Setback effect on blowout speed?

[aaronmt73]

On our 98 Velocity im running 10"s of setback and still feel I need to run more positive trim then I should.Ive seen 83.5 and believe there is a bit left but also know im nearing the blowout speed of the Torquemaster.I ran it with 12"s with a previous motor and know its good for a bit of speed since its carrying the bow easier.The question I have is does going back raise the blowout speed of the lower or make it more likely to blowout at a lower speed.The boat isn't fastest enough to go to a sporty simply because its not a 85mph boat everyday and we mostly run in the 60-70mph range.It seems to me it would be cleaner water back a bit more therefore better water,but im not sure exactly.Thanks for your Thoughts Aaron

[Greg G]

Is your 300XS Torguemaster lower coned or factory snub nose?

[steve@scp]

I know of a few guys that run t/m at near 90 and haven't blow em out. I sure wouldn't try it.

the setback doesn't cause the blow out. it will just give the boat the ability to lift the bow more and the prop to
run in cleaner water.

at your speeds 83.5 ... I sure would consider have that case coned. depending on the weight of the boat. if it's heavy stay
with the t/m.. if it's light and has the ability to run faster the coned case will help and be safer.

[aaronmt73]

I know of a few guys that run t/m at near 90 and haven't blow em out. I sure wouldn't try it.

the setback doesn't cause the blow out. it will just give the boat the ability to lift the bow more and the prop to
run in cleaner water.

at your speeds 83.5 ... I sure would consider have that case coned. depending on the weight of the boat. if it's heavy stay
with the t/m.. if it's light and has the ability to run faster the coned case will help and be safer.

Its a fairly heavy boat its a 98 22ft Velocity,its the newer style hull not the lighter/faster style 85/86 hull.It may have a bit more left but certainly it cant be a hole lot.I think im going to go ahead and add 2.5"s to to setback hopefully this will allow me to run less trim and the prop to be more efficient.Id like to see the gps flash 85 but im not sure its possible.

[aaronmt73]

If I was able to run a bit higher would that lesson or increase the blow out chances.Im thinking I could block off another hole to allow it to maintain water pressure a bit higher.

[steve@scp]

jmo.. I don't think the setback has a lot to do with the possibility of a blow out.

I have turned around bullets' with 10" setback at 50mph, just cause I trimmed too much..lol.
it's more of a wait till it sits right and hammer it and bump up the trim. trim too fast and it'll blow out. go too fast and the water goes over
the case too fast and diverts away from prop and you blow out. (t/m case and stock cases).

[Greg G]

I may have missed a page but I just remembered that you are running a new 300XS I believe. If that is the case doesn't that TM have four nose inlets as well as holes on both sides of the lower unit?

[aaronmt73]

Im running a 300xs and yes it does have the 4 inlets in the nose.I have 6 of the side holes blocked off with allen plugs.I was running with 5 blocked off then tried 6 this weekend and I believe I am able to maintain pressure higher.I will be smoothing out the the transition on the top 6 holes, hopefully it will allow a bit cleaner water back to the prop.Im not sure how much it will help when running high but it shouldn't hurt.I did order a 2.5" setback to try.When I add at I will also raise the motor one hole at the same time.

[Greg G]

So if I am understanding you correctly, your stock TM lower unit has 4 nose inlet holes from the factory, and then 6 side inlet holes on each side of the case. You have already
threaded the 5 highest side holes and closed them with allen plugs but the plug heads are still protruding, correct? Post a close-up picture of what you have done so far to the lower.

[aaronmt73]

It had 8 on the sides I have the top 6 plugged.I will be using moraso 2 part epoxy to smooth the transition out.The plugs are not protruding they are sunk in.