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loader tuning
6K views 26 replies 13 participants last post by  slowboy 
#1 ·
So I put a closed center loader with longer ramps into my boat to see if it would be better than the open center loader that was in it. I really like how the boat handles, with the diverter all the way down, feels real loose and does not porpous at all. The front could be a little higher, as it is riding a little wetter than I would like. If I put the diverter up one click, it porpouses very bad. I have never really gotten this boat to take a nice set.....Yet.

The boat is a 18 foot mako, delta bottom, dominator pump, 1/4 inch shoe, pump is set way back, handhole cover is outside the boat. It has a droop, diverter and one small wedge and a ride plate that is pretty much set all the way up. It also has a nozzle insert in it, I believe it is the blue one.

With my old loader, we were having problems getting pump inlet pressures above 20 psi, just couldnt do it, not even with a 5/8 shoe. With the new loader, our pump inlet pressures were around 35-38 psi with the 1/4 shoe. I think this is a good thing? The engine is a sbc 388 with an intercooled blower on it, spinning a b impeller 6000-6100 rpms at 84-85 miles per hour. I know it will run better if I can just get it to take a set already.:|err With the diverter down, where it does not porpous, there is zero roost.

Where would be a good place to start, should I try the larger shoe? Last time I had it on, the boat road really really wet. Or should I mess with the ride plate for starters?

I am still learning with this but do seem to be making some progress, and I think my hull really likes this loader.

Thanks, Ryan
 
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#2 ·
So I put a closed center loader with longer ramps into my boat to see if it would be better than the open center loader that was in it. I really like how the boat handles, with the diverter all the way down, feels real loose and does not porpous at all. The front could be a little higher, as it is riding a little wetter than I would like. If I put the diverter up one click, it porpouses very bad. I have never really gotten this boat to take a nice set.....Yet.

The boat is a 18 foot mako, delta bottom, dominator pump, 1/4 inch shoe, pump is set way back, handhole cover is outside the boat. It has a droop, diverter and one small wedge and a ride plate that is pretty much set all the way up. It also has a nozzle insert in it, I believe it is the blue one.

With my old loader, we were having problems getting pump inlet pressures above 20 psi, just couldnt do it, not even with a 5/8 shoe. With the new loader, our pump inlet pressures were around 35-38 psi with the 1/4 shoe. I think this is a good thing? The engine is a sbc 388 with an intercooled blower on it, spinning a b impeller 6000-6100 rpms at 84-85 miles per hour. I know it will run better if I can just get it to take a set already.:|err With the diverter down, where it does not porpous, there is zero roost.

Where would be a good place to start, should I try the larger shoe? Last time I had it on, the boat road really really wet. Or should I mess with the ride plate for starters?

I am still learning with this but do seem to be making some progress, and I think my hull really likes this loader.

Thanks, Ryan
You may want to look at the bottom before making any more r/p and shoe changes! If you have a large hook in the bottom trying to drive the bow down you could have a ride by hull and ride by intake fight and it will be a fight that you will never win!!!! Straight edge the bottom and that will tell the story. Manufactures build boats for a good ride and if you try to free the boat up with out working the last 4-5 feet it is a costly and never ending battle. M
 
#5 ·
Some boats like them some boats don't, have heard of them causing probs before. Of course who knows if a short droop will work better or a straight snoot might work its all trial and error. I would start by just removing it and see if it helps at least it won't cost anything but time.
 
#10 ·
I cant remember the exact degree it is set to, and would have to check it with my angle finder, but I do know that it is all the way up right now. If I was to guess I would say 8-10 degrees up. This was where it rode the best last year.
 
#8 ·
35 psi is good compared to your old numbers. Having to lay the boat over with your diverter to avoid the porpoise is killing you. You should have a 4-5 ft. roost.

I would try and eliminate the porpoise with the droop,etc. on the boat, in the long run its probably something you will want on the boat. Moving weight around in the boat would be a fix for the porpoise but its always hard to move things around, try less rideplate angle, that still probably wont fix it, Id be looking into a small set of trim tabs if you cant get rid of it by working on the setup.
 
#9 ·
I do have some weight in the boat, there are a pair of 12 inch subs under the front, as well as a couple of amps. This is lake boat and tunes are needed for the sandbar.


I am going to try a drastic change on the ride plate today, just to see if the boat handles different, I know in the past, it has not, but maybe with this new loader things will be different.

I will say though, with the diverter down, this boat has never rode so nice:)devil, but you can definatley feel the boat loosen up and pick up speed when you raise the diverter up a notch or two. The boat has always run the fastest with the roost about 4-5 feet high. You can feel it slow down when it comes down on the porpous, killing speed. Thanks for the input, I really appreciate it.

Ryan
 
#13 · (Edited)


I wet sanded the bottom from the area where I started in this picture, down to the first ridge, and all the way to the back of the boat. Then speedcoated that area.


This is when it was in primer, I blocked it out from the center skag, (should have removed it) all the way back, it is completly flat with no hook or rocker.


 
#15 ·
loose the droop snoot!!!!! best thing youll ever do. call duane a htp and get his straight snoot and try 6 degrees of wedge. you have way to much wedge in there already. it porpuises because you dont have enough power to run the boat that far out of the water. my boat is a delta pad and does not like to ride high like these v's and tunnels. call duane, a droop is like treating a symptom, instead of an illness
 
#16 ·
sleekcrafter said:
Blockers are used to give lift and make the boat think it's got more ponies (more RPM's)
not hardly. where did you come up with that theory? somebody's old wife???


if you place a straight edge along the keel centerline, what is the depth of the shoe biting edge (1/4 or 5/8), and what is the depth of the loader ramp leading edge?
when you know the depth of the ramp leading edge(s) compared to keel centerline, measure your loader as described at the bottom of this page:
http://home.pacbell.net/jmcclure/Loaders.html then you'll know exactly what you are changing with respect to ramp location with any other loader...

going from a 5/8" thick shoe to a 1/4" thick shoe is a massive change. the biting edge of the shoe and the ramp leading edges should both be very close to keel centerline, with both functioning to load the pump as equally as possible.
short story... several years ago, there was a guy that would routinely run 120s and would win his class, but his boat always had a porpoise to it. he sold it minus engine, and the next owner brought it out. at 105-110, it was porpoising even worse. looking under it, the loader ramps were almost an inch above keel centerline. i asked the previous owner about it - it was the same loader he had always run. since our boats were similar, i loaned him my mpd loader that placed the leading edges -slightly- below keel centerline, and prestochango, with no other changes there was no more porpoise... after several offers to buy it (no way), i got it back at the end of the day and he ordered his own... still no porpoise several years later.

getting pump loading squared away may not affect your porpoise, but you should look at it anyway. beyond that, i agree with cs - work with your plate, and if it's still there, consider installing small tabs... there is a track record of tabs resolving this issue when all else fails.
 
#17 ·
The shoe that is on it right now is 1/4 below the keel, the loader that was on it was about 1/8 above the keel. When I ran the 5/8 shoe with the original loader, the boat ran smooth, but also ran very, very wet.

This new loader is about 3/8 below keel. The ramps on it also seem to go much higher than my other loader, towards the top of the impeller.

I am certain that the loader is blocking most of the shoe at this time.

I tried turning down the ride plate a bunch to see if there was a massive change in how the boat handled, and there was not much change. The ride plate is set right now around -5 degrees off the bottom of the boat. I am going to change it back to +5 degrees, and install the thicker shoe I have. The shoe should stick about 1/4 below the loader. Easy change to try. If that does not help, I am going to try removing the droop.

The wedge has nothing to do with this porpous, because I can change my diverter angle.

As far as not having enough horsepower, I dont think that is the problem either, small block powered boat running mid 80's, with full gear, and stereo? I just want it to run a little smoother, and faster:p. 200 pounds of stereo equipment in the bow does not help, plus the engine should probably me moved forward a little bit as well, just dont want to give up seat room.

I have talked with Duane a bunch last year, I just dont like bothering him with every question that I have.

I will tell you one thing though, this is the best intake pressure I have ever seen with this set up, and I think we are headed in the right direction.
 
#18 ·
The shoe that is on it right now is 1/4 below the keel, the loader that was on it was about 1/8 above the keel. When I ran the 5/8 shoe with the original loader, the boat ran smooth, but also ran very, very wet.

This new loader is about 3/8 below keel. The ramps on it also seem to go much higher than my other loader, towards the top of the impeller.

I am certain that the loader is blocking most of the shoe at this time.
slowboy, are you saying that with shoe "a", the biting edge is 1/4" below keel centerline, and with shoe "b", the biting edge is 5/8" below keel centerline???

if your new loader ramp leading edges are 3/8" below keel, that's a bit deep, but if it's working stick with it.

why would you be certain the loader is blocking the shoe??? do you have empirical evidence to support that, or is this another story from an old wife???

if you take a close look at the loader, the ramps should gradually curve upward into the intake. they should NOT be "straight", like a piece of straight stock. the reason they're curved is the same reason people add spoons, or add material to the front of the intake to "curve" upward into the suction piece - that curve creates a low pressure on the backside of the ramp, causing water to flow up behind it. consequently, if the loader is designed and constructed correctly, the biting edge of the shoe will always be in the water.

I tried turning down the ride plate a bunch to see if there was a massive change in how the boat handled, and there was not much change. The ride plate is set right now around -5 degrees off the bottom of the boat. I am going to change it back to +5 degrees, and install the thicker shoe I have. The shoe should stick about 1/4 below the loader. Easy change to try. If that does not help, I am going to try removing the droop.

The wedge has nothing to do with this porpous, because I can change my diverter angle.

As far as not having enough horsepower, I dont think that is the problem either, small block powered boat running mid 80's, with full gear, and stereo? I just want it to run a little smoother, and faster:p. 200 pounds of stereo equipment in the bow does not help, plus the engine should probably me moved forward a little bit as well, just dont want to give up seat room.

I have talked with Duane a bunch last year, I just dont like bothering him with every question that I have.

I will tell you one thing though, this is the best intake pressure I have ever seen with this set up, and I think we are headed in the right direction.
you are making some really huge changes with your shoes and ride plate, that may be taking you from one extreme to the other. it's very difficult to evaluate your shoes without seeing them. it's not difficult at all to make shims for the 1/4 shoe, and drop it down in smaller increments. i can make an 0.030 change in shoe depth, and see a definate change in suction pressure. if i dropped half an inch, handling would be ridiculous and downtrack it would blow the tail... a 10 degree plate angle change is also huge...
another approach would be to make a small change, make a pass and write down what it did (if it porpoised, at what speed? with what setup?), then do it again with the next change. it's nice-to-have someone watch it that knows what they're looking at, and can write that down too, but that's not always an option...
 
#21 ·
my intake is an old alpha marine intake. while the mouth looks very similar, would need to see top pics to be sure.

slowboy, howler439 on this site also has a flat keel, and routinely runs in the mid 90's without a bobble. it's not ideal, but it can work...
i'd try shimming the shoe down 0.030, try it, then shim it another 0.030, then another. i'd also like to see pics of your shoes...
 
#22 ·
I will pull the intake out later and take a picture of it. The shoe on the boat right now is one that I made out of 1/4 aluminum, but the 5/8 shoe I purchased from Duane at HTP. I can get a picture of that one up as well. My goal for this boat is to try and make it to 90, we had it a solid 86 yesterday.

The boat also needs an impeller in the worst way, as the one in it right now is an aluminum b. I think I am going to put in an aa and then turn the boost up to the lower rpms. But that is for another time. Thanks again, Ryan
 
#24 ·
That appears to be the Alpha Marine intake as Josh thought when he read this thread , He's just used one in his boat and the Mach1 I bought from Hotrodcars also has one as well . Its a very nice piece IMO but can use some work Also the reason I ask you about the Angle the suction mounting surface plate was/is at is its critical to your original question as that intake (at least in our cases) is truely a 5 degree casting (its also wider) This means if you run a sombodys 4* loader in it the exit side of the loader ramps where they approach the face of the impeller will be "off" . We corrected this by modifying our 4* Open loader in a "Bench intake" for mockup . Also Loader pad to shoe biting edge measurements are critical here as well (depending on HP and intended use etc . My boat works well with this intake (80 out of the box with 500hp) and I will know soon how it works with some HP. Josh's boat (intake/suction) is nearly done theyve been throated and blended and ready for the Jetaway and Hi helix and we may.. test soon as well Tom

Beezer install:



Mach 1
 
#25 ·
that's an alpha marine low profile, just like mine. mine is 5 degree as well.

it has worked just fine up to 9.40s/111 so far (last year), and even better now since MPD reset it over the winter. it's always been a very tunable intake, such that small changes do not take it from one extreme to the other.

i've always used an MPD blocker loader (4 1/2" block). i can go from idle to max rpm (with a bit more than 500hp) with 0 cavitation, and consistent suction pressure all the way down the track. years ago, i tried a couple of open center loaders and it was a waste of gas.
 
#26 ·
Slowboy, the bottom of your hull does not look like the "delta pad" I am familiar with. Looks like your keel is flat from transom all the way forward. Delta pads are usually at an angle(1-2 degrees?) to the keel and look like a long triangle, hence the name "delta". Got any shots from the side?

I've got the same hull as "Howler" that BP mentioned. Has a Delta pad that extends about 3' forward of transom. I believe Greg Shoemaker said it's at 1.5* to the keel line. Mine runs into the mid 80's with no sign of porpoise.

Here's a pic of a "delta" pad I saved from someone else's post years ago.
You can see that it is at an angle to the keel and strakes.

 
#27 ·
I could be off with the term "delta pad". I was told by a couple of people that that was what my hull was.


I took it out again today as the weather was just super nice. Boat ran super good, and smooth, could use just a little more tuning to just get the ride wot a little better, but it is far better than it has ever been (and faster too). This is starting to be a little more fun now, as it seems changes are finally starting to reward me with more speed and a better ride. I plan on keeping this boat for a long time.

I think that is good news that it has an aftermarket intake in it. I did spend a little time blending out the intake to the pump suction housing last year, but after grinding on it for a day, I gave up:)st. I did end up with a quart mix cup of aluminum shavings though. I am thinking about ordering an impeller sometime this next week, we will see.
 
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