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kraig1995
06-14-2011, 09:30 PM
I am currently running a 350 Vortec TBI with standard trans. I know there is considerable increased hole-shot power upgrading to a Powerslot. Will there be any increase in speed or fuel economy? So the question is Powerslot swap or Swap the current motor for a 383 stroker motor?

east tx skier
06-15-2011, 11:17 AM
I wouldn't expect an increase in either top end or fuel economy. Doing the swap will require replacement of everything after of the engine, i.e., transmission, shaft, strut, prop.

Gear reduced transmissions are fantastic if they come with your boat. But I don't know that I would want to go to the trouble of replacing a working transmission with one.

As for the motor, it just depends how much money you want to spend. I think there are things you can do to get more out of the 350 TBI. Send Bret a PM. His 350 TBI in his 94 supposedly screams.

Kyle
06-15-2011, 12:38 PM
Slot uses more gas and has a lower top end unless you add some ponys to the engine. The engine turns 1.5 times while the prop turns 1 time.

A slot is a stump puller.

Do engine mods to your current engine.


My buddy and I have the same boat but he has standard trans and I have the slot. His top end was way faster until I added some extra HP. How they run about the same.

east tx skier
06-15-2011, 03:48 PM
Slot uses more gas and has a lower top end unless you add some ponys to the engine. The engine turns 1.5 times while the prop turns 1 time.

A slot is a stump puller.

Do engine mods to your current engine.


My buddy and I have the same boat but he has standard trans and I have the slot. His top end was way faster until I added some extra HP. How they run about the same.

Does the slot really run that much slower. Remember, it is turning a bigger wheel with more pitch than the 1:1. My guess is that the fuel usage between the two are pretty negligible. I bet the baselines at ski speeds are pretty close.

rspiecha
06-15-2011, 04:20 PM
Why do you need more speed??? barefooting???

ahhudgins
06-15-2011, 04:40 PM
I've owned both the 1:1 and two power slots. I now have the power slot on my Maristar. The engine turns the same RPMs in both cases so I don't see how it will make any difference in the fuel economy. Both of my power slots did about the same top end (44-45) which is the same as the 1:1. The slot has a lot better hole shot and holds speed better after adding a 4 blade.

ahhudgins
06-15-2011, 04:43 PM
Does the slot really run that much slower. Remember, it is turning a bigger wheel with more pitch than the 1:1. My guess is that the fuel usage between the two are pretty negligible. I bet the baselines at ski speeds are pretty close.

It's just like you said, the engine is turning about the same RPMs but the prop is turning slower, but it's larger. Gear reduction is a great thing.

east tx skier
06-15-2011, 08:21 PM
It's just like you said, the engine is turning about the same RPMs but the prop is turning slower, but it's larger. Gear reduction is a great thing.

And more pitch. Traditionally a 14x18 versus a 13x13 on a MC IIRC. At least in the vintage we're discussing.

kraig1995
06-15-2011, 09:35 PM
the idea was for better holeshot and top end speed for barefooting. I've had people tell me to go to the stroker block for the extra power. The inlaws own a machine shop, so strokers are cheap for me!

DooSPX
06-16-2011, 09:58 AM
You are going to have to find a way to tune the TBI or switch to carb.

Kyle
06-17-2011, 12:52 PM
Does the slot really run that much slower. Remember, it is turning a bigger wheel with more pitch than the 1:1. My guess is that the fuel usage between the two are pretty negligible. I bet the baselines at ski speeds are pretty close.

My old low HP engine would turn 4800 4950 Rpm's and do 41 42 and when you added a footer it would drop to 36 and still be spinning the same rpm. I never understood it. Now with the same prop and a lot more power I'm running 46 to 47 gps not speedo speed and drop a footer I may loose 1-1.5 mph and still turning 4950 Rpm's. I don't and still don't understand rmp vs prop rotation on the same prop with all the variance. So I stepped up and threw a new engine in with HP.

The op needs more power. The tranny should be left alone.

As far as gas milage. Now with the high HP with the slot it's out of the hole and on plane very fast. This is how my gas goes. I don't play when it's time to pull someone up. It's my job to drive straight and their job to hold on to whatever I give them.

I lined up next to a buddy who has a jet boat that runs 80mph. He thought he had me out of the hole and top end. I said let's see your hole shot. All he could say was damn. Obviously we never raced at top end speed since his boat runs 30mph faster but I win as far as hole shot. If you are not holding on I can put the observer on the floor without a power turn.

east tx skier
06-17-2011, 03:49 PM
My old low HP engine would turn 4800 4950 Rpm's and do 41 42 and when you added a footer it would drop to 36 and still be spinning the same rpm. I never understood it. Now with the same prop and a lot more power I'm running 46 to 47 gps not speedo speed and drop a footer I may loose 1-1.5 mph and still turning 4950 Rpm's. I don't and still don't understand rmp vs prop rotation on the same prop with all the variance. So I stepped up and threw a new engine in with HP.

The op needs more power. The tranny should be left alone.

As far as gas milage. Now with the high HP with the slot it's out of the hole and on plane very fast. This is how my gas goes. I don't play when it's time to pull someone up. It's my job to drive straight and their job to hold on to whatever I give them.

I lined up next to a buddy who has a jet boat that runs 80mph. He thought he had me out of the hole and top end. I said let's see your hole shot. All he could say was damn. Obviously we never raced at top end speed since his boat runs 30mph faster but I win as far as hole shot. If you are not holding on I can put the observer on the floor without a power turn.

You're turning over 4,900 hp with a 351 HO? What am I missing how you are set up? Did you have the 250 hp 351 and upgrade the heads to GT40 for an extra 40 hp?

Agree that for top end, hp is the answer. Just curious about the speed and fuel economy statement. And, of course your max rpm on that engine.

Of course, as far as top speed goes, the biggest hurdle is the hull. Horsepower will only get you so far before you hit the point of diminishing returns. I figure that's likely in the very low 50 mph range.

Kyle
06-18-2011, 01:18 PM
You're turning over 4,900 hp with a 351 HO? What am I missing how you are set up? Did you have the 250 hp 351 and upgrade the heads to GT40 for an extra 40 hp?

Agree that for top end, hp is the answer. Just curious about the speed and fuel economy statement. And, of course your max rpm on that engine.

Of course, as far as top speed goes, the biggest hurdle is the hull. Horsepower will only get you so far before you hit the point of diminishing returns. I figure that's likely in the very low 50 mph range.

4900hp??? I don't understand. 4900 to 4950 rpm.

The only thing factory on my engine is the accessories, alt, impeller, etc.

I had to buy a block and start from scratch remember.....Got better pistons, rods, it's not stroked. Have gt40p heads
have factory intake, 4160 carb, new electronic ignition, new everything.

Digital rpm off pp is exact but the analog guage shows anywhere 4800+- And my timing is at 10 btdc like everyone else.

The hull is wet and drives through the water. When I'm by myself I run 44ish. I load the boat up and put a back seat full in I can get the boat on top of the water by weighting the back of the boat and changing the shaft angle. Then we are hitting 46.5 or 47. I'm sure I could play with different props and cupping or a slight pitch change to get more speed but it's not necessary. I have plenty of HP as it still has the same hole shot loaded vs empty.

east tx skier
06-19-2011, 10:52 AM
Understand. Thought you were running a factory setup under the hood.