Steam ports on heads
Thread Starter
Staging Lane
Joined: May 2017
Posts: 61
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Steam ports on heads I'm putting together a 2003 lq4 . and put the crossover steam pipe on that's on the front of engine. The back 2 are blocked.
NOW...I was walking through a local salvage yard and noticed a 5.3 that had a steam pipe that connected all 4 corners of the heads???
Which is the better setup and why ?
NOW...I was walking through a local salvage yard and noticed a 5.3 that had a steam pipe that connected all 4 corners of the heads???
Which is the better setup and why ?
That's a can of worms that has been covered in a lot of detail. Short answer, if you have a NA, using just the front ports is fine. GM eliminated the rear ports later in the evolution of the LS engine.
Andrew
Andrew
Nobody knows why the rears are blocked in some applications. I have done extensive research on this subject and the best guesses are that in some vehicles, the back of the engine sits lower, so they can block the rears. In a swap, if the engine is level or tilted upwards in the rear, having rear blocked steam ports might lead to air being trapped.
In a swap it is generally recommended to connect all 4 corners for peace of mind. The 4-corners should run to the upper radiator tank in the majority of swaps.
In a swap it is generally recommended to connect all 4 corners for peace of mind. The 4-corners should run to the upper radiator tank in the majority of swaps.
I think its simplier than that, the rear of the heads are blocked bcuz they can easily be the fronts too. The heads are interchangeable from left to right side. There fore reversing the steam port positioning.
I have the kurt urban kit connecting all 4. Gunna return it into high point in my radiator. Already a bung there. Hope it works/helps
I have the kurt urban kit connecting all 4. Gunna return it into high point in my radiator. Already a bung there. Hope it works/helps
I really don't know because I am not able to test (can't afford the temp sensors and to drill/tap the head for them to measure water or air temp in those spots) it would cost $$ to recover useful data regarding the actual result over a multiple testing (re-run the experiment 20 to 2000 times in different engines until it has given satisfactory data for whether or when rear steam ports matter)
If we treat the engine like a cube, then I see potential for air to rest at the highest locations, as with any cube or 3-dimensional object.
Suffice to say that when my engine has a melt-down, I will not be able to say "well maybe if I had all 4-corner steam ports connected I wouldn't has lost #7 today". It just helps rule out causitives in a sea of possibilities. Is that a word? cuasi .. .scausi
If we treat the engine like a cube, then I see potential for air to rest at the highest locations, as with any cube or 3-dimensional object.
Suffice to say that when my engine has a melt-down, I will not be able to say "well maybe if I had all 4-corner steam ports connected I wouldn't has lost #7 today". It just helps rule out causitives in a sea of possibilities. Is that a word? cuasi .. .scausi
TECH Senior Member
Joined: Jun 2016
Posts: 22,291
Likes: 3,616
From: Central Cal.
4-corner steam pipes ARE best, but were deemed not totally necessary sometime back. rkupon1 is right, being the heads are interchangeable, ports exist on both ends, and whichever ones are up front are the ones used. Simple as that!
I DO think bleeding the system would be easier if all four corners were used.
I DO think bleeding the system would be easier if all four corners were used.
TECH Resident
Joined: May 2004
Posts: 792
Likes: 2
From: SoCal
Nobody knows why the rears are blocked in some applications. I have done extensive research on this subject and the best guesses are that in some vehicles, the back of the engine sits lower, so they can block the rears. In a swap, if the engine is level or tilted upwards in the rear, having rear blocked steam ports might lead to air being trapped.
In a swap it is generally recommended to connect all 4 corners for peace of mind. The 4-corners should run to the upper radiator tank in the majority of swaps.
In a swap it is generally recommended to connect all 4 corners for peace of mind. The 4-corners should run to the upper radiator tank in the majority of swaps.
Andy1
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EVERY track prepped vette I've seen has all 4 corners tied together, doesn't matter if they used OEM parts or fancy kits. These are road race cars and they worry about longevity at high rpm (lots of heat for a long time) with repeated WOT to heavy braking.
Drag cars typically keep it simpler with rears plugged or T'd. Fronts Y together then tie in to upper water pump or upper radiator port for the low pressure source. Some choose to do this for simpler setup, less potential leak points, save a few ounces, or just to get it back together quicker and cheaper.
Drag cars typically keep it simpler with rears plugged or T'd. Fronts Y together then tie in to upper water pump or upper radiator port for the low pressure source. Some choose to do this for simpler setup, less potential leak points, save a few ounces, or just to get it back together quicker and cheaper.
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Verdad Gallardo TECH Senior Member
Joined: Jun 2016
Posts: 22,291
Likes: 3,616
From: Central Cal.
EVERY track prepped vette I've seen has all 4 corners tied together, doesn't matter if they used OEM parts or fancy kits. These are road race cars and they worry about longevity at high rpm (lots of heat for a long time) with repeated WOT to heavy braking.
Drag cars typically keep it simpler with rears plugged or T'd. Fronts Y together then tie in to upper water pump or upper radiator port for the low pressure source. Some choose to do this for simpler setup, less potential leak points, save a few ounces, or just to get it back together quicker and cheaper.
Drag cars typically keep it simpler with rears plugged or T'd. Fronts Y together then tie in to upper water pump or upper radiator port for the low pressure source. Some choose to do this for simpler setup, less potential leak points, save a few ounces, or just to get it back together quicker and cheaper.
Just my .02....