1992 290da 7.4 31 mph ?

Quint4

Quint4

Well-Known Member
TECHNICAL Contributor
Oct 6, 2006
6,751
NC
Boat Info
CY 3375
Engines
7.4 MPI twin
My 290da 7.4 454 Bravo II ( bottom painted ) achieves 4400 rpm at WOT throttle and 31 mph lightly loaded with 1/2 tank of fuel. The WOT throttle rpm is in range but is 31mph about right or slow ?
 
That is a big boat for a single engine. I have a 7.4 in a 1993 270 weekender. top speed is around 40-42mph with a 17 1/2" 23P prop at 4600 rpms.
 
Quint4 said:
My 290da 7.4 454 Bravo II ( bottom painted ) achieves 4400 rpm at WOT throttle and 31 mph lightly loaded with 1/2 tank of fuel. The WOT throttle rpm is in range but is 31mph about right or slow ?
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We had a 90 270 (twin to yours) with the same power ,however ours was Bravo 1.I was able to squeeze 43 mph by trimming out.Remember you are swinging a much bigger prop(diameter) and a much bigger gear case.A close friend has a 94 290 same power package as yours,he gets 37 mph .Try trimming the drive out some see if you get a few more MPH.You can also see if your trim limit switch is set too low by using the trailer switch in short bursts after your range using the trim switch runs out.Once the drive cavatates trim in.
 
Thanks everyone..it sounds like I am not too far off with 31mph with a carbed motor and a painted bottom ( and a 15yo boat ). The aluminum prop on the boat is looking tired. It has a good ding on the edge. I may get out the check book and get a Stainless ( $540 ) .
 
I am using a 17.75 X 21 aluminum. Thanks for the link to the stainless for $500. I also have a gennie which adds some weight.
 
at WOT with two of those engines, i can get my pig up to 30mph! but the floscans are just about maxed out (they stop at 32gph on each engine). needless to say, i dont spend much time at that rpm! :smt089
 
rondds said:
at WOT with two of those engines, i can get my pig up to 30mph! but the floscans are just about maxed out (they stop at 32gph on each engine). needless to say, i dont spend much time at that rpm! :smt089
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60 gallons per hour and 1/2 mile per gallon, I swear the oil companies invented boating as a way to increase sales! Even dropping back to your optimum cruise, it's probably about double the mileage and half the fuel use. I've GOT to get some oil stocks!!
 
in the pic you see below, i'm chugging along at about 18.5 mph, burning about 27gph (total) and making about 0.7 MPG. with all the idle speeds and time, i average about 20-21 GPH for the entire season.
 
Sorry that was a gps speed...I pay no attention to boat speedometers. I hope to run at WOT only once a year just for the hell of it !
 
Quint4 said:
Sorry that was a gps speed...I pay no attention to boat speedometers. I hope to run at WOT only once a year just for the hell of it !
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I do it twice a year and for a good reason! Once in the spring to see what my top speed and WOT rpms are and then again at the end of the season to see if anything has changed. I only do it for about 30 seconds or so and watch the GPS to see if the speed is still climbing or not. It takes about that long to get it up to speed and trim it out. Once done, I log it and I can compare it to the prior year or earlier in the year. I've got over 240 hours since the last tune-up and I really noticed a change fall on the 250 DA. So, first thing on the books is a tune up! I try to pick a calm day and make notes regarding who's aboard and the load so that I have some benchmark for comparison. It's a quick and easy barometer!
 
Is there a difference in hull design from say an early 90's sundancer to late 90's sundancer? 31 just seems slow for some reason, no?

Doug
 
There was a name change in 92 or 93? I can't remember. In 90 - 91 or 92 it was labeled the 270. In 92 or 93 through the next few years the exact same boat was labeled a 290. That might explain some of the variation.
 
Sundancer said:
There was a name change in 92 or 93? I can't remember. In 90 - 91 or 92 it was labeled the 270. In 92 or 93 through the next few years the exact same boat was labeled a 290. That might explain some of the variation.
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I thought it went down from 270 to 260 after 1992.... something about counting the swim deck (maybe they added it and it did go to a 290...)
 
That's the funny part. The 91 270 and the 94 290 are the same boat. I know they change things and lengths just to mess with your head. In 1990 the swimplatform is no longer a bolt on, it's an integral part of the hull. My 300 DA is an 89 and I think it was the last year they did that. So in 94, the 270 is the same as the 91 250. The whole product line changed like that and it's confusing!
 
My 350 EB 1992 Hull became the 370 Hull in 94 or 95
I run 31 MPH on the GPS at 3100-3200 RPM
Top out at around 39-40 MPH at 4000 RPM
Can't stand to see the gas gauge move faster than the tach! :smt089
Hoping my 8'6" dinghy with 6 hp outboard likes to see a lot of use this summer!
Dan
 
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