She's Almost Ready

[Brad Christy]

Justin,

Some air ports in the cowl deck above the tank would work very well, too. I like to put three or four small holes (3/16" or so) on either side of the cowl "bubble" in a diagonal like relative to the C/L of the tub. Nearly anywhere but near the carb bellmouth is suitable. You can shape them however you like. There are shapes that work better than others, as well as turning them into "scoops" like Charles did has considerable affect, but just giving the engine area something to breathe in through is a big help.

Thanks. Brad.

Titan Racing Components

BlackJack Hydros

Model Machine And Precision LLC

 

[JUSTINROGERS]

Thanks guy's i will be test with the cowl on tomorrow. Did some testing today and having some issues getting it to be consistent. Got to love test and tune lol just part of it.

 

[Charles Perdue]

Charles that would be great if you could post a pic of the openings. Im all for suggestions and help. Its much appreciated. The industry didn't get where is today from everybody hiding all their secrets and input.

Thanks again Charles

OK, these are a few of my cowls that I have installed the simple front vents that I use.

To make them, I tape over the carbon fiber surface with masking tape to help prevent splinters and CF dust, then I lay out the vents with a marker, usually on a surface area that is rising, getting higher or wider from the center of the airflow over the boat (due to the increased pressure, these vents flow more air for the same given open area, if you want to put the intake vents on the flat sides of the cowl then just make the opening area a little larger) by marking two lines parallel to each other and a line connecting those toward the rear of the cowl. Cut along these lines, I use a Dremel with a common abrasive cut-off wheel, I then cut the side wedges for the vents from 1/16 plywood using scissors. Gently press down the rear of the opening and glue the ply sides into place with CA. It is important to keep the floor of the vents bent in a gradual arc. This allows the air to follow this contour into the vent openings like a NACA Duct. I seal the ply with the CA and when I am finishing the boat, I cover this with epoxy or whatever.

To test your new ducts use a water hose to flow the water over the cowl. You can then see how the water/air follows the contour right into the vents.

Charles

Cowls and inlet vents 002.JPG

Cowls and inlet vents 007.JPG

Cowls and inlet vents 009.JPG

In the top and middle photo, the third cowl from the left, as looking at the photo, is a "cross flow " cowl for a front exhaust engine with a wrap around pipe. It worked very good on providing air to the carb without over cooling the engine, this is also without allowing any water in the carb all the while keeping the pipe hot. It also shielded the pipe from the spray from other boats.....No sagging of the engine when being wet down from the prop wash of another boat.

Charles

 

[JUSTINROGERS]

Ok update. Im getting it dialed in 62 MHP on GPS today but I have a new question I keep blowing glow plugs when i bring it in and hit reverse to kill it. It is mostly just breaking the coil but it did suck it completely out once. Is it from the head clearance? 60% nitro

https://youtu.be/rKBvnCdOYMw

 

[shoboat]

Justin,

I think you just need to try a few other propellers now.

Looking good, but more speed is there, you just need to find it?

H-7, 1815, or a different 1450.

Thanks For The Video,

Mark Sholund

 

[Terry Keeley]

Ok update. Im getting it dialed in 62 MHP on GPS today but I have a new question I keep blowing glow plugs when i bring it in and hit reverse to kill it. It is mostly just breaking the coil but it did suck it completely out once. Is it from the head clearance? 60% nitro

https://youtu.be/rKBvnCdOYMw

Lookin' good! Trust me, a smooth handling 62 mph will put you near the top of the heap on any weekend, don't get sucked in to the "90 mph keyboard 20 hydro" vortex!

If the plugs look good (fairly shiney, pulled out a bit - not all distorted and dull grey looking) but are just broken so they don't light it's usually just vibration taking them out. How is the motor mounted?

What plugs RU running?

 

[JUSTINROGERS]

Thanks guys! Mark im actually running an h-7 now with a little bit of cup. It won't swing the 1450. As far as the glow plugs McCoy number 9's o'donald blues and the new old Donald odo 9. And the plugs are breaking on the first run I think the pipe might be a little too short. Saturday will be my final testing before open water on Thursday. Terry I know what you mean by chasing high speed it was only doing 55 before so I'm pretty happy with 62 just hope I can solve the plug problem give me a little bit more confidence in it being consistent.

Thanks again everyone for the input and help. It's much appreciated

Justin

 

[shoboat]

Justin,

You have too much cup in the propellers if it won't pull the 1450 or the H-7 with better RPM.

You see too much cup on the trailing edge of the propeller loads the motor too much. Do you

know how much cup you are running and what the diameters are? What head clearance are

you running? Ever measure the bowl volume? Cup numbers of 3.21" works very well.

Have you ever run the boat with the cowl off ? and just the fuel tank taped in? I think the cowl

Is cutting off the air supply to the carb. Try running no cowl and see what it does?

Let Me Know Please?

Mark Sholund

 

[JUSTINROGERS]

Mark i don't know how much cup is in the h-7 it's 46.66mm in diameter and the 1450 is just b/s. It runs the same with the cowl off. I don't know the head clearance off the top of my head. I will try and get it for you.

 

[JUSTINROGERS]

I misinformed you it will pull the 1450 but the RPM's are not as high as the h7 and it's not as fast

 

[ALLAN YUEN]

Justin better use 1445 3.3" cup or H-4 for your MAC 21 Thumb up Good luck!

 

[dave roach]

I would check the head clearance and see were it set at.Set it at .006 and check the bowl volume.what pipe are you running.

Dave

 

[JUSTINROGERS]

I'll give it a try Allan.

Im going to check the clearance tomorrow Dave. Im running an ops 3280 pipe. How do i check the bowl volume?

 

[ALLAN YUEN]

I'll give it a try Allan.

Im going to check the clearance tomorrow Dave. Im running an ops 3280 pipe. How do i check the bowl volume?

Fair OPS pipe best use CMB AB 21 Nitro pipe or Brown Fat 21 pipe ( more power) Good luck!

 

[Terry Keeley]

Breaking the wire if usually always vibs, not fuel, prop, pipe etc.

Again, how's the motor mounted. Just a shot?

 

[shoboat]

Terry and Justin,

I think the crankshaft will need to be rebalanced for sure after the race,

but now we are just trying to help you with a little more performance with

the motor, propeller, and pipe combination. You have too much diameter

on your 1450 for sure so reduce it down to 45.75 mm if you can?

What is your address Justin? I will send you a few better options.

Keep Testing,

Mark Sholund

 

[dave roach]

Justin

I ran the 3280 pipe on my MAC for a long time.I put the new CMB nitro pipe on and never looked back.That pipe is great for the MAC set it at 7-7/8 long.Stu Barr sales them.

 

[JUSTINROGERS]

Terry i don't know what mount it is. I didn't build it i got it from Rick Reisinger here on the forum. It is isolated.

Mark i sent you a pm with my address.

Dave i was going to get that pipe but went with the ops. Now wishing i got the cmb. You live and you learn lol.

Thanks again everyone for the help

 

[Blackout]

Breaking the wire if usually always vibs, not fuel, prop, pipe etc.

Again, how's the motor mounted. Just a shot?

Would a more solid or more compliant mount be more likely to blow a plug?

 

[JUSTINROGERS]

Update. Head clearance is about .011 with the shim and .007 without. It feels like the piston is hitting the button at .007