4.3GXi-J / SX-A with 1.51 ratio?

[RegalJames]

I’ve got a Regal 1900 with this engine/drive and from what I can see in most 19’ bowriders this combo runs 1.66 ratio or higher.
I’m struggling with holeshot but top end is good with a 4x14x17 Patriot SS.
Prop calculators show it should be decent with that but it struggles to plane quickly with 4 on board. Once planing, it’s awesome. On launch, it wont go past 3000rpm until you get up some speed which is no good getting a skier up.
I’ve ordered SX Smart Tabs to try. Any other suggestions?

 

[QBhoy]

I’ve got a Regal 1900 with this engine/drive and from what I can see in most 19’ bowriders this combo runs 1.66 ratio or higher.
I’m struggling with holeshot but top end is good with a 4x14x17 Patriot SS.
Prop calculators show it should be decent with that but it struggles to plane quickly with 4 on board. Once planing, it’s awesome. On launch, it wont go past 3000rpm until you get up some speed which is no good getting a skier up.
I’ve ordered SX Smart Tabs to try. Any other suggestions?

Hi. Not too long ago…I messed about loads propping a friends regal 1900. She had the same engine, but In mercruiser form and an alpha.
What was immediately apparent is the noticeable lack of low down grunt these 4.3 mpi have…or certainly on that hull at least.
After messing with lots of props, we managed to get her as good as she was going to get. That meant propping her to where she was just a tiny bit below the limiter. As close to as possible really. The limiter is at about 4920-4950 give or take. That meant that she was as good as she could be low down and as quick as she could be up top. We settled on a tempest plus 3 blade. Outstanding results from that prop. Allowed the hull to take advantage of the steps. She was then capable of around 52-53 mph gps and showed an optimistic glance on 60 on the dash dreamometer gauge.
His outdrive was a 1.6 ratio I’m sure. 19” tempest plus. Very fast boat once going.
Stepped hulls on heavy boats that size and type do take a while to get going usually. Mine is the same. Very important to get a good hull lifting prop on that hull. So you’re able to allow the steps on the hull to do their stuff and take air in under the hull.

 

[RegalJames]

Hi. Not too long ago…I messed about loads propping a friends regal 1900. She had the same engine, but In mercruiser form and an alpha.
What was immediately apparent is the noticeable lack of low down grunt these 4.3 mpi have…or certainly on that hull at least.
After messing with lots of props, we managed to get her as good as she was going to get. That meant propping her to where she was just a tiny bit below the limiter. As close to as possible really. The limiter is at about 4920-4950 give or take. That meant that she was as good as she could be low down and as quick as she could be up top. We settled on a tempest plus 3 blade. Outstanding results from that prop. Allowed the hull to take advantage of the steps. She was then capable of around 52-53 mph gps and showed an optimistic glance on 60 on the dash dreamometer gauge.
His outdrive was a 1.6 ratio I’m sure. 19” tempest plus. Very fast boat once going.
Stepped hulls on heavy boats that size and type do take a while to get going usually. Mine is the same. Very important to get a good hull lifting prop on that hull. So you’re able to allow the steps on the hull to do their stuff and take air in under the hull.

Thanks. So you would think the stern lift from Smart Tabs should help? I’ve got some coming, I guess I’ll try them and see what happens!
Do you think the 1.51 drive on that engine is right? Seems a bit low ratio to me.

 

[QBhoy]

Thanks. So you would think the stern lift from Smart Tabs should help? I’ve got some coming, I guess I’ll try them and see what happens!
Do you think the 1.51 drive on that engine is right? Seems a bit low ratio to me.

I personally wouldn’t put tabs on a hull like that. Will force the hull into the water more than I’d like. I’d just get her propped right.
As for the gear ratio…what rpm and speed are you seeing now ? Is it a 17” you have now ? 1.5 seems a little high perhaps. Not sure on these VP to be honest. If you tell me your number above, could take a well placed presumption at the ratio from there.