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89 mid cabin performance
Posted: Sat Nov 26, 2022 9:12 pm
by mrrudely
hey guys
I recently pulled out the Trojan manual that's kept on the boat
and saw a performance page
however it seems it has nothing to do with reality
I am not seeing the mid cabin numbers listed but it does have the express listed
and the sedan and aft cabin combined listed separately
numbers are as follows:
@2500rpm 17mph 21gph (express)
13mph 21gph (sedan and aft cabin)
@2400rpm 12mph 20.1gph (my average)
@3000rpm 23mph 26gph (express)
19mph 26gph (sedan and aft cabin)
@3000rpm 16mph 37gph (my average)
@4000rpm 35mph 52gph (express)
32mph 52gph (sedan and aft cabin)
@4000rpm 23mph 48gph (my average)
I have 454's with carburetors and HEI distributors all running well
W.O.T. is about 4200rpm
thanks for any feedback
rr
Re: 89 mid cabin performance
Posted: Sun Nov 27, 2022 9:04 am
by prowlersfish
I was trying to find my specs on the mid cabin with no luck yet. Do to the set up on the mid-cabin I would expect to to be a bet slower than the express. shaft angle and smaller props maybe a factor. Trojan specs were optimistic. ( like everyone elses) And test were done under perfict conditions and fuel burn was calculated using engine manufactures spes. With that said your seems a tad slow. 4200rpm at wide opens is great.
Things to look at prop condition, having them scanned and tuned to class A can do wonders.
Bottom condition?
4200 rpm at wot is where your what to be, Is props size at stock or slightly less? Or are the way less?
The amount of gear on board?
/
Re: 89 mid cabin performance
Posted: Mon Nov 28, 2022 4:45 am
by RWS
It's all about weight
think about the options:
- generator
microwave
2nd anchor
chain rode
all that furniture/wetbar/icemaker in the cockpit
spares
tools
and any other options not listed equates to a whole lotta weight
They likely tested these boats with one skinny guy and a coast guard kit !
BEST !
RWS
By the way, here's my new to me boat:

- IMG_4498.JPG (88.91 KiB) Viewed 6155 times
Re: 89 mid cabin performance
Posted: Mon Nov 28, 2022 10:24 am
by BobCT
Harris, that new boat looks great!
For the mid cabin, I have years of video showing fuel burn/speed at different RPM's (both 454's and now my 8.1's). I posted that before, let me see if I can dig it up. Yes, 4,200 is ideal, 4,000 is probably close enough. The thing with the mid cabin is once you get over 3,500 it's a whole lot more fuel and very little payback in speed and the flo scans just max out. I really only pay attention to fuel burn at cruise and above so I don't have much at lower RPM's. I have my Garmin set to knots.
Looking at your data below, 16 MPH is 18.4k and that's damn good at 3,000 RPM's. At 4,000, 26k+ is about right as well. With my 454's, I was happy at 17k burning 32GPH. Maybe your fuel burn is a touch higher but I think you are right in the ballpark.
@3000rpm 23mph 26gph (express)
19mph 26gph (sedan and aft cabin)
@3000rpm 16mph 37gph (my average)
@4000rpm 35mph 52gph (express)
32mph 52gph (sedan and aft cabin)
@4000rpm 23mph 48gph (my average)
Bob
Re: 89 mid cabin performance
Posted: Mon Nov 28, 2022 8:49 pm
by mrrudely
thanks guys
not sure if I feel better or worse
I'll just have to live with it
rws-
awesome!
I'm jealous
what model is it?
rr
Re: 89 mid cabin performance
Posted: Tue Nov 29, 2022 7:17 am
by RWS
Was very difficult for me to do this, especially after sneering at this brand for years.
Boy oh boy, did I get an education on these boats
this is a 1996 450 Sundancer running CAT 3126 - 420 horse diesels
posting some info and data - whups - can't attach a pdf
KNOTS - NOT MPH - THIS IS MY ACTUAL DATA
.90 NMPG @ 23.6 kts - WOW
then throttle back to 17 kts and the NMPG goes up to 1.10 NMPG
apologies for the hijack
RWS