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MORE HORSEPOWER!


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#1 13utchy

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Posted 16 September 2012 - 09:44 PM

I have an '05 Chaparral 204ssi with a 5.0 Volvo GL. (rated at 220 horse)

I would like to get some more top-end speed on this at reasonable / cruising RPM 3000 - 3500.

Any suggestions? I believe it is a standard Holley 2bbl & I've been reading a swap out to a 4 bbl is relatively easy (I would still be hiring a mechanic to do this!). Would this make any noticeable difference? I've thought of thru-hull exhaust before as well, but my buddy said I would look like a boob out there running thru hull on a 305.

I've also read up a bit on props, but again, getting up to plane is no issue -- just looking for some added cruising speed. 45 mph was nice today, but I'm pushing around 4000 - 4500 RPMS at that speed & won't that really wear the motor out? The boat has approx 210 hours on it presently.

Thanks for any advice!

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#2 krmartonik

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Posted 17 September 2012 - 12:21 AM

I would suggest to keep it the way it is and get more horsepowre on your next boat :boating: You will most likeley get foot-itus after a while :dancinguy:

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Kris
2008 215 Ssi/ Volvo 5.0 GXI, SX
Puget Sound, Lake Washington, Lake Tapps

2014 GMC 1500 SLT All Terrain


#3 13utchy

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Posted 17 September 2012 - 10:39 AM

This is only my first season as a boat owner, so I want to keep the 204 for a 2nd/3rd season before getting something with a bit more room. I just didn't know if there was an easy / inexpensive fix for some added ponies that would make a noticeable difference on top-end.

I see you have the GXi so you get an extra 50 HP or so out of that than the standard 5.0 GL. I'm sure that means you don't have to work the motor as hard when you're cruising around over 40 MPH.

#4 13utchy

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Posted 17 September 2012 - 10:40 AM

This is only my first season as a boat owner, so I want to keep the 204 for a 2nd/3rd season before getting something with a bit more room. I just didn't know if there was an easy / inexpensive fix for some added ponies that would make a noticeable difference on top-end.

I see you have the GXi so you get an extra 50 HP or so out of that than the standard 5.0 GL. I'm sure that means you don't have to work the motor as hard when you're cruising around over 40 MPH.

#5 13utchy

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Posted 17 September 2012 - 10:40 AM

This #%^$&%$ site has issues still .... double posting ..........

#6 bob and betsy

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Posted 17 September 2012 - 11:22 AM

13utchy
That's the first question every new boater has.
You can add a 4bbl carb and new manifold and pick up 20-25hp. That should equate to 4-5 mph if propped correctly. You should be able to get 4500-4700 rpm out of that motor, so that would help your holeshots while still helping top end speed. i don't think you need to worry about wearing out that motor. 210 hours if maintained, is no big deal.
The real question is why do you need more speed than 45mph with that boat?
Kris brings up a good point that if you want more speed, many times a bigger boat and motor fits the equation.
There's always costs involved when wanting more speed. Trust me. I can motor along with the best of them, but remember, there's always someone faster.
You can add a twin screw supercharger and really help your cause but a smaller hull doesn't have the build for too much more speed anyways.
Getting that 5mph will cost you more then the "bang for the buck" in my opinion.
Save the money until you can upgrade.
Bob and Better Half
92 Chaparral Villain lll, 598 ci
86 Wellcraft Elan 197, 4.3L, 205 hp, Alpha One
2007 Ford F-250 PSD, CC, SRW

#7 13utchy

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Posted 17 September 2012 - 01:20 PM

Thanks Bob & Betsy -
Is it normal that people cruise around for 20 - 30 minutes at 4500 RPM? I just always think back to an automobile & running about 2500 RPM on the highway at 70 MPH & start thinking I'm really going to stress the motor running like that so typically; (conditions permitting of course), I stick to between 3000 - 3250 RPM, which is good for around 25 - 27 MPH according to the GPS.

This of course being more economical considering gas prices!

But then I was thinking yesterday that it would be nice to maintain a speed of 40 MPH + running around 3000 RPM, which led me to searching around the net on swapping out the 2 bbl for a 4 bbl. But again, I wouldn't want to be spending much over $500.00 for something like this (and plus I would be shelling out more money at the pumps!).

Would a prop make any difference or is that merely to get up to plane faster?

I'm running the standard 3 blade aluminum prop right now.


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#8 gl115

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Posted 17 September 2012 - 03:23 PM

look into trim tabs and a stainless prop,those always help chaps.

Anyone can benefit from a safe boating course.

 

 


#9 sktn77a

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Posted 17 September 2012 - 03:31 PM

A prop is like a final drive on a (one-speed) car. Changing the prop to increase top speed (or speed at any given rpm) will slow acelleration a bit but it's probably the cheapest change you can make to drop your RPMs at 45mph. The 204SSi was good for a little over 50mph at ~ 5000 rpm (give or take) with a 5L Merc or Penta GL engine when new, so your results are consistent with this. Changing the prop may reduce your rpms a little but not down to 3000-3500 at 45mph.

The 4 barrel Holley may increase horsepower a little if you can't get the reults you want with a different prop. For what its worth, I get about the same speed (45mph at 4500rpm) with my 5.0GXI in the same boat.


Keith
2004 204 SSi
Volvo Penta 5.0GXi/SX

#10 Wingnut

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Posted 18 September 2012 - 06:10 AM

Thanks Bob & Betsy -
Is it normal that people cruise around for 20 - 30 minutes at 4500 RPM? I just always think back to an automobile & running about 2500 RPM on the highway at 70 MPH & start thinking I'm really going to stress the motor running like that so typically; (conditions permitting of course), I stick to between 3000 - 3250 RPM, which is good for around 25 - 27 MPH according to the GPS.

This of course being more economical considering gas prices!

But then I was thinking yesterday that it would be nice to maintain a speed of 40 MPH + running around 3000 RPM, which led me to searching around the net on swapping out the 2 bbl for a 4 bbl. But again, I wouldn't want to be spending much over $500.00 for something like this (and plus I would be shelling out more money at the pumps!).

Would a prop make any difference or is that merely to get up to plane faster?

I'm running the standard 3 blade aluminum prop right now.


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If you are at 27/3,000 now and you are looking for 40 @ 3,000, that equates to an additional 200 HP. A 13 MPH gain at cruise would take an aluminum big block. I'm just saying. Enjoy your boat and think long and hard about trading up to something getting less than 3 mpg.

W
2008 256 SSX
496 Merc HO 425 HP
Bravo III-X Drive

#11 leonid

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Posted 18 September 2012 - 09:56 AM

If you are at 27/3,000 now and you are looking for 40 @ 3,000, that equates to an additional 200 HP.


That says it all :haha-7383: :yb624:

#12 krmartonik

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Posted 19 September 2012 - 10:27 PM

Or you could get one of these....
https://www.dropbox....xv/P9183638.AVI

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Kris
2008 215 Ssi/ Volvo 5.0 GXI, SX
Puget Sound, Lake Washington, Lake Tapps

2014 GMC 1500 SLT All Terrain


#13 superpop

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Posted 20 September 2012 - 07:36 PM

Squeezing more oomph out of the 5.0 is going to be tough. I would probably do the 4 barrel conversion and switch to an eidelbrock if it was me, easier to tune and less tempramental. I have the same hull and I added smart tabs to mine and that made a huge difference, best 100 bucks I spent on the boat, I also went to a 19P 4 blade stainless prop but with that prop I top out at around 45, it leaps out of the water though. You will not hurt the motor running for extended periods of time at WOT of around 4700RPM's. Boat motors are overengineered to a certain degree to compensate for this, so it is not like a car motor where you need to shift to go faster without over revving the motor. I would start with smart tabs and then do the carb, those two upgrades should make a noticable difference.
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2006 Chaparral 204 SSi
270HP VP 5.0L GSXi
SX Drive System
Samson Tower

There is no replacement for displacement

#14 13utchy

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Posted 22 September 2012 - 05:13 PM

I think if I swap boats with Wingnut; my horsepower issues will be solved!

#15 Wingnut

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Posted 22 September 2012 - 05:22 PM

I think if I swap boats with Wingnut; my horsepower issues will be solved!


Keep yours, send cash.

W
2008 256 SSX
496 Merc HO 425 HP
Bravo III-X Drive

#16 13utchy

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Posted 22 September 2012 - 05:24 PM

May not be a Chaparral, but this is music to my ears:



Looking at the boating mag., count on about 1 1/2 miles to the gallon cruising around like this!

http://www.boatingma...sea-ray-270-slx

#17 13utchy

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Posted 22 September 2012 - 05:30 PM

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Hey baby! Uhhhhhh huh huh huh huh huh huh!

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#18 brick

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Posted 22 September 2012 - 09:45 PM

It costs big deer to increase the top speed of a boat, and you may be disappointed with the performance increase for the money spent. Save your money, spend on gas next season.
brick
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#19 DonaldG

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Posted 23 September 2012 - 10:53 AM

Just put a B&M blower on it, run c-110 fuel, put the top down, and get used to chime walking. O yea rebuild the lower unit a few times, and put a piston in once in a while cause it went lean and keep thinking MORE POWER is better. Bark Bark.
He who dies with the most toys....still dies.

#20 Wingnut

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Posted 27 September 2012 - 06:42 AM

http://www.potterper...INE-PHOTOS.html

One simple phone call is all it takes to sink a Chap.
2008 256 SSX
496 Merc HO 425 HP
Bravo III-X Drive