Super Jet I want to bump compression and have some question.

[paczowski123]

As it states I want to bump the compression on my ski but I have read all of the horror stories of cracked cylinders so I have a few question.

1. At what point is a girdled head necessary vs. a stock milled head for let's say 180 psi or leas? I am installing my b pipe tonight so I've read a lot that compression plus pipe can lead to a cracked cylinder? Thoughts?

2. At what point does dual cooling come into play? I ride in the southeast and water temps in the summer vary between high 70's to 90's depending on the time of the year. Would dual cooling be necessary or recommended once compression is bumped or will the stock cooling be sufficient?

Also when adding dual cooling where is a common place to add the second npt? Do most use the extra raised port on the side accross from the stock fitting and drill all the way through, or do they drill and tap the pump housing directly?

 

[schicks]

i think cracked cylinders can happen when you have a pipe that has a mount on top of the head. Not so much of an issue with b-pipe. If I had a high compression head, i would run a girdle head, better save than sorry. Dual cooling is not entirely necessary, but helps run more water through the cooling system...usually 1 line to the pipe and 1 to the engine. I would tap the pump at that fitting and drill through it and put a hose fitting on.

 

[paczowski123]

That's what I was thinking next time I have the pump out. Anyone think its necessary to add another fitting on the pipe manifold? I'd hate to do mess with the pipes warranty by doing something like that?

 

[tor*p*do]

Factory Pipe Warranty? BWAA HAA, you are new to this game!
Dual cooling is a must in the south IMHO

 

[paczowski123]

That bad huh? I can see that considering how rude and short their employees are when I called to order and ask a couple questions. Is it necessary to run two fittings on the manifold, it seems to me either way your only getting one line worth of feed to the manifold?

 

[Matt_E]

Cylinder cracking happens even with b-pipes and mild compression.

 

[paczowski123]

Ok so it seems girdled is the way to go. What about adding a second fitting on the manifold?

 

[schicks]

i have two fittings on my manifold...i have one line going to them though, so I have a Y in the line going to the manifold. Run another line to the bottom of the b-pip head pipe.

 

[kevbo]

As it states I want to bump the compression on my ski but I have read all of the horror stories of cracked cylinders so I have a few question.

1. At what point is a girdled head necessary vs. a stock milled head for let's say 180 psi or leas? I am installing my b pipe tonight so I've read a lot that compression plus pipe can lead to a cracked cylinder? Thoughts?

2. At what point does dual cooling come into play? I ride in the southeast and water temps in the summer vary between high 70's to 90's depending on the time of the year. Would dual cooling be necessary or recommended once compression is bumped or will the stock cooling be sufficient?

Also when adding dual cooling where is a common place to add the second npt? Do most use the extra raised port on the side accross from the stock fitting and drill all the way through, or do they drill and tap the pump housing directly?

We ran stock milled heads at 170-180psi on 50mph skis for over a decade with no cylinder cracking. These skis also used stock single line cooling. Newer castings are visibly rougher than early ones and most people are running more timing and compression than ever on pump gas. An ADA girdled head will prevent cracking but needs dual inlets and more total water since it has no gasket to control flow. I would lap the cylinder deck before installing one.

 

[paczowski123]

Eventually I will run dual cooling but I wasn't sure if I needed to add another fitting on the manifold since either way your only getting one line worth of water unless you choose to run both feeds Into the manifold, which to me I like the idea of dual circuits to be able to tell if there is a problem with either of them.

 

[paczowski123]

Anyone feel its necessary to have a T in the line going to the headpipe? I get the idea of feeding both sides equally but to me that seems it could actually cut the water feed down per cylinder since your splitting a line in half?

 

[iangdesign]

You could also run a large fitting from the pump then Y it off after the bulk head. My 300sx conversion has has a 1/2 inch line coming from the pump to the exhaust mani. Also running a 2nd 3/8th line from the pump as well.

My SJ is running dual cooling. One to the exhaust and one directly to the head then over board, 2 outlets so I can watch how both are flowing.

 

[paczowski123]

Yeah I will also probably run two separate circuits to watch each one. But just didn't know if it was totally necessary to have two fittings on the manifold fed from one single line that had been T'd as it still gets the same water amount?

 

[iangdesign]

The purpose of two on the head is one in and one out. If you are running dual cooling, the out will go overboard from the head so you can monitor the cooling flow from the head vs. going back into the exhaust, then overboard.

 

[paczowski123]

Yeah I understand that I was more so asking about one single line T'd going into two npt on the manifold. My question was would that be necessary since either way you are only feeding the manifold one line worth of water why the need to split it? Just to try and feed each cylinder an even amount of water?

 

[kevbo]

Yeah I understand that I was more so asking about one single line T'd going into two npt on the manifold. My question was would that be necessary since either way you are only feeding the manifold one line worth of water why the need to split it? Just to try and feed each cylinder an even amount of water?

There is more an issue of distribution over quantity. Water circulation within the cylinder is less efficient without a head gasket.

 

[lanmine657]

If you go with an after market head, girdled is cheap insurance, you will be fine with a stock milled head at 170-180 comp, you will get better performance out of an aftermarket due to the different shape of the domes, a stock milled can rip hard too. I am fan of dual cooling on any ski, stock limited or mod, some say you can make it too cold but i always like being able to monitor the water separately from head and pipe as I'm riding. Riding dirty lakes can blow motors faster than a bad setup

 

[paczowski123]

Well after all my contemplating I finally pulled my manifold ( all I had installed for my b pipe) as I was waiting for a carb rebuild and jets to move forward and drilled and tapped it for a second fitting. Now it will already be done when I add another line for the pipe.