Reply With QuoteHave a 25' Checkmate that does about the same, been in a few friendly races with those size Scarabs and it usually depends on who has more passengers. Anyone, other than a blower?
I just bought a Scarab 22 with a 7.4. Any ideas how to make this go "fast"? It tops at about 62 mph..
Anyone out there with smaller Scarab?
Have a 25' Checkmate that does about the same, been in a few friendly races with those size Scarabs and it usually depends on who has more passengers. Anyone, other than a blower?
How fast is "fast"? If you are looking for just a couple miles an hour props are a good place to start. Check your speed and rpms and talk to a good prop shop. They may recommend trying some props through a demo program or perhaps blueprint the prop you have.
Originally posted by Jochum:
I just bought a Scarab 22 with a 7.4. Any ideas how to make this go "fast"? It tops at about 62 mph..
Anyone out there with smaller Scarab?
I have the same boat/motor, 80-82 w/whipple!
Hey dmed.
Thank you for that idea..
How much did that operation set you back??
Jochum, I know someone with a 22 ZX Donzi[similar size as the Scarab]who had the same dilemma.He supercharged it ,now the boat does around an honest 75MPH.He had some trouble with changing pistons, to lower compression ,and his engine builder recommended him the hypereutectic pistons.Needless to say the boat ran fine for 1/2 hour and had a 6 piston meltdown[could have been due to a lean condition ,don't know full details on the setup].I recommend forged pistons and upgrade with ARP bolts with supercharger.Talk to Whipple,about your application.
Originally posted by Jochum:
Hey dmed.
Thank you for that idea..
How much did that operation set you back??
Not exactly sure, I am the second owner. the previous owner took excellent care of it and had it installed. It had 91 hrs. when I got it. Talk to Dustin he is very familiar with my boat as it was one of the first 7.4 installs. So far(knock on wood), I have 170 hrs. no problems, with all stock cast internals. Dustin did an excellent job and installed boost,EGT, and fuel pressure gauges along with all the warning lights bells and whistles.
I have a 1995 22 Scarab that came with the 7.4. It also ran 62 mph top end. First I changed intake, carb, and exhaust. This gained nothing on the top end but gave more midrange punch. Next I changed the heads to rectangular port heads and changed the cam. Boy did this make a difference. Went from 62 to 69.9 GPS. This was fine for a year then I spun the main bearings with no warning and plenty oil pressure. I dont think the stock cast bottom end components could withstand the extra power (420hp). So I bought a 502/502 assembled shortblock new from GM Performance and used my near new rectangular port heads. I changed the valve springs to the correct ones for the new roller cam and bought new roller rockers. I milled the heads to achieve a compression ration of 9.4 to 1 (just like the 502/502 with aluminum heads). Bolted everything up and she now does upper 70's GPS with plenty of bottom end to get out of the hole. It pulls a 27" Mirage to just over 5000rpm. Ive seen a best of 78GPS but Im sure she has a little more left.
The best part is I just bought a new boat and this ones for sale!
Ron
rjcardinal@eatel.net
I've got a 21' Scarab. It's got a Jasper Marine 350 in it and with 2 people and a a half tank of gas it will run 60 mph on the GPS with a 22 Pitch turbo prop with some added cup to the blades. I'm also trying to find ways to get a few more MPH out of this boat. I've got a 400 small block that I'm thinking about building, but I'm not sure I want to give up on the Jasper quit yet. I'm thinking about changing cams and see what that does.
Just bought a '95 22 Scarab. It's got a stock 454 turning a 23 pitch Mirage. 56 - 58 MPH according to GPS. Is anyone running a 25 Pitch. The 23 is winding up to 4800 RPM.
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