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coolant ports on the l series intakes


hacked521

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You wouldn't heat a performance intake from a strictly performance point of view. You would want the intake air as cool and dense as possible. To be sure it runs well you just run it rich. While daily driven cars would welcome the performance, the car also has to be counted on to be driven under extreme conditions of weather and temperatures and do so reliably and economically. The best way is to control the warmth of the incoming air so that fuel fully evaporates and mixes with the air regardless of outside temperatures or humidity. This would allow the engine to run more consistently at all times and give good economy as all the fuel is vaporized and burnt.

 

The U-67 head does not have the manifold water holes because it uses heat from the hot exhaust below it. Both manifolds are bolted together and hot exhaust is directed up against a thin plate under the carb. Fuel is vaporized when it contacts this plate. There is a thermostatic control that opens and closes the valve for heating.

 

Here are the two manifolds bolted together...

http://i138.photobucket.com/albums/q251/datzenmike/L%20Z%20Heads%20and%20Motors/620headU-67Large.jpg[/img]"]620headU-67Large.jpg

 

 

Here is the heat riser valve. There is a rod passing through the manifold with a 'flap gate' inside. To the right you can see a spring wrapped around the shaft and a weight on the end. As the spring warms it expands and un-winds turning the valve off.

http://i138.photobucket.com/albums/q251/datzenmike/L%20Z%20Heads%20and%20Motors/L20Bexinstovepipesetup002Large.jpg[/img]"]L20Bexinstovepipesetup002Large.jpg

 

This works ok but if that plate rusts through the intake and exhaust are now connected and there is a big vacuum leak. Also there are mechanical moving parts that can break or rattle.

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Ya see there is a lot of misconceptions I'm seeing here. Not that I know best, I'm just saying. Cold AIR is air itself(negligibly effected if at all by the area of an intake manifold), the coolant is meant to heat the INTAKE, and that is only on WET intake manifolds meaning the fuel is being dumped through it, not after it like on most batch/sequential injection set ups. It is more important on a wet manifold because the manifold itself it helping to control the air/fuel mix and atomization inadvertently by being soaked with fuel. Even on performance builds you gain NOTHING by blocking the ports, you in fact loose efficiency unless you tune to the change, still gaining at best a hair more simplicity.

 

Even more modern dry manifolds/plenums (such as the z32) and certain race cars run coolant lines UNDER the plenum to help. Idk people can block them, to me its on par with the egr myth, waste of time.

Edited by 72240z
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hmmm so they dont hurt you having them there but it also doesnt hurt if you take them away. I could understand why it would benefit you to take them away...but not so much why it would benefit you performance wise if you left them there. the reason why i was asking is because im throwing a holley two barrel on my L-20 and the flange comes a little close to where one of the coolant lines come in. thanks for the replys!

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It can most definitely hurt by being removed. When fuel is sprayed into the intake manifold some evaporates and the air temp drops. When you add that to a cold engine you can get frozen fuel inside the intake mani and even a sticking/frozen butterfly. At best the fuel condenses which is a bad thing. If it is a performance engine and running nos it would compound the problem even more. That aside once the engine and intake is warm, the coolant lines keeping it at running temp helps the fuel atomization and efficiency. Which is more important in a carbed motor since atomization is already piss poor.

 

Like I said this is only on wet mani's on a dry mani like for multi point efi it doesn't matter as much because the fuel is being sprayed into the back of a most likely piping hot valve.

 

On the L series a turbo would help eliminate the need because the turbo sits right under the intake mani heat soaking it.

 

What do you gain by removing them?

Edited by 72240z
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.... im throwing a holley two barrel on my L-20 and the flange comes a little close to where one of the coolant lines come in. thanks for the replys!

 

Trust Nissan, they knew what they were doing when they incorporated the heated manifold. IF, there is any performance loss it is minimal compares to the loss of drive ability and economy.

 

The coolant line close to the flange is actually the outlet. Warmed head water exits the intake and returns to the lower block inlet at the bottom rad hose.

 

L20B intakes, the outlet is near the upper right carb mounting stud.

DCP_8981.jpg

 

Here's what I would do.... leave the warm water system intact. Install an in line shut off valve just in front of the water outlet from the manifold. Do not install below the thermostat housing but as close to the carb as you can. Now you can have it on for regular driving and off for performance. I think you will find the performance doesn't change much but mileage will with it off.

Edited by datzenmike
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I noticed his location. It would still cause the fuel to condense and poorly effect atomization. If he ever drives somewhere not as hot as the sun it will be worse.

 

My question still stands too what does someone gain that warrants screwing up fuel delivery/deficiency/economy?

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[quote=72240z;

My question still stands too what does someone gain that warrants screwing up fuel delivery/deficiency/economy?

 

Are you saying that no matter what,he will have a " screwed up" fuel delivery/deficiency/economy siutation?

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No I'm saying even living where he does capping of the lines will.

 

Are you saying it never gets cold in Arizona? I remember cold nights during winter months.

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No I'm saying even living where he does capping of the lines will.

 

Are you saying it never gets cold in Arizona? I remember cold nights during winter months.

 

 

Of course not.But the coldest it gets here in Tucson is low 30's for no more than 5-6 hours OVER NIGHT at max.Will it be a little "persnickity bastard" when cold?MAYBE.With a properly functioning choke and properly set up carb,the issues will be minimum at worst.

 

Other climates-another story.

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I am totally confused. I live about 125 miles north of hacked521 and in the 90's I put a Z20 with a Canon manifold and a Weber 32/36 and a custom header in my 521. There was no water or preheating to atomize the fuel, and this combination ran great. Gas mileage was 30 mpg.

 

I am currently building a 66 520 that I am putting a L20B automatic trans in and it will not have water on it's manifold either as I will be running another Cannon Manifold with a Weber 32/36.

 

I think that in the desert water in the manifold will only cause the manifold temperature to stabilize at the running temperature of the coolant there by on a hot day reducing atomization of the fuel that would be atomized at a quicker and a finer atomization without the wet manifold.

 

Is there a manifold doctor present? LOL

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Of course not.But the coldest it gets here in Tucson is low 30's for no more than 5-6 hours OVER NIGHT at max.Will it be a little "persnickity bastard" when cold?MAYBE.With a properly functioning choke and properly set up carb,the issues will be minimum at worst.

 

Other climates-another story.

 

Don't get me wrong I'm not saying its the end of the world. Just that's its better to have then to not in a multitude of ways. The most common regardless of location would be efficiency equating to hp and mpg. Which everyone likes more of no? :-)

 

And still besides fitment necessity no one can name a plus to eliminating them?

 

There was no water or preheating to atomize the fuel, and this combination ran great. Gas mileage was 30 mpg.

 

Glad to hear that, my stance though is that it would run better and the mpg would be higher with then without.

 

I think that in the desert water in the manifold will only cause the manifold temperature to stabilize at the running temperature of the coolant there by on a hot day reducing atomization of the fuel that would be atomized at a quicker and a finer atomization without the wet manifold.

 

Idk what your trying to say here. On the hottest day in az the intake manifold will not be as warm/hot as if it had coolant running through it at running temp.

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Don't get me wrong I'm not saying its the end of the world. Just that's its better to have then to not in a multitude of ways. The most common regardless of location would be efficiency equating to hp and mpg. Which everyone likes more of no? :-)

 

Cooler intake charge resulting from lower manifold/carb temps is what leads to more HP

 

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And still besides fitment necessity no one can name a plus to eliminating them?

 

 

 

Glad to hear that, my stance though is that it would run better and the mpg would be higher with then without.

 

Better than 30 MPG?THat's asking a lot.

 

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Idk what your trying to say here. On the hottest day in az the intake manifold will not be as warm/hot as if it had coolant running through it at running temp.

 

Actually underhood temps especially right over the exhaust manifold/header will be HIGHER that coolant temp.

 

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I just bought a holster for my IR thermometer.Also,my wifes 620 WITHOUT the water passages is getting ready to come on line in the next month.I expect the same results as Charlie.But not to worry,i'll post them.

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The point I am making is in the desert our motors run more consitent without wet intakes and heat from the exhaust. In the desert we strive to keep our motors running cool so when we hit a hill we do not over heat. I run dry manifolds and seperated exhaust manifolds with heat shields to help keep from having "ping" preignition knock which is associated with a lean condition. In the desert if you atomize the fuel to quick or to fine the result can be ping. Ambient temperature in the desert can be as high a 160 degrees f. Temperatures are taken in the shade (I know this first hand from having to report weather stats daily to the National Weather Bureau when I lived in Bagdad Arizona).

 

Why attach an exhaust manifold to an intake manifold and then pipe water through it?

 

All you non desert dwellers might also research VAPOR LOCK!

 

And please check out the links below.

 

http://wiki.answers.com/Q/At_what_temperature_does_gasoline_freeze

 

http://www.freepatentsonline.com/7210472.html

 

Non computerized engines are tuned for the conditions the are going to be utilized in. Hence temperature range, altitude, road conditions (flat/Hills). Comperterized engines have made vehicles (I Feel) more versitale. Performing better over a broader spectrum of conditions.

 

By the way I do not think that hacked521 is thinking about running nitrous oxide unless it is to boost his flame thrower. LOL

 

I hope this helps hacked521.

 

Charlie

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Posting links to wiki saying when gasoline freezes doesn't change a thing, nor does posting ambient temps. Anyone owning a datsun knows about vapor lock, once again nothing to do with this. The patent link I'm calling flat out bullshit, free patents online as a source? Seriously lol? Idc what it says vapor or not nos is a chemical intercooler and will drop temps when introduced, the end.

 

Intake manifold interior surface temp is the only temp here that matters.

 

Post a link to how much temp drops at night in the winter or how much temp drops inside the manifold as gas evaps or the pair combined. Post a link as to what you gain by eliminating the coolant lines.

 

Even baja trucks that ran carbed motors ran wet mani's. What would endurance dessert racers know......

 

Honestly though to each their own, no sense arguing this anymore. I laid out the facts at hand and Nissan (plus every other car manufacturer) spent millions in r&d coming to those conclusions. If people that just so happen to live in the dessert think they know better power to them.

 

Best of luck

Edited by 72240z
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Wow, well i wasnt expecting such a fuss over the manifold. I think its more a matter of opinion. Personally im gonna buy a shut off valve and get to the bottom of this, plus with the shut off valve i can pump coolant back through when it does get cold those three or four times of the year.

 

With as hot as it gets and stays i dont think there will be the type of problems you are thinking of 72240z. Especially when underhood temperatures and the manifold is dam close to the exhaust, closer than i would ever want it. If i was driving in pinetop or flagstaff, somehwere northern, it would be understandable to expect less performance, economy and efficiency with no coolant, but im not going to be driving up there for a long time.

 

Thnaks everyone for their input, but im just going to put a valve on it and see which way the motor performs best.

 

Oh yeah vapor lock.....worst thing ever...haha

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Wow, well i wasnt expecting such a fuss over the manifold. I think its more a matter of opinion. Personally im gonna buy a shut off valve and get to the bottom of this, plus with the shut off valve i can pump coolant back through when it does get cold those three or four times of the year.

 

With as hot as it gets and stays i dont think there will be the type of problems you are thinking of 72240z. Especially when underhood temperatures and the manifold is dam close to the exhaust, closer than i would ever want it. If i was driving in pinetop or flagstaff, somehwere northern, it would be understandable to expect less performance, economy and efficiency with no coolant, but im not going to be driving up there for a long time.

 

Thnaks everyone for their input, but im just going to put a valve on it and see which way the motor performs best.

 

Oh yeah vapor lock.....worst thing ever...haha

 

I hear ya, we all have dif needs and requirements. I was just voicing my side on the matter for future Idk other readers and the like? :blink:

 

The difference is going to be smaller in the dessert there is no doubt about that. My whole thing is that THERE IS a difference noticed or not and to me that's important. One of the most fun things I personally enjoy about cars is trying to get MAX efficiency. Some people don't care about the 2% and that's fine, but I do lol.

Edited by 72240z
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