raytart

Yeah-somewhere in the ballpark of 10 grand
What am I thinking?

bobl

Here's my latest prop shaft dyno test results. I tested a stock 496 Mag, non HO. It made 363.6 PSHP at 4700 RPM. Straight thru transom exhaust with no mufflers. Just a little more data for the gear heads.

raytart

Hey Guys
I tried a stock 30 bravo 1 today but to my disappointment it didn't work that great. It was sluggish throughout the entire rpm range. Although when the water was fairly choppy and I got the boat flying I did hit the same top speed as with my 28 pitch with the added cupping at 5000 rpm. It was difficult to get the rpm that high. For the most part it would only run at about 4700 rpm. I didn't document the speeds at different rpm because I just didn't like the response I was getting. I think maybe a labbed 30 may work. Or I'll just stick with what I have.

Nordicflame

Friend with our old Heat bought BobL's 1" spacer and it completely changed the attitude of the boat.
HP500EFI (at 5000 feet) best before spacer was ~67 and is now touching 70 on speedo. The boat rides much higher out of the water than before and runs better across the board.
Best money spent on a Heat

Steve Zuckerman

I have seen improvement with 4 blades and the 1" spacer (acelleration/midrange cruise/top end).
With TU blueprinting on my 30" B-1 and the spacer, it is within 1-2 mph across the board with my 5-blade Hydro 28".
The Hydro doesn't seem to care about the spacer, but does carry the hull with loads a little better, so I'm leaving it in.
Steve

Nordicflame

Interesting...I thought Bob picked up a bunch with his 29 Hydro 5 blade by adding the spacer...
A very non-exact science to say the least
Dave

bobl

I picked up almost 4 MPH with the spacer using a 29 P5X. But, I have the ITS and I believe the "X" is too high as originally installed.

Steve Zuckerman

Actually,
This does make some sense, as Bob's boat is a midcabin/open bow, and probably needs more hydrodynamic lift than the hard deckers, and I think he's still using a stock gearcase.
I do think I had partially solved my problem by loading the prop better with the Imco gearcase. Even with my old Merc lab B-1 (now replaced by a TU version) slipping it's usual high teens, I did pick up one mph with the Imco.
Dave, is the 97mph Heat using a spacer?
Regards,
Steve

Nordicflame

No...(not yet )

Actually I've told him "if it's not broke, let's not fix it"

raytart

Hey Guys I haven't had much to say lately but now I need some feedback and thought someone here may have some. Here's my situation. Going against what a few people had advised against but I did it anyway. I changed my gear ratio from 1.50 to 1.36 just as an experiment. I tried my orig 28 bravo with added cupping but the motor couldn't spin it to full rpm (4500) I then tried a stock 28 bravo and it got better but still not good. Now I'm spinning a stock bravo 26 to 4800 rpm and going 77-78 mph. I need a few hundred more rpm and the speed should also pick up. The problem is this _ The boat feels like it riding high in the stern although the bow lift is good. It feels like the boat is completely riding high and it dances on the tail to a point where it feels unsafe. Is it possible that the added prop shaft rpm is giving me stern lift? I have no problem getting on plane and the throttle response is acceptable. I'm just searching for a few mph up top and I'm willing to experiment. I tried it with the 1" spacer in and also out. It's not as bad with the spacer out. And according to my calculation I'm at 11% slip (1.36 @ 4800rpm @ 77 mph).