For anyone interested in top speed with Swirl Impeller...

[scooper77515]

...I took my 97 challenger out today, still working on breaking the engine in. Promised Seadoosnipe, who is interested in the Skat Swirl for his boat also, that I would take out the GPS and measure top speed. I was told that it would come out of the hole faster, which it does...MUCH faster, but was supposed to lose 1-2 mph off the top end.

I know I measured the top speed with GPS prior to swapping the impeller, and a search on here may show what it was, but today, with 300 lbs of passenger/cargo, full tank, bimini down, and only moderately choppy lake, it hit a nice sustained 41 mph.

Best of all is it got there VERY quickly, and held much more speed during sharp turns.

So call Dave at Impros and get your stock impeller swapped out for something with a bit more BITE!!!!

 

[scooper77515]

OK, I did a search, but did not find it.

Snipe, can you give me your top speed with similar conditions?

Just want to see what, if anything, I lost...

 

[Gunsrunner]

Theres a thread under modified- your challenger top speed.

 

[Dans97challenger]

If I remember right Karl said he had that boat going 51mph with just him in it on his GPS when he had the boat. So that would mean you lost 10mph not just the 1-2 they stated you would loose.

 

[seadoosnipe]

speed?.....

I'd say under the conditions you were boating in, it doesn't appear you lost any top end. I really haven't rode in choppy waters, except to wave jump. I ride mostly on the river here. Crossing the bay, I normally do on calm days. If there is a chop on the bay, I don't go out. I don't like being beat to death. It hurts my back.:rofl:

Most here already visit Riva racing for impellers, such as Skat Trak and Solas. But I found the web site you told me about at Impros has very useful info on common questions about our propulsion choices. I don't normally use http but this site is dedicated to our pump nozzles, grates and impellers, so feel free to check them out:http://www.impros.com/

 

[swill777]

If I remember right Karl said he had that boat going 51mph with just him in it on his GPS when he had the boat. So that would mean you lost 10mph not just the 1-2 they stated you would loose.

I think you would have to perform the test with the SAME boat before and after to get an accurate result.. each boat can have slightly different factors that can effect the stock top speed..

condition of original impeller
engine performance (are they both running strong at rev limiter?)
wear ring condition?
pump to hull seal, pump to venturi seal, intake seal, thru hull seal (all could have some degree of ventilation leaks) all possibly contributing to cavitation
how much fuel is in the boat, full tank = weight.
weight of passengers
nozzle alignment
etc.. etc.. etc..

like I said, you would really have to take the same boat out and run it full on with the stock impellers.. take it out of the water.
pop in the new ones, and run it the same exact way and compare the readings..

 

[vilord]

Well it was the same boat...

but it has a new engine and a new impeller and a new wear ring (as far as I know), so the hull seal was redone...

And a different driver, different amount of fuel, etc.

In *my* '96, I got up to about 45mph sustained on the GPS in ABSOLUTELY smooth water with no wind or current. That is at about 6950 rpm. no matter how much messing I did with the throttle linkage and so on it still stayed at 6950rpm WOT, so I'm going to leave it alone, that's plenty fast for me.

 

[scooper77515]

According to the onboard speedometer, I didn't lose 10 mph, and it was pretty accurate, within 2-3 mph compared to the GPS.

I am a little bigger than Karl, but not 10 mph bigger.

I had a full tank, my 210 lb butt, and some waterskis, ropes, anchor, etc that would normally be in the boat.

And it doesn't "feel" any slower, for what that is worth.

 

[Dans97challenger]

Just being in it and on the water you will never notice a 2-3 mph change seat of the pants. It is like putting an exhaust on a car. You gained 10-15hp but you can't feel it seat of the pants. I wouldn't sweat it. You have a nice boat like I do!!!

 

[scooper77515]

I agree. The wife and I are having a blast with it. Almost like a new boat, even comes with a 10-hour break-in period...:ack: