Simon Performance Flash - 2017 175TXW w/75HP Fourstroke

[msupc]

It's 3/4" difference......I'm set up this way and have more than enough water pressure.

[alanhore]

Mine also.

Yes. Outboard is in the 3rd hole too.

[alanhore]

Pretty sure my 2013 75 four stroke is a 2.33 gear ratio.

Interesting. I wonder why the performance discrepancy between the 75-115 Optimax flash and the 75-115 Fourstroke flash? Wilds and others were getting 50+MPH and turning 24" props, while it seems we are merely capable of spinning 18"-19" props and MAYBE mid-40's. Our lower unit has a gear ratio of 2.07:1.

I believe I will raise the motor and see what happens. What difference did you experience when raising the motor?

[TritonTRXV8]

Trying to go over everything in one post here. The vengeance prop is not a very good prop for performance. I would not could on that prop to deliver much speed. Also jumping from an 18p prop to a 21p 4 blade just from a flash is probly not going to happen. Biggest reason being the 2.07:1 ratio vs the optimax and older 4 stroke 75 and 90 outboards running 2.33:1 ratio. Made a huge difference in prop selection. Also keep in mind fhe guys getting the higher speeds were also running a jack plate. To turn the bigger props you need to raise the motor more than you can on the transom and you need the additional setback to maintain water pressure and handling. Im also in the belief that the optimax engines from
The 2014 and older era ran much stronger than these new 4 strokes do they just seemed to push the same boats a little quicker (in most cases not all). If you want more speed id suggest a laser prop most likely a 19p will be best all around. You wanna shoot for 5800 rpm if i remember correctly on these engines.

[msupc]

So I had her out today after raising the engine, and the results are somewhat disappointing. MPH decreased to 40.5 and RPM increased to 5750 or so. I can keep trimming it out and RPM goes up, but speed drops to 39mph and steering gets tight. This makes me wonder if I didn’t need to lower the engine instead of raising it? Also, would a laser 2 prop have better bite when trimming up? It seems like the sweet spot before and after raising the engine is just where the exhaust starts to get louder. I am going out tomorrow, and I am going to try the Spitfire X7 21” again after having raised the engine to see how it performs, because why not.

If the X7 doesn’t perform well, and I am doubtful, I will be considering either lowering the engine one or two holes. Seems strange.

[TritonTRXV8]

To be blunt get rid of that vengeance prop those are just a ss version on a blackmax prop they suck and dont perform well the reason you are spinning rpms and no speed is because that prop has zero cup in the blades and has no bite. See what kind of rpms and speed you get with the 21p x7 and report back. The laser was the fastest prop on my boat but i had it cupped to handle better in turns.

[Tim Kelly]

I'd be suspicious that there's something not quite right with your motor to start with. Pulling the restricted plate and having the engine die seems odd to me. No amount of flashing or height adjustments will help if there's a motor fault.

[msupc]

To be blunt get rid of that vengeance prop those are just a ss version on a blackmax prop they suck and dont perform well the reason you are spinning rpms and no speed is because that prop has zero cup in the blades and has no bite. See what kind of rpms and speed you get with the 21p x7 and report back. The laser was the fastest prop on my boat but i had it cupped to handle better in turns.

Based on the results today I am with you. The X7 is now faster despite significantly lower RPMs. The Vengeance prop, as explained by Mercury, is indeed basically a SS version of the Black Max.

Results so far:
1. Motor in second hole:
18” Vengeance: ~5500 RPM & 42 MPH
21” X7: ~4900 RPM & 41MPH
2. Motor in third hole:
18” Vengeance: ~5800 RPM & 40.5
21” X7: 5200 RPM & 42 MPH

These results seem to insinuate that an 18” or 19” Laser 2 or X7 would bring RPMs up and bite better yielding higher speed. My thinking is that a prop with better grip would allow more trim, which raises RPM. Thoughts?

[msupc]

I'd be suspicious that there's something not quite right with your motor to start with. Pulling the restricted plate and having the engine die seems odd to me. No amount of flashing or height adjustments will help if there's a motor fault.

This hasn’t been documented at all in online forums (trust me - I looked). Mine is a 2016 75HP Fourstroke. When I pulled the restricting ring and ran it, whenever the engine would get near maxing out while trimming up, the Merc Monitor would kill power. My guess is that it detected a lean condition? I did it multiple times; there was a sweet spot that if you gave it all the throttle after a certain trim point it would kill it. I cruised for a while enjoying the new-found giddtyup, and made sure to not push it to the engine “kill zone”. The engine had only 50 hours on it when I got it and ran very well before fooling with it. Still does as a matter of fact.

[TritonTRXV8]

These 2.1l 4 strokes have a restrictor in the throttle body? My coworker has a 90/65 jet and his is just an open throttle body unless the 75 is the only one that does not a good idea however yo remove the air restricote if there is one without at the same time increasing the fuel curve otherwise you are just running the engine too lean. More air without increased fuel to go with it is uselss for making power that honestly probly did more harm than good. Your engine was going into gaurdian mode because the parameters were not right. Without the computer probly would of hurt the motor.

[msupc]

These 2.1l 4 strokes have a restrictor in the throttle body? My coworker has a 90/65 jet and his is just an open throttle body unless the 75 is the only one that does not a good idea however yo remove the air restricote if there is one without at the same time increasing the fuel curve otherwise you are just running the engine too lean. More air without increased fuel to go with it is uselss for making power that honestly probly did more harm than good. Your engine was going into gaurdian mode because the parameters were not right. Without the computer probly would of hurt the motor.

Yes; the 75HP have the restriction plate only. My thoughts exactly.

[Tim Kelly]

Wouldn't the flash have taken the fuel/air mixture into account and compensated? That's pretty much what a flash is, isn't it?

[msupc]

Wouldn't the flash have taken the fuel/air mixture into account and compensated? That's pretty much what a flash is, isn't it?

It did. The issues I was experiencing were occurring pre-flash. Post-flash the engine runs superb. I am just trying to figure out the best prop and motor height.

BTW - I just dropped the Vengeance prop off to have cup added before I consider increasing pitch or trying another prop (ie Laser 2). Stand by.

[alanhore]

I have had good luck with the Mercury x7 spitfire in a 19 pitch and a 20 pitch LazerII. The lazer seems just a bit too much pitch for my set up and boat. No jackplate on my hull.

[TritonTRXV8]

Never ran an x7 prop on my Tracker when i had it. Tried a trophy 4 blade a couple times always fell back to the worked laser for all around performance. A cupped 19p should run pretty good wiuld be my guess.

[msupc]

Never ran an x7 prop on my Tracker when i had it. Tried a trophy 4 blade a couple times always fell back to the worked laser for all around performance. A cupped 19p should run pretty good wiuld be my guess.

Depending on what happens when I get the Vengeance back from getting cupped, this is what I may end up doing (cupped 19” laser 2).

[bshort]

Depending on what happens when I get the Vengeance back from getting cupped, this is what I may end up doing (cupped 19” laser 2).

I can spin the 17P X7 up to 5750. That good enough for me. Figured one could spend a tidy sum chasing a few rpm's and maybe 1 or 2 mph.

[fishon396]

I can spin the 17P X7 up to 5750. That good enough for me. Figured one could spend a tidy sum chasing a few rpm's and maybe 1 or 2 mph.

That would be close to perfect for the 75hp flashed I would think.

[krr6581]

Most 4 stroke props like to run high in the water column. Try the 21P X7 again now that you've raised your motor. The three blade prop which I assume your 18P is won't like running that high and you'll probably have issues with blowout. Also it seems that folks forget that for every pitch increase you have you will drop approximately 200 rpms. Let's say you have a 19P prop that is running 5400 rpm's at OT and then go up to a 21P prop your rpm's will drop approximately 400 rpm's. Technically a larger prop should help you increase your speed but you won't be able to get max performance out of your boat. I agree with TritonTRXV8 that a cupped Lazer 19P would probably make you happy. Lastly, you probably voided your motors warranty removing the restrictor from your throttle body.

[msupc]

Most 4 stroke props like to run high in the water column. Try the 21P X7 again now that you've raised your motor. The three blade prop which I assume your 18P is won't like running that high and you'll probably have issues with blowout. Also it seems that folks forget that for every pitch increase you have you will drop approximately 200 rpms. Let's say you have a 19P prop that is running 5400 rpm's at OT and then go up to a 21P prop your rpm's will drop approximately 400 rpm's. Technically a larger prop should help you increase your speed but you won't be able to get max performance out of your boat. I agree with TritonTRXV8 that a cupped Lazer 19P would probably make you happy. Lastly, you probably voided your motors warranty removing the restrictor from your throttle body.

It seems you may have missed some of the thread. I have tried the X7 21" pitch prop since raising the motor, and the results were lower RPMs (~5200rpm) and higher top speed (~42mph). I am definitely well aware, now and before, about RPMs dropping with pitch increase. This seems to correlate directly with my findings. I agree that 1" of added pitch yields a reduction of 200 RPMs. I currently have the Vengeance 3 blade 18" pitch prop at a local shop being cupped both along the rake lines and pitch lines, and I am hoping this will allow the prop to bite better while trimming.

From what I have read, adding cup tends to reduce RPM. My thought is that adding cup in my instance may allow for more trim ultimately negating the RPM loss and increasing top speed. If that doesn't pan out as planned, I will likely secure a 19" Laser 2 and try it out!

I understand the warranty issue, but this should not be understated. It MAY be on my dime if something goes wrong with the engine; this is a risk I knowingly and willingly assumed when venturing down this path.