Building a jet boat

[antonmies]

As someone of you may already have noticed that I have another thread under the Blower Motors (Here (http://www.***boat.com/forums/showthread.php?t=105881)). What I have there is overall specs of my boat. I already had some answers regarding my motor but I guess here is the place to ask about choosing impeller, loader scoops, rideplates etc. This is my first jet boat.
I would appreciate all information you can give me. URLs, pics, etc...
Thanks in advance!

[SmokinLowriderSS]

A little good basic info for ya to start with as I am not one of the guys running high-speeds (over 80).
Impeller Choice
Make sure to fit your impeller and engine so you can get to your engine's peak power. This seems kind of confusing I will try to clarify. I have seen instances of big HP engines being too weak on Torque in the lower-mid range (3K to 5K RPM) to be able to reach their HP which was up above 6K. Usually not a problem with blower motors tho.
Here is one link to get some info, and has a chart at the bottom.
http://www.berkeleyjet.com/products/impeller-info.htm
In general, larger impellers push more water at lower RPM's and accelerate better/quicker, smaller impellers spun faster run faster on top end. This is not a guarantee, nor a hard & fast rule, but is generally accurate. A lot relates to your engine also.
Top Loader
The faster you go, the harder it is to get water to turn the corner and go UP into your pump. The bottom of the impeller sees increased water pressure while the top looses pressure. At some point, this results in cavitation. A top-loader (loader) helps this as it guides more water toward the top of the pump to feed the impeller evenly. There are a lot of different designs, some work better on some aplications, others on others. Only 1 way to find out which is best, spend $$ and test-run it (or borrow one).
Ride Plate
For best top end speed, you need to get as much of the boat airborne as possible. Air drag is a fraction of what water drag is. The ride plate serves 2 purposes IMO. 1, to help "set" the attitude of the hull to the optimum angle when the boat is flat out and the jet nozzle (diverted up making a roostertail) is trying to lift the hull as high as it can. 2, to prevent the hull from lifting too much inducing a porpose (on most v-hulls and at lower speeds) and to try to prevent the boat from catching too much air and flipping over (the FAST boats, tunnels & hydros generally).
Nozzle Diverter
The most useful and desireable thing on a lake-jet-boat IMO. It allows the nozzle to be aimed up & down to allow you to deal with various water conditions and activities. Wityh a nozzle trimmed downward, it helps deal with rougher choppy water, and IMO helps with holeshot/pulling acceleration. Trimmed fully up helps lift the bow, fly the hull dry, to get maximum speed. Anywhere in between depending on water conditions. I set about level towing tubes/skiiers. I set aprox 1/2 full up cruising to get best speed at moderate RPM. I cannot carry full up at cruise unless water is very smooth, a mild porpose sets in and is annoying.
Shoe
The back edge of the pump inlet, generally adjustable by shimming or grinding/filing. This is the part that actually scoops, the loader does not generally stick out below the boat. You can have it too low below the boat and feed too much water to the pump, drag then slows ya down. Too high up and the pump starves at higher speeds.
Straight Snoots & Droop Snoots
Extensions between the bowl and the nozzle. Sometimes helps with the setup on a particular boat, sometimes not. The droop seems to help lift the stern higher at speed. The straight snoot adds length to the pump and helps the nozzle lift the bow (leverage) of a heavy-nosed boat.
If you notice a theme of "each boat is different, and one setup may or may not work as well on another boat", then you are right. The hardest part about making a jet perform at it's best is the fine-tuning of all the parts. There is a lot of knowledge here that is willing to help ya go in the right direction.
That is about all the comonplace parts that there are. I think I got all the basics correct, more experienced speed guys can come on here & refine it. My Taylor was bought by my father 28 years ago, been driving it about 25 years, she has been mine for 3. I've been watching and learning a lot over the last 3 years.

[jdf]

A little good basic info for ya to start with as I am not one of the guys running high-speeds (over 80).
Impeller Choice
Make sure to fit your impeller and engine so you can get to your engine's peak power. This seems kind of confusing I will try to clarify. I have seen instances of big HP engines being too weak on Torque in the lower-mid range (3K to 5K RPM) to be able to reach their HP which was up above 6K. Usually not a problem with blower motors tho.
Here is one link to get some info, and has a chart at the bottom.
http://www.berkeleyjet.com/products/impeller-info.htm
In general, larger impellers push more water at lower RPM's and accelerate better/quicker, smaller impellers spun faster run faster on top end. This is not a guarantee, nor a hard & fast rule, but is generally accurate. A lot relates to your engine also.
Top Loader
The faster you go, the harder it is to get water to turn the corner and go UP into your pump. The bottom of the impeller sees increased water pressure while the top looses pressure. At some point, this results in cavitation. A top-loader (loader) helps this as it guides more water toward the top of the pump to feed the impeller evenly. There are a lot of different designs, some work better on some aplications, others on others. Only 1 way to find out which is best, spend $$ and test-run it (or borrow one).
Ride Plate
For best top end speed, you need to get as much of the boat airborne as possible. Air drag is a fraction of what water drag is. The ride plate serves 2 purposes IMO. 1, to help "set" the attitude of the hull to the optimum angle when the boat is flat out and the jet nozzle (diverted up making a roostertail) is trying to lift the hull as high as it can. 2, to prevent the hull from lifting too much inducing a porpose (on most v-hulls and at lower speeds) and to try to prevent the boat from catching too much air and flipping over (the FAST boats, tunnels & hydros generally).
Nozzle Diverter
The most useful and desireable thing on a lake-jet-boat IMO. It allows the nozzle to be aimed up & down to allow you to deal with various water conditions and activities. Wityh a nozzle trimmed downward, it helps deal with rougher choppy water, and IMO helps with holeshot/pulling acceleration. Trimmed fully up helps lift the bow, fly the hull dry, to get maximum speed. Anywhere in between depending on water conditions. I set about level towing tubes/skiiers. I set aprox 1/2 full up cruising to get best speed at moderate RPM. I cannot carry full up at cruise unless water is very smooth, a mild porpose sets in and is annoying.
Shoe
The back edge of the pump inlet, generally adjustable by shimming or grinding/filing. This is the part that actually scoops, the loader does not generally stick out below the boat. You can have it too low below the boat and feed too much water to the pump, drag then slows ya down. Too high up and the pump starves at higher speeds.
Straight Snoots & Droop Snoots
Extensions between the bowl and the nozzle. Sometimes helps with the setup on a particular boat, sometimes not. The droop seems to help lift the stern higher at speed. The straight snoot adds length to the pump and helps the nozzle lift the bow (leverage) of a heavy-nosed boat.
If you notice a theme of "each boat is different, and one setup may or may not work as well on another boat", then you are right. The hardest part about making a jet perform at it's best is the fine-tuning of all the parts. There is a lot of knowledge here that is willing to help ya go in the right direction.
That is about all the comonplace parts that there are. I think I got all the basics correct, more experienced speed guys can come on here & refine it. My Taylor was bought by my father 28 years ago, been driving it about 25 years, she has been mine for 3. I've been watching and learning a lot over the last 3 years.well put there smokingare you going to come to tx this year

[antonmies]

Thanks SmokinLowriderSS for telling me the basics by components! Great information
How should I mount the engine? Now it has been installed on rubber bushings similar way as in cars.

[antonmies]

I have been busy and the boat thing has been standing still, but now I managed to remove the intake. As I fastly made some measuring before starting to clean things up and tearing the whole s*it apart, it seems that the intake is "mounted without measuring" as it's about 10mm away from the centerline. It also seems that it's a little bit at an angle. Fucc!
I guess this is one of those "Easy projects"....
I'm wondering some sort of rail mount for engine. I will also need help regarding to installing the intake, as this is my very first time... I would appreciate it VERY much if you would email me some detailed pics for rail kits and intake installation, also advices would be nice. Thanks guys in forward!
My email is anton(at)hevosvoima.com
Looks crap, doesn't it...
http://koti.mbnet.fi/hi-po/Argo/intake_removed2.jpg
http://koti.mbnet.fi/hi-po/Argo/intake_removed3.jpg

[boater012]

I have been busy and the boat thing has been standing still, but now I managed to remove the intake. As I fastly made some measuring before starting to clean things up and tearing the whole s*it apart, it seems that the intake is "mounted without measuring" as it's about 10mm away from the centerline. It also seems that it's a little bit at an angle. Fucc!
I guess this is one of those "Easy projects"....
I'm wondering some sort of rail mount for engine. I will also need help regarding to installing the intake, as this is my very first time... I would appreciate it VERY much if you would email me some detailed pics for rail kits and intake installation, also advices would be nice. Thanks guys in forward!
My email is anton(at)hevosvoima.com
Looks crap, doesn't it...
http://koti.mbnet.fi/hi-po/Argo/intake_removed2.jpg
http://koti.mbnet.fi/hi-po/Argo/intake_removed3.jpg
What is your basis for saying that the ointake was off center??? did you measure from the stringers??????
I've seen this mistake made several times and the stringers arent usually dead center and sometiomes just the thickness of the fiberglass that is oput over them can throw off you measurements!!!
Measure fromn the outside chine to the dead center of the boat. I repeat DON'T expect the stringers to be exactly in the right spots!

[antonmies]

Transom.jpg, 640kt (http://koti.mbnet.fi/hi-po/Argo/transom.jpg) (Opens in new window)
As you can see in the pic , I've drawed lines that follow the bottom to see where the center should be. I made some circles that cut the transom housing holes on the right side but not on the left side.
I've made this to several pictures and the result is pretty much the same.
I made measurements from the chines but their accuracy is compromised a bit by the fact that the bottom and chines are a bit worn... But the measurements indicate that the intake wouldn't be off center. Anyway not as much as I told before
The transom pic suggests that the whole drive would't be straight with the centerline.
When I purchased the boat it was turning more aggressively to right than left. It also seemed that the bowl and nozzle wasn't perpendicular with the transom... :220v:

[boater012]

Take your time doing the intake and dont rush it. the intake is one of the most important factors in setting up your jet to run right. I have personally never done one before but I am sure that I could. I would certainly get some serious advice before I did it!

[antonmies]

Take your time doing the intake and dont rush it. the intake is one of the most important factors in setting up your jet to run right. I have personally never done one before but I am sure that I could. I would certainly get some serious advice before I did it!
I'm waiting for the advice. No intention to rush it because I'm not in hurry...

[Ken F]

How should I mount the engine? Now it has been installed on rubber bushings similar way as in cars.
Here's a good pic of a railmount system done by Duane & Brain @ HTP.
Pretty well shows you all the pieces. This is a dragboat, so you wouldn't need to go this extravagent if you didn't want to. Second pic is my boat which is not near as fancy, but still very functional.
Ken F
http://www.hotboatpics.com/pics/data/3145/878DCP_1762.jpg
http://www.hotboatpics.com/pics/data/500/878DSC02828.JPG

[antonmies]

Thanks Ken! These are just the pictures I need! Many of the pics I've seen before don't show the details so well as these did. Thanks again!
Does anyone have a good pics for making the intake?

[colechillin]

buy a v-drive!!!!!

[antonmies]

Nah, none of them available back here in Finland, besides, they are too low :rollside: and I'm used climbing a$$ forward to a tree :crossx: If I always went the easy way, I wouldn't be learning things :idea:

[Ken F]

You are more than welcome-glad to help.
Try going to www.Hi-TechPerformance.com
They have complete kits made up for Ford & Chevy which are pretty reasonable. Shipping may be another deal, but.......
If you need any more pics let me know...I've got hundreds.
Ken F

[antonmies]

Nothing has basically happened to the boat as I've been busy as hell running my shop, finishing my Garage (http://koti.mbnet.fi/hi-po/Garage) and as it "hasn't been enough" now I've got this (http://koti.mbnet.fi/hi-po/Dyno) to be able to spec my engine before choosing an impeller :devil:
There has been some progress to the garage after taking these pics... The dyno room and the operator room walls will be located (roughly)from the brick wall (on the right in pic IMG_0721) to the pyle (next to the loudspeaker) and from it to the long wall between the two windows.