G23 H6 vs XR7, not just the specs

[G23Family]

I'm selling my 2010 Tige RZ2 and just placed an order for a 2018 G23. I have the options figured out, but cannot decide between the base 450hp and upgraded supercharged 550hp. I understand how the torque works with the gear reduction to provide twice the low end power at the prop. When I do the math, the difference seems minimal 930 (465ft-lb x 2) vs 1100 (550ft-lb x 2). So, beyond the specs, how do the two really compare in real world use near sea level? Does anyone know on my specific boat details like time to plane, time to surf speed, time to wakeboard speed, fuel consupmtion at cruising speed etc. Any information would be appreciated, either dry or loaded or both.

[GMLIII]

https://www.planetnautique.com/vb5/f...-g23-questions

Go to this thread on Planet Nautique, good info comparing the 450 and 550 .

[G23Family]

Thanks for link. I'm not surprised that the fuel consumption is greater on the supercharged engine. Understanding that premium fuel is also required will increase the cost to operate as well. If neither are a concern to me, any idea of how they compare in the G23? Generally speaking, the consensus seems to be that the H6 is fine and that you will never run out of power in the XR7. I'm hoping to hear about real perfrmance comparisons also.

[charlesml3]

There's a little more to it than that. The bigger engines are popular on high-altitude lakes such as Lake Tahoe. At 6200 feet ASL, the air is thinner and non-supercharged engines can lose as much as 30% of their horsepower. So the idea that you'll "will never run out of power" has a big "it depends" attached to it.

-Charles

[G23Family]

Thanks Charles, I thought about that, but realistically the boat will be at sea level 90% of the time. I'm not trying to overlook those fair performance differences. I'm really just out for a sea level engine comparison. My research suggests go with the H6. I'm willing to spend the money on the upgrade if it really performs better.

[Infinity]

I would not upgrade for the money unless you are high altitude or plan to run crazy amounts of ballast/lead. 450 will do everything you want easily and will do better on fuel efficiency. I think you will lose most of the motor upgrade money on the resale too.

[OKWAKEBDR]

I ride at sea level also. I have the 450 in mine and it is more than enough. I typically don't use any extra ballast, BUT I have a friend (neighbor) with the same boat and he runs 2k of ballast over stock and still has no problem. Unless you intend to run CRAZY amounts of ballast, or are at high elevation, there's no need for the 550. Of course...we're not really talking about "need" with these type of boats anyway. I have been in one with the 550 and there is a noticeable difference in performance, but I have no regrets about getting the 450 in mine.

[blueroom]

Hi

Superchargers also experience similar altitude effects. Unlike a turbo, which maintains manifold pressure via some tech and compensates for altitude change, a supercharger is a mechanical device that blows the same amount of “"air"” all the time based on its pulley/belt set up and engine RPM. Unless you are changing your supercharger pulleys to adjust the supercharger to elevation changes, highly unlikely on these boats, the engines suffer HP loss on a similar scale. It isn't an apples to apples curve, and there are some other factors that affect the math (compressing air at greater than atmospheric pressure, etc.) but at a high level this is the case. This is why serious car guys with superchargers will change out pulley configurations (different supercharger compression at RPM) based on the altitude they run at and tune for.

Coming up with a terrible example, let's say oxygen molecules are rocks and your supercharger and turbo chargers are like buckets. At sea level a one gallon bucket of rocks weighs 5 pounds for both the supercharger and turbo buckets. When you go up in elevation the rocks get lighter, but stay the same physical size. The supercharger bucket is a fixed one gallon size and can only hold the same volume of rocks, so the 1 gallon supercharger bucket gets lighter as you increase in elevation (because the rocks weigh less). However, the turbo charger bucket can adjust it's size up and down to always hold 5 pounds of rocks - the bucket dynamically gets bigger as you increase in elevation and smaller as you go down. Talking about some of the other variables, maybe a supercharger can overflow the bucket slightly, but the bucket size will not change. In order for the supercharger to hold more of the lighter rocks at altitude, you need to manually change the bucket size (ie. change the pulley size to compress more air).

This is all a huge oversimplification - mostly for illustration purposes.

What the supercharger really does get you is more power to lose before it becomes detrimental.

That at being said, we have the XR7 and love it, I will never order a standard motor. We use non-ethanol fuel in all our toys, which is always premium anyway, so no concerns there. Having the extra power available is really nice - whether you want to go to a high lake, run some crazy ballast configs, pull more than one rider, run a bunch of people in the boat, etc.

In in the West, resale could better in some cases, as so many lakes are higher up. Some dealers in Utah, for example, only order supercharged engines.

[SierraWave]

I love my xr7 but run in Lake Tahoe. If I ran at sea level I would have gotten the 450. I tested the 450 in tahoe and it was passable...but every guy that I talked to with a G on Tahoe had the 550 except one who said he had the 450 then changed it out to the 550.
Again, at sea level I would have the 450. However I don’t add more than the stock ballast. Plus, the 17x17 prop is optimized for the 450. You have to change the prop to a higher pitch with the 550 to get the fuel consumption acceptable.


Sent from my iPhone using PLT Nautique