MyPetViper

Finally finished, prop tested and running.

23 foot deep V with 496 Mag HO, spinning Laser 24" (3 blade)

2 people, half tank of gas, 68 mph GPS, 50s air temp.

AFTER Raylar BCK 103 conversion, stock exhaust:

2 people , full tank of gas, 78 mph GPS, 80s air temp, spinning labbed 28" Bravo 4, just hitting rev limiter.

It feels like there is some more to be gained with a higher rev limit. Also, to add some CMI headers.

The boat will plane at 1900 rpm with one person, half tank of gas. The mid range has a significant increase in punch. It idles smoothly at 640 rpm.

Before being rigged back in the boat, the engine dynoed at 527 hp on a unit that is known to be accurate and reliable.

We have spent a good deal of time with Rmbuilder taking photos and test rides for a magazine article.

Dave M

Congrats on your results. What kind of boat do you have? It sounds like it responds well to HP increases.

Strip Poker 388

iTrader: (6)

Congrats on the package . Thats some good #'s. Bob said its going to be a good story for the mag.


Rob

MyPetViper

It is a Stingray 230SX. Not your typical Hi Perf hull, but it is very efficient, planes easily, so I thought it might respond well to more HP. It is not stepped.

I boat on a larger inland lake. With 2 - 3 foot chop it sits right up and goes.

I would like to thank all the members of OSO from whom I have gotten advice, directly or indirectly.

Also, thanks to Jeff Zeigler of Modern Marine for doing the nearly impossible rigging that boat. More to follow on that.

Escape Velocity

Dave, if I may, I'd like to add some long overdue results and recognition to Raylar for an improvement they made to my 106 kit (600 HP version). They sent me their new polished 1000 cfm throttle body to experiment with in August. At that point I was hitting the rev limiter with a 28" labbed Bravo 1 @ 77.4mph GPS in my Velocity VR-1. I switched to a non-labbed 27" Hydromotive Q-IV and ran 75.0mph GPS, below the rev limiter.

After installing the new throttle body, the Bravo 1 prop ran exactly the same speed (rev limiter constraint). However, the Hydromotive ran up to the rev limiter @ 78.1mph GPS - a 3.1 mph increase. The air temperature was slightly lower that second day, so even giving that the benefit of 1 mph, there is still a 2 mph improvement. All other aspects of engine performance from idle to full throttle remained as good as ever.

MyPetViper

Randy,

What does the new throttle body look like? I might try it if it will fit in my smaller engine compartment.

I had suggested to Jeff at Modern that we try a Hydromotive, but the Bravo worked better on mine also, with stock throttle body.

Escape Velocity

Here's my attempt to paste a link that will take you to a picture of the 600 HP engine version with the new polished throttle body.

http://www.offshoreonly.com/forums/s...ghlight=Raylar

If this doesn't work, it's under "Question for Raylar", post #22.

The throttle body is only slightly larger in diameter so fitting it in the engine compartment isn't an issue. My guess is that it may not make any improvement to your engine. The reason for using the larger throttle body is because they found that the 600 HP version was running out of air beginning in the upper 4000 rpm range due to the longer duration and higher lift camshaft. Raylar will know whether that's the case or not.

The Bravo I prop is a little better behaved, especially out of the hole, but I'm willing to sacrifice ease of planing for the higher midrange and top speed. I understand that the Bravo prop was the best performer at all speeds for your boat and that's great!