RX DI Hole Shot

[nevereddy]

I have a bone stock 2001 RX DI with 120 hrs that I want to start modifying for a quicker hole shot and better midrange without doing major engine mods. I'm considering changing the stock impeller to a Solas Dynafly ST-DF-12/18 because, even though the ski is already a respectable performer, my rpms never exceed 6950 at WOT so I feel I can drop pitch for better low and mid range acceleration without hitting the limiter. I don't care as much about top speed. I spent a lot of time optimizing the rave valve settings and here is my best results from the last run of the season using a Garman GPS-72:

water temp: 68 degrees/air temp: 80 degrees- flat water, dead calm
1/4 tank of Shell V-Power 93 octane, Amsoil Interceptor synthetic 2-stroke.
61.5mph@6950 rpms with 200lb rider and gear (no stopwatch, but about 12 seconds to top speed)

I'm also considering an R&D rideplate and intake grate to keep the pump loaded and improve handling. The pump doesn't cavitate out of the hole, but it doesn't stay hooked up very well in rough, choppy water.

Any thoughts or opinions on the impeller selection? Are there other ways to get better bolt-on holeshot performance?

[Bill O'Neal2]

Re: RX DI Hole Shot

The main advantage of the R&D Aqua Vien and R&D rideplate combo is that you get a grate that locks into the rideplate and takes the stress off of the inserts in the plastic ride shoe, which are prone to pulling out if you put an aftermarket grate onto the RX and use the oem inserts to hold it onto the boat.
As with most aftermarket grates you will usually see a slight reduction in top speed, but a slight gain in pump hookup to the water.

The other impellor to think about is the Skat Trak 13x19-83 swirl. It is an excellent holeshot impellor.

[nevereddy]

Re: RX DI Hole Shot

Thanks for the response, Bill.

What do you think about some light engine mods like replacing the air box/spark arrester with K&N or similar low restriction filters? I know that seems to be a popular thing to do, but if the stock box has sufficient cfm flow, I don't want to risk water intrusion in case I do something stupid. I've also been thinking about having the head shaved (reshaped..?). I'm getting good quality 93 octane gas but I don't know what you can actually do with the head and not run into problems. None of this is worth doing if it doesnt improve the hole shot.

[Bill O'Neal2]

Re: RX DI Hole Shot

I'm sorry, I do not have any suggesstions for modifying DI engines.