Prop talk velocity 280
#21
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Talked to young performance marine, going with his updated injection set up for the 575 sci and the whipple intercooler. Just the updated injection will make a huge difference, the tune on this engine is beyond pig rich
for the fuel curve. I have some afr 315 heads with the iconel valves and a hydro roller. Just dont really want to pull engine.
for the fuel curve. I have some afr 315 heads with the iconel valves and a hydro roller. Just dont really want to pull engine.
#23
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Yup, i have been around performance big blocks for 30 years and this guy knows his stuff. He told me the difference with the way the engine runs is amazing and much more efficient. Murc set this 575 up extremely rich to the point the oil smells like fuel in no time.
#24
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Got the young performance injection conversion done on my sci 575, WOW what a difference in Fuel economy and smooth power. Boat has never ran so clean!!
Yesterday we were out all day and i did the same loop we always do, normally i would use 63-67 gallons and yesterday i used 46!! ran her up to 80 a few times.
Boat is a 2003 velocity 280. The fit and finish on this kit is amazing, and only 3 wires to connect haha. Great customer service.




Yesterday we were out all day and i did the same loop we always do, normally i would use 63-67 gallons and yesterday i used 46!! ran her up to 80 a few times.
Boat is a 2003 velocity 280. The fit and finish on this kit is amazing, and only 3 wires to connect haha. Great customer service.




Last edited by hpmaniac; 06-09-2025 at 11:02 AM.
#25
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Boat is running strong, still playing with props. My bravo 30 pitch labbed chine walks a little much, my labbed hydromotive almost has zero chine but begins to porpois at 70, I have to trim down to stop it and then I loose speed. If I drive through it and smooths out past 80. Boat has been 88 -90 gps. I just ordered a 29 pitch max 5 prop. I feel like the p5x prop doesn't have enough bow lift, runs real wet but cruises great and has amazing hook. 10% slip.
#27
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From: Lakewood, NY, USA
This may seem like a dumb question but what do you have in the cabin.? The 280 can be quite sensitive to weight distribution. If you are carrying alot of "stuff " in the cabin you will need a prop with more bow lift. In my experience bow lift is usually not a problem with a 280.
Thanks for the report...it is a beautiful boat.
Padraig
'
Thanks for the report...it is a beautiful boat.
Padraig
'
#29
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It might be too much weight in the stern, that blown big block with 80 gallons of fuel, 2 optima batts and other things is a bunch of weight back there. REALLY hope she like the max5 because they are not cheap lol. The labbed 30 pitch bravo is fast but boy she gets loose, almost maybe to much stern lift. I am learning as i go. my p5x is running 10% slip and all around is a great prop.
#30
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I checked the boat again and nothing in the front for extra weight except life jackets and some blankets and stuff. Trying to learn, the porpoise is from not enough bow lift in the prop or not enough stern lift?? it does NOT porpoise with a bravo prop but want's to chine walk with my labbed bravo, i have not tried a stock bravo 30 or 32 so that is next. Hopefully she likes the max 5 because the hydro motive p5x works better all around than my bravo.


