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Thread: Performance Improvements possible with newer 4 stroke outboards

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    Quote Originally Posted by Ron Hill View Post
    One of my customers claims a re ground cam helped his Honda, noticeably. He has a 100 hours on the cam.

    From second hand information via Mercury Marine, all their smaller 4 Stokes are tamed way down, so they can sell you newer, more powerful ones later.

    I do know the early Yamaha 4 Stokes were "Weak Sucks". BUT THE NEWER ONES SEEM TO HAVE SOME LOW AND AND TOP IN GRUNT.

    If there was a package I'd buy it but once you start messing with Cam duration and what not a special tune would need to be made I would think, Simon performance does have a tune for the Merc 60, boosts up low mid range power pretty good, and supposedly adds about 5-7 hp where it supposedly makes around ,68 at 6300 rpm, that puts it over 70.i have been trying to find someone who has used their tune to get a real world answer. It's 650$ and for it to do nothing would be a waste and could buy more props. I have a merry 12x22 cleaver Wich I believe will be a bit big for my boat but if it's tuned it may work perfectly.

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    Default My Customers Have Said, "No improvement" by Flashing the Computer

    Quote Originally Posted by twzted View Post
    If there was a package I'd buy it but once you start messing with Cam duration and what not a special tune would need to be made I would think, Simon performance does have a tune for the Merc 60, boosts up low mid range power pretty good, and supposedly adds about 5-7 hp where it supposedly makes around ,68 at 6300 rpm, that puts it over 70.i have been trying to find someone who has used their tune to get a real world answer. It's 650$ and for it to do nothing would be a waste and could buy more props. I have a merry 12x22 cleaver Which I believe will be a bit big for my boat but if it's tuned it may work perfectly.
    I have been told that them motors still won't rev, and the valve spring are too weak. With a re ground cam and heavy duty spring, "FLASHING" the computer helped a lot.

  3. #33
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    Quote Originally Posted by Ron Hill View Post
    I have been told that them motors still won't rev, and the valve spring are too weak. With a re ground cam and heavy duty spring, "FLASHING" the computer helped a lot.

    Ron, have you herd of anyone that used Simons tune and said it was worth it? I would like to try one of your semi cleavers once my 13' bullet boat is done, will try my 12x22 merc cleaver first and get a base line but I anticipate its a little to big.

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    Quote Originally Posted by Hounddog View Post
    T Class is a UIM World Class...the weights for both T750 and T850 came from those rules. APBA similar classes were DE for T750 and EP for T850...I am not sure about the DE weight but APBA EP was 850 lbs. With 3 cylinder drag in 2019 the T guys may want a heavier weight..It would be a class decision. Remember OPBRA is looking to revise T850 for the 2020 season.
    I just noticed on the TORC......Toronto Outboard Race Club..site that the link to the rule book is a link to the 2019 UIM Rule Book....T Class starts on page 194. There is no change in the T750 weight. The GT classes for the New motors are much heavier and are horsepower based not displacement based as the two stroke classes. Our new composite Critchfields weigh 225 lbs without the cowl, we will see the new 2019 redesign Deltas this race season and they could be lighter and quicker than the Critchfield or Allison. One reason OPBRA is looking at reducing the horsepower in T850 is the boats are having turning problems in the corners due to the increased top end speeds on the straights.
    They may want to go back to the original spec rules and eliminate the altered 56 fishing motor. Under the original rules you could run a UIM spec 49 OMC or 70CES, an APBA spec 59 cubic inch Mercury, an APBA spec SST 60 with the larger cc 160 compression head or a blueprinted stock 56 fishing motor with the 160 compression head. All of these motors were competitive, some had better acceleration while the OMC 49 and SST 60 had a bit more top end. Made for multiple winners and super racing for the fans.
    Simple solution for the OMC 56’s......must run 31.5 cc head regardless of resulting compression and 73D maximum jet size.. That will slow down the altered motors and is easy to check at inspection.
    Last edited by hydrospeed77; 06-03-2019 at 05:01 PM. Reason: OPBRA typo fix

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    Quote Originally Posted by Hounddog View Post
    I just noticed on the TORC......Toronto Outboard Race Club..site that the link to the rule book is a link to the 2019 UIM Rule Book....T Class starts on page 194. There is no change in the T750 weight. The GT classes for the New motors are much heavier and are horsepower based not displacement based as the two stroke classes. Our new composite Critchfields weigh 225 lbs without the cowl, we will see the new 2019 redesign Deltas this race season and they could be lighter and quicker than the Critchfield or Allison. One reason OPBAR is looking at reducing the horsepower in T850 is the boats are having turning problems in the corners due to the increased top end speeds on the straights.
    They may want to go back to the original spec rules and eliminate the altered 56 fishing motor. Under the original rules you could run a UIM spec 49 OMC or 70CES, an APBA spec 59 cubic inch Mercury, an APBA spec SST 60 with the larger cc 160 compression head or a blueprinted stock 56 fishing motor with the 160 compression head. All of these motors were competitive, some had better acceleration while the OMC 49 and SST 60 had a bit more top end. Made for multiple winners and super racing for the fans.
    Simple solution for the OMC 56s......must run 31.5 cc head regardless or resulting compression. That will slow down the altered motors and is easy to check at inspection.
    Hounddog, how does Toms 4stroke Merc perform? I'm sure it dosent accelerate as quick as the two stroke and being stock how does it compare? Is he running in the modified class of 2 strokes with it or is he running with stock 60 2 strokes? I heard he hit 65 mph with a prop of a nother boat that couldn't run 65 with it. I only ask because I have one and will be putting it on a 13' bullet curious your opinion. I know they are super reliable and great on fuel.

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    Quote Originally Posted by Hounddog View Post
    I just noticed on the TORC......Toronto Outboard Race Club..site that the link to the rule book is a link to the 2019 UIM Rule Book....T Class starts on page 194. There is no change in the T750 weight. The GT classes for the New motors are much heavier and are horsepower based not displacement based as the two stroke classes. Our new composite Critchfields weigh 225 lbs without the cowl, we will see the new 2019 redesign Deltas this race season and they could be lighter and quicker than the Critchfield or Allison. One reason OPBAR is looking at reducing the horsepower in T850 is the boats are having turning problems in the corners due to the increased top end speeds on the straights.
    They may want to go back to the original spec rules and eliminate the altered 56 fishing motor. Under the original rules you could run a UIM spec 49 OMC or 70CES, an APBA spec 59 cubic inch Mercury, an APBA spec SST 60 with the larger cc 160 compression head or a blueprinted stock 56 fishing motor with the 160 compression head. All of these motors were competitive, some had better acceleration while the OMC 49 and SST 60 had a bit more top end. Made for multiple winners and super racing for the fans.
    Simple solution for the OMC 56’s......must run 31.5 cc head regardless of resulting compression and 73D maximum jet size.. That will slow down the altered motors and is easy to check at inspection.
    propshaft height is another way to slow boats down and helps safety re spins
    Thanks Ron Hill thanked for this post
    Likes Ron Hill liked this post

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    Quote Originally Posted by twzted View Post
    Hounddog, how does Toms 4stroke Merc perform? I'm sure it dosent accelerate as quick as the two stroke and being stock how does it compare? Is he running in the modified class of 2 strokes with it or is he running with stock 60 2 strokes? I heard he hit 65 mph with a prop of a nother boat that couldn't run 65 with it. I only ask because I have one and will be putting it on a 13' bullet curious your opinion. I know they are super reliable and great on fuel.
    There is a big difference between running in a oval boat race and seeing the best top speed. The oval boat race is about the fastest lap time not the fastest speed. Tom runs against stock 2 stroke motors. The top runners in the class have good acceleration and hit over 61 mph on the straight. Tom can match their acceleration with a 19 pitch prop. Problem is they have the extra mile or two top end. When Tom runs his 65 mph prop they have superior acceleration and he cannot catch them.
    To be Honest Tom does not get the best clock starts and is usually not the first boat to the first turn. When he has, he has been tough to catch. I think with a 21 pitch and a good start he can win.

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    Quote Originally Posted by Powerabout View Post
    propshaft height is another way to slow boats down and helps safety re spins
    We currently have a prop shaft UIM rule.....basically it must be below the bottom of the boat and we allow nose cones but not low water pick up nose cones or remote transom water pick-ups. We put the nose cone rule in because many T boat owners up here ran SST 60 lower units. At first in 2006 we thought the SST 60 lower units would be an advantage over the nitro case. This was race proven to be false, the nitro case is the faster case on a T boat. The Yamaha small case is even better and the Mercury case even better provided the carrier did not come out. APBA VP75 run the large case with the prop shaft 5 inches?? below the boat plus a much heavier minimum weight. That class has really grown and has many good looking expensive boats racing....and it is much slower compared to our T classes. A few years a go we ran a short shaft big foot 49 with the 725 lb T850 minimum weight in T750. The actual boat and driver used was well over 850 lbs. The boat was a top 3 runner back then. We dropped the idea after one season because it was obvious that had the boat been close to the 725 lb weight, it would dominate.
    Maybe??? When T850 is reviewed for 2020 we could revisit this idea with a minimum weight at 850 lbs.
    Thanks Powerabout thanked for this post

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    Quote Originally Posted by Hounddog View Post
    There is a big difference between running in a oval boat race and seeing the best top speed. The oval boat race is about the fastest lap time not the fastest speed. Tom runs against stock 2 stroke motors. The top runners in the class have good acceleration and hit over 61 mph on the straight. Tom can match their acceleration with a 19 pitch prop. Problem is they have the extra mile or two top end. When Tom runs his 65 mph prop they have superior acceleration and he cannot catch them.
    To be Honest Tom does not get the best clock starts and is usually not the first boat to the first turn. When he has, he has been tough to catch. I think with a 21 pitch and a good start he can win.
    Yea i knew it was a higher pitched prop not best for oval racing, im not racing but i do long runs down in the Florida keys 100+ miles ( all straight ) sold my supercharged waverunner and am building this boat, i plan to go with all the skis i used to ride with so i want to try and keep up. I have a 12x22 labbed Merc cleaver for it. Like i said i dont plan on racing but want the best performance i can get out if it, I was really just seeing your thought on the engine in perticular performance wise. whats the difference between the T750 boats and the 850? i know most are 70+ hp but whats the speed difference like?

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    Quote Originally Posted by twzted View Post
    Yea i knew it was a higher pitched prop not best for oval racing, im not racing but i do long runs down in the Florida keys 100+ miles ( all straight ) sold my supercharged waverunner and am building this boat, i plan to go with all the skis i used to ride with so i want to try and keep up. I have a 12x22 labbed Merc cleaver for it. Like i said i dont plan on racing but want the best performance i can get out if it, I was really just seeing your thought on the engine in perticular performance wise. whats the difference between the T750 boats and the 850? i know most are 70+ hp but whats the speed difference like?
    The T750 boats are 55 to 67 hp. The T850 altered 56 OMC s are 100 hp plus. Speed wise the T750 record is over 65 mph. Our best T850 recorded speed is 80 mph while the UIM T850 record is 68 mph. Overall all the feedback I get about the 60 is positive. Interesting that you have a 12 x 22 Mercury prop. The original model of that prop is liked by many T guys. With your boat you may find it is too much prop. I would not be surprised if an 11.5 x 18 works better. One last comment....I had a fellow running a 1998 59 cubic inch 2 stroke Mercury switch to the 4 stroke. The 2 stroke acceleration was better, but the 4 stroke was only 1 mile an hour slower. So for a non race application...equal!!

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