Here are a few LaveyCraft NuEra 29's, this is the same hull we are using (the middle one may be the 2750 race boat.......... I'm not sure, BUP can clarify if needed)

This is BUP's boat in case you missed the link at the beginning of the thread. You can see the entire build process at : http://www.laveycraft.com/construction-of-29-nuera

I know it's not the same hull or even close to it , but I ran a #6 on a 30' single engine Checkmate with over 1500 hp and never broke the drive. It was bolted to a 12" box so the engine didn't need to be moved forward as the transmission was set in the extension box. While it would be more expensive, you would probably never break the drive or transmission.

Yes, and somewhat no. The middle picture is in fact the same bottom (hull) as the 2750, but that middle isn't the 2750. It's the 28 SVL, pleasure version is the 28 EVO or EVO-R depending if it has the actuated/removable top option.

Sorry in advance, this is going to be a long reply. But it doesn't make a big difference in what was said just to clarify some things...

There have been 4 (possibly 5) twin engine 29 NuEra's made, I don't remember right now. Twin; Merc 500, Merc 525, Merc 496 HO, and Merc 600. I THINK there was two 29's built with Merc 500's but for some reason my memory isn't 100% sure right now... None the less, ALL with stock mercury bravo 1 drives.
Again, not 100% positive but I think there was a 29 NuEra single w/ Merc 600 that was made with a Merc ITS. This particular boat did not receive in depth testing so comparison cannot be made as to if that setup worked better with the added set back... I do know that it did handle just fine but cannot comment if it was a better combination vs mounting the gimbal/drive directly to the transom.

I can personally state there are 5, possibly a couple more, 2750 Nuera's built with a Merc ITS and they all handled better with this setup vs standard.

As far as the 28 EVO, to include the 28 SVL race boat, ALL have been setup from the factory with the full 12" set back Imco standoff box and they all in fact performed better with the standoff box setup. In the testing stages, Lavey tested the 28 EVO/SVL with the standard setup gimbal/drive mounted directly to the transom along with the standoff box setup both in BACK TO BACK testing on the same exact day on the same exact lake with the same exact boat. I know that statement for a fact because I was the one in the drivers seat and I was the one doing the wrenching to change the setups. To clarify possible questions/comments to come on how that's possible... quote "if you add the standoff box you also have to change the X dimension. How did you do that all in the same day?!" reply - we already had a new set of motor mounts ready that raised the engine the required amount, removed the standard setup, swapped motor mounts, notched the transom cutout to allow higher bell housing/driveshaft height, used the imco +3" box so we could use original gimbal mount holes but still raise the engine, installed all parts and went back to the lake.

The 29 NuEra in my personal first hand experience will handle perfectly fine in the standard setup gimbal/drive mounted to the transom and I would not change that setup with the possible increase in performance/handling. For reference, Lavey has built a 29 NuEra with a TCM 825 w/ Teauge platinum drive that runs 100mph+ and it runs perfectly.
Now, if I was a millionaire and had the time/money to test a different setup then yes I would. But reality is most of us are not and why be the test mule to change an already great proven setup... I would set this boat up with Lavey's standard setup and run an Imco SCX w/ SC lower. Then IF you have access to the parts, test it with a -2 SC lower. OR start with the SC -2" lower and then test with spacers as needed. I prefer the method of setting up near the highest X you'd run as per Lavey recommendation and then test with spacers.

Sorry BUP and 900hp, I did not mean to hijack your thread. Back to the engine build this thread was started for!

One of the comments earlier had me thinking. I forget who it was (edit: it was Black Baja) but they mentioned engine braking on decel when the throttle is pulled back during rough water running. It has me re-thinking about the ignition timing table for the boat. Why you ask? because timing directly controls engine torque. It's instant, if you remove timing you remove torque.

I have attached 2 photos below of the 16x16 timing table I get to work with. The left column is manifold vacuum in Kpa and the bottom row is RPM. As manifold vacuum increases the map goes higher. (example: idle = 16 inches of vacuum, wide open throttle = 0)

If I set up the table correctly, it will pull timing out when you chop the throttles. Anytime you cut the throttle you will have a big increase in vacuum causing the load cell to go to the bottom of the chart. I included the 3D table to help you visualize what I'm talking about but basically, you cut the throttles it also pulls the timing WAY back killing the torque too. The timing doesn't come back in until the engine gets loaded and manifold vacuum drops.

The next neat trick I get to do is the rev-limiter. We have a hysteresis zone before the "hard limit"........ what that means is that if we are at 6000 rpm and the boat comes of the water I can set the hard rev-limit to 6500 rpm but I can set a 300 rpm hysteresis where it will pull the ignition timing back as many degrees as I want. What happens is the engine becomes very "lazy" and doesn't bang into the chip, it just kind of lays over....... it won't put the timing back in until the engine is out of the hysteresis zone meaning once the boat is back in the water.

I think these two things added together will go a long ways towards drive longevity in rough water. Do you guys have any thoughts or questions?

Lavey Jr. aka Chris Jr. of Laveycraft - you chime in at will and thank you for your time. No problem at all. Glad you found this thread . Hope things are well. I was going off my memory as well plus what I have seen in person and pics..

Like I said, why go against what you guys have proven to work very well up to this point. Thanks John

This thread is about the engine and Laveycraft located Corona CA

www.laveycraft,com

Throttles Performance in Fargo ND

and little old me. haha

Only speaking of boat handling and not outdrive/equipment longevity... Some engine braking is good and useful. Boats don't have brakes so what do you do when you need to slow down? You pull back on the throttle. So let say for example the boat starts to get a little too loose... You want to cut back on the throttle and (hopefully) rely on water drag on the bottom and equipment in the water to slow the boat down in order to help settle the boat. If you do this in a boat with a #6 style cleaver propeller, especially twin engine, it will settle quite quickly due to the substantial drag increase. Now with single engine bravo style outdrive and bravo style propeller you have a lot less drag in that application. So, I personally feel that some engine braking is beneficial in order to provide a little more resistance on the wetted items that are in the water to help grab, slow down, and/or settle the boat. Of course you don't want a sh*t ton of engine braking but I think you get what I'm saying. As far as engine braking running in rough water, if you are experienced and know how to read the water and work the throttles on takeoff-entry then I don't think that should make a huge factor when it comes to the engine tuning to prevent the engine braking.

I don't know how that will work when running hard in big water, just "pulling timing" to keep it off the rev limiter. If you have an engine at 6000rpm, running at full throttle, full load, and the prop comes out of the water , its nanoseconds that the engine free rev's when you have completely disengaged the drivetrain from the load. You'll have an engine that is producing say, 800ft lbs of torque , and need to reduce its output to probably 50ft lbs of torque, to keep it from acclerating in a free rev condition.

I could be wrong. Just my thoughts. Mike from MDC who developed the drive guardian system, has alot of data from torque measurements on the drivetrain in rough waters. The torque spikes are incredible on what the drivetrain sees. Way more than what the flywheel produces. Thats what breaks stuff. Some guys can make a drive last 500 hours in calm water. Take it in rough water, and it might not last 5 hours, with the same engine in front of it.

You would be surprised at how effective this is and how instant it reacts. Drag race car can miss a gear at 7500rpm+ and not tag the limiter hard. Timing is very very effective and INSTANT at keeping rpm from climbing. If you are at 38º at peak power and the timing gets pulled back to 4º you just cut over 400 hp out of it, no joke.