270 OUTRAGE Twin Engines: Engine RPM at WOT

Optimizing the performance of Boston Whaler boats
D4655
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270 OUTRAGE Twin Engines: Engine RPM at WOT

Postby D4655 » Fri Mar 10, 2017 6:26 pm

I am a newbie to this forum (so thank you for reviewing my post) and am in the process of purchasing an [2007] 270 Outrage, which has been maintained well and whose engine[s] passed compression tests, but [the boat] failed a survey. The surveyor could only get 4800-RPM at WOT with 19-pitch stock four-blade stainless-steel propellers.

The seller is arguing that [during the test the boat] wasn't trimmed properly. I haven't had experience with twin outboards only twin sterndrives. A 270 with twin 225-HP engine should be able to produce more than 4800-RPM with fully-[trimmed]-down engines--shouldn't it?

Any help or experience is greatly appreciated.

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Phil T
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Re: 270 OUTRAGE Twin Engines: Engine RPM at WOT

Postby Phil T » Fri Mar 10, 2017 9:12 pm

There are a lot of variables:

What was the fuel load?
Were all the wells, lockers empty?
Holding tank full or empty?
All the plugs inserted?
Bilge dry?

What was the sea state? Winds, current?
If the motors are not trimmed out it will greatly affect performance.

Easiest way to do it:

When you get on plane, 3/4 throttle, you trim motors out until GPS speed stops increasing or you start to bounce. If you increase throttle, trim in a bit then back out watching GPS speed.

You will also see the boat wake change too, flatten out as the boat attitude changes.

Drive the boat again yourself.
270outrage2.jpg
270outrage2.jpg (71.84 KiB) Viewed 8295 times


A review in one boating mag says:

Despite the crowd, the 270 stepped out nicely, with the twin 200-hp Mercury OptiMax outboards pushing us through the two-footers on our way offshore. According to the manufacturer's figures, the 270 turns 40.6 mph cruising at 4000 rpm while burning 10.5 gph, and tops out at 54.7 mph at 5500 (wide-open throttle), burning 21.6 gph.


cf:http://www.saltwatersportsman.com/boats/boat-reviews/boston-whaler-270-outrage-0
1992 Outrage 17
2019 E-TEC 90
2018 LoadRite 18280096VT
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jimh
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Re: 270 OUTRAGE Twin Engines: Engine RPM at WOT

Postby jimh » Fri Mar 10, 2017 9:53 pm

It's helpful when asking for comments about engine performance to mention the model of the engine. Is the boat we are discussing equipped with twin VERADO 225-HP engines?

If that presumption is correct, then the report from your surveyor that the engines could only accelerate to 4,800-RPM is troubling.

According to Mercury specifications, the wide-open throttle engine speed for VERADO L6 engines should be in the range of 5800 to 6400-RPM. For the engine to only be able to accelerate to 4800 is far off the mark. The target at WOT should be at least the mid-point of the suggested range, thus about 6,100-RPM. This boat is far from that mark. Can that significant difference be blamed on engine trim setting? I don't know how to judge that. I cannot image there would be another 1,300-RPM to be achieved with just a change in trim.

If the owner thinks the surveyor didn't know how to drive the boat, why didn't he correct the trim himself? (I assume he'd go along on the sea trial.)

If the boat has twin OptiMax engines, well, all bets are off.

ASIDE: is there an on-line archive of the original performance report from Boston Whaler for this boat? I searched for one but couldn't find it.

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Phil T
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Re: 270 OUTRAGE Twin Engines: Engine RPM at WOT

Postby Phil T » Fri Mar 10, 2017 9:55 pm

Aside: I searched BostonWhaler.com as well as Webarchive.org for the years 2007-09 and could not locate the PDF.
1992 Outrage 17
2019 E-TEC 90
2018 LoadRite 18280096VT
Member since 2003

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Don McIntyre - MI
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Re: 270 OUTRAGE Twin Engines: Engine RPM at WOT

Postby Don McIntyre - MI » Sat Mar 11, 2017 4:33 pm

First thought I had was is a 19" the proper pitch for the motor and boat weight? I'm with Jim regarding the supposed lack of proper trim; yea, it could make a difference, but not that much.

If you can, I'd reschedule and try running on only one engine. You may have to get up on plane, back off on one and go to neutral, kill it and raise the engine. Go WOT on the running, and note the top RPM. Stop, drop the off engine. Start and repeat. What you want to achieve is max WOT with only one engine. The chances of two motors (if bad) only able to achieve the same WOT top rpm would be pretty rare. If they both top out at the same, within a few hundred RPM, I'd look towards an incorrect rigging concern (wrong pitch, motors mounted too deep), weight of boat, condition of the wetted surface, etc.

Regards - Don

conch
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Re: 270 OUTRAGE Twin Engines: Engine RPM at WOT

Postby conch » Sun Mar 12, 2017 1:15 pm

D4655, not sure what you mean by "stock propeller" but turning 19in FOUR blade props could be asking too much from that combo.
Certainly not a deal breaker, let the seller have corrections made to your satisfaction regarding WOT RPM. Common 4 blades for that rig are the Mercury Rev 4 in 17in. not 19in. How was the hull bottom? Need to start with which engines you have and mounting height. Good compression is well "good", but a lot more info is needed for a better answer on a lack of performance at WOT.

Chuck

D4655
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Re: 270 OUTRAGE Twin Engines: Engine RPM at WOT

Postby D4655 » Wed Jan 24, 2018 6:11 pm

Circling back around, I wanted to thank everyone for their input and report the findings...better late then never, and in case someone else stumbles across this situation. As it ends up, there was a problem with the supercharger leaking. WIth the cowling removed a mechanic could quickly identify the whistling leak. WIth some minor repairs we were able to move through the deal. What I found once I owned the boat is that there is a pretty significant change in RPM from trimming this boat out. WIth twin 225 Verado’s and a light load (50 gallons of gas and only safety equipment), with the motor trimmed all the way down, 4500 rpm’s is about all I could get (all other conditions relatively neutral: wind, waves). WIth the boat properly trimmed, 5900 was obtained and approximately 51 mph. Thanks his was pretty standard for this package especially considering 700 hours on the engines. Thanks again

heatxcape
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Re: 270 OUTRAGE Twin Engines: Engine RPM at WOT

Postby heatxcape » Fri Jan 26, 2018 2:20 am

I recently sold my 2006 270 with Merc 225 opti’s, which was able to hit 58mph trimmed up at 5800 rpm without any problems, full load 4 adults. OptiMax engines are 125-lbs lighter than the VERADO, but she ran great.