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  1. #1
    Member
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    Mar 2008
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    Uxbridge, ON
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    2016 21TRX with 300 Pro XS V8 repower

    I've been getting quite a few PM's asking about the performance of my new 300 Pro XS 4.6L V8.
    Thought I'd take a few mintutes to update my progress so far with my new motor setup and performance.
    I wasn't sure which section to post in, so since I've got a Triton, I put it here.
    I apologize in advance for this being a little long winded. I did pare it down quite a bit.


    I did the initial 2 hour break in last Sunday, following break in procedure to the letter. When it
    came time to go WOT, I could only spin motor to 5000 rpm (56 mph). I just assumed that I was overpropped
    with the 26p Fury 3 blade off my old motor.
    Even though I no top end, hole shot was incredible. I was up on plane in 3 to 3.5 seconds.
    I always start with jackplate all the way up and motor tucked in. I could really feel the increase intorque from my 2 stoke.
    The motor had strong acceleration all the way to 5000 rpm.
    (found out the next day my throttle wasn't calibrated and only had 80% power)


    Went back out Tuesday to put some more time on the motor and test some props.
    I started with a stock 25p Tempest Plus with 3 large plugs.
    Hole shot was the same (3 to 3.5 seconds to get on plane).
    Spun it up to 6000 rpm and hit 74 with little effort. I didn't push it past this point as I was just past
    the 2 hour portion of the break in.


    I did notice that the boat had a completely differant feel than with the 2 stroke. Seemed to be a little
    more squirrely and took more effort controlling the chine walk. Previously the boat had very little bow
    lift and drove very flat like some Rangers I've been in. Had plenty of bow lift now, not sure if its
    because of motor or the addition of 2 degree wedges or a combination of both.


    I swapped out the prop back to my old 26p Fury 3 blade and the motor still had excellent hole shot and acceleration.
    I got to 6000 RPM and 75 mph and suddenly there was a god awful loud rattling noise coming from the engine.
    Scared the crap out of me as I assumed the worse and thought I had blown my new motor to bits.
    I backed off the throttle and the noise disappeared.
    I checked the motor and everything seemed fine. I accelerated again whle my buddy watched the motor.
    Hit 6000 rpm and 75 mph and the rattling came back. Turned out that my port power pole was catching spray
    and the spike was pulling away and slapping back into place. This never happened with my 2 stroke.




    Anyway, so far I am very pleased with the performance of the new motor. It pulls alot harder than my 2 stroke
    and gets the boat up to speed alot faster. The motor sounds pretty cool at start up. It has a very throaty growl
    to it. My buddy compared it to a small block chevy on a muscle car.


    Mercury Tech told my that once the motor loosens up, I should gain another 150 or so RPM's, so I think I'm close
    with either prop. As I said before, the boat feels and acts completely differant so I'm going to have to
    play with trim and jackplate to get my best setup (and raise my power poles). I am optimistic that I will
    get close to breaking the 80 mph mark once I get the setup right.


    2016 Triton 21TRX dual console
    2018 Mercury 300 Pro XS 4.6L 4 stroke
    2 power pole blades
    45" 36 volt Ultrex
    10" Bob's hydraulic jackplate
    2 degree positive wedges
    4 AGM batteries
    Dual 9" Lowrance GEN 3's at console
    12" Lowrance GEN 3 at bow
    Vessel View Link displayed to Lowrance


    Windy with a slight chop
    Water temp 71.9 f
    water pressure 4 psi at idle
    water pressure pegged at 30 psi WOT
    3" p2p
    26p Fury 3 blade (b&b'd with some cup added)
    6000 rpm @ 75 mph
    2 people (350 pounds)
    3/4 tank of fuel
    med load


    I will update stats once I get my setup fine tuned.

  2. Sheepdog mike464's Avatar
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    Mar 2005
    Location
    alberton montana
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    #2
    That's great to hear, thanks for the review. It will ease a lot of minds and I wonder what the 250 4 stroke will do compared to a 250 Optimax. Lift is what the Optimax powered TRX21 lacks.

  3. Member
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    May 2018
    Location
    Limestone, TN
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    1,297
    #3
    Interesting read. Would enjoy checking the setup out and hearing the motor.

  4. Member
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    May 2007
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    slo
    Posts
    812
    #4
    The difference between a 26 fury and 25 temp is more like 2". You should try a 25 fury or a 26 temp. What rpm does it rev to on the holeshot?

  5. #5
    Awesome! Please keep us up to date on your progress. What were you getting on top end out of your 2 stroke 250 XS?

  6. Member
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    Mar 2008
    Location
    Uxbridge, ON
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    102
    #6
    Quote Originally Posted by leo13 View Post
    The difference between a 26 fury and 25 temp is more like 2". You should try a 25 fury or a 26 temp. What rpm does it rev to on the holeshot?
    All I could get my hand on besides my 26 Fury was a 24 Fury and 25 Tempest Plus. I'll try more props if I can find them. Wasn't really paying attention to RPMs on holeshot. Will pay more attention next time out.

  7. Member
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    Mar 2008
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    Uxbridge, ON
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    #7
    My 2 stroke 250 Pro XS topped out at 74.3. The midrange seemed awful and took a long time to get up to speed. New motor was alot quicker to get up to speed. Still had room to play but backed off when the power pole spike started slapping against the arm.

  8. Member
    Join Date
    Jul 2004
    Location
    Lacoochee , Florida
    Posts
    2,676
    #8
    Quote Originally Posted by monkeyfish View Post
    My 2 stroke 250 Pro XS topped out at 74.3. The midrange seemed awful and took a long time to get up to speed. New motor was alot quicker to get up to speed. Still had room to play but backed off when the power pole spike started slapping against the arm.
    My poles have done that sounds like a tin can rattling.

    Rick Someillan
    Lacoochee, Florida
    2016 21 TRX
    250 Pro XS

  9. Member
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    Mar 2008
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    Buchanan TN
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    5,530
    #9
    How did you get past max hp for that boat? My 20x2 says only max 250hp.

  10. Member
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    Mar 2008
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    Uxbridge, ON
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    102
    #10
    21 TRX is rated for up to 300HP

  11. Member
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    Jul 2004
    Location
    Penn PA
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    15,104
    #11
    What is the weight of the motor according to the sticker on the motor?



  12. #12
    I think the new V8 motors may be about the same speed as the two stroke motors but where they shine is hole shot and acceleration...Good thing you went with the 300!

  13. Member
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    #13
    Quote Originally Posted by Savage View Post
    What is the weight of the motor according to the sticker on the motor?
    IMG_20180615_083528-480x640.jpg

  14. Member
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    Mar 2008
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    Uxbridge, ON
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    #14
    Quote Originally Posted by bassmasterffej View Post
    I think the new V8 motors may be about the same speed as the two stroke motors but where they shine is hole shot and acceleration...Good thing you went with the 300!
    I'm hoping to get a little more, but happy with my upgrade nonetheless. The 250's are delayed about 2 months up here in Canada but there was a 300 available. I pulled the trigger in anticipation of possible tariffs being imposed as of July 1st. Motor could cost me up to 5k more if I waited.......besides, it was my birthday. Beat the socks my wife gave me as a gift, Lol. She still hasn't noticed that I switched motors and I'm not saying a word.
    Last edited by monkeyfish; 06-15-2018 at 08:01 AM.

  15. #15
    LOL!

  16. Member
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    #16
    Quote Originally Posted by monkeyfish View Post
    Thank you for the picture!

    Which mid section did you order?



  17. Member
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    #17
    Quote Originally Posted by Savage View Post
    Thank you for the picture!

    Which mid section did you order?
    Got the CMS

  18. Member
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    #18
    Which lower unit?



  19. Member
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    Dec 2004
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    Bridgewater, NS
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    #19
    TM Gen 2 Savage if this is the same video we have been sharing up here from Dwayne and the 300 V8 on the Triton. Regardless, have a peek at the video if you have Facebook. :)

    https://www.facebook.com/dwayne.zamm...8432160539248/

  20. Member
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    #20
    Thanks Mark..........



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