Best Exhaust Manifold for my 1st GEN?

[Samzer]

Ok, i am looking into getting a new exhaust manifold for my stock 1st Gen Turbo Talon. I just was wondering what i should go with for more power and for practicality. I am really looking at the Evo III Ported Exhaust manifold or maybe headers? I see performance gains for both, but which would be more suitable for all year driving? Any help would be appreciated.

 

[VanIsleDSM]

That's what I'd like to know nightspeed.. what can get you faster spool?? what about the mild steal tubular manifolds? do they crack as much as the SS ? I'd just get the mild steal ceramic coated.. I want the fastest spool possible.. what is my best option for a manifold? I'm no expert at reading dyno graphs.. but it appeares like the cast brings on the power slightly faster probably due to it's increased thermal efficiency.. but then the cast falls off because of it's descreased flow, am I right here? But what if the mild steal tubular manifold was ceramic coated?... hmm.. so many options.. I just want the fastest spool I can get.

"As it cools, the air becomes much denser, therefore more volume" I just wanted to take that quote that someone mentioned above to clear something up.. if the air cools and becomes desner, it does not take up more volume, it takes less.. hot=expand, cold=contract.

 

[JayRolla]

If its going to be an everyday DD than I would go with cast. Ive heard of a lot of people having problems with tubular on a DD.

 

[DRAGONBALLER20]

2g ported is the way to go for price and practicallity if you're tryin to save some $$$$$

 

[perley03]

That's what I'd like to know nightspeed.. what can get you faster spool?? what about the mild steal tubular manifolds? do they crack as much as the SS ? I'd just get the mild steal ceramic coated.. I want the fastest spool possible.. what is my best option for a manifold? I'm no expert at reading dyno graphs.. but it appeares like the cast brings on the power slightly faster probably due to it's increased thermal efficiency.. but then the cast falls off because of it's descreased flow, am I right here? But what if the mild steal tubular manifold was ceramic coated?... hmm.. so many options.. I just want the fastest spool I can get.

"As it cools, the air becomes much denser, therefore more volume" I just wanted to take that quote that someone mentioned above to clear something up.. if the air cools and becomes desner, it does not take up more volume, it takes less.. hot=expand, cold=contract.

Air is more dense at lower temperatures than it is at higher temperatures. You can pack more oxygen molecules when it is colder out than when its warm. Thats why when you start your vehicle it richens the fuel until it warms up, or when you start your lawnmower you need to choke it, which does the same thing. More air=more power, the more air you can in the more power you can make. Same way with exhaust. As it cools, it becomes more dense, and that expansion also increases with velocity. Like i said above, the more it cools across the wheel turbine, the more dense the air becomes, which would increase the velocity rate, which would make the turbine spin faster and quicker.

 

[VanIsleDSM]

Air is more dense at lower temperatures than it is at higher temperatures. You can pack more oxygen molecules when it is colder out than when its warm.

That's exactly what I said.. when it's colder it contracts, not expands.. meaning velocity decreases as the exhaust cools.. otherwise it would be more efficient to put the turbo behind the rear axle.

As it cools, it becomes more dense, and that expansion also increases with velocity. Like i said above, the more it cools across the wheel turbine, the more dense the air becomes, which would increase the velocity rate, which would make the turbine spin faster and quicker.

you contradict yourself here.. you had it right in the first statement.. as the exhaust becomes more dense it contracts.. it does not expand... this is why there is more air in a given volume of colder air vs warmer.. and why when your air is colder you can burn more fuel.. ect....

http://www.physlink.com/Education/AskExperts/ae40.cfm

 

[nightspeed87]

If its going to be an everyday DD than I would go with cast. Ive heard of a lot of people having problems with tubular on a DD.

yes because of it cracking from the weight of some much larger turbos.
Some have made braces to support the weight, this is why i was suggesting a cryotreated tubular manifold.

As far as spooling im not going to get into colder denser air vs warmer more contracted air, but I will say that if you are looking for mega spool consider this.

Ok just say you have stroker, you have ball bearing, pretty good compression etc.
Even on a 60 trim you should still get pretty good spool with that set up
( considering you cant have mad power at the top and bottom end, theres always a compromise. )
Now suppose at this point you couldnt change the rpm the turbo makes full boost
but you can reduce the time it takes to get to the rpm that makes full boost....

Hmm, i would suspect lightened flywheels, perhaps pulleys, serious weight reduction
and just in general more power then guess what. Your engine revs faster because of increased power. Well increased power directly means better VE hence more combustion. More combustion means more pressure to the turbine which translates to faster spool.
Well ok then, your thinking this is all applicable for "once boost hits" since you have a huge turbo that wont even get you to your good VE range till later in the powerband.
I suppose tuning then may help. Leaning out, and adding more timing before boost will create more off boost timing I suppose which will make the car hit "feel" like it spools faster.
Then quoting what I just said -

Now suppose at this point you couldnt change the rpm the turbo makes full boost but you can reduce the time it takes to get to the rpm that makes full boost....

Maybe not making full boost at a sooner rpm, but making the rpm sooner that gets full boost... Kind of a overlooked thing upon spool. Feel free to disagree.

 

[perley03]

That's exactly what I said.. when it's colder it contracts, not expands.. meaning velocity decreases as the exhaust cools.. otherwise it would be more efficient to put the turbo behind the rear axle.



you contradict yourself here.. you had it right in the first statement.. as the exhaust becomes more dense it contracts.. it does not expand... this is why there is more air in a given volume of colder air vs warmer.. and why when your air is colder you can burn more fuel.. ect....

http://www.physlink.com/Education/AskExperts/ae40.cfm

Hahaha, you're right That's what happens when you have a few beers, and try to explain something at the same time.

 

[92awd6bolt]

I've had a tubular that rocked, spool up was great, but it cracked because it was cheap, after that i bought a sbr cast manifold took a little long to spool but now has 60k(@20psi) and no cracks. Tubular manis rock for spool up but if you want one that won't crack then you'll pay for it simple as that

 

[DSMunknown]

Here is the info you wanted from your PM

http://auto.howstuffworks.com/framed...onda/info.htmlA turbocharger, however, is driven by the thermal energy of the exhaust gases of the engine. With non-turbocharged vehicles, these gases are simply discharged out of the engine as quickly and efficiently as possible, wasting a surprising amount of energy in the form of noise and heat. A turbocharger uses some of that energy (which would otherwise be wasted) to drive its
compressor, without the attendant horsepower loss of a crankdriven system.

Click HereAfter the fuel is burned in the cylinder it is exhausted during the cylinder's exhaust stroke in to the exhaust manifold (5)
The high temperature gas then continues on to the turbine (6). The turbine creates backpressure on the engine which means engine exhaust pressure is higher than atmospheric pressure
A pressure and temperature drop occurs (expansion) across the turbine (7), which harnesses the exhaust gas' energy to provide the power necessary to drive the compressor.

VTG
Scroll down to VTG and read. They say that this technology is mostly ignored in gasoline engines due to the higher EGT than diesels, thus making this system useless because of the flow of exhaust. The higher the exhaust temperature, they higher the amount of energy is used in turning the turbine wheel. Its simply physics, look up thermal effieciency.
As the exhaust gas is being pushed across the turbine wheel from exhaust pulses, it cools, therefore providing more energy to drive the turbine wheel. The higher the temperature, the more energy is harnessed from the hotter air cooling down. As it cools, the air becomes much denser, therefore more volume; the more volume, the more energy is harnessed and that energy is what is turning the turbine blade.
Take an example of the turbo setups on the Corvette's. They are using turbo's mounted past the rear axle. But they use smaller turbine housings to spool the turbos due to the lower EGT at the back of the car. Why? Because the farther away from the heat source, the more cooler the exhaust is going to be.
I'm not going to argue with you that heat does not have a factor in driving the turbine wheel. It just does. Do your research, just like I had to when i first wanted to know how turbochargers work. If you don't believe me, then ask a Physicist. I have taken over 2 semesters of Physics in college and high school. Use the formula, do the math. Heat is the key ingredient when it comes to turbos.
I'm done now. I've stated my facts and knowledge that I've encountered over the past few years, and I backed them with facts.

I read something recently that reminded me of this thread:

Momentum transfer is the physical process that ultimately causes the turbocharger shaft to spin. Momentum is defined as mass multiplied by velocity. For a turbo, this means that the speed of the gas molecules striking, or impinging on the turbine wheel is critical in the process of making the wheel rotate. But armchair engineers often point out that it's the "heat" of the exhaust stream that spins the turbine. Others say that it's the kinetic energy. What's the difference? Or is there one?

Simple physics show us that the only thing that can physically accelerate a turbine wheel is a gas stream with a velocity. It literally takes moving gas particles impinging on the blades of the turbine wheel to make it rotate. This is momentum transfer. Kinetic energy of the gas stream is converted to the kinetic energy of the wheel. The faster the gas flows, the faster the wheel can spin.

There are two main sources to the velocity of the gas flow through the turbine. First is the basic exit velocity of the exhaust flowing from each exhaust port during blow-down and the piston's exhaust stroke.

Blow-down occurs when the exhaust valve opens as the piston approaches bottom dead center. The pressure difference between the hot, pressurized gas in the combustion chamber and the cooler, more expansive exhaust manifold cause a flow of gas. Added to this flow velocity is the effect of the piston rising and physically pushing the gas outward. The speed of the gases flowing into the exhaust manifold flowing into the exhaust manifold at this point can be 350 ft/second or more. Let's call this blow-down speed Vb.

The exhaust gas that has left the cylinder also has heat energy contained within it. The heat energy of any physical substance is a measure of how active its molecules are. The higher the temperature of a gas, the more exited its molecules behave. And when exited, gas molecules tend to move apart, or expand. If constrained, say by the fixed volume of an exhaust manifold runner that is "blocked" downstream by a turbine wheel, pressure is conserved.

The upstream side of the turnie is subjected to this relatively high gas pressure, while the downstream side of the turbine is at a lower pressure. This is because the downstream side is essentially open to the outside, or ambient environment via the exhaust pipe and muffler. In other words, there is a pressure gradient, or drop across the turbine. This in itself causes an acceleration of the gas flow that is added to its initial velocity, Vb. (Simply crack open the outlet calve of a pressurized air tank to understand how this pressure-driven type of flow acceleration works. The air inside will rush rapidly out of the tank, equilibrating from high pressure to low.)

The higher the pressure difference between the upstream and downstream side of a turbine, the faster the exhaust gas will accelerate above Vb as it passes across the wheel.

...

What this all means is that the flow of how exhaust gas that crosses a turbine can be at a relatively high velocity. And this of course means that the momentum transfer can be high, and the turbine wheel can rapidly accelerate. A combination of the initial bulk gas kinetic energy, and the thermal (heat) energy contained in the exhaust stream, is transformed into rotational (kinetic) energy of the turbine wheel.