Crownline 202 prop????

[GINTONIC]

We have a 99 Crownline 202 w/454 and currently has 22p mirage 4 blade. Works well with the current set but was wondering if different prop might give better top end for times that just speed is wanted. Also, where should I be for rpm's at WOT. Thank you for your time

GinTonic

[Throttle Up]

There are possibly some options to increase your top end. Can you tell a little more about your set-up. Is your motor the 454 Mag, is it carb. or MPI.
This will determine the WOT RPM we need to prop for.

Julie

[GINTONIC]

Our motor is the 454 MPI.

[Throttle Up]

That being the case then you should run at 4900-5000 RPM at WOT.

Julie

[GINTONIC]

What prop should I try for more top end speed? Or do you need some more details first such as rpm's, speed, etc.

[Throttle Up]

Gintonic,

If you could provide the WOT RPM and speed we can take a look at improving your top end. Could you also tell me more about the 22P Mirage . Is it a Mirage PLUS or an older style Mirage? How did it become a 22P? They are cast in the odd numbers 21P, 23P etc. We can then run the numbers and see where you are.

Julie

[GINTONIC]

Here are the numbers:
454 MPI
Prop is a Bravo I 48-831910 22p
4600 Engine RPM WOT
60-61 mph on the Speedo
1/3 tank fuel
1-2 people
1100' elevation

I am very satisfied with the current prop for all-around performance, but was just wondering for fun if another would get me better top end speed.
Any help you may give would be greatly appreciated.

[GINTONIC]

I left out the gear ratio is 1.5

[Throttle Up]

GinTonic,

Your Bravo I 22P is running to low of an RPM to WOT at 4600 RPM. Great for cruising but not top end. The 454 MPI achieves peak HP at about 4900-5000 RPM which of course is were the speed is. So in your case it is good news, as there is probably more speed to be found. You are about 300-400 RPM shy. We should look at some props or services that will bring your RPM up and produce greater top end speeds.

Julie

[GINTONIC]

What would you recommend for a prop or other services? What props do you have available?
Once again thank you!

[Throttle Up]

You could consider downpitchng and labbing your prop. This would increase your RPM from 400-500 RPM at WOT. THe down pitch is good for 200 RPM and the labbing is good for another 200-300 RPM. This would put you at about 4900 RPM where the peak HP is produced.

Another option would be to consider a 3 Blade prop. You would have to sacrifice your hole shot, acceleration and cruise speed but you find another 1.5 knots on the top end.

Julie

[GINTONIC]

So for a four blade prop drop 2 degrees or go to a three blade and what pitch and size would you recommend?

[Throttle Up]

In a 3B I would start with a 19P Mirage Plus.

Julie

[GINTONIC]

Does Throttle Sell Props or have a trial program and are you able to lab my current 4 blade bravo I? Or should I speak with someplace locally?

[BigDaddy]

GT - I would just give Julie a call, I'm sure she can get you set up [smilie=042.gif]

[Throttle Up]

Feel free to give me a all!

Julie
Throttle Up Propellers
877-842-6855

[GINTONIC]

Julie,

Got the 19p mirage and finally had a chance to try it out. Here are the current numbers with 4 people and 1/3 tank fuel:

19p mirage
52.5 mph gps
5100 rpm

22p bravo
53.8 mph gps
4650 rpm

I will try to call Thursday or Friday with a couple more questions.


Thank you

[Throttle Up]

GinTonic,

I am glad you got some test time.

The 19P Mirage is running a bit high on RPM. We adjustthe prop to a 20P and shoot for the 4900-5000 RPM.

The 22P Bravo I seems to be to tall for you. The RPM is to low. However if you were to lab a 22P Bravo I it should put you at about 4900 RPM at WOT.

Julie

[GINTONIC]

I have the 24' bravo I from you and wanted to get some information on getting lab finished. What can you tell me as far as performance, cost, durability, etc. Once again the motor is a 7.4 efi. Thank you

[Throttle Up]

The Lab Finihnsing process of course is performed to a prop to acheive increased top end. Lab Finihing produces 2-4 MPH increases in speeds and an increase of 200-250 RPM as will. Our Lab Finishing process is computer assisted and includes one adjustment afterwards at NO CHARGE! We truely believe in blueprinting here at Throttle Up. One of the points of lab finishing is that you have created a propeller that is extremely true to pitch as well as, geometrically equal or efficient. However there are some other things to consder. The propellers are now thinner than stock therefore they are more susceptable to sustaining damage upon impact. Additionally they may be increased maintainence because of this.

With the 7.4 L motor your ideal RPM should be around 4600 RPM at WOT. So if you are running around the 4400 mark we should be good to lab it.

Julie