Thanks Jeff! Even though the wind didn't quite cooperate it was still a great weekend meeting people and re-meeting others (alcohol). Hope to meet up with you guys soon.

Nothing like a poker run of 70 boats with serious hardware and rough conditions to humble a guy. Lake winnebago was probably the roughest I've seen. We topped out at 32mph out there and averaged about 27... Got up to about 55mph (woo hoo) on the river before we had to slow for the next bridge. But the main goal was to have everything hold together and that it did! Motor ran great, drive shifted good. The four blade 30 still gets the boat up and moving quickly even despite the high slip at higher rpms.

Hoping to get out and do some prop testing soon. Stay tuned we're not done yet.

Wrong forum...lol

Wrong forum again. Sorry !

Made it out to Green Lake by BBlades to run some props today. Had 5 props to play with, 31" p5x, 28" Maximus, 30" Maximus, 30" 4 speed and 32" four speed in addition to my 30 labbed bravo 1. First up was the p5x. Won't lie, got a little discouraged when we could only spin it to 4900rpm 77mph, pretty good bow lift, slip around 20%. Then 30" 4 speed was higher in slip above 20%, could only spin to 5000 74mph. Started thinking ok I guess I have too much boat in the water or this scx takes 250hp away.... Put the 28" Maximus on 5200 78mph, felt really good, great control and bow lift. Then the 30" max, 4800 77mph. After the first couple props I started wondering why I don't hear that cherry on top back there howling like it should. So at this point all I can figure is the motor/blower is not making any boost, so I'm basically running a slightly hopped up 525efi.

so my question is, is the 4.875" pulley too big for a 509 with -20cc pistons. I figured comp ratio to be around 7.8. Do I need a smaller pulley? I can't get a boost reading through the smart craft. That might just be a sensor issue though. As soon as I got home I hooked a mechanical gauge to the manifold that I will check out while underway asap. Thankfully they let me bring the 30" Maximus home so if I get it figured out I can run it with some real power

Not out yet

Ok so started investigating first thing this morning. Began with removing bypass valve to see if it was really closing. While taking it off I noticed that after I pulled the easier to reach bolt out, the part of the bypass that attaches to the intake manifold was loose already. Hmm. Took the other bolt out, saw the valve was infact closing all the way but noticed "fuely" residue on the bypass body and spacer plate right where the bypass mounts. Long story short, the wrong bolts were put in the wrong spots, one is 1/4" longer than the other, the metal is thicker on the bypass body where the longer bolt should go. The longer one was bottoming out before the bypass body would tighten up to the intake. So I'm pretty sure this is where the positive pressure has been leaking out.

How I found the bolts
Attachment 568393

How they should be
Attachment 568389

Fuel residue on bypass and spacer plate
Attachment 568390

Attachment 568391

Aluminum is thicker at one hole than the other, thinner in the one inside the opening for the bypass. Have to remove the hose fitting to even get to this bolt
Attachment 568392


gotta get her out again and see if this dog can hunt

Awesome on the prop testing!

Hopefully you found your problem!

Be safe!

You'll get it dialed in, just need more setup time. Don't get too discouraged with your motor, those SCX drives zap a lot of power.

Yea I think you're right about the time to get her dialed in. :rolleyes: more time and money

Got her out on the smaller local lake near us. Mechanical gauge showed vacuum and about 6lbs of boost. Yay. Could definitely hear a blower this time. Yay. Unfortunately I couldn't open her up though, just ran out of lake too quick. But I'll get her out on a bigger lake soon and see what happens. Trying to get a hold of anybody at Whipple that could give me some info on the tune. Transom seems to get pretty sooty

Got out on Winnebago last Wednesday with 30outlaw for a couple WOT runs after the bypass valve fix. Fixing the leak netted me 200rpm. Not as much as I thought, but it was a leaking HP nonetheless. We saw 80mph @5000rpm with the 15.625" dia x 30" pitch Maximus. About 15% slip, don't think I can complain about the slip much with this high of an X dim on a single Baja. Slip is even lower 10-12% at cruising speeds where less trim is needed. The Maximus carries the boat great. Good control at all speeds.

So I need to be at at least 5600rpm WOT. A 28 Maximus would gain me another 400rpm and labbing will gain 300-400rpm according to BBlades. That would put me at 5700-5800 which if slip were to stay the same would be 87mph, theoretically. I'd be happy with that with this monster scx back there!

Enter a 4.375" pulley. Bumping boost to 9.25ish from 6.25psi. I've talked to multiple builders and professionals and it just doesn't seem to make sense why a engine would've been completely rebuilt with better parts than original and lowered compression to 7.7:1 - 8.3:1 comp (depending on if the pistons are -20cc or -10cc, I'm figuring -10cc to be on the safe side) to run 6.25psi. The Whipple kit for a stock 525efi is 7psi (.125" smaller pulley than I currently have bolted on), that's with 8.75:1 compression and questionable valve train. With 9.25psi of boost the motor effective compression ratio would still be lower than that of a bone stock 525efi with 7psi added.