intake grates

[86 catalina]

I have a couple diffrent types of intake grates,my boat is 21 foot open bow with a 496 being put in saturday.One of the grates has alot of small runners in it as to keep stuff out of the pump,but also restrict the flow..The other one has a very open intake on it with little scoops to help bring the water in faster,but not much to keep out river debris.I run the boat by blythe.ca where the water is shallower ...so that is a concern....Also i am trying to get this big boat going faster. I had a v drive that i ran out there all the time and never hit the bottom once,but i am more concerned about the weeds and b.s. floating on the top of the water....Retired v driver tring out jets ....boat pic attached..

[SmokinLowriderSS]

The one is called a "rock grate" normally. The other is called a "loader" or "top loader". It's purpose, as you have already come close to divining is to help keep part of the water colum folowing the upper part of the suction housing. As speeds climb, the water hates to "bend" so pressure rises at the bottom of the impeller and drops at the top. This reduces efficiency and, if it gets severe enough, it causes cavitation (air bubbles) to form at the top of the impeller, which causes REAL problems. The rock grate isn't really all that restrictive I don't think but it does nothing for the intake pressure issues as speed climbs. In a heavy boat like that, I think you should run whichever one you want. I don't think you'd see any performance gain from the loader. The grate won't stop everything, but it will stop most things. I have an old loader made from a grate, still has the center 4 or 4 "fingers". E/F serries Berkley pump, want it?

[BUSBY]

I have seen your posts and can answer here ... but there might be a couple of others here that are more experienced ... I'm just a guy getting back into jets from a v-drive myself ...
there are a lot of Blythe runners here that will post up sooner or later ...
the one that has a lot of little bars is most likely a stock grate to keep crap out and the other is most likely a loader which will help performance ...
something to remember is that there are a lot of other small things (set up) to do with making your boat faster. you should find one reputable (sp?) shop that will help you look at your combination and stick with them as you do mods ... there are a lot of different opinions here and none of us can actually see your boat to help diagnose what will make it pick up mph ...
not saying that there isn't invaluable information here ... just keep in mind that we are going off what you are typing instead of seeing it ...
glad to have you here on the boards!
Brian

[86 catalina]

The one is called a "rock grate" normally. The other is called a "loader" or "top loader". It's purpose, as you have already come close to divining is to help keep part of the water colum folowing the upper part of the suction housing. As speeds climb, the water hates to "bend" so pressure rises at the bottom of the impeller and drops at the top. This reduces efficiency and, if it gets severe enough, it causes cavitation (air bubbles) to form at the top of the impeller, which causes REAL problems. The rock grate isn't really all that restrictive I don't think but it does nothing for the intake pressure issues as speed climbs. In a heavy boat like that, I think you should run whichever one you want. I don't think you'd see any performance gain from the loader. The grate won't stop everything, but it will stop most things. I have an old loader made from a grate, still has the center 4 or 4 "fingers". E/F serries Berkley pump, want it?
U got a pic???

[86 catalina]

I have seen your posts and can answer here ... but there might be a couple of others here that are more experienced ... I'm just a guy getting back into jets from a v-drive myself ...
there are a lot of Blythe runners here that will post up sooner or later ...
the one that has a lot of little bars is most likely a stock grate to keep crap out and the other is most likely a loader which will help performance ...
something to remember is that there are a lot of other small things (set up) to do with making your boat faster. you should find one reputable (sp?) shop that will help you look at your combination and stick with them as you do mods ... there are a lot of different opinions here and none of us can actually see your boat to help diagnose what will make it pick up mph ...
not saying that there isn't invaluable information here ... just keep in mind that we are going off what you are typing instead of seeing it ...
glad to have you here on the boards!
Brian
Thank you for your help.......Picking peoples brains is very helpful to me i have a good understanding for what is goung on just need a push in the right direction.....Now im gonna go get a beer....thanks

[SmokinLowriderSS]

Unfortunately, no pic. The digital camera is temporarally misplaced somewhere in the house.
The outer bar on each side has been cut off and a piece of steel angle extrusion has been welded to it, is flush with the outside and extends upward into the suction housing. It was the best performance mod way of the day (circa 1979) to feed the pumps better at higher speeds. Mine will only fit a berkley "E" or "F" series insert-style pump (like in my Taylor SS, my avatar). The intake on it is shorter and steeper, which is NOT the best way for them to be for performance, but it does work well.
Part of my hull is actually mold-shaped ARROUND the pump suction piece, and actually forms the front part of the intake and suction piece. On most other jet pumps, there are 2 holes cut in the boat, 1 in the transom, 1 in the bottom, the intake is epoxy set and bolted to the hull, the suction piece bolted to the intake (and sealed to the back of the hull), and the pump bolted to the suction housing.

[Aluminum Squirt]

I vote for the rock grate. I run one and I'm running in the 70's. All (at least that I have seen?) of the aluminum boats, to include the race boats run rock grates and there are plenty of people in the upper classes running above 110 MPH, some above 120 MPH. I don't think that its really hindering performance if guys can run that fast with them. A proper set up and bottom are very important. I've run over many things in my sled and if it can make it through the rock grate, it just gets processed through the pump with little or no damage to my impellar. Some of the lake guys are probably having good luck with loaders and open intakes, but unless you are after all out speed, I would stick to the grate. Better safe than sorry and a good set up guy will get you all the speed you need with a grate-Aluminum Squirt

[HammerDown]

American Turbine's Rock Grate has small ramps that actually help divert water into the intake. I did a modification to my old stock Berk rock grate just for giggles. I would say it did infact help keep the pump loaded better. And kept the unwanted junk out!
However I later traded up for a Tom Papp design loader for my 21' Daytona.