Tikotiko

  • Karma: +0/-0
Octane choice
« on: June 29, 2020, 05:38:50 PM »
Quick question. I got into a discussion today at work. This dude was telling me he has to run 91 octane on his stock 460 for his boat. I told him i run 87 because the previous owner told me thats what he ran and it doesnt matter if I put in it, its gonna eat it up regardless.
I have a 460 with a rv cam. What should i be running but most importantly Why?
I dont know anything about my compression thanks guys

Sent from my SM-G975U using SoCal Jet Boats mobile app

  • Like
    Dislike
    Love
    HaHa
    Angry
    Surprise
    Sad
    Party

angermgmt

  • Karma: +8/-0
Re: Octane choice
« Reply #1 on: June 29, 2020, 05:41:51 PM »
Compression?


Sent from my iPhone using SoCal Jet Boats
  • Like
    Dislike
    Love
    HaHa
    Angry
    Surprise
    Sad
    Party

Tikotiko

  • Karma: +0/-0
Re: Octane choice
« Reply #2 on: June 29, 2020, 06:03:27 PM »
Compression?


Sent from my iPhone using SoCal Jet Boats
I wish i knew

Sent from my SM-G975U using SoCal Jet Boats mobile app

  • Like
    Dislike
    Love
    HaHa
    Angry
    Surprise
    Sad
    Party

angermgmt

  • Karma: +8/-0
Re: Octane choice
« Reply #3 on: June 29, 2020, 06:22:04 PM »
Be safe go 91


Sent from my iPhone using SoCal Jet Boats
  • Like
    Dislike
    Love
    HaHa
    Angry
    Surprise
    Sad
    Party

Tikotiko

  • Karma: +0/-0
Re: Octane choice
« Reply #4 on: June 29, 2020, 06:52:17 PM »
Be safe go 91


Sent from my iPhone using SoCal Jet Boats
Ok will do thank you

Sent from my SM-G975U using SoCal Jet Boats mobile app

  • Like
    Dislike
    Love
    HaHa
    Angry
    Surprise
    Sad
    Party

Tikotiko

  • Karma: +0/-0
Re: Octane choice
« Reply #5 on: June 29, 2020, 07:02:48 PM »
Be safe go 91


Sent from my iPhone using SoCal Jet Boats
Found some info on the cam. 8.4.1 compression ratio.

Sent from my SM-G975U using SoCal Jet Boats mobile app

  • Like
    Dislike
    Love
    HaHa
    Angry
    Surprise
    Sad
    Party

FordLover

  • Karma: +72/-0
Re: Octane choice
« Reply #6 on: June 30, 2020, 11:17:02 AM »
Be safe go 91


Sent from my iPhone using SoCal Jet Boats
Yep. 91 in a boat for sure.

Sent from my LG-TP450 using SoCal Jet Boats mobile app

  • Like
    Dislike
    Love
    HaHa
    Angry
    Surprise
    Sad
    Party

96Laveycraft21Xt

  • Karma: +0/-0
Re: Octane choice
« Reply #7 on: June 30, 2020, 12:10:26 PM »
my factory marine power 454 has " 8:0 " compression.  more likely 7.8. i always run 87 no problems there. 


The ONLY way to know what you need, is to know your compression. 

you can also do a compression check to get a feeling for cylinder pressure and work backwards with the cam from there.

and for all those that say "always 91 in a boat"  just remember that if you dont have enough compression, the motor will actually perform WORSE with the higher octane.

Second - altitude makes a big difference too as the air, and therefore compressed air is less dense. Thats why places with high elevations offer 85 octane fuel at the pumps.

where are you boating? 

  • Boat #1: '96 Laveycraft 21' XT Ski
  • Like
    Dislike
    Love
    HaHa
    Angry
    Surprise
    Sad
    Party

Tikotiko

  • Karma: +0/-0
Re: Octane choice
« Reply #8 on: June 30, 2020, 01:17:59 PM »
my factory marine power 454 has " 8:0 " compression.  more likely 7.8. i always run 87 no problems there. 


The ONLY way to know what you need, is to know your compression. 

you can also do a compression check to get a feeling for cylinder pressure and work backwards with the cam from there.

and for all those that say "always 91 in a boat"  just remember that if you dont have enough compression, the motor will actually perform WORSE with the higher octane.

Second - altitude makes a big difference too as the air, and therefore compressed air is less dense. Thats why places with high elevations offer 85 octane fuel at the pumps.

where are you boating?
Lake perris and hopefully the river soon

Sent from my SM-G975U using SoCal Jet Boats mobile app

  • Like
    Dislike
    Love
    HaHa
    Angry
    Surprise
    Sad
    Party

96Laveycraft21Xt

  • Karma: +0/-0
Re: Octane choice
« Reply #9 on: July 01, 2020, 04:59:41 PM »
Nice! maybe ill see you at Perris soon, if they dont close it back down

for reference, at the same temp - say 100*f , my boat will pull about 100 - 150 rpm less at Perris then at Parker.  Pulls 250 rpm less at Powell then Parker.
« Last Edit: July 01, 2020, 05:04:52 PM by 96Laveycraft21Xt »
  • Boat #1: '96 Laveycraft 21' XT Ski
  • Like
    Dislike
    Love
    HaHa
    Angry
    Surprise
    Sad
    Party

 


Null

SMFPacks CMS 1.0.3 © 2020