Older bayless dual dcnf intake question

dllubin said:
Ideal gas law: PV=nRT
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Hmmm, I was thinking there was more to it and you could not treat the mixture as an ideal gas. I was thinking it was a big equation of state formula where you look-up enthalpy in a table and such....but that was 30 years ago and really I was sh*t as a student to begin with. :confused:
 
Paul Valente said:
Hmmm, I was thinking there was more to it and you could not treat the mixture as an ideal gas. I was thinking it was a big equation of state formula where you look-up enthalpy in a table and such....but that was 30 years ago and really I was sh*t as a student to begin with. :confused:
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I'm sure there is more to it, but first order, that drop in pressure is going to drop the temperature.

Regarding whether or not disconnecting the water jacket on a dual DCNF manifold will improve performance or not, the only information I have is what Joe Serra told me in ~1980. He said that performance was better with it disconnected. Keep in mind that he was focused on racing, not driving the car in frigid weather. I went with his suggestion but I've always wondered whether or not with this particular engine and the proximity of the intakes to the exhaust ports if the water would actually cool the intake rather than heat it once the engine got up to operating temperature.
 
man you guys took it to a new level, lol...my thoughts on coolant passages were that it might keep temps consistent, as it is sitting right over an oven, and might keep the vapor lock situation a little better under control...and it originally had coolant passages, soooo...but anyways, my car runs cool considering I'm in Texas. When I rebuilt the car couple of years ago, I paid particular attention to the cooling system, up until then, for the 20 years I owned the car, I thought I would never have it dependable, and not overheat, always ran hot. the heater tubes were rotten, and had tons of leaky hose connections, etc....not anymore, car never gets questionably hot anymore. amazing how cool it runs when you replace everything, lol...anyways, going with a non jacketed intake from Steve, because I think correct float levels might be more important. thanks for all the input, interesting s*** I never thought about
 
25 years ago, I ran both kind of intakes with DCNF's on my X19, one with and one without the coolant passages. I never noticed any différences. The change was just because I got a deal on a better set, so I sold the old one.
 
There is a minor advantage to the non-coolant manifold, you can block off the coolant ports on the head and no longer have to jerk around with coolant everytime you want to remove the intake manifold. Of course this applies to coolant type manifolds too, they just become dry.
 
Paul Valente said:
The throttle plate expands the air i.e. there is less pressure after the throttle than in the atmosphere so the gas/fuel mixture expands as it passes the throttle plate and absorbs energy as it does so. Or are you thinking I meant that the heat of the intake expands the air? There is a difference between a cold air charge and a cold manifold. I would be quiet surprised; no flummoxed* if there was a measurable increase in power from defeating the coolant circuit in an intake manifold on a Fiat X1/9.

Yeah, with the popularity or port injection and now direct injection, there is no danger of condensing fuel on the runners but there is still the possibility of the humidity in the air turning to water ice on the throttle plate so some cars still heat just the throttle plate.
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It occurs to me that the same "latent heat of evaporation" or whatever you engineer types call it :D, was present in a port injection system as well, but is dispensed with in a direct inject situation. My reasoning is this.

If the small amount of pressure differential (let's say 14 psi atmospheric, vs 7 PSI "vacuum" in a manifold = 7 PSI pressure differential) across a throttle plate can cause it to ice, then I would think that the much greater pressure difference from the fuel being released (let's say, 38 PSI in the rail down to 7 PSI in the manifold = 31 PSI pressure differential) would cause the same problems - in this regard, port FI must be somewhat self-defeating if the goal is maximum atomization. Would not the cold induced by the injection process itself be working against the maximum atomization goal?

I realize that we are talking about a lot of air moving across the throttle plate, and not much actual fuel being injected, so it's not apples to apples. Still, fuel weighs more.

What are your insights on this, Paul?

Kevin, sorry to derail your thread further.

Pete
 
Pete Whitstone said:
It occurs to me that the same "latent heat of evaporation" or whatever you engineer types call it :D, was present in a port injection system as well, but is dispensed with in a direct inject situation. My reasoning is this.

If the small amount of pressure differential (let's say 14 psi atmospheric, vs 7 PSI "vacuum" in a manifold = 7 PSI pressure differential) across a throttle plate can cause it to ice, then I would think that the much greater pressure difference from the fuel being released (let's say, 38 PSI in the rail down to 7 PSI in the manifold = 31 PSI pressure differential) would cause the same problems - in this regard, port FI must be somewhat self-defeating if the goal is maximum atomization. Would not the cold induced by the injection process itself be working against the maximum atomization goal?

I realize that we are talking about a lot of air moving across the throttle plate, and not much actual fuel being injected, so it's not apples to apples. Still, fuel weighs more.

What are your insights on this, Paul?

Kevin, sorry to derail your thread further.

Pete
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I think that is where you need the equation of state formula (e.g. Peng-Robinson) that doesn't treat the substances as ideal gases. This guy doesn't show you the calculation, but the temperature drop would be different for liquid gasoline vs a gas consisting of the atmosphere (nitrogen+oxygen+CO2+whatever) + a small amount of gasoline vapor. I'm sure it gets colder as it comes out the nozzle. How much? You'd have to do the math. I'd guess a few degrees.
The L-jetronic system is not really great at atomizing as far as I can tell. All the injectors fire in unison regardless of where the their respective cylinder is in its cycle so it just sort of piles up the atomized fuel which maybe condensing on things until the valve opens and sucks it in. But it is still better than a carburetor or throttle body injection (TBI). Sequential Fuel Injection (SFI) is a step up and of course Direct Injection (DI) even better.
 
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I am not capable of doing that math. :p

Sounds like what I say has some truth but the effect is pretty negligible.

Paul Valente said:
All the injectors fire in unison regardless of where the their respective cylinder is in it's cycle so it just sort of piles up the atomized fuel which maybe condensing on things until the valve opens and sucks it in.
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As far as this, I hear this a lot, that SFI is better because it fires when the valve is open. I get that. But I think that what people tend to forget is that when you are at 100% throttle under heavy load, the injectors are near static anyway. So if the injector is firing, let's say, 90%, and the intake valve is open maybe 30% of the time, I don't see that there's much benefit. Under lighter throttle loads, when the injection event and the intake valve opening are both at 30% and can be aligned, then sure, good benefit. But it seems that when you need it most, it's helping you less.

Pete
 
Paul Valente said:
The L-jetronic system is not really great at atomizing as far as I can tell. All the injectors fire in unison regardless of where the their respective cylinder is in its cycle so it just sort of piles up the atomized fuel which maybe condensing on things until the valve opens and sucks it in. But it is still better than a carburetor or throttle body injection (TBI). Sequential Fuel Injection (SFI) is a step up and of course Direct Injection (DI) even better.
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Wait are you saying that the X1/9 stock EFI squirts fuel into every cylinder at once no matter what stroke it is on? I believe the EFI system is in the intake runners before the intake valves. Does that mean the that each half revolution 3 cylinders are spraying fuel on the top of the valve and only 1 is actually open? As you may know my cars both X and 124 are carbed. I have never really researched a car with an ECU of any sort. I would have assumed Fiat would have thought SFI or bust (carb) and that this shotting in the dark method and hopefully 1 cylinder would be ready for fuel.

PS. I think this topic has gotten majorly derailed. PO speak up with your original question is still open or want to get us back on track! :rolleyes:
 
AKimball92 said:
Wait are you saying that the X1/9 stock EFI squirts fuel into every cylinder at once no matter what stroke it is on? I believe the EFI system is in the intake runners before the intake valves. Does that mean the that each half revolution 3 cylinders are spraying fuel on the top of the valve and only 1 is actually open?
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Yes, that is how L-Jetronic works. With K-Jetronic (AKA CIS) all injectors are spraying continuously. Even with sequential fuel injection, the injectors sometimes spay into the hack of a closed valve. At high load / high RPM the valve-open time just isn't long enough for the injector to squirt the amount of fuel needed.
 
carl said:
There is a minor advantage to the non-coolant manifold, you can block off the coolant ports on the head and no longer have to jerk around with coolant everytime you want to remove the intake manifold. Of course this applies to coolant type manifolds too, they just become dry.
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yeah, if I had only did this when I had her apart, blocking the water jackets that is...was thinking about that...also gone would be the "pain in the ass" factor of leaking coolant should a problem arise, due to putting all this aftermarket stuff on. When I first got my X, I had leakage problems at the manifold, that led to a stripped intake stud...was young, and dumb, didn't know about the thick crush washers, or even think about the used exhaust manifold that had a thick layer of rust on the facing, causing the intake to not get enough gasket crush

Would like to tap the jackets, but don't want metal shavings in my coolant system, lol...been thinking about a way to do this with motor in the car, I have a set of taps, but how to clear the debris from the hole?
 
AKimball92 said:
Wait are you saying that the X1/9 stock EFI squirts fuel into every cylinder at once no matter what stroke it is on? I believe the EFI system is in the intake runners before the intake valves. Does that mean the that each half revolution 3 cylinders are spraying fuel on the top of the valve and only 1 is actually open? As you may know my cars both X and 124 are carbed. I have never really researched a car with an ECU of any sort. I would have assumed Fiat would have thought SFI or bust (carb) and that this shotting in the dark method and hopefully 1 cylinder would be ready for fuel.

PS. I think this topic has gotten majorly derailed. PO speak up with your original question is still open or want to get us back on track! :rolleyes:
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Hahahahah! I don't care, sometimes you learn new stuff this way....altho I still think the intake, with the intake above the exhaust, would be better with water jackets.....but it has been proven (sorta) that they are not necessary. The fact that the guys that designed the engine, and have for the last 100 years keep doing it kinda proves the point....I do see that it's probably for heating AND cooling....I think consistency is the key point, especially on a street vehicle....
My real question was about split angle manifolds, and I've made my decision to not have to f**** around with float levels, which is the more important issue
 
You may be able to grease the tap which would hold the metal bits hopefully. Also you could just drain the block when done and that would hopefully drain out the aluminum bits if any did get in the coolant in the engine. Notice I kept saying "hopefully"!
 
On my 1300, I plugged the ports with silicone. It still looked fine after 30+ years. However, for my 1500 I tapped the ports. There was not a whole lot of residue but I stuck a vacuum cleaner up to it and it sucked out the residue easily. My engine had no coolant in it, so being real dry probably kept the fragments from sticking in the hole. I used a 8mm X 1.25 drill, tap, and set screw with a little drop of pipe joint compound.
 
thanks for the tapping ideas....was thinking NPT threads, as I can find plugs easier? maybe....used npt for my oil pressure add on, so I could use cheap after market sending units :)
 
ng_randolph said:
Yes, that is how L-Jetronic works. With K-Jetronic (AKA CIS) all injectors are spraying continuously. Even with sequential fuel injection, the injectors sometimes spay into the hack of a closed valve. At high load / high RPM the valve-open time just isn't long enough for the injector to squirt the amount of fuel needed.
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interesting fact about those fuel injection systems...I never knew that
 
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