I recently purchased a 1990 175 HP Johnson. What octane fuel should I use? 87,89,91?
C cddetelich Petty Officer 3rd Class Joined Oct 7, 2004 Messages 99 Dec 2, 2005 #1 I recently purchased a 1990 175 HP Johnson. What octane fuel should I use? 87,89,91?
W walleyehed Admiral Joined Jun 29, 2003 Messages 6,767 Dec 2, 2005 #2 Re: fuel octane If it's not a GT 175, I'd run 87 only..<br />I'm not against 89 in a GT/XP, but I can't say I have noticed any difference, so I run 87 in my XP.
Re: fuel octane If it's not a GT 175, I'd run 87 only..<br />I'm not against 89 in a GT/XP, but I can't say I have noticed any difference, so I run 87 in my XP.
P phantoms Petty Officer 1st Class Joined May 14, 2005 Messages 246 Dec 2, 2005 #3 Re: fuel octane As far as I know, the GT is only an "appearance" package, thus requiring no different fuel than a non-GT.
Re: fuel octane As far as I know, the GT is only an "appearance" package, thus requiring no different fuel than a non-GT.
J jy118lfd Chief Petty Officer Joined Jun 18, 2004 Messages 497 Dec 5, 2005 #4 Re: fuel octane Gt/xp motors have different carbs and heads as well as 200 porting on some models
W walleyehed Admiral Joined Jun 29, 2003 Messages 6,767 Dec 5, 2005 #5 Re: fuel octane Yes, Jon, you're correct. The GT/XP 150/175 uses the 200 Block with different carbs. They also have high compression heads, and some have timing advance as high as 34 degrees insted of 26-28.
Re: fuel octane Yes, Jon, you're correct. The GT/XP 150/175 uses the 200 Block with different carbs. They also have high compression heads, and some have timing advance as high as 34 degrees insted of 26-28.
P phantoms Petty Officer 1st Class Joined May 14, 2005 Messages 246 Dec 8, 2005 #6 Re: fuel octane Is the 89 100GT the same (uses different carbs, etc.), or is just an apperance package and the same as the non-GT 100 of that year?
Re: fuel octane Is the 89 100GT the same (uses different carbs, etc.), or is just an apperance package and the same as the non-GT 100 of that year?
W walleyehed Admiral Joined Jun 29, 2003 Messages 6,767 Dec 9, 2005 #7 Re: fuel octane I don't know about the GT 100, but I would guess it's a 115 under cover.....
