Props for 700HP Cafe
 

Hey there. Re-powering 90 cafe with engines showing a little over 700 HP/FP on the dyno undressed with 5" open pipes. Going to be running dry Gil this year so I expect some loss in power. Previous best speed on GPS was 65 (full fuel, 3 adults and gear, light chop freshwater) at 5100 with 509s turning Hydromotive 22s wtth 1.5 B1s. I don't know what power those were putting out because one was hurting (it gave up the ghost soon after) and I could never get it to peak HP (builder said 5600). Called one prop manufacturer for advice and he couldn't make any suggestions without knowing what I had been running before (and I have no idea since I never had that power on a dyno).

SKramer has been very kind to lend me some 25s to get a baseline but I would appreciate any thoughts on whay anyone with a similar power setup is running and what speeds your are seeing (don't worry about commenting on the drives - I know, I know).

Thanks!

Dave

I run 26 4 Blade B1's on my Cafe.

I think I put out somewhere in the 580-600 HP range.

You need more than 25's with 700 HP. Mine spin right in the 5100 rpm range.

props
 

was running stock carb 502s with 24 4 blade 1.5 bravos ran just over 5100 [rev limiters set at 5400] ateco rebuilt to 525 hp and im still breaking in / dialing in but 26 4 blades are working real well. I have a set of 28- 4 blades I bought and probably are not going to use . email me if you are going to need them we can make a deal im north of chicago

750 H.P running 26 Bravo's or 27 Mirage 3 blades did 85 gps's turned 5800
-Mike

Call Brett at BBlades he can get you there. Tell him he can use your power numbers with the data he has on my boat (93) Cafe. In fact he has my props right now trying to tweak a bit. I am guessing you will be in a 28p 4 blade. Brett also has a demo program. If you call him tell him you have the same boat as Frank in CT. Good luck and let us know your numbers, how about some pics of your rig?

I would guess at least 28 4 blades. I know its not apples to apples but my 40' with 700's is turning 28 5 blades at about 5400. Your X will determine the difference.

Frank, way cool said he has a spare set of 28s a couple posts up! maybe a second set for you for the right price???

Mike you are leaving quite a bit on the table with those numbers and props. that is 400 hp total more then my rig and it is only netting 5mph approximately. I would run 28's and bring down the rpm a little and pick up speed.http://go-fast.com/boat_speed_predictions.htm

Waycool are those props new or used? Hubs or no hubs? What is the pre seaon sale price?:drink:

Dude! Don't bogart on an offer on my thread before I have a chance to read it!! :lolhit:

I am interested in the 28s - PM sent.

Wow! I sense a little hostility!! Dont mess with a mans boat parts I guess! I think we should give the seller a chance to auction them off and maybe make the post worth his while. I will start the bidding for the props at $200.00!!!!!!!!!!!!!:lolhit:

Reverse Dutch Auction!!! I offer $195!!!

I'm running labbed 30P Bravo One's on my 35 Top Gun w/ Vortech charged 500efi's (700HP each). It's similar to a Cafe in some regards, but lighter.

Well, I'll chime in as well since I'm playing with props as well.

When I bought the boat the previous owner Jeff was thinking the motors were putting out about 550 hp.

It had a pair of bravo 1 26s on it, and ran right at 72 at 5200 rpm. That was a bit more rpm than we wanted for those big motors, I was looking to get closer to 4800. (they are 582 cu. carb motors)

So, I put on a friend's pair of 28s, and got 74 at 4800, so got the rpm number dead on. I had bought a pair of 30s, and we put those on, and now I'm at 76, and still at 4800.

Another friend has a set of 5 blade 28s on his Donzi, so that might be the next experiment. He has more hp, but I think I'm close to him on the torque, so we'll see what happens.

The top speed didn't change much between the 28s and the 30s, but I did notice the speed at 4000 jumped up 5 mph!

Bob

Bob do you know what rpm those motors make peak hp? I am guessing 4800 rpms is still a little light. I am not sure whats most important to you but with the peak hp rpm number you can get more speed by running a bigger prop and have it labbed finished to the right rpm. I am running a labbed 26p Bravo 1 with about 560 hp, running those motors at 5150-5200 I saw 78.9mph on gps. The props are back at BBlades to get another 150-200rpms to try to get me to cross the 80 barrier. I have seen unbelievable gains from the right prop combo. Good luck and keep us posted, that thing must be a torque monster!

We're running 28 Pitch - 3 blades from unknown ratio #3s. Our HP is in your range and we can spin them at 5800 RPM.

Good Luck.

Chad

Unfortunately no, I have no true dyno info, just having to go with estimates from the builder with different heads and exhaust. But he did say that torque was their real forte. I'm like you, I would think a little higher is where they would peak out, but there is a lot of mass moving around in there, and I would rather have them last a little longer at the expense of a little top end.

I'm going to try the 5 blade props, and that same friend has another set of 5 blade Herrings with the defuser trimmed off that I can try as well. So, we'll see what those do this weekend and down the road I may ping Brett about doing some work on the ones I finally settle with.

I am no expert by any means but just as important as not over revving those motors you don't want to lug them either. Are they roller motors? If so they will like the rpm's. Maybe someone here can shed some more light in to it. Also are running Bravo's or TRS?

I would be worried about detonation with the motors loaded that hard.