Dave M

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.

502SCS

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

Revd Up

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

nitro/max

My 23 SCS was the orange one too.

mwdill

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

502SCS

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.

outriggers

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

502SCS

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

502SCS

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

robyw1

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