TylerBurich

I don't have dual planes, my boat came with the weiand single planes and 1" open spacer. I am replacing them because they are corroded throughout the water passages. I honestly believe a good single plane would be far better than the poor single planes I currently have.

endeavour32

iTrader: (4)

Yes a good single plane would be better than that old Weiand but the Merlins are typically for big displacement engines. Go to the technical section, I'm willing to bet 9 to 1 you will be told to run an RPM. 5200 is just to low for a single plane intake. A lot of guys also had problems with the Merlin intakes sealing up.

pgolder

These were the 420's Rhyne Competition Racing Engines built costom 525hp 496's bored .30 over JE pistons, stroker cranks, Dart high rise intakes, Merlin head's ported & polished, Lightning Marine Exhaust Headers . She spins the 25s with ez to 5200 rpm pops up on plan FAST! Oh yeah and just to save face they left the swim platform on and just drilled "4 6' Inspection holes" under the plateform to give it a real distinct RUMBLE!!!

endeavour32

iTrader: (4)

This would be a good comparison. My 420's are all stock other than the cam (231/237) and intake (Performer RPM) and I'm spinning 25 4 blades at 5000 for 70 MPH. My timing is very conservative at 32 degrees. Next season I'm going to run 36 degrees and a 1" open spacer, so there is still some power on the table yet. This was the first year on the rebuild so I wanted to play it safe.

pgolder

Alot of the power came from the heads. twin 525hp engines really bring the boats throttle response & power up.

endeavour32

iTrader: (4)

pgolder- Have you had the engines dynod or did Grand Sport Center tell you they were 525 hp? What props and what kind of GPS speeds are you getting? I'm kind of shocked that we are both spinning 25 props at close to the same RPM and you have 50 more cubic inches and aftermarket ported heads. Something seems off. Any idea what cams you have in your engine?

TylerBurich

pgolder which merlin III's do you have, I went with the 310's do to only being 454. I'm thinking with a longer intake runner compared to my weiand xcelerator short runners the torque will come in faster. Sounds like you and I are running very close numbers right now. Before I put her up this year I spun my 25 mirage non plusses to 5200. I know there is a little left in it though, just trying to take it easy on the new builds!

pgolder

Grand Sport dynoed them for me befor i bought it with a prop dyno
Rhyne Competition Racing Engines built them
Their Dyno sheet 95 octane 515hp
110 octane 525hp 650lbs of torq
I spin my 25 mirage non plusses 5200 all day full tank 2 coolers and 5 people.
my boat flights out of the hole like a jetski lol. what drives do you have? I have trs drives with bullets

endeavour32

iTrader: (4)

Interesting- I've got the original non-speed Bravo drives. By that I mean they have a blunt nose and a short case. With the non-plus Mirage 25's I'm at 5200 as well. I didn't realize the TRS drives had that much drag. You may want to talk to some TRS guys, the nose cones may be holding you back. I was thinking about adding them to my drives but Hydromotive didn't think I was going fast enough for them to do anything. I'm right on the edge of the them either helping or hurting speed. If I had the newer style lower I definitely would not need them. I think the new drives are good to over 80 MPH.

pgolder

The 311 with the trs also has tannies i've read that the were a lil heavier than the bravo 311.
I have gps the boat with my iphone to 74 but it keep falling of the dash.lol The original owner claimed it was a white knockle ride at 80mph in 3 fot of chop. I've ran this boat for the last couple years and its one of the faster V bottom boats around here. Not to say i havnt been pasted by a 1400hp 40 outterlimets, or a offshore cat befor lol. She hang with all the 500hp flat bottom v boats sonic, foutain, cigerette, and the baja.