Octane boost or not!?!?

R

RazorRobb

New Member
Apr 23, 2008
113
Seattle WA
Does it work for you? I have a new 3.0 alpha 1 rated at 135h.p. in a 2000lb boat. I currently had 15 hrs. on it ( just broke in). I put 1 bottle of 104 octane boost in 21 gals. of gas( a full tank). My top end went from 47 to 49 m.p.h.. I know it's not a hi-po motor, but it still made a difference. I've done this experiment twice now and have gotten the same results. I'm going to experiment with a cheaper brand this weekend. If you have a V-8 or hi-po motor I'd try it.
 
What brand are you using?
What were you thinking of switching to?
I wouldn't put any additional in until you fill up again.
 
The tank is almost empty now, and it has untreated 87 octane Shell gas in it. I use the same fuel everytime( my companies gas card" it's a write-off"). I don't know what I am going to try. Probably a name brand on sale. It will be driven on the same lake in almost the same weather conditions. The weather don't change much around here. I always burn all my fuel before I add or change things. Oh. I believe the brand is called "104 octane boost" bought it at Shucks.
 
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RazorRobb said:
Does it work for you? I have a new 3.0 alpha 1 rated at 135h.p. in a 2000lb boat. I currently had 15 hrs. on it ( just broke in).
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Are you sure it's broken in at 15 hours?? I'd ease into things a bit more until I approached 50 to 100 hours and several oil/filter changes. My 250DA had a new 454 when I bought it from SR and they advised to avoid WOT for extended times and also avoid constant RPM cruising at the same RPM for I think 50 hours. As for the octane boost, doesn't it burn hotter:huh:? Not sure. Good luck
 
The mech at Lake Union Sea Ray advised me of a 10 hour break in period. It might not be fully broke in 'til 50 or 100hrs., but after 10 I can use it like I choose. I don't hammer on it much anyway. I juice it every now and then because it's fun and I can. Besides, I got a 6 year stem to stern warranty on it. I plan on trading it in around then anyway. The temperature guage stayed the same. the only thing that increased was the top speed.
 
An increase in octane in an engine that does not require it will provide no performance gain whatsoever. Increased octane allows an engine builder to increase the compression without experiencing detonation. If your engine does not experience detonation (and no stock Mercruiser will aside from the HP racing engines), anything over 87 octane is of no value.
 
That's what I thought, but you cannot argue with the results. Both times I tried it the top speed increased. The weather and boat loads were both the same or (constant). The only difference was the octane boost. I even bought the fuel at the same Shell station.
 
Are you relying on the speedometer in the boat for this research project that you doing? :huh:
 
Octane booster in a stock engine... it is impossible to increase power output; the volatility of fuel decreases as octane increases. This means you don't get a full fuel burn and you there for lose power. Something has got to be at play here other than the booster.
 
Yeah I agree Robb.
I think you're dumping $$$ into a 3.0L that for the rarely seen WOT is really not worth it.
I have added additive into my old Oldsmobile which had 11.25:1 Compression ratio and saw the results in putting a load on it.
The 3.0L really only needs 87 and it's too new to see benefits of injector/fuel system cleaner or Octane boost.

At the WOT under full load the reason you may have seen benefits is only because the higher octane may have burned slightly more consistently but not at a higher HP level.

That's why I asked what you were using. A 104 Octane additive diluted into 22 gallons of gas really is like sprinkles on a cupcake. If you had that thing warped into a 3.0L on steroids with higher compression then would see the benefits of running without pre-detonation.

That little engine isn't made for more than Merc has already tested it for.

A "High Five" stainless prop (if you don't have one already) is a nice little upgrade ...but not sure you can "write that off" :grin:
 
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I think the old adage of "There's no replacement for displacement" applies.
I am not trying to be a jerk with that comment, but all engines have there limit. Break your engine in nice and easy with varying speeds, so that the rings seat in the cylinders evenly. You don't want pre-mature engine failure from exceeding the designed specs. I am sure that there are exclusions in the warranty just like an insurance policy. Don't be on the wrong end of that with Merc.

The mercury marine website has a FAQ sheet about how to get more out of your engine.
 
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You don't need Octane Booster if the engine isn't pinging. I don't know what, if any, connection there is between the higher top speed and the Octane Booster, but for the few times you are going to run at WOT is it really worth the price of the Octane Booster?
 
330DA said:
I think the old adage of "There's no replacement for displacement" applies.
Click to expand...

Somewhat true, but technology has really played a big role over the last 5-7 years in getting more horsepower from the same displacement. For example, the engine I have gained 40HP when it went from carbs to Fuel injection -- displacement stayed the same of course. Getting cleaner, colder air into the engine can also give you more horsepower. Interestingly, the octane level of fuel will NOT give the engine more horsepower but will improve detonation quality which is critical when you increase compression ratios within the engine.

Octane and sparkplugs affect detonation quality.... but air temp, air pressure, displacement, exhaust system, fuel type, fuel delivery, etc. affect horsepower.

That being said, nothing wrong with adding octane boost if you like to, especially if you run WOT often..
 
I'm going to give it another run with and without to see if there's a difference. I've never been an advocate of octane boost, but if it works, use it.
 
"Getting cleaner, colder air into the engine can also give you more horsepower"

Interesting point Gerryb. For those of us who live in cold climates, did you ever notice how much hp gains we get in our cars in winter? Air coolers have been around for decades. Why are they not stock on engines today? They don't have to. The average auto consumer doesn't know better and most don't care about performance over reliability anyway. As for boat engines, same thing, the average boat owner doesn't know better, but if they knew the benefits of increased hp on the water the demand would force manufacturers to incorporate the technology.
 
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