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Installing aftermarket "TWIST" Head on 787.. confused!
- Thread starter Crazy685
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Head....
I'm totally unfamilar with this type head. The pix you have looks cool, it looks really clean.
There are a couple things you can or should have done. On our stock head, the water comes in on one side, travels across the top of the head to help prevent detonation, then over to the tuned pipe to preheat before coming into the cylinders base.
What you should have done, looked at the bottom of this cover to see how the baffles are laid out so you knew the direction of flow. I have a feeling, you have two outlets because there is a petition in the middle that keeps both cylinders seperate.
What you can do? If you are sure both the nipples are outlets, take your water inlet hose from your pump, route it directly to your tuned pipe, where the stock head crosses over, which is normally about a 4" piece of hose.
Then, on your outlet, you'll need to make a "Y" fitting and connect both those nipples to your outlet hose. Do not block off either of the outlets. I bet they both have got to be used to flow water out of the head......:cheers:
I'm totally unfamilar with this type head. The pix you have looks cool, it looks really clean.
There are a couple things you can or should have done. On our stock head, the water comes in on one side, travels across the top of the head to help prevent detonation, then over to the tuned pipe to preheat before coming into the cylinders base.
What you should have done, looked at the bottom of this cover to see how the baffles are laid out so you knew the direction of flow. I have a feeling, you have two outlets because there is a petition in the middle that keeps both cylinders seperate.
What you can do? If you are sure both the nipples are outlets, take your water inlet hose from your pump, route it directly to your tuned pipe, where the stock head crosses over, which is normally about a 4" piece of hose.
Then, on your outlet, you'll need to make a "Y" fitting and connect both those nipples to your outlet hose. Do not block off either of the outlets. I bet they both have got to be used to flow water out of the head......:cheers:
One per head....
So, I was right. You have a nipple for each side. The problem is you have no initial cooling across the top of the head for helping to prevent detonation.
You cannot use those nipples as inlets. I guess you could but you would be running your cooling system backwards.
If you put water in from the top of those nipples, you will not know if your cooling system stays flooded because at the bottom of each cylinder, you have a drain line. It's located at the bottom of your cylinders on the port side. If your exhaust manifold is on, you might not see it. But, you might be able to look down between them to see the line I'm referring to. This line comes out the back side and connects to your exhaust system, just before exiting the hull.
If you push water down across the top of that head, you have to overcome that drain, then fill the bottom of the cylinder to the point water dumped out and over the top of your exhaust loop, where your pee line connects to. Then, once the water dumps over the top of that pipe, it'll come out that 1/2" nipple half way down the tuned pipe.
What's wrong with that? The normal flow of water for the 787 is to preheat the tops of your cylinder heads, since they see the most temperature at startup. Then, the water crosses over to the tuned pipe for pre-heating before going into the bottom of your cylinders. The water is then pushed up to the top of the head, then out the nipple on the starboard side and out of the boat/ski. Without running that water through the tuned pipe, your resonance is going to change. That affects the performance of the motor.
The idea of water flow in our motors is that the pump "pushes" the water up and through the cylinder head.
In your layout now, the water would come in through the top and fall to the bottom of the cylinder, where the water outlet also is. This can leave pockets of air inside the casing.......
The head looks cool but I don't think I'd like the idea of using something that didn't follow the standard water flow guidelines............:cheers:
So, I was right. You have a nipple for each side. The problem is you have no initial cooling across the top of the head for helping to prevent detonation.
You cannot use those nipples as inlets. I guess you could but you would be running your cooling system backwards.
If you put water in from the top of those nipples, you will not know if your cooling system stays flooded because at the bottom of each cylinder, you have a drain line. It's located at the bottom of your cylinders on the port side. If your exhaust manifold is on, you might not see it. But, you might be able to look down between them to see the line I'm referring to. This line comes out the back side and connects to your exhaust system, just before exiting the hull.
If you push water down across the top of that head, you have to overcome that drain, then fill the bottom of the cylinder to the point water dumped out and over the top of your exhaust loop, where your pee line connects to. Then, once the water dumps over the top of that pipe, it'll come out that 1/2" nipple half way down the tuned pipe.
What's wrong with that? The normal flow of water for the 787 is to preheat the tops of your cylinder heads, since they see the most temperature at startup. Then, the water crosses over to the tuned pipe for pre-heating before going into the bottom of your cylinders. The water is then pushed up to the top of the head, then out the nipple on the starboard side and out of the boat/ski. Without running that water through the tuned pipe, your resonance is going to change. That affects the performance of the motor.
The idea of water flow in our motors is that the pump "pushes" the water up and through the cylinder head.
In your layout now, the water would come in through the top and fall to the bottom of the cylinder, where the water outlet also is. This can leave pockets of air inside the casing.......
The head looks cool but I don't think I'd like the idea of using something that didn't follow the standard water flow guidelines............:cheers:
Surprise design.....
I think someone had some left over stainless steel and made something from it, then called it a cylinder head.
I did some research on it, trying to find out where it came from and who the manafacturer is. It's got to be one of a kind. The only thing I came up with is your ad trying to sell it on Sea-doo net. So, I guess it's safe to say, when you google something, it only returns what you are looking for by the name someone gave it.
There were no other returns on the thing.
I'll have to excuse myself from this one by saying, .......I would not use it. It does not fit the application in which our stock 787's run and cool. It would probably cause more damage than good. Please don't try and sell it on our forum....................:ack:
I think someone had some left over stainless steel and made something from it, then called it a cylinder head.
I did some research on it, trying to find out where it came from and who the manafacturer is. It's got to be one of a kind. The only thing I came up with is your ad trying to sell it on Sea-doo net. So, I guess it's safe to say, when you google something, it only returns what you are looking for by the name someone gave it.
There were no other returns on the thing.
I'll have to excuse myself from this one by saying, .......I would not use it. It does not fit the application in which our stock 787's run and cool. It would probably cause more damage than good. Please don't try and sell it on our forum....................:ack:
Twist heads were made by MSD. I've seen them in my catalogs (I was a dealer for MSD PWC parts) but I've never used them. I've only installed Miller, Buckshot, Bullet, Rossier, R&D and PSI on Sea-Doo's. The PSI head was pretty cool, you could change the compression in less than 2 minutes without removing the head.
Take your Twist head apart and post a picture of the water jackets.
Chester
Take your Twist head apart and post a picture of the water jackets.
Chester
Msd...
As Chester pointed out, he's seen them in his catalogs...
I've never seen the application before, in books or likewise. When I started searching for more information, the only thing that came up with Google was an add you had placed looking to sell it.
With that piece removed, you can see how the vortex is set up for cooling. But, it still follows an un-orthodoxed route to cool the engine, or preheat the water before coming in contact with the cylinders.
Chester has a lot of experience as a mechanic. He's seen this configuration before (if only in a book). If he knows someone who has, then maybe he can tell us if it's beneficial or something that can be substituted for the OEM head.
The forum is built on helping members with problems on their engines. This is based on the OEM configuration of the shop manuals. We do not really offer any help on aftermarket parts. There are too many variables. This would be something best suited for the "Mod" area........:cheers:
As Chester pointed out, he's seen them in his catalogs...
I've never seen the application before, in books or likewise. When I started searching for more information, the only thing that came up with Google was an add you had placed looking to sell it.
With that piece removed, you can see how the vortex is set up for cooling. But, it still follows an un-orthodoxed route to cool the engine, or preheat the water before coming in contact with the cylinders.
Chester has a lot of experience as a mechanic. He's seen this configuration before (if only in a book). If he knows someone who has, then maybe he can tell us if it's beneficial or something that can be substituted for the OEM head.
The forum is built on helping members with problems on their engines. This is based on the OEM configuration of the shop manuals. We do not really offer any help on aftermarket parts. There are too many variables. This would be something best suited for the "Mod" area........:cheers:
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Oh no, as I said, I truly appreciate the time you gave me in trying to help me figure this all out! It definitely looks like a silly way to route the cooling on this head. If I had the choice, I'd definitely trade for a purple buckshot head ( not only would it match evrything I have being buckshot, but the color would match everything on my ski as well! )
But unfortunately this is what came on the ski, and Im trying to complete it at this price.
But unfortunately this is what came on the ski, and Im trying to complete it at this price.
Sale....?
Then, if you like, your welcome to see if anyone is intersted in modding there ski with that type head. I dont' think we have many, if any, racers in the forum. But, if you'd like to put it in the buy/sale/trade section as a modification to the 787cc engine, then your welcome to do so. I was agains't it pretty much out of ignorance. I have just never come across one.
If you do, you might find someone that will pick it up on trade.
If you decide to use it, then you'll need to "Y" off your water inlet from the pump to attach both nipples on the head, then connect your outlet to the fitting on the lower end of tuned pipe. It seems like it will be running the water system backward but, I guess if your protecting the cyliders first, at least you won't blow the engine.
As for the resonance of the exhaust, I have no idea how that would be affected...........:cheers:
Then, if you like, your welcome to see if anyone is intersted in modding there ski with that type head. I dont' think we have many, if any, racers in the forum. But, if you'd like to put it in the buy/sale/trade section as a modification to the 787cc engine, then your welcome to do so. I was agains't it pretty much out of ignorance. I have just never come across one.
If you do, you might find someone that will pick it up on trade.
If you decide to use it, then you'll need to "Y" off your water inlet from the pump to attach both nipples on the head, then connect your outlet to the fitting on the lower end of tuned pipe. It seems like it will be running the water system backward but, I guess if your protecting the cyliders first, at least you won't blow the engine.
As for the resonance of the exhaust, I have no idea how that would be affected...........:cheers:
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