Bullet prop question
 

Since there has been a recent flurry of Bullet threads, I thought I'd throw one out. On the long list of things to do on my boat, one of the items are looking at some different props sometime this year. The current ones are not in the best shape (dinged, not by me)

Boat info is:
1988 Bullet with NO transom notch
Bravos with 27P 3 blade Mirages
454's with B&M 250 chargers (single carb)
Mechanics guessing have told me engines are around 550hp (not dynoed)
Runs about 6 lbs boost at WOT
WOT is about 5000 rpms with these props

Performance:
props blow out at anything over about 1/2 throttle getting on plane (not really a problem)
Hard turns can blow out props if trimmed up any
Boat wants to porpoise slightly at speeds above 65mph
Top speed is only about 71 on GPS (with 1/2 fuel and 3 guys)which seems too low. I was expecting at least 5mph more and was hoping to see 80.

Am I overly optimistic with what I expect speed to be? Should I go to a 4 blade? Thanks to anyone with advice.

Yes, a 4B propeller should hook up better for you....as long as your prop shafts are not to deep. I think with an 88' you should be OK. If your motors are mags thne you should be running a higher RPM at WOT. If no-mags then you should try some 28P Bravo I props (assuming your 27P Mirage Plus props are stock).

Julie

WAYNOFZR,

i spoke to Kevin from Midwest Powerboats who has owned and re-done several bullets. Some good advice he gave me was you have to trim the crap out of bullets to find the sweet spot and he was right. wot i trim mine to 7-8. try it if you havent already. makes a big difference in performance.

My indicators are not hooked up at the dash (one more thing to do), so trimming is by feel until I get that fixed. When trimmed high, I gain RPM's, but not much speed. I've trimmed high enough to start about a 3' - 4' high rooster, but it still porpoises.

Steve, what engines and prop combos are you running?

Definitely need to get your indicators operational. Because as you said, the sweet spot may not be the "highest" trim angle. So, once you hit the sweet spot, how will you find it again if your indiactors don't work.

same props as you. old style 27p mirage. 7-8 gives me the same size rooster as you describe. ~ 520 hp 540's. are you running in smooth water? its always at least a 1-2' chop at loto so i dont know if mine would porpose a lot in smooth water or not.

I don't seem to notice the porpoising as much if there is a chop and I don't have any in 2-3' rollers. You really notice it on smooth water. What is your top speed with the old Mirages?

they really like rough water. mid 70's.

I have an 88 Bullet without the notch, 500HP (dynoed) 509's, running labbed (Bblades) 25" MiragePlus, 4900 RPM WOT. Best on GPS was 69MPH, 1/2" Tank fuel. As others have said, they take alot of trim.

Don

I guess I'm hoping for too much to see 80 with my current power. I can live with mid 70's.The only prop recommendation I saw above was a 4 blade 28P Bravo I or maybe a 26 and spin higher. Does anyone have any other prop suggestions? Has anyone done nosecone mods to Bullet or older Cafe with Bravos and had good results?

I do plan to go into the engines (in a year or 2) to actually find out all the specs and will probably take them to 496ci when they're freshened and still use blowers, but I have a long list to do before then, probably in the following order:
Hook-up/repair Tab and Drive Indicators
Cockpit Upolstery
External Steering
Update dash
Then work on engines
Finally, new paint

All in my 5 year plan :)