MPG, prop, and hole placement questions on 208 F225 combo

awp

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I recently repowered my 208 with an F225. I tried the 15 1/4 by 17 prop from the old OX 66 first and it over revved with WOT at 40 mph and 6100 with some throttle left to go. I switched to a 15 1/4 by 19 michigan wheel and now get 45 mph at 5700 with a full tank of gas. Problem is this - the mpg figures don't look any better than about 3.3 at cruise of 3500 or 4000 or 4500. I had expected more like 4 mpg judging from the Grady "performance data" of such a combo. Question - what kind of mpg do you guys with similar combos get? Which prop do you use? Which hole do you have the F225 mounted in?
 

GWcpa

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I've never figured out how they got those numbers for the perfomance data on the 208. The fuel flow figures are too low.

The F225 /205 Tournament figures are more accurate.

I have a mirage+ 15 1/4x17 and get 3.7 max mpg at cruise and a wot of about 43 mph/5900 with my F200. This is better than I got with a yamaha SWS prop of the same pitch.

I think a Mirage+ 19 would give you slightly better performance and rev closer to 5900 with better bow lift. Bow lift on this hull improves efficiency in calm water.
 

CJBROWN

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The 225 is a big motor. I thought it would get you closer to 50. These hulls obviously are not fast hulls no matter the power. Looks like you've found a good prop for your combination. I wonder what a SSII would do for you in the 15-1/4X17 size. They have a pretty aggressive cup. What kind of prop was on your OX?

My little F150 turns 5800 for 38.5mph with a stock aluminum, 15-1/4x15. I run about 4300 for 27mph cruise, but I have no idea what my burn is. I know I can make a LOT of trips on that 85 gallon tank!

I sold off my stainless in the same size as it chattered at idle when in gear - very annoying and can't be any good for the gearset. I guess the weight is too much on the drive gears. I wonder if this is the cause of this well-known ilk of the fourstroke yamahas that everyone complains about. BTW, the SSII is not recommended for the F150, but the reliance is.

I tried a number of props hoping to get to 40mph and cruise at 30. The best performance was a Reliance 14-7/8 X 17. I picked up about one mph at wide open and at cruise, but still a hair short of my target. It just wasn't worth the $600 so I went back the aluminum.
 

awp

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Thanks for the tip on the Mirage 19, GWcpa - I'll check it out. And - I'm beginning to believe I've been "had" by believing the "performance data" figures for the 208. You are right the 205 mpg figures are more like what I'm getting. I see the point about bow lift but I'm wondering if I have too much since mine was "porpoise - ing" up and down in calm water until I added a little trim tab in.

CJBrown the prop on the the OX 66 had the characters "M 17" on it and I looked it up and I think I remember it was a standard issue prop for that motor and year - a SWS probably. Glad you mentioned the chatter - I have a friend whose F200 sounds like it is clanking and clunking and about to fall apart when at idle. Hope mine doesn't start doing that, cause I can't use an aluminum prop around here - the sand will eat it up before breakfast. Are you saying that the SS prop was causing or contributing to the clanking?
 

CJBROWN

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awp said:
>snip
Are you saying that the SS prop was causing or contributing to the clanking?

Totally. It started when I put it on and it quit when it took it off. If you bump up the R's to 800 or so it goes away, so that's what I got into the habit of doing. At the idle throttle stop at 650 or so, it chatters like crazy. Not only is it annoying, it can't be any good for the gears. Any docking maneuvers have a lot of idling in gear, as well as for trolling.

I have heard good things on Mercury props but have no first hand experience with them. I was told the Revolution-4 is the prop for the F150, but never had the chance to try one. They're a four-blade which supposedly is for high speed work, like for a bass boat.
 

BobP

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The F gets mounted in same hole as your former engine, presuming it was done correctly originally.

There's more talk on the F gear case rattling over at Andy's on THT.
 

Parthery

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My 205/F225 combo would turn 5900 and 46 mph with the 15.25x17 SWSII Prop. I was nowhere near the 48-49 mph that GW says I should see. Best fuel economy was 3.7 mpg at about 32 mph.

Past experience with the Mirage prop (on my 226) resulted in an increase of 2-3 mph. Although I sold the 205, I would have liked to try the Mirage on it...I think the boat would have gotten close to 50.

The 209 is the lightest of the 3 hulls...but also potentially has the most wind drag if you have a t-top. The 208 is heavier because of the cabin.
 

captbone

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My 2 cents.

I would suggest the following props

20pitch Enertia

19pitch Mirage Plus

17pitch Revolution 4
 

fishhrd

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I just repowered a 209 with a 225 honda and my top end is 43. I was expecting something near 50 but it will not get close. I cruise at 4400 rpm burning 12 gph running about 35 mph. My prop is a 14 1/4 by 19 but I am going to try a 14 1/4 by a 17 to get my rpm's up.
These hulls are not made for speed that's for sure.
 

awp

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Thanks for all the info guys! It is becoming more clear to me that I can't expect better mpg than the mid 3's with my current set up. The report from fishhrd convinced me - if Honda isn't getting much better then I won't either.

I heard back from Grady customer service and they said the performance "data is seven years old and we will try and update it this spring". Sounds like a recognition that there may be a problem. Oh, and they also said "whoever said it was correct" in pointing out the 205 "data" figures are more realistic for this combo. Thanks, GWcpa for pointing that out.

Let's go fishing!!!!
 

GWcpa

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Now that I think about it, I wrote 19' Mirage plus, but I doubt you could turn that 5900. I'd probably go with a 17" Mirage Plus for better midrange efficiency. I had 19"s on my 232. doh.