Anybody have an idea?

« **on:** March 30, 2014, 11:12:21 PM »

I'm new to jet boating and love it- first off!!!! But was wondering if any one has any idea how fast i will go. I have a 77 Tahiti 18 ft. Quarter stringer, 460 bored .60 over, flat top pistons, Dove heads polished/ported/surfaced, roller rockers, Hydraulic flat tappet cam, tunnel ram, Dual 600 holleys, 10/1 ratio, 9 qt oil pan, msd ignition, good coil, high volume fuel pump, high flowing oil pump, Berkeley jc completely rebuilt with an A impeller and a manual place diverter. Dyno test says its doing 452 hp/501 ft. of tq.($6800 later!!!!!) all this done this winter cause of a spun bearing from the summer. The weather is not warm here yet so i cant test run and I'm dieng to take her to the water!! Any ideas and or tips would be very helpful!! Thanks for reading!

« **Reply #1 on:** March 31, 2014, 12:00:58 AM »

Is 452 your un-corrected horsepower? At what RPM? Un-corrected horsepower is what you want to look at when contemplating impellers.

Throw on some warm clothes, get it wet, and make some passes to see what it will do now. After you make a few passes to get a feel for how it performs, you can then take the next steps.

Cheers,

Joe

« **Reply #2 on:** March 31, 2014, 12:16:38 AM »

Sorry i forgot the rpm's but the machine shop said it was corrected horse power-452hp 501ft of torque @5200 rpm's. We ran out of time on friday and had to stop the tests, they say they need some more time to do some fine tunning, they expect 475hp and about 515ft of torqu when its all said and done. PS. Thanks for replying joe!

« **Reply #3 on:** March 31, 2014, 12:42:48 AM »

Good luck bortherman. Dyno sessions are not the fun time that most people expect. Since you are still in your dyno session, make sure that you get the following information; it will help you with your future tuning. Temperature, barometric pressure, your timing, final jet sizes (and what cylinder each jet size is over if not all the same) from your baseline tune. Most of this should be printed on your dyno sheet, just in case. At least for me, it doesn’t take long to forget all of that. Now is also a good time to start a notebook if you haven’t already. Document everything! It will pay off in your future tuning.

Care to share any more of your engine specs?

I am curious, what fuel are you testing with? Hopefully, you are testing with the same fuel you will be operating with. Did the dyno operator take a reading on the specific gravity? If so, what was it? This is something that I would like to monitor in greater depth.

Cheers,

Joe

P.S. Don’t forget the pics.

« **Reply #4 on:** March 31, 2014, 01:03:41 AM »

As far as specific engine specs i forgot, they told me everything in detail, sizes, diameters, tolerances all that but it was over my head so i dont really remember details like that. What i do know is that mark kidd ( owner of magic valley engine/kidd performance of twin falls idaho) was very professional at what he does, made sure we were testing at the proper altitude/air pressure and all that confusing stuff. And he was using 91 octane, what he recommends i use on the water.
And i cant seem to post pics! I have a ton of them!

« **Reply #5 on:** March 31, 2014, 01:54:45 AM »

It isn’t so much testing at the proper altitude/pressure. It is all about knowing where your baseline is so that as the weather changes or you go to a different lake/river (altitude), you can adjust accordingly. For example, I tuned my boat at Lake Havasu, which has an elevation of about 448 feet above sea level. Now, I want to go run at Lake Tahoe, which has an elevation of 6,224 feet above sea level. Documenting where I started would allow me to use readily available charts and formula to aid me in determining a new tune for the new elevation. However, I wasn’t that smart.

Just saying, it is better to get all of that information now, while you have the technology of the dyno facility available to you. Also, the temperature in the dyno cell is not truly representative of the temperature at which you will be running your boat.

« **Reply #6 on:** March 31, 2014, 03:10:43 AM »

I hear ya, on april 8th were doing the last testing/tunning. I'm getting a print out of all the info on how my engine performed on the Dyno, ( was told to keep in mind that this is in a controlled environment-results could vary on water as well as where i go) also what adjustments they made(the jetting of the carbs/timing and so on) and i'm getting every detail of what exactly is in my motor(brand/size/measurements) i know some things but not small details. My buddy said we still might have to do some adjustments once on the water. So i have an idea of the next steps. i kind of jumped the gun a little and wanted a guess of what my speed might be, gonna have to wait and see. Any way thanks joe for the tips! Will keep them in mind!

« **Reply #7 on:** March 31, 2014, 06:41:02 AM »

65-70mph
ditch the tunnel ram and put on a single 4 you will probably pick up some power
1300cfm is way too much for that motor

208BBF460

Anybody have an idea?

Flusher

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208BBF460

Re: Anybody have an idea?

Flusher

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208BBF460

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Flusher

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208BBF460

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Ralph Brunt

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