Reply
 
Thread Tools Search this Thread
 
Old 03 October 2008, 00:46   #1
Member
 
Locozodiac's Avatar
 
Country: Other
Town: Lima-Peru
Boat name: Nautile
Make: Sea Rider 450 Rib
Length: 4m +
Engine: Tohatsu 5/18/30 HP
Join Date: Sep 2007
Posts: 1,998
Gasoline Octane & Performance

Have been reading several engine tech manuals in which it's specified that high octane unleaded gasolines performs and cleans the engine better as having better gas cleaners compared to lesser octane unleaded gasolines.

Ok for this point, was wondering if using unleaded premium 95 octane gasolines compared to same 90 octane would make a difference in speed/engine performance. Don't know if it's my idea but when using 95 octane compared to 90 feel the sib/engine performing much better, with instant punch on the throttle. What are your thoughts about this issue ?

We only have 90/95/97/98 unleaded pure gasolines, with no alcohol mix whatsoever.

Happy Boating
__________________
Locozodiac is offline   Reply With Quote
Old 03 October 2008, 01:48   #2
Member
 
Country: UK - Wales
Town: swansea
Boat name: Too Blue
Make: BLANK
Length: 8m +
Engine: Suzuki DT225
Join Date: Mar 2004
Posts: 12,791
Our minimum is 95 but there are different ways of measuring it. To think in WW2 Britain had 150 octane!!!

Most engines will only benefit if they are tuned for it. Altering timing and mixture etc. Some modern computer controlled engines haver a sensor which will allow you to take advantage of better fuel.

Having said that most engines will benefit a little in smoothness etc if your wallet will stand it.

Just remember that fresh low octane is better than stale high octane!!!
__________________
codprawn is offline   Reply With Quote
Old 03 October 2008, 07:29   #3
RIBnet admin team
 
Poly's Avatar
 
Country: UK - Scotland
Boat name: imposter
Make: FunYak
Length: 3m +
Engine: Tohatsu 30HP
MMSI: 235089819
Join Date: Sep 2005
Posts: 11,622
loco - I think you would need to try it to see in your engine, but I doubt it will make a huge difference. as cod says there are differences in how octane is measured in the US and Europe so be cautious when comparing people's claims.
__________________
Poly is offline   Reply With Quote
Old 03 October 2008, 09:10   #4
Member
 
Bigmuz7's Avatar
 
Country: UK - Scotland
Town: Glasgow
Boat name: stramash
Make: Tornado
Length: 5m +
Engine: Etec 90
Join Date: Feb 2006
Posts: 5,090
I'm not really sure why its sold in the UK as I have never found any difference in any car engines i've tried with the higher octane stuff. I can imagine it giving a small 2 stroke a little edge though, .. maybe my strimmer is crying out for super unleaded and I've denied the little fella all these years
__________________
Bigmuz7 is offline   Reply With Quote
Old 03 October 2008, 10:32   #5
RIBnet admin team
 
Nos4r2's Avatar
 
Country: UK - England
Town: The wilds of Wiltshire
Boat name: Dominator
Make: SR5.4
Length: 7m +
Engine: Yam 85
MMSI: 235055163
Join Date: Jul 2005
Posts: 13,053
RIBase
I notice the difference on the bikes between unleaded and super-but all 3 are carbed. Saying that, it makes as much difference if I stick a tablespoon of tcw3 in the tanks
__________________
Need spares,consoles,consumables,hire,training or even a new boat?

Please click HERE and HERE and support our Trade Members.

Join up as a Trade member or Supporter HERE
Nos4r2 is offline   Reply With Quote
Old 03 October 2008, 12:06   #6
Member
 
Country: Canada
Town: Rigaud, Que.
Boat name: Rigaud Explorer
Make: 6m Bombard
Length: 6m +
Engine: Yam115
Join Date: Aug 2008
Posts: 90
Stock setup theirs zero benefit and pretty much all engines are sold to run on low octane fuel. Engines especially 2 stroke with high compression heads, big bore carbs or throttle bodies, ect.. than you would pretty much have no choice but to use higher octane fuel.

Just keep your set up properly tune all the time and you'll have no issues.

Been there done that.

Cheers
__________________
Rigaud is offline   Reply With Quote
Old 03 October 2008, 17:14   #7
Member
 
Locozodiac's Avatar
 
Country: Other
Town: Lima-Peru
Boat name: Nautile
Make: Sea Rider 450 Rib
Length: 4m +
Engine: Tohatsu 5/18/30 HP
Join Date: Sep 2007
Posts: 1,998
Quote:
Originally Posted by Polwart View Post
loco - I think you would need to try it to see in your engine, but I doubt it will make a huge difference. as cod says there are differences in how octane is measured in the US and Europe so be cautious when comparing people's claims.
Pol, to compare will need to have 2 tanks available, one with 90, other with 95, get a gps and on very calm waters full throttle same given distances with both gasolines to compare: same or better performance. The 90-95 price difference is not a big pocket issue, the largest engine used is a 30 HP, can have a full day divertimento with just 3-95 gas/gal/oil for about $ 15.00. So will stick with 95 octane for the moment. Thanks for all inputs fellow boaters.

Happy Boating
__________________
Locozodiac is offline   Reply With Quote
Old 03 October 2008, 19:06   #8
Member
 
jambo's Avatar
 
Country: UK - Scotland
Town: Girvan & Tayvallich
Boat name: Breawatch
Make: Ribcraft
Length: 5m +
Engine: Mercury 150 F/stroke
MMSI: ex directory!!
Join Date: Sep 2008
Posts: 6,203
RIBase
gasoline octane &performance

I read the same at begining of the summer and checked with my mariner dealer who advised there was no benefit in running the higher stuff, the most important thing was the oil!
__________________
jambo is offline   Reply With Quote
Old 03 October 2008, 19:50   #9
Member
 
Locozodiac's Avatar
 
Country: Other
Town: Lima-Peru
Boat name: Nautile
Make: Sea Rider 450 Rib
Length: 4m +
Engine: Tohatsu 5/18/30 HP
Join Date: Sep 2007
Posts: 1,998
Quote:
Originally Posted by jambo View Post
I read the same at begining of the summer and checked with my mariner dealer who advised there was no benefit in running the higher stuff, the most important thing was the oil!
Maybe run the slight higher gasoline because of having better cleaning components as advertized by gasoline stations, but who really knows. Other issue, would both gasolines form the same amount of carbon builup inside engine ?
__________________
Locozodiac is offline   Reply With Quote
Old 03 October 2008, 19:56   #10
Member
 
jambo's Avatar
 
Country: UK - Scotland
Town: Girvan & Tayvallich
Boat name: Breawatch
Make: Ribcraft
Length: 5m +
Engine: Mercury 150 F/stroke
MMSI: ex directory!!
Join Date: Sep 2008
Posts: 6,203
RIBase
Quote:
Originally Posted by Locozodiac View Post
Maybe run the slight higher gasoline because of having better cleaning components as advertized by gasoline stations, but who really knows. Other issue, would both gasolines form the same amount of carbon builup inside engine ?
One of the things he did tell me to stay clear off was the supermarket fuel as it has to much sulphur in it and tends to go off quicker especially in deck tanks.
J
__________________
jambo is offline   Reply With Quote
Old 03 October 2008, 23:14   #11
RIBnet admin team
 
Poly's Avatar
 
Country: UK - Scotland
Boat name: imposter
Make: FunYak
Length: 3m +
Engine: Tohatsu 30HP
MMSI: 235089819
Join Date: Sep 2005
Posts: 11,622
Quote:
Originally Posted by Locozodiac View Post
to compare will need to have 2 tanks available, one with 90, other with 95, get a gps and on very calm waters full throttle same given distances with both gasolines to compare: same or better performance.
yes but bear in mind the benefit might be fuel ecconomy, or acceleration which won't show up so clearly on the GPS
__________________
Poly is offline   Reply With Quote
Old 03 October 2008, 23:32   #12
Member
 
Country: UK - England
Town: Sussex
Make: Ceasar Surfcat
Length: 4m +
Engine: Tohatsu 50hp
Join Date: May 2006
Posts: 105
Quote:
Originally Posted by jambo View Post
One of the things he did tell me to stay clear off was the supermarket fuel as it has to much sulphur in it and tends to go off quicker especially in deck tanks.
J
Id agree generally- but Tescos super unleaded is the 2nd best out there as far as tuning is concerned-the best is Shell's V Power. When ive been remapping ecu's on cars you can run a lot more ign advance with these fuels without any detonation occouring compared to any other "super" unleaded.
But as said before, you dont gain any performance on a std engine unless it has the ign timing altered and fuel leaned out to make use of the higher octain. Not all cars are mapped to run on low octain, I used to have a BMW M3 that stated in the manual that it should be filled with a minimum of 97 ron fuel(super unleaded).Jap import cars are also mapped for high octain.
As far as 2 stroke's are concerned(never tuned them for high output), im not sure whats best to do with the ignition as ive read in some cases its better to lower the advance(skimmed heads/high compression), and others to raise the advance.

Locozodiac-fill up with a tank of the good stuff and advance your ign a couple of degrees(easy to to on your Tohatsu's), lean the mixture out a bit(keep an eye on your plug colours) and you should get a crisper throttle response and gain a bit of power + gain a bit of fuel economy while you're at it!!
Just dont lean it out too far - again, keep checking the plug colours are OK.
__________________
Easyrider is offline   Reply With Quote
Old 04 October 2008, 13:53   #13
Member
 
Country: UK - Wales
Town: swansea
Boat name: Too Blue
Make: BLANK
Length: 8m +
Engine: Suzuki DT225
Join Date: Mar 2004
Posts: 12,791
Quote:
Originally Posted by jambo View Post
One of the things he did tell me to stay clear off was the supermarket fuel as it has to much sulphur in it and tends to go off quicker especially in deck tanks.
J

Believe that and you will believe anything - there are only a small handfull of refineries in the UK and the fuel can come from any of them. There are strict EU rules on fuel and it is all the same stuff excluding certain "special brews"!!!
__________________
codprawn is offline   Reply With Quote
Old 05 October 2008, 14:34   #14
Member
 
Locozodiac's Avatar
 
Country: Other
Town: Lima-Peru
Boat name: Nautile
Make: Sea Rider 450 Rib
Length: 4m +
Engine: Tohatsu 5/18/30 HP
Join Date: Sep 2007
Posts: 1,998
Quote:
Originally Posted by Easyrider View Post
Locozodiac-fill up with a tank of the good stuff and advance your ign a couple of degrees(easy to to on your Tohatsu's), lean the mixture out a bit(keep an eye on your plug colours) and you should get a crisper throttle response and gain a bit of power + gain a bit of fuel economy while you're at it!!
Just dont lean it out too far - again, keep checking the plug colours are OK.
Thanks for the imput, but all my Tohatsu's are running great with 95 octane, nice starts, acceleration, etc, and still factory adjusted. One issue that don't get clear, personally don't like to play with engine settings if engines are working ok, if need to, with a vernier measure all distances, gaps, etc and take a close-up photo on area before re adjusting, so in case need to put back as was before will do so with no prob.

Was the air gas mixture screw supposed to be just for idle (ralenti) speed adjustment only, as having un adjustable fixed air/gas inside jets according to manuals. Or this mixture screw works also when at any speed different from idle ? Any ideas.

The issue of taking the plugs out to see a brown like color, must be done after a full wot for some time, that is stop engine/take plugs out to check ? What moment would be the correct procedure to check this out ?

Happy Boating
__________________
Locozodiac is offline   Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off




All times are GMT. The time now is 22:34.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2024, vBulletin Solutions, Inc.