Is This As Fast As It'll Go?
 

I have a 1992 27ft Fountain, 700 HP, 540. It's been dyno-ed. Has an XR drive, 1.5 gears. It's making 700 HP at 5600 RPM's and 655 lbs of TRQ. This is as high as I can get it to spin up; 5600 RPM's with a Bravo 4 blade prop done by BBlades. The fastest I can get it to go is 80 MPH on the GPS in "perfect" conditions. Tried a 28 pitch prop Merc labbed 5300, 79 MPH on GPS, a 27 pitch Hydromotive labbed at 5500 RMP's which gave me 79 MPH on GPS. Also, tried another 26 pitched prop, labbed but not sure by who, 5700 RMP's gave me 80 MPH with too much stern lift so had BBlades do me a prop. Final result was 5600 RMP's and 80 MPH on GPS. Trimmed up to 4, tabs set the same, used a straight edge on tabs. If I lift them I don't gain anything. If I trim more, it seems to loose speed.

Just seems like it should go faster for the HP; maybe I'm wrong. Any advice is appreciated.

Thanks,
Todd

I had a 92/29 w/ twins (502's). 80 was max, and always faster w/ a 3 blade vs. a 4 blade. Is your XR set at the same height the original drive was? If so, add 1 pitch and get a Mirage +, 3 blade to improve top end.
Carder

Thanks for the input, Carder. I tried a 3 blade once before but it blew it out. Also, I'm pretty sure the new XR drive is set up the same height as the old drive. It's 5 1/2 X dimension.

BTW: nice boat! We boat up in Bay City also and saw you over Memorial Day Weekend. We have the fountain with the blue flames on it. :D

seems slow to me for 700 hp...

My '94 27 with a bolt on B&M 250 blower package, less HP than yours would run 83 GPS with a stock 27" Hydro prop.
Stock Bravo drive. 5800rpms

Thanks for the reply, US1 Fountain. This is a N/A engine. Don't know how much difference there is between that and a blower motor; I would imagine quite a bit. This engine actually makes 740 HP @ 6200 RPM's but I can't get it past 5600 and to get it to 6200 you would have to lab a 24 pitch which Brett @ Bblades said it would be wash and you'd loose cruise speed, etc. So not sure where that leaves me. Seems like a lot of wasted horse power.

~Todd

Was the dyno run done with the dyno shop headders of your marine exhaust? Full accesories and sea water pump, as it is in the boat? Can make a huge difference in the horsepower.

Just outta curiosity. What is the dyno HP at 5600 vs. the HP at 6200?

Hey Ragged Edge,

I was told it was run with marine headers (not mine) but with my C pump. Thanks.

~Todd

Hey Pachanga thanks for the reply. It made 700 HP @ 5600 & 655 TRQ and 740 HP @ 6200 & 637 TRQ. Engine was dynoed by Platium Designs out of Norwich, OH. Engine was built by Champion Performance out of Center Line, MI. Champion Performance is some of Sterling's old guys that parted off and opened their own shop. Great group.

~Todd

The X dimension you are refering to, is that propshaft to bottom?
I have a -93, my propshaft is 4 1/2" below the lowest point of the hull, my came with a Mach sterndriver 4 blade. I beleive most -92´s came with Mirage props.
80mph seems slow for the hp you are running.
Have you checked the bottom for a hook?

Wow! That does seem slow. Sounds like you need a serious dialing in to me. Perhaps badluck is onto something! Have you tried a bigger prop and tried trimming it up? I'm still in the setting up stage with my Pachanga. My mechanic had it up to somerwhere around 84 on GPS and I'm sure I have no more than 650! That was around 5400RPM's.(He said there was more left!)My Pachanga with quite a bit less HP loves trim with a high X. From what I understand...HP/HP your fountain should do as much or more than mine with the same HP.

I am patiently waiting on him ta get mine outta the shop! It's getting twin ram full Hydraulic steering, headers, and tabs. I'll not push him because he does excellent work and stands behind what he does. Then it's into testing props(am definately giving BBlades a chance!). I screwed up the prop(labbed 30 Bravo) that he was in the mid 80's with. :( Before I put it in the shop after I had the Bravo 30 brought back to stock it would only do 78 on GPS.

Thanks for the reply Bad Luck. I used a straight edge and checked the hull for a hook; no hook in hull. Thanks.

Todd

Thanks for the reply Pachange. I have already tried a bigger prop on it. I have to trim it to the moon; doesn't handle that good trimmed up that far and isn't any faster either. Just not sure. Thanks for the input.

Todd

You seem to have exhausted your propeller supply. I would say its time to move the X up.....try a $horty.

Sounds about right for a flat bottom. Might get 2-3 with dialing in props.

Talk to Jim V. he runs a 27 at the LOTO shoot out, and he's right up there in the triple digit mark. He looks pretty loose, but he's done it year in and year out.
I had a 95, 27 Fever, pro charged HP 500 with an IMCO polished shorty on it, and it would hit 85, but scared the chit out of me.
So you've got some room left, good luck, and be safe.

I'm thinkin' it's the stepped bottom that gets the extra 3-4MPH. I got a 92 w a blown 502. Roller cam, rockers ,JE Blower pistons 6 lbs of boost...High 6's maybe 700 Hp.. The best ever has been 77 with the wind and perfect chop..Mine runs 73 - 75 on normal calm water..

I'm starting out with another prop as well.The bottom of my baot has no cracks but looks pretty wavey along the bottom. I'm sure were loosing a couple there too..But I think low 80's is it w/o the step .Unless you have a blower 2 carbs headers and burn lots of gas.

I have 1 dominator and it uses little fuel, probably could do better w 2 carbs.. But with gas....Were still not going to beat that damn tunnel w the 2 2.5 Merc efi's no mater what we do.But we have all the comforts of home.:D

arneson!

Todd,
We did see you Memorial Weekend...Still too cold to play @ the Bay City State Park Sandbar, tho.
I would give a larger 3 blade a try, for top end gains. BBlades has some, I'm sure.
Is your rev limiter set at the 5600 mark or the 6200 mark?
If it is set too low, that is your limiting variable.
Carder

Do you have any props for sale?:party-smiley-004:

Thanks for the reply Reggie. How do I get in touch with this Jim V....e-mail? Phone? etc. Thanks.

Thanks for the reply Carder. I will try to get my hands on some 3 blade props and I have a MSD ignition; it was set for 5800 RPM's but I pulled the chip out.

Todd

Thanks for the reply MCProDesign. No, sorry I don't have any props for sale.

Thanks, Todd

Go over those dyno #'s then again with twins he only got 80:Whatever:

Todd,

Something is not right with your setup?? with your HP you should be running a 27 Hydro, nailing 5600rpm with that HP and GPS well into mid 80's area. To give you a point of reference 24 Hydro used to come std on 502mag 415hp 27 fevers 70mph. 25 Hydro with 500efi 74mph. I've owned both, as for the step, over 70mph shouldn't make a difference only the notched transon is in the water at those speeds anyway.

I think your drive is too low (X-Dim) or your motor is not making the HP that was promised.

Keep the info coming and with the knowledge of everyone here we should be able to get you straight. BTW JIM V would be a great reference.

I agree. My 93 will run 71mph with a carb HP500 and March 4b 24 14 1/2 at 5300rpm. Propshaft 4 1/2 below bottom.

I had the same problem with my '93 27. I had 675 hp and with a labbed 28, could never get over 80mph.