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74.3 Is there anymore to be had?

A

aaronmt

Member
Just to refresh everyone my set up a 87 starflite(bow foam removed) 87 yamaha excel 240hp(heads mill .010) no air box, 12" jackplate 1 1/2" below the V spinning a 25 pitch trophy plus at 6000rpm.This summer I tried a 23p turnigpoint, 23 tepmest plus a 25 tempest and a 24 trophy plus as well as a quiksiver lightspeed 25. I learnd that the starflites definatley prefer smaller daimeter props like the lightspeed/laser2 and trophys. I have a few ideas being my motor is an older yamaha im limited what i can do. Im thinking of having the heads milled a bit more and having the squish band milled in(it has domed pistons). I will be redoing the cowling as well with louvers facing backwords for fresh ambient air not forced it will also have new 150hp stickers on it:thumb:. Im also considering reeds not sure what type and what if any performance is to be had.I will be haveing the trophy plus blue printed and labbed by BOGER this winter when I can get away with sending it out without being notice by the gf:sssh: . I have talked to RAY NEUDECKER (great guy to deal with on yamahas) he also sugested switching to ALISYN zero weight gear oil , hes seen as much as 300rpm gains. Im already at a low slip factor of .053 how low can you get on this hull? Im lookin for maybe 3more mph is it possible ? Thanks Aaron:bigthumb:
 
aaron, thats cookin. good job. im sure you can get some more out of it. i have heard reeds can add a couple hundred rpm.
 
Thanks ILLMATIC, i dont think ill be catching up with anytime soon but i got think i can find a bit more speed somewhere. Any ideas guys,besides a black motor i do wish it was a merc but it does surprise some how fast it is with the old yammy on the back.:thumb: Thanks Aaron
 
aaronmt said:
Thanks ILLMATIC, i dont think ill be catching up with anytime soon but i got think i can find a bit more speed somewhere. Any ideas guys,besides a black motor i do wish it was a merc but it does surprise some how fast it is with the old yammy on the back.:thumb: Thanks Aaron
Click to expand...

Why would wish for black when you already have the best? Your Yammie will still be cooking when the Merc is cooked. I would think the speed you gain by motor mods will hardly be worth the $. If you want cheap MPH, I would opt for 3-4" more setback.
 
I started off on the transom with 64mph then went to 10" and now at 12" I think thats as far as i feel comfortable going. I do agree these hulls need lots of setback, but Id get nervous any further back. I must agree i do like the yamahas reliability , it will definatley look sharper with more modern decals this winter as well as the darker yamaha grey , the excels are kind of different color then most and dont look that sharp with the gold decals. Anyone ever have the trophy worked by boger props i hear he is the best on trophy plus hands down. Thanks guys, keep the ideas coming ,looking for ever bit of help i can get like I said when I first forund this site I was doing 64, now its truly a differntboat. Aaron
 
imo, 15" of set back would be way out of line. imagine the amount of force being applied to the transom. take a 10 lb weight and set it on the end of a 15" pole. now try to hold it straight out. do the math.

i would exhaust all prop options before opening up the engine. i went from 74 when i first hit the water to 82, just playing with the setup and props. spend some cash on a prop to try. you can always get your money back out of it.

have you tried a 26 trophy or laserII? i have a 26P laserII you can try if you like. it ran 78+ on my boat. if you have a flow torque hub its all yours. let em know.

matt
 
illMATTic said:
imo, 15" of set back would be way out of line. imagine the amount of force being applied to the transom. take a 10 lb weight and set it on the end of a 15" pole. now try to hold it straight out. do the math.
Click to expand...

Alright, let's do the math. Whatever % you increase your setback, you will increase lift the same %. It's Newton's second law. So, if you move from 6" setback to 12" you effectively double your bow lift. And, as you alluded, you double the effective torque on your transom. It's a balancing act (no pun intended) between transom stress and performance.
It takes very little setback to accomplish this on a smaller hull like a Predictor. 5-6" has you covered. Unforunately, the Starflite is very bow heavy and probably requires more setback than the transom can bear.
Check out SCT's 28' Convincor..... 20" of setback, and it won't be too much.
 
mark, you are totaly correct in your statment. however, the math i was refering to is related to the added weight on the transom. :thumb:
 
Anyone ever run the alisyn 0 weight gear oil, what type of reads is everyone running? Mark what do u have in your yamaha? I know I have horisontal already in there. Aaron
 
Set back is key, I went from 10" to 15.5" and left everything else the same, I gained 6 mph. Like they all say, how much stress do you want to put on the transome. I built a custome bracket that redistributes the load out farther on the transome and is working out very well.
Has anyone tried "Speed Rails"? They are like a wedge you add to the outside of the strakes to help add lift to the hull. My brother had a set on his old SideWinder, worked pretty good but then again he had a 200 on a 15'.

F150GT
 
Speed rails? Never heard of them of them yet but i will definatley look. F150 do you have a pic of the distribution bracket you made my transom is quite strong but I definatley wouldnt mind a some extra strength. Thanks Aaron
 
There is a pic of a similer one I built on the Blue Enchanter in my picture this forum under F150GT, I have some The Starflight but none posted yet. I'll see if I can get some on.
 
14" set back bracket

F150GT1.jpg
 
Depends on how it rides, does the bow seem pretty loose now? if so more setback may not help. I would say more HP is the way to go, you can try props till you are blue in the face but it sounds like you are pretty close to the max you are ever going to get from that weight of boat and Hp engine. How fast do you want to go? 74 is pretty good and the cost to go faster goes up exponentially, the question becomes "is it really worth it". To reliably run in the 80's range you will probably want to upgrade to something with more torque like a 3.0L merc. If I were you I would be proud of what you did, you achieved 74 mph with a 21' V-hull that handles rough water fairly well and is also affordable. I know that speed is addicting and you always want more but It seems to me every hull has a point where going faster becomes finacially impractacle, I would probably change my mind if I was rich though, shane
 
He's not a genius for nothing.74 mph great, if u feel the need for speed your in the wrong boat. U need a hyper lite air entrapment hull. your going to break something and then where will u be! 0 mph
 
I think im going to go ahead and do the boyeson reeds and work on my fuel restriction I have, for now. I will be redoing the cowl with the louvers as well as trying the alysin gear oil. I can do all that for around $200 so thats not to bad if it doesnt make it any faster itll certainly be a bit more efficiant, as for the prop Ill probably wait on that unless my rpms go up more then I like. Sure be nice to hit the elusive 75. Looking around at other post and what HP and speed numbers there getting Ive got to realize theres not much more without serious expense involved. BUT, im at 6000 so if i can get it to turn 6100-6200 I may get the numbers im looking for. I think 100rpm more would be me at 75. So close yet so far away.:cheers Aaron
 
Time to empty boat of all unnecessary equipment, low fuel, slight wind at your back(give you a little chop on the water) lose a few pounds, shave all exposed hair, throw on one of those aerodynamic speed helmets and you're there !:lol:

From my calculations if you picked up 100 rpms that should net you 1.2 mph ?!

Good luck keep us posted.
 
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