Pirata, need better fuel economy

[Cooose]

Assuming you were looking to repower a older pirata and the primary objective was improving fuel economy, are there engine options available which help in fuel without taking a bath on torque?

[chris young]

Nope.


Seriously, you can spend a lot of money on fuel, and I mean A LOT, before the difference between a modern fuel injected and a properly tuned carbed V8 would pay for a re-power. Without crunching the numbers, I would hazard a guess that you would never pay for a new motor with fuel savings. Ski boats by their nature are gas guzzlers, that's just the way it is.

[Wulphie]

Assuming you were looking to repower a older pirata and the primary objective was improving fuel economy, are there engine options available which help in fuel without taking a bath on torque?

Fuel economy in boats is more related to weight and drag of the boat than it is the engine.

I have a bbc Pirata and all things considered it is a very fuel efficient boat.

[Salty87]

^ weight, drag....and a good prop. Any idea how old yours is? Few changes will make as big of a difference as a new prop compared to an old one. In addition to improved hole shot & top end is somewhat better economy.

But, ducking as I type this...weight...wet foam adds lots of weight and it's unfortunately not uncommon.

[lively]

They make throttle body closed loop kits . But it will set you back 2500


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[Cooose]

Thanks for all the feedback guys, I was pretty sure of the answer when I threw it out there but thought I would give it a shot.

Salty - good thought on the prop, probably worth starting down that way.

[gogger]

Don't pull a tube.

[chris young]

But, ducking as I type this...weight...wet foam adds lots of weight and it's unfortunately not uncommon.

I know this might be heresy, (my turn to duck) but I don't think wet foam is even detectable as a performance degradation. My first windsurfers were made from pour in place foam like the stuff in our boats. These boards were fragile and would eventually start taking on water. When the foam was really saturated they had about 10 lbs of water in them. That's a 100 litre volume board. To put that in perspective a standard SUP board these days is around 200 litres. How many SUPs could you cram under the floor of your boat? 4 or 5 maybe? That would be about 100lbs in extra water and I highly doubt that it's even that much.

[Wulphie]

I know this might be heresy, (my turn to duck) but I don't think wet foam is even detectable as a performance degradation. My first windsurfers were made from pour in place foam like the stuff in our boats. These boards were fragile and would eventually start taking on water. When the foam was really saturated they had about 10 lbs of water in them. That's a 100 litre volume board. To put that in perspective a standard SUP board these days is around 200 litres. How many SUPs could you cram under the floor of your boat? 4 or 5 maybe? That would be about 100lbs in extra water and I highly doubt that it's even that much.

I took about 6 trash cans of wet foam out of my boat at about 100 pounds each. Some people say they have taken close to 1,000 pounds out but not sure how accurate that is. My friends Malibu sunsetter is wet and it drives and has a wake like it has a few fat sacs in it so I would not be surprised if it has 1,000 pounds in it haha.

[Jetlink]

I weighed my Comp both before and after I rebuilt it on the exact same scale with a slight variation in the fuel load in the tank. Anyways, with all the work that I did, I ended up removing close to 1,000 pounds out of my boat between eliminating the tower, the wet foam and the rotten stringers. I also ended up overbuilding it when I put it all back together so when you factor all that in it is not hard to imagine how much soaked foam weighs. As an aside, my boat pre-cap off restoration had the platform in the water at rest while now it rides a full 2-3 inches above the waterline.

[Salty87]

I could see 1k lbs happening. Along with the wet foam would be saturated stringers and even water trapped in voids between/under foam.

[chris young]

I stand corrected, I can't argue with Wulphie Jetlink's observations, I'm quite surprised. Jetlink, I'm curious if you still know what the "after" weight was? Just curious how that matched up with Supra's published weight for the boat.

[Jetlink]

I stand corrected, I can't argue with Wulphie Jetlink's observations, I'm quite surprised. Jetlink, I'm curious if you still know what the "after" weight was? Just curious how that matched up with Supra's published weight for the boat.

Well, I put mine on an extreme an extreme weight loss plan. I removed anything frivolous that was not required to use the boat for skiing. Removed the radio, removed all old wood in the boat except for the divider along the ski locker in the top cap. Removed the metal exhaust pipes and replaced them with fiberglass mufflers (one of which was faulty from the factory) where the two that went in weighed less than one that they replaced and so on. If I recall, I believe my boat is now just slightly lighter than the factory number that Supra published. Put it this way, when I skied behind it last year for the first time since I did all this work, my wife freaked out at first because for the first time in owning this boat, she felt everything I was doing with the rope and the ski. I was causing the boat to surge as I would load up the rope and such if you follow.

[Sdc77]

Tune it ! Pirata/Saltare with 454 are efficient boats.
Mine went from 8 gallons/hour to ... 4.75 gallons/hour ! With the factory 13x13 propeller. I will change it next season to see if I get even better milleage.
With a good carburetor rebuild : pay big attention to the secondary lock arm, tends to bend and let air/fuel passing through even when primary is closed (my issue for 2 years, fixed last season).
Add a new $50 car HEI ignition (plus a few upgrade to marinize it, follow Michael post : https://forum.supraboats.com/showthread.php?18206-Marine-HEI-Distributor&referrerid=14935 ), new plug wires, new sparkplugs. Go to 12° BTDC (instead of 8° in the repair manuel) will save tons of fuel.
Good luck

[lively]

Tune it ! Pirata/Saltare with 454 are efficient boats.
Mine went from 8 gallons/hour to ... 4.75 gallons/hour ! With the factory 13x13 propeller. I will change it next season to see if I get even better milleage.
With a good carburetor rebuild : pay big attention to the secondary lock arm, tends to bend and let air/fuel passing through even when primary is closed (my issue for 2 years, fixed last season).
Add a new $50 car HEI ignition (plus a few upgrade to marinize it, follow Michael post : https://forum.supraboats.com/showthread.php?18206-Marine-HEI-Distributor&referrerid=14935 ), new plug wires, new sparkplugs. Go to 12° BTDC (instead of 8° in the repair manuel) will save tons of fuel.
Good luck

I'm interested in the hei , I bought one like 2 years ago and tried to fit it up but the thermostat housing was in the way , I had MS mill a aluminum spacer and it worked ok , but may try the msd setup on the new build . Any clearance issues on yours ?


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[Sdc77]

Hi Lively,
No celarance issues on a 454, the thermostat housing is on opposite side of the engine.
Chears