Re: How fast is a 96' 22 Scarab with 502/415hp?
 

Hi Steve,
Yes we are Freezing up here! Was wondering if you were following this thread, and yes Janaky's got my Mirage dialed in. I have to agree on the factory rigging. How else can you explain the huge difference in speeds? BTW, those billet battery boxes worked great.
Steve

Re: How fast is a 96' 22 Scarab with 502/415hp?
 

Is that steve take it easy snider? whats he know about freezing weather? Greg

Re: How fast is a 96' 22 Scarab with 502/415hp?
 

I agree. From my research on the subject of supercavitating propellers, the blade loading that most single engine powerboats encounter put it on what I call the "low side" of the propeller's "sweet spot". By this I mean that even your best propeller, on its best day, can't exceed about 76% efficiency, and there are combinations of advance ratio (another form of representing propeller slip), speed and loading which result in the prop working well. You can stay at or near this 76% efficiency number by running most props between about 15% slip and 6% slip. Any more slip, and you are throwing water around; any less, and you're dragging too much blade through the water. As you fall off the prop's design point, sometimes you get horrible performance and efficiency. Look at the slip ratios of some of the normal high-performance rigs while they are running slow, at say 40 mph. Some of them see 40% or more slip at those speeds, and efficiencies down in the sub 50% range. That's the answer to the question of why many boats get as good or better fuel economy cruising near WOT than they do poking around. Single engine boats, and some really heavily laden twins run down at more than 15% slip (some as high as 20% or more), while the well set up twins hook up and run at about 8%. The unfortunate reality of all of this is, especially if you are dealing with a Bravo drive, there just aren't a wide variety of prop diameters available, so you are really using the "parts bin" approach to setting a boat up. SSM folks have more options to get the "right" prop for the application.

There are cases, mostly on big ships where the "wake fraction", or water entrained by the ship causes the apparent advance speed of the propeller to be lower than the surrounding free stream. These cases cause the prop slip to look very low, but a careful wake survey will reveal that the prop is still just doing what it is supposed to, and there is no magic or free lunch. High-speed powerboats don't have enough hull in the water to encounter any significant wake fraction.

That's a lot of words to say, if someone reports a top speed of a single engine boat that results in less than about 14% propeller slip based on the engine RPM and drive gearing at WOT, I would immediately raise the BS flag and start looking for hard, cold GPS numbers.

Re: How fast is a 96' 22 Scarab with 502/415hp?
 

Hello,
Wow this is an education and I mean that! This is why I recently joined this group. So much of the internet is junk and no fact comments that is nice to see real debate and after that last post ... Well over my head for sure so if it is BS you got me because it sounds good :-)
Anyway with that complementary commentary out of the way ... Thanks for the education guys.
In trying to explain why I saw my results and to in my own mind prove that I had not lost my mind on my resent GPS run of 76 in my 97 23' Scarab SCS w/502-415 turning just over 5000 RPM with a Bravo 1.5 I assume and 25P Mirage Plus I did do is look at these tools and start using them ( http://www.rbbi.com/folders/prop/propcalc.htm ) .
The results I got were 5200+1.5+25+.14=70.6 So I see where this makes little sense.
I just purchased a Mirage Plus 29P for a future upgrade ( part of the Procharger + 29P has got to be great upgrade :D ) so I ran the same calculator with that prop and came up with 81.9. How does this sound guys?
Thanks again for the great input.
Wayne

Re: How fast is a 96' 22 Scarab with 502/415hp?
 

wow, this is a killer thread!! we've even got good local coverage here!!

steve, you gonna procharge that thing or what?? i think thatd be a blast!!

good info here for you though.....see ya

kevin

Re: How fast is a 96' 22 Scarab with 502/415hp?
 

I recently saw a couple of 22 scarabs for sale on another site. One had a procharger on it and ran upper 80's gps, the other had a whipple on it and ran low 80's gps. BTW 502SCS the calculations don't work out right for my boat either! And yes, I'm considering a procharger.
Steve

Re: How fast is a 96' 22 Scarab with 502/415hp?
 

If you get to the project before me share the wealth of info and I will do the same in return. When you said the calculator did not work for you ?? Does yours run faster on the GPS than the calculator says it should? Do you have a 502/415hp?
Wayne

Re: How fast is a 96' 22 Scarab with 502/415hp?
 

There is a good prop slip calculator at Bam Marine, at http://www.go-fast.com/Prop_Slip_Calculator.htm
===
Sorry, but some numbers from this thread are not physically possible.

502SCS, if you are turning around 5,200 rpm, then your 76 mph speed is around a 7% slip! That is VERY good. I am impressed!

I have never seen below 10% slip with a Bravo 4 blade prop. My old Mirage Plus was at about 13%. The Donzi does not like the 3 blade though, as it also has a relatively high 6" X dimension, and is also aerated by the step. I could hardly get on plane with the Mirage.

Take care,
Kent

Re: How fast is a 96' 22 Scarab with 502/415hp?
 

modded 454-MPI 1.36:1 Bravo (why 1.36 I do not know) Houston Prop Accelerator 25-P 73.5 MPH @ 4400 RPM on the GPS

Roby

Re: How fast is a 96' 22 Scarab with 502/415hp?
 

Robyw1's numbers look very accurate.

I have a close friend with a 22. He's got a Flagship 510ci (basically a stock rebuild 502) with Gil Exhaust.

Hes got a huge stereo ( 4-15's under the bow ) so balance is way off.

He see's about 75 most of the time and 76is on a good day

Re: How fast is a 96' 22 Scarab with 502/415hp?
 

When checking speeds via gps it is important to have the speed filtering feature set properly for intended purposes. This feature allows time based averaging of speeds to smooth readings and make them more meaningful. You could get an erroneously high reading by having the filtering times set low (say 1 sec), or low readings by having the filtering times set too high (say 30 sec). Many gps units have this feature. This can be a big deal in offshore performance boat racing as they watch (disqualify) for an overpowered boat "breaking out" or exceeding the max speed for thier respective class.

BTW... I personnally run a Scarab and everyone knows that they are hands down the best and fastest boats on the water :drink: :D

BT :cool:

Re: How fast is a 96' 22 Scarab with 502/415hp?
 

Oops, someone doesn't believe me.

Roby

Re: How fast is a 96' 22 Scarab with 502/415hp?
 

I had a scarab 23 SCS for 5 years with the 502 MPI(415) 25 pitch prop (not labed) and it is truly a 70+ MPH boat. Here are the perfomance figure for 1997 23'3" SCS. Powerboat Feburay 1997 top speed Radar 73.2 at 4900 with a 25 pitch prop. Zero to 15 sec 64MPH. Boating magazine April 1997 top speed 74.1 at 5000RPM with 502MPI 25 pitch prop. The 23 scarab is an awesome boat I still miss mine.

Re: How fast is a 96' 22 Scarab with 502/415hp?
 

Here's a simple prop slip calculator that's helped me many times. Also, Bravo 4 blade props are actually 1 pitch less than what's stamped on the prop. If you're running a 28p bravo, then enter 27p into the calculator. Hope this helps... :D

http://www.boatpropellers.com/propcalc.html

Re: How fast is a 96' 22 Scarab with 502/415hp?
 

I'm coming up with about 7% slip too. 502/415 , 25p Mirage Plus, 74 GPS , 5000rpm

Re: How fast is a 96' 22 Scarab with 502/415hp?
 

Some amazing #s. :rolleyes:My 98 22 scarab 7.4 b1 labbed 25mp. Best - 64.2 on fumes. Just me in the boat. Nordscog gps.

Re: How fast is a 96' 22 Scarab with 502/415hp?
 

I don't understand why they are not still making this 23' Scarab, or someone did not buy the molds for it after Wellcraft stopped making performance boats. It had to be the most effecient hull on the water. In fact, it sound like they were pretty close to rewritting the physics book. Remember, the prop does not care what is making it turn, whether it is a 502 or a 283. At 5000 engine RPM with a 1.5:1 drive and 25 inch prop, the speeds I am hearing here are very remarkable.

Re: How fast is a 96' 22 Scarab with 502/415hp?
 

The 23 SCS was agreat boat but very expensive. Powerboat magazine printed the list price at 57800.00 in 1997. That with the 502 and full hydraulic steering.

Re: How fast is a 96' 22 Scarab with 502/415hp?
 

Hey Nitro/max good to keep hearing things that make the calculator wiz's scratch their heads. You ever get down south I have an 97 Orange SCS that I will take you for a ride in ..with minor tuning replicates the same numbers the the factory says it ran out of the show room ( wont say how fast that is because of the lip lashing I got last time :-) ). My boat has 130 hours after my ride down the river today and love it .. Did however find out the hard way not to jump on an Allison with a 250ss on the back .. guy said it went 101 on GPS whew .. fast little boat .. hmm wonder how he takes 3 footers ... story might change :cool:

Re: How fast is a 96' 22 Scarab with 502/415hp?
 

yeah them ally outboards will open a can of whoop azz in good water wont they!!

Re: How fast is a 96' 22 Scarab with 502/415hp?
 

I would agree that some of the numbers mentioned in this thread sound unbelievable. However, in order to get my numbers to gell with those prop calc programs I have to lower the slip to 6 or 7 percent. That low of a slip sounds unlikely. I can't explain, just going by what my tach and my GPS say.

Re: How fast is a 96' 22 Scarab with 502/415hp?
 

Yea ... Nice guys .... Talked a bit after the beating. Never really saw an Allison up close... Nice boat.

Re: How fast is a 96' 22 Scarab with 502/415hp?
 

robyw1, what kind of mods did you do to your MPI engine, and what kind of performance increases did you see?
Steve

Re: How fast is a 96' 22 Scarab with 502/415hp?
 

My 23 SCS was the orange one too.

Re: How fast is a 96' 22 Scarab with 502/415hp?
 

a higher x dim really makes a big difference on the 22 scarab, had abuddy with one 385 hp 25p x dim raised 2 inches, 74 mph

Re: How fast is a 96' 22 Scarab with 502/415hp?
 

The company I purchaced it from had the computer worked on and beter flowing manifolds. Thats it so far. Hope to add a procharger in the next couple of months.

Re: How fast is a 96' 22 Scarab with 502/415hp?
 

What's the fastest 22 Scarab you have heard of ? Do they get squirrelly? Tab's, Hydraulic steering? I was thinking of a shorty -1. Doug

Re: How fast is a 96' 22 Scarab with 502/415hp?
 

Here is a link to mine.
http://www.isphub.net/Wayne/personal.htm

Re: How fast is a 96' 22 Scarab with 502/415hp?
 

Mine does wabble at high speed until I trim down a touch then I loose a few MPH until I bring nose back up. Someone said it may be loose steering. If I grab the drive while out of water I can pull it 1-2 in. back and forth so might be that.
anyway I kinda like this one
http://www.hotboat.com/classifieds/a...rab%2023%20SCS
:eek:

Re: How fast is a 96' 22 Scarab with 502/415hp?
 

On this run the only mods I had were:

Walbro 255lph fuel pump
Adjustable FPR
TB gasket modification*

* in the 7.4 MPI if you open the throttle wide engine off you can see down the throttle body bore and notice that the gasket blocks almost 1/2 of the bore. I removed the throttlebody and cut the gasket perfectly round and replaced the throttlebody. This modification alone didn't increase performance until I increased fuel pressure.

In my particullar case I couldn't get a big increase in fuel pressure until I replaced the pump. I don't know if my pump was bad or if it was just a cheap, restrictive pump.

After those mods alone I would estimate I picked up 25-30 Horsepower. That is just an estimate. The power over the whole RPM range seemed to be up.

However Let me caution you about this engine. It won't take too much power before it self destructs. This engine has brittle cast internals and RPMs MUST be kept below 5000.

I'm not going to be doing any further mods to this engine because I feel that it is pretty much at it's limit. I want the thing to last. There is actually a Whipple supercharger kit available for this engine that boast close to 500 Horsepower. perhaps they know better than I what this engine will take.

Roby

Re: How fast is a 96' 22 Scarab with 502/415hp?
 

502SCS, I read somewere that there were only 12 orange built. One was weecked in the movie face off.

Re: How fast is a 96' 22 Scarab with 502/415hp?
 

Wow! I never heard that. I know I looked for almost two years for one. I wonder how I can verify that. I will send Wellcraft and see if they can tell me. Well at least I know there is at least 10 others crazy enough to buy an orange boat :-)

Re: How fast is a 96' 22 Scarab with 502/415hp?
 

I just recieved this email from Wellcraft looks like your ifo was good see below.

From : Marsha Y. Bone <[email protected]>
Sent : Tuesday, February 8, 2005 10:24 AM
To : <[email protected]>
Subject : 97 Scarab

Hi,
According to our research, 14 orange 23 ft Scarab's were built in 1997 model
year.

Hope this information will be helpful.

Marsha

-----Original Message-----

Contact Request from Wellcraft Website

Re: How fast is a 96' 22 Scarab with 502/415hp?
 

Another update from wellcraft Interesting.

From: W Fountain [mailto:[email protected]]
Sent: Tuesday, February 08, 2005 11:00 AM
To: Marsha Y. Bone
Subject: RE: 97 Scarab


Thank you for the info. Were there others orange in the couple of years the scs was built.

Again Thanks got the info .. This sorta stuff keeps people looking to wellcraft.

Wayne

From:Marsha Y. Bone
Subject: RE: 97 Scarab

No, the solid orange was only built in 1997.

Marsha

Re: How fast is a 96' 22 Scarab with 502/415hp?
 

last year i installed a 1999 hp500 with cmi etops into my 96 scarab 22. it's like driving a sports car. props of choice are a 27p and a modified 29p mirage plus, spinning the hp at 5250 rpm. it's a blast.

Re: How fast is a 96' 22 Scarab with 502/415hp?
 

Anybody have a feel for 4 blade bravo1 props? My 23' SCS pulls to 5k rev limit fast with the 25p Mirage Plus. I tried a 29P 3 blade and found it was too much prop. How does a 28P 4 blade bravo1 compare. Think I should try it?
Thanks

Re: How fast is a 96' 22 Scarab with 502/415hp?
 

Here is a good way to give the group a good chance at helping me with this .. Watch this video from this weekend. The very end is a shot of me coming toward the cam then I let off the gas and the sound is loud ..
http://www.isphub.net/wayne/day-in-boat.wmv
It just started when I took prop off and tried a new one, then put old 25p back on for these pics
thanks

Re: How fast is a 96' 22 Scarab with 502/415hp?
 

Hpscarab22, Have you gps'd that little rocket? g:reg

Re: How fast is a 96' 22 Scarab with 502/415hp?
 

502sc, almost a "whistling" sound?

Re: How fast is a 96' 22 Scarab with 502/415hp?
 

I could not push a 28P Bravo 1 enough rpms. 45-4600. Speed was down a little to 71.9 GPS. The boat handled much better though. I want to try a 26p Bravo 1 next.
Steve