boost guage to know that? or by sound?
So you are saying without going into boost, octane rating is not / less important? boost comes in at what rpm?
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Old 07-04-2014, 08:06 PM
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With positive displacement superchargers as found on the 575's and many other Merc SC'd engines Boost comes with throttle position.

Octane Boosters rating are deceiving. If it says add x amount to y amount gas to get 5-7 points octane it will actually just raise it .5-.7 octane numbers.

Points = 10th's of an octane number.
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Old 07-04-2014, 09:06 PM
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Originally Posted by jeff32
do you have a boost guage to know that? or by sound?
So you are saying without going into boost, octane rating is not / less important? boost comes in at what rpm?
Anything boosted should have gauges, IMO. I also have fuel pressure gauges. The engine is 7.5:1 without boost, it would prob run on 82 octane without the charger
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Old 07-04-2014, 09:09 PM
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Originally Posted by SB
With positive displacement superchargers as found on the 575's and many other Merc SC'd engines Boost comes with throttle position.

Octane Boosters rating are deceiving. If it says add x amount to y amount gas to get 5-7 points octane it will actually just raise it .5-.7 octane numbers.

Points = 10th's of an octane number.
I agree with you on the octane booster, not a fan of their deceptive advertising.

The boost however I respectfully disagree. Load plays a factor as well. Running wet with a full load and I make boost at 3500. I can run loose and light at 4200 (after I get there) with more throttle position and get it to run out of boost.
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Old 07-05-2014, 07:19 AM
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Originally Posted by 4bus
I agree with you on the octane booster, not a fan of their deceptive advertising.

The boost however I respectfully disagree. Load plays a factor as well. Running wet with a full load and I make boost at 3500. I can run loose and light at 4200 (after I get there) with more throttle position and get it to run out of boost.
We don't disagree. I was keeping it simple. LOL. In a boat it will be throttle position vs rpm. Load will determine how much throttle you need for how much rpm.

RPM determines how much air your exact engine wants and throttle position determines how much air it gets.

Just like NA, as example, say you have drive tucked down and same with tabs. Half throttle your engine is at 4000rpm and intake vacuum is at 4"hg. Raise tabs and trim drive for fastest speed, same throttle setting will produce more intake vacuum (if SC this would show as less boost) while picking up say 300rpm. Bump throttle a little farther foward for more speed and a touch more rpm, but intake vacuum still a little higher than where it was before you raised the tabs and drive.

Again, still trying to keep this halfway simple.
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Old 07-15-2014, 02:24 PM
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Hey guys,

Someone from the Boyne Thunder poker run brought this thread to my attention. Especially the 1350s. below is a picture of a 52 ft skater that is running 1350's and protecting them from 90 octane marine gas by raising the octane to 95 with BOOSTane. We also ran in our 2 pro charged 598 cu.in. 1200's.

Some small examples of how we were utilized at the last Poker Run in Boyne City. We can effectively raise 90 octane pump gas to 107 octane. This is all done with our proprietary carrier. The carrier that makes sure that your active ingredients don't settle to the bottom of your tank you when you store your boat, clogging filters and injectors.

Thats just a quick rant. If you have specific questions, feel free to fire away!

[ATTACH=CONFIG]526071[/ATTACH][ATTACH=CONFIG]526072[/ATTACH]
Attached Thumbnails need fuel info on 575 merc-img_1131.jpg   need fuel info on 575 merc-phoca_thumb_l_boyne14_boostskater.jpg  
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