Scarab 377 speed and stuff
 

Hey guys, hope everyone enjoyed their labor day weekends. I took my new to me Scarab 377 out last weekend. It has staggered 730hp blower 540's with 1.68 rstio speedmaster 3 drives with 28 pitch 3 blade props turning out. The best I could get out of it was 5000rpm (engines peak at 5700) at 70mph gps trimmed out in 1-2 ft waves with 5 people on board with half a tank of fuel with 2 coolers and overnight stuff. The boat seemed very bow heavy and didn't respond much to trim, breaking water in front of the windshield. That being said I've been told by several people to switch the drives and turn the props in to get more bow lift. I also have a set of 26 pitch 4 blades to try. Was curious what everyone else's thoughts were. Any advice is appreciated! Thanks everyone!
https://cimg0.ibsrv.net/gimg/www.off...847d9d3a1f.jpg

You're at 11% slip which seems really good. Don't know if you could get much better.
Looks like you're lacking HP.
What blowers are on a blown 540 with a single dominator?
Clean boat. Did you buy it in Jenison, MI?

Weiand 177's. Bought it just west of Jenison.

That's a really big heavy boat, in my 30' century with 620hp and SSM3's gutting the cabin really made a difference in how it would carry the nose. It seemed to hurt the balance in rough water but picked up a few mph in the light chop.

I don't believe a 177 is capable of making 730HP. Others correct me if I'm wrong please.

That's what the dyno sheets said, its getting bigger cams this winter, so i guess ill find out when it gets dynoed with the new cams. Regardless of what the engines make, my question was about the setup of the boat, not here to argue about engine power numbers.

The 177 is pretty small for a 540, the static compression must be high to start with. You should verify how much they are over-driven. 5700 rpm at max over-driven is too much.
The max I could squeeze out of stock headed 468's with 8:1 compression was 620.

I think the power numbers are relevant. The 177 is going to get really hot trying to feed 540s with any kind of real boost. That's going to lower power (especially in a hot engine room) and may possibly cook something. What kind of boost pressure were you seeing?

Like Rookie said, the slip number is good. If the engines are making 650-ish as installed in the boat, that may be about right. I would think the 3-blades would give you better bow lift but would depend on what the props are.

Nice looking Scarab!

That is a nice looking boat! I think your slip numbers are good and 70 is pretty respectable for a 37ft boat that likely weigh 5 or 6 tons?!!

The engines are currently running a little over 3 lbs of boost (from what the gauge tells me), the engines feel good like they wall keep pulling but just hit the wall at 5000 rpm. New blowers are out of the budget right now, just trying to work with what I have for now.