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 :)

If you are already in the mid 70's and looking for 80, you might want to move this up to #1 on your priority list.

my 91 bullet 600hp normaly aspirated 26 bravos 1 & std. bravo drives tops out at 83 at 5600 rpm need alot of 380 tabs to overcome porpoising. a friend is loaning me a pair of 30 3blade let you know what hapens.

My 88 Bullet has 454 bored 30 over, edelbrock air gap manifolds, 750 holleys, gil exhaust, trs drives and 4 blade hydromotive props. I trim my drives to only 3-4 on the indicator and only see 60mph on the GPS. Should I trim them out farther?

I'm sure someone else will pony up here since I've got no indicators. You need to give some more info. Pitch on props and RPM's, etc.

Like I said earlier at lunch Wayne... we need to go through the tune and make sure she's right, then play around and see what's up! I think there's a few MPH left in her the way she sits.

Some labbed pros would probably help her bite more, too.

my '88 notched transom trs. 500 bulldog 540, gps 72 smooth water 4b 24bravo 5300. takes somewhere around 625 to run 80. one of kevins ran 85 with 725s. i redid my motors might gps tom. 28 4blade bravo.

28 4blade bravo 5000 77.2 gps

5050, can you give me your engine details? Was it dynoed? I would be happy to see that kind of speed out of mine. Do you know what you cruise at around 3500 to 4000rpm? Like Tom said, we still need to play around with it. I'm lucky to know 3 good mechanics that are friends :)

540s j&e flat top pistons, eagle crank & rods, dart intake, demon 1090 carb, comp. custom grind hyd. roller .648 .648 254 262 duration @.050 110 lobe separation with 4 degrees of advance. chineses aluminum procomp heads. crane roller rockers. cmi dry exhaust.

i might have 1 or 2 mph left in it still runin way rich at idle if anyone could help with that i would appreciate it & would a 29 3blade give me anymore rpm and speed?:D

Maybe you just need to go out on a more windy day.:cool-smiley-027: lol! What did those motors dyno?

did not have time to dyno. i like using my boat as how your boat sits for 2 yrs. and barely breaks 60. LOL.:violent-smiley-045:

What are you talking about sits for 2 years thats why you have plan B boats.:ernaehrung004::D:D

Well, the season's over here. Time to start saving money for winter projects :)

Next question on this thread....

Anybody modified their Bravos with nosecones and had good results?

My 89 has nose cones and a notched transom and I think I like them better without. I had a friend that had one with trs's and nose cones he removed them and picked up speed.

OK, can anyone else tell me ANYTHING they've done for more speed by modifying stock bravos? Any aftermarket drives or shorties been tried on Bullets? Replaced with newer Bravos?Cones? Low water pick-ups?

Since my drives are not in the best shape, I want to have a solid plan to determine how much I can afford and a plan of attack before I just yank em off.

Has anyone had hard shifting with the Bravos?

I have heard shorties work well. I think I am going to try a set that a friend has and see for myself.