engine upgrade/pump work (could be 2nd post sorry)

['97 Scarab Jet]

I don't think my first post actually got posted, so I'll try again.
My name is Joe. I am fairly new to this forum, and still a little ignorant when it comes to jet boats. I have a '97 SCARAB Jet, that I purchased 2 summers ago. I like the boat however I want/need it to be QUICKER AND FASTER. And thats the reason for the post.
FACTORY BOAT SPECS (just a little background):
19' in length w/7' beam, 225HP Volvo/GM V-6 w/Volvo-Legend pump w/ 'D' impeller, Dry weight 2300lbs, 30 gallon fuel tank, deadrise 20 degrees, draft 18", bridge clearance 3'.....
time to plane 3.5 sec, top speed 50.2 MPH @ 4630 RPM, cruise speed 31.3 MPH @ 3500 RPM w/ 95 mile range. Sorry, if thats was too much info.
My objective is to make the boat as fast as possible on pump gas w/out having to fill the tank every hour. And in doing so, also creating a bigger rooster tail. Due to some rocks getting in my way, the impeller has now been changed to "B" cut (approx 44MPH top speed now but with a little better hole shot).
Question: should I have pumped worked over before even thinking about a different engine? If so, got any ideas on who could do it in the Houston, Texas area. I know of Mike's Pump & Speed, but he didn't seem too interested in my pump (although he did appear to be a nice guy).
Question: got any ideas on what kinda horsepower and torque (and where to get it) I would need to be able to run with some of ya'll bad boys (girls too)? I have been looking a some killer engines (600+ HP) but they're not marine approved. BTW, what would happen if I put a non-marine engine in a boat?
All thoughts and comments welcome, PLEASE.
Joe

[Scarabjet]

Joe,
I've done all the mods permissable to my Scarab before hitting the next stage where the big bucks come into play.
I've removed the muffler, ran the exhaust straight through the transom,installed a K&N flame arrestor, place diverter, c-cut Legend impeller and a cavitation reducer. The best I got out of the V-6 was 54-55 MPH with just fumes (1/4 tank) & myself in the boat.
As I mentioned in my private e-mail, the next step will either be a modified V8 or a Supercharger, since the current motor only has 50 hours.
My local Speed shop was researching which Supercharger worked for the V6 but since then my wife & I had our first born & Scarabtime is kinda on hold....
I was going to evaluate the total cost of installing the Supercharger and necessary engine mods vs. a straight swap to a V8.
There is someone in the forum that has gone though the major undertaking of shoehorning a 502 in his Scarab and he may be the one to ask for real feedback. I believe his last post mentioned the top speed to be in the 60's range.
Basically, what it's going to come down to is how much money do you want to spend????

[flat broke]

I think you're looking for THIS
Chris

[miller19j]

In my opinion your best place to start when trying to get more speed out of a jet is the Pump. I would try to make it as efficient as possible so you can make the most of your current power and any engine mods that you make. Find a good shop that you trust and have them blueprint your pump. Then start building more horsepower. A jet boat is only as good as its jet.
I am sure that you will get several recommendations of shops from the people on these boards.
And Welcome to the boards!

[PLACECRAFT20]

I DONT KNOW TO MUCH ABOUT THE SCARAB BUT, MIKES PUMP AND SPEED IN HOUSTON TEXAS IS A VERY GOOD JET MECHANIC AND CAN PROBABLE HELP YOU WITH ALL YOUR QUESTIONS. HE HAS A WEB SITE LISTED AS WWW.MIKESPUMPANDSPEED.COM. GIVE HIM A CALL OR TAKE YOUR BOAT BY.

[Scarabjet]

Thanks Chris! I forgot he had posted on your website. I also have some killer pics he sent me privately of the motor installed without the engine cover. What a beast compared to the 4.3!
I agree with Miller on the pump. However, IF your pump is good, I don't think we are going to be able to squeeze any more than low to mid 50's out of our Scarabs equiped with the normally aspirated V6.
Rick

[flat broke]

I'm going to differ from Miller's statement for the following reason. You are planing on building more HP. If that is the case, build the HP first, then have your pump guy tailor the pump to the motor. If you have the pump detailed and inpeller setup for your current power, then you re'power, you're impeller will not be matched to your new power curve.
If you were going to leave the 4.3 in there, then I'd say go after the pump, but first get your new powerplant taken care of. Then the work your pump guy (I personally recommend Jack at MPD) will be far more relevant and beneficial to your setup.
Good luck,
Chris

['97 Scarab Jet]

First I want to say thanks for the info so far.
Just curious, what are ya'lls thoughts about these motors (crate):
520 HP 383 cid
530 HP 427cid
I know they are crate auto engines, but I have no idea where I can find high performance marine engines (that don't cost an arm and leg). I'm looking more to the small bocks because of the engine compartment room. Yes, I've seen the 502 SCARAB, but thats looks pretty tight and even more weight. BTW, how can I contact that guy?
Just a thought, has anyone had any dealing with this company:
powertorque.net
Curious what is the average cost and turn around time on a blueprint for the pump? I will be calling Mike's Pump & Speed again tomorrow. But just in case, does any body know of another place to get pump work done in Texas?
I know I just keep asking question after question, but thank ya'll for everything. Who knows maybe 1 day I'll know more about this stuff to help another.
Joe

[Mike J.]

SEE Topic about Same post.
Scarab Jet
Mike J.

[SB]

Pump work might run $2k, and turnaround for marine work is often slow. Which brings me to the following thought: I agree with flatbroke and am not contradicting any of the above advice, but if you're project is going to run above $10k and/or you need above about 65 mph, consider a different hull. There are hundreds of boats available that are already set up for a big block engine.