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Jakee's 4.0 SOHC Build up discussion and motivation thread

After Camber adjusters, Body bushings, rear sway bar, and brakes are complete, I'll be posting baseline dyno numbers. First things first. Must be safe!


EDIT (11-6-2007)

Let me save you some time by posting the summary to this thread. The thread is filled with a bunch of off topic ramblings. Read on if you want but be warned.

Summary to this thread....

I'm going to attempt to close this thread because the N/A goal is coming to an end. I really lost interest in the N/A goal a few months back, and It just doesn't make sense (from a $/HP perspective) to buy anymore bolt-ons when the force feed options are available for us 4.0 SOHC guys. I would rather save the money to buy a turbo than to keep spending big bucks for little gains. And so, this is what I did, and these are my opinions on how the mod worked out.

The first thing was the intake. I can remember going around in circles trying to figure out which one to buy. The Volant? no, the K&N....wait a minute, the MAC is cheaper? Anyways, I finally decided on the MAC intake because of the cost. All and all, an intake is an intake. You're not going to see a big huge difference between any of them, but I still feel the best out there is the Volant. I believe in a "Closed" intake. In other words; I don't like the idea of sucking hot engine air thru an open filter under the hood. That's just me and the difference between a "Closed" intake and an "Open" is very small. I did, however, see a gain from customizing the MAC intake by closing in the air filter with a trash can....Yes, you heard me right, a freaking trash can that I cut to fit in the engine bay. It worked good and people usually don't notice what it is. They just think it looks cool. Anyways, I also replaced the MAC filter with a Volant filter; cut a 3-1/2" hole thru the fender and placed a Volant filter thru it. No water can get to it, well....not from this area....I then added spectra hoses from the front of the vehicle where the fog lights were for a "Ram air" attempt. I had a couple of aluminum parts machined for a clean install. That was it for the intake.

Next, I believe I ordered the 73MM C&L from hensonperfromance. This housing uses the same electronics but is just a bit bigger than the stock plastic MAF housing. The gain was small, but was worth it. I believe I've found dyno's of a 7 RWHP gain? Not sure, but there is a gain there.

The TB was the next thing. I purchased a 4.6 TB from KBX performance because I heard a guy named James had discovered it to work with the 4.0 SOHC. I later fooled around and half shafted it. Basically, what that does is removes half the rod that the butterfly is attached too. Do a search on "half shafting a TB" or something like that to get more details. I believe this mod really doesn't give big HP; more throttle response than anything but it's worth it.

When I had the TB off, I noticed this big tube right in the way of the airflow. The tube is the EGR valve and the reason it's sticking in there is to evenly vent exhaust gases back in the intake. Do not remove the EGR valve; it actually helps you. What I did was remove the part that's in the way of the air-flow. I have no idea if this helped me, but It felt like it did. The only ill effect I can think of is maybe one side of the engine is getting more EGR flow; however, I haven't seen traces of this on the spark plugs so I believe it's good.

Now for the exhaust....yeah, it's hard to get a 4.0 SOHC to sound good. In fact, I think mine still sounds pretty bad. I started off with the Gibson Cat back and if your looking for a "Slightly louder than stock" exhaust, then this is the one for you. The gain was good and I liked the sound but I wasn't satisfied. I felt there might be just a little more power I could unleash so I tried a higher flow muffler; a magna-flow. I started off by having a custom Y-pipe made. It has 2-1/4" primaries that y's into a 3" single exhaust. The pipes run back a little ways and goes into a 3" magnaflow cat, then into a 2-1/2" magnaflow muffler, and dumps right before the rear axle. The flow is there but the sound.....I hate it.

I also added JBA stainless headers. I have to say that headers are very expensive for the 4.0 SOHC but there is gain, trust me. If your looking for EVERYTHING you can from the engine, add headers to it later on down the road.

Next is under-drive pulleys....This is one of the better mods in my opinion. The under-drive crank pulley works by slowing down the serpentine belt, which in return, slows down all the accessories running off the belt. The result is more power to your back tires. The only problem I had was it slows the alternator down too much. The fix is an overdrive alt pulley and I added one to speed the alt back up. Problem solved. I'm also running a underdrive water pump pulley with no problems what so ever.

Another good mod is a electric fan. I went with the flex-a-lite 180 and haven't had a problem yet. Very good quality pc.

The best mod, in my opinion, is a tuner. I went with a SCT XCAL II that I picked up from hensonperformance. I think this changed my truck the most and I'm very pleased.

I believe this about sums it up. Every pc of info I just typed here is on the net, and most is right here in this forum, but I wanted to compile some of it for reference purposes....

I made a goal at the begining of this thread, but I'm really not interested anymore. It doesn't make a hill of beans to have high dyno numbers, but it is nice. The only dyno I had sucked; I made 189 to the rear wheels. I'm thinking I'm a bit higher than that but I'm not worried about it.


Next project......TURBO!! and I'll probably do a baseline for this. If so, I'll add the baseline dyno here so there will be N/A results.
 



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Jakee
This is an old picture--look closely at the lower fog light holes--

Those are air filters---
It is a good idea-but I was afraid it would suck water---
 

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Jon - Where did you get those?

I figured everyone is doing the water injection when force feed so that's my water injection!?? (Joking)
 






Okay - I think it was the weather. I'm back down to a low 7sec 0-60. I'm gonna try and get a vid today with sound.

This was confirmed by a very respectful guy...No names but u can trust that this came from someone with a lot of experience with sixers.


Jake,
If your single cat was old and breaking down, then it may actually be hindering overall performance at the expense of falsely increasing low end torque.

If your exhaust system is properly sized with a low restriction muffler, your exhaust system should be ideal with or without a cat.
 






A cat or back pressure does nothing for torque exhaust velocity does, most people go to large with the pipe diametor, the only job of a muffler is to keep volumes in check.
 






A cat or back pressure does nothing for torque exhaust velocity does, most people go to large with the pipe diametor, the only job of a muffler is to keep volumes in check.

I agree completly.
 






Who ever said Doug from BAMA can get 200rwhp out of a stock X is mistaken, those numbers must be obtained with a DYNO tune, CAI and catback exhaust.

:bsnicker: stock 200rwhp

I just saw an episode of Rides where they Dynoed a stock 2005 5.4 Triton Expedition. The rear wheel numbers where 167hp, they fixed this problem by dropping an Eaton Supercharger onto the intake.
 












Al, Read Post #453.

Jakee, what is that wrap on your intake pipe.

I saw an intake heat wrap a while back with Velcro fasteners, it was not worth it to me though at $75, for a cheaper price I would love to do this though.
 
























Al, Read Post #453.

Jakee, what is that wrap on your intake pipe.

I saw an intake heat wrap a while back with Velcro fasteners, it was not worth it to me though at $75, for a cheaper price I would love to do this though.

Lazz - It's header wrap. I wrapped all the way back until the planned sts turbo. I painted the aluminized pipe and let dry. Then wrapped it and painted the wrap. Only the tailpipe wrap is not painted.

I've gone back and forth between turbo and supercharger. It's just a learning process for me because I have no experience with force feeding. I think I'm leaning towards the turbo again but I don't want to keep sounding wishy-washy about it so I'm just going to concentrate mainly on what I've started here.

I'll hopefully have all the pulleys and a new belt for next weekend. I'm trying to do this without pissing my wife off. I have to be careful..
 












I thought this to interesting.

Urban Legend #1:
Headers produce scavenge, thereby increasing exhaust airflow, allowing the engine to burn more air/fuel, and make more power.
The Truth of the matter:
Most headers designed to create scavenge actually slow down exhaust airflow, creating back pressure, which is why longer duration exhaust cams can improve the performance of a header equipped engine. There is only one way to make more horsepower; increase dynamic cylinder pressure.
FACT:
Only dynamic cylinder pressure can create horsepower. Scavenge is defined as a suction or a less than atmospheric pressure.
REASON:
There is no way that a suction can create an increase in dynamic cylinder pressure. Maybe headers do work, in some applications, but scavenge alone can not be credited with creating performance improvements.


Urban Legend #2:
Scavenge removes burned exhaust gases from combustion chambers, to allow more fresh air fuel to be burned, making more horse power. More scavenge is better. In fact, mankind has gone to the moon, but mankind has never, ever, created too much scavenge.
The Truth of the matter:
Everything has diminishing returns. More scavenge may not improve power. It seems illogical to state that more vacuum creates more dynamic cylinder pressure.
FACTS:
Scavenge, created and maintained by a resonant 4into1 header, does not remove burned gases from the combustion chamber of an internal combustion engine. As the combustion mixture is burned during the power stroke, the mixture begins its burn from the sparkplug and continues burning toward the descending piston. When the exhaust valve opens in the latter portions of the piston's descent, the gases nearest the valve, and sparkplug, are the first to leave the chamber, under hundreds or even thousands of pounds per square inch pressure. As the light, hot, energetic combustion product gases pass out of the chamber through the exhaust port, chamber pressure drops as potential energy (cylinder pressure) is converted into kinetic energy (exhaust gas velocity). This high velocity exhaust gas column then tends to stay in motion, even after all of the hot, burned, exhaust gases have left the chamber and the chamber pressure drops to zero. Scavenge is then created as the still rapidly exiting exhaust gas column evacuates the chamber by sucking any unburned air/fuel, remaining at the bottom of the chamber, out the exhaust port. No dynamic cylinder pressure increase here.
About 60 degrees before the end of the exhaust stroke, the intake valve opens, exposing the intake tract to the scavenge created vacuum now in the combustion chamber. If the scavenge vacuum is greater than manifold vacuum at that instant (say the throttle is wide open), air/fuel mixture will be sucked out of the intake manifold, through the combustion chamber, past the still open exhaust valve, and out the tail pipe. No dynamic cylinder pressure increase here. In fact, cylinder pressure will be reduced in the very next compression cycle because a portion of the available air/fuel has been lost, never to be burned. Opps, you have just lost dynamic cylinder pressure, the one thing needed to make power.


Urban Legend #3:
Fuel mixture must be made richer in fuel when a scavenge header is installed. The reason is that the header's powerful scavenge allows the engine to breath better, burning more air/fuel, making more horsepower.
The Truth of the matter:
Fuel must be added because the scavenge header is sucking the same amount of fuel, the amount that must now be added, out the tailpipe; the phenomenon is known as over-scavenge.
FACTS:
All intake systems compensate for airflow changes by proportionately adding fuel to air passing through the intake. Carburetors use a simple Ventura that generates a stronger vacuum signal with greater airflow, pulling more fuel through jet circuits, spraying it into the intake air stream. Fuel injection systems use various airflow sensors and air/fuel maps to precisely meter fuel to match air flow. So, even if intake air flow were to increase because of the installation of a scavenge header, the correct amount of fuel would always be added; there would be no need to rejet or remap air/fuel mixtures.
Typically, the more highly tuned the header, and the less the back pressure after the header (i.e. mufflers or catalytic converter restriction), the greater the over scavenge generated and the greater the amount of fuel that must be added to the fuel delivery curve. The additional fuel has to be added because an equal amount of the originally jetted or mapped fuel is lost. How? By over scavenge of the initial air/fuel charge, the richest portion of all air/fuel delivered to the combustion chamber. How do we know this? Because 1) fuel economy (BHPHR/#fuel) does not improve, 2) the mixture leans out only at the scavenge power peak (resonance) rpm, it becomes richer (needs less supplemental fuel) below and above that rpm, & 3) HC (unburned hydrocarbon) emissions go up within such tuned rpm range.
REASON:
Scavenge quickly becomes over scavenge, sucking the richest portion of delivered air/fuel out of the intake manifold and through the combustion chamber during the 60 or so degrees of valve overlap, when both intake and exhaust valves are open at the same time. Ironically, 3, 4 and 5 valve engines are the most likely engines to suffer over scavenge due to the much greater valve curtain from which air/fuel is allowed to escape under minimal vacuum conditions. High flow or ported 2 valve heads suffer the same fate due to increased air flow propensity. So, the better the head, the more likely that scavenge will become over scavenge, and dynamic cylinder pressure will drop.


Urban Legend #4:
4into1 headers flow better than cast iron manifolds.
The Truth of the matter:
A smaller, well designed iron manifold can perform better than most headers.
FACTS:
1. Airflow velocity is generally limited to the speed of sound in that medium. The speed of sound at STP (standard temperature and pressure: sea level) is about 1100 ft/sec. The speed of sound increases to about 1400 ft/sec at about 1100 degrees Fahrenheit.
2. As air flows into a pipe with a different cross sectional area, airflow velocity changes according to that change in area. If the area increases, airflow velocity drops and pressure goes up. If the area decreases, airflow velocity increases and pressure goes down. This is known as Bernoulli's Law.
REASON:
Headers typically flow less than OEM manifolds, because they typically increase the cross sectional area more than manifolds. More area increase means that as the exhaust gases travel through the header, they must expand more, causing the exhaust gas velocity to drop, resulting in back pressure.
A 4into1 also creates additional back pressure at high rpms because the exhaust pulses are slowed down and can't get out of the header before more pulses stack up behind them in the exhaust system.
Say you have a 30mm (1.18" dia.) exhaust valve. Say that the area under that valve, the seat throat region is 80% of the area of the valve head; .7 square inch area. If that is the smallest cross sectional area in the exhaust flow path, it becomes the "choke point", meaning that once the air in that region reaches the speed of sound, it becomes the limit of air flow for the entire system: the "weak link" in the chain of flow elements. Each increase in area brings about a reduction in subsequent flow velocity.
Next, say that the head pipe is 1.5"o.d. & 1.4" i.d. When the air flow passes from .7 square inch area to 1.543 square inch area, the velocity drops from say 1400 ft/sec to 634.8 ft/sec. Likewise, when that air flow then passes into a 3" collector section (7.069 square inch area), airflow drops to 138.57 ft/sec. And finally, when the airflow continues on to a 4" megaphone (12.566 square inch area), airflow makes its final drop to 77.95 ft/sec.
A 4into1 on an engine running 9,000 rpm produces 75 exhaust pulses per second. So, if airflow velocity is reduced to 77.95 ft/sec., each exhaust pulse is compressed making it no longer than 1.04' long. Bernoulli's law predicts that as the air flow is slowed, its pressure increases. This pressure increase is high rpm back pressure!
A 4into1 slows exhaust gas flow and creates back pressure at high rpm, even though it produces overscavenge during the overlap period at the "tuned" rpm.


Urban Legend #5:
Step headers flow more because they increase scavenge.
The Truth of the matter:
Each time that the cross sectional area of the exhaust system increases, exhaust gases are forced to expand to fill that new, large area. When gases expand they cool down, contract and become denser. Expanding/cooling gases slow down as their energy is lost. Each transition in size creates sonic shock waves that travel throughout the system, absorbing even more kinetic energy, slowing the exhaust gas flow further, in jerks.
FACTS:
1. As airflow expands into a greater cross sectional area pipe, it tends to cool down.
2. Exhaust airflow is driven by combustion chamber pressure, released into the exhaust when the exhaust valve opens. The potential energy in the combustion chamber (high pressure) is converted into kinetic energy (velocity, up to the speed of sound), when the exhaust valve is opened.
3. When the cross sectional area is increased in the header, velocity drops, see above.
4. When the exiting, high velocity, gases pull a vacuum, energy is converted from kinetic energy (velocity) into potential energy (scavenge: negative pressure), thereby slowing the exiting exhaust gases by absorbing some of their energy (velocity is reduced).
5. When a gas stream expands into a larger cross section pipe, it cools, due to that expansion.
6. The speed of sound in the exhaust gases is reduced each time that those gases expand and cool. (The velocity of the exhaust gases is limited to the speed of sound. When gases cool, they can not exceed that cooler, slower, speed of sound. They are forced to slow down, preventing exhaust gases from exiting at a higher velocity, creating back pressure.)
REASON:
There is no free lunch, even in a step header. The valve seat I.D. limits the rate of exhaust gas escape, because gas flow rates can not exceed the speed of sound. As exhaust gases enter the head pipe, they are forced to expand, cool, and slow down. With each increase of inside diameter of the exhaust system, the process is repeated. Even though the pipe is larger, the gases can not flowing faster. In fact, the gases slow down with each step. A larger diameter pipe has a greater circumference, and therefore greater surface area to allow exhaust gas heat to escape. The cooler the gas becomes, the more energy it loses from its velocity (thermal energy is lost, allowing the exhaust gases to contract, becoming denser and heavier) and the slower its speed of sound (maximum velocity) in those gases.


Urban Legend #6:
Long duration exhaust cams allow headers to make the most horsepower because headers flow better than stock cast iron exhaust manifolds.
The Truth of the matter:
Long duration exhaust cams are necessary with scavenge headers because such headers convert exhaust gas velocity into scavenge, slowing the rate at which exhaust gases can escape from the engine. Longer duration exhaust cams give the exhaust stroke more time to blow down exhaust gases. Longer duration exhaust cams give that unmistakable big cam (stumbling) idle, because at idle the intake vacuum is the greatest & scavenge is the weakest, allowing exhaust gases to be sucked into the intake manifold during valve overlap, diluting intake manifold mixture, which in the subsequent intake stroke, fills the combustion chamber with inert exhaust gases that don't burn, causing a misfire (stumble).
FACTS:
1. Exhaust blow down rate is usually limited by exhaust valve seat inside area. Exhaust gases can not exceed their speed of sound: 1400 ft/sec @ 1100 degrees f.
2. Headers can work better with long duration exhaust cams. But, not because headers flow better. Rather, headers flow poorly and need more time to flow the same amount of exhaust.
3. Long duration exhaust cams open exhaust valves earlier, dumping combustion energy into the exhaust system. The extra combustion energy and the extra exhaust valve open time (duration) allows the header to expel more exhaust gases than it otherwise could with the shorter duration stock cam.
4. Opening the exhaust valve earlier shortens the power stroke, drastically reducing thermodynamic efficiency of the engine.
5. Opening the exhaust valve earlier dumps hotter, still burning air/fuel into the exhaust port and header, making them hotter. Hotter exhaust gases shorten the life of exhaust valves, cook headers, and add heat load to the cylinder head.
6. If headers really flowed so well, a shorter duration exhaust cam, one more like stock, would allow a longer, more efficient, power stroke, kind of like a stroker crank vs. a stock crank. The longer stroke usually makes more power.
7. Hp = Work/sec (1 HP = 33,000 ft lbs./minute = 550 ft lbs./ second)
8. Work = Force X Distance (Work = (area of bore X combustion chamber pressure) X (power stroke length))
9. If all else were equal, reducing the power stroke will reduce Work done by each cylinder and total engine HP.
10. In a four stroke engine, the crankshaft rotates 720 degrees in order to complete all four of its strokes (4 X 180 degrees).
11. If one degree of duration is added to the exhaust stroke, one degree must be subtracted from one of the other three strokes (intake, compression, or power).
REASON:
Since the exhaust stroke generally can not be expanded into the intake stroke, due to the increased probability of valve to valve and valve to piston intersection during the valve overlap period, degrees are usually subtracted from the power stroke. If a long duration exhaust cam is, say, 20 degrees longer than stock, usually it also makes the power stroke become 20 degrees shorter than stock.
For example, a Ford 302 has a 3" stroke. If the stock exhaust cam forces the valve open at 70 degrees BBDC (before bottom dead center), the power stroke is 2.013". If the long duration exhaust cam opens the valve only 20 degrees earlier (in order to add 20 degrees of exhaust duration) the power stroke is reduced to 1.5". The long duration exhaust cam, with just 20 degrees more duration, has reduced the power stroke by .513"! That is the opposite effect of a 1/2" stroker kit!
People spend thousands to put even a 1/4" stroker crank in their engine, to make more power. You've just done the opposite. You've just cut your stroke by 25%. All else being equal, you can expect to lose about 25% of your engine's thermal efficiency (its ability to convert heat (thermal energy) into horsepower (mechanical energy)).
If a header really did flow better, wouldn't a person be smarter to leave the power stroke duration stock?
The reality is, a header does not flow very well at all, because it expands, cools and therefore slows the exiting gases. The long duration exhaust cam is really just a marketing band aid for the very poor flowing 4into1.



Enough with the Urban Legends. You are set free. Now, you know he truth of the matter.
 









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Urban Legend #1:
Headers produce scavenge, thereby increasing exhaust airflow, allowing the engine to burn more air/fuel, and make more power.
The Truth of the matter:
Most headers designed to create scavenge actually slow down exhaust airflow, creating back pressure, which is why longer duration exhaust cams can improve the performance of a header equipped engine. There is only one way to make more horsepower; increase dynamic cylinder pressure.
FACT:
Only dynamic cylinder pressure can create horsepower. Scavenge is defined as a suction or a less than atmospheric pressure.
REASON:
There is no way that a suction can create an increase in dynamic cylinder pressure. Maybe headers do work, in some applications, but scavenge alone can not be credited with creating performance improvements.



There is kind of a grey area in this one and to tell ya the truth I got bored by about #3 so I didn't read all of them.

The reason scavenging or increased exhaust airflow helps with power is not directly linked to the piston pulling the A/F mixture into the engine on its downstroke when the intake valve is open. It has to do with when the exhaust valve is opening and the piston is on its upward stroke trying to push that exhaust out the exhaust valve and into the exhaust. The more exhaust gas that is bottlenecked up in the exhaust manifold or header the harder it is to push that next parcel of exhaust gas out behind it. If we think of it in terms of just air pushing air then we tend to have a hard time thinking of HOW THE HECK CAN AIR PUSHING AIR AFFECT HORSEPOWER BY THAT MUCH!!! But it can when things are increased exponentially... Factor in the fact that this engine is not rotating in slow motion like we sometimes tend to imagine it. It is rotating at anywhere from 5000-7500 rpms depending on redline and all that. Lets break that figure down a bit. We will use 6000 rpms as it is a decent average figure here. Using that figure divided by 60 gets us 100 full rotations per minute... Then take that figure devided by half because were are dealing with a four stroke engine and we get 50 times PER SECOND that EACH cylinder has to push its exhaust gas out of that port in its head and through that manifold... To put that in a more applicable perspective, that would be like me trying to breath through a coffee straw... :D While it does not have DIRECT affect on A/F burn in and of itself, it does play a part in having a large part AFTER that cylinder's A/F mixture has been burned... Either way, pressure pushing back on the piston still creates drag that the piston has to overcome by using more horsepower to push it out of the way. Ok I am done now...
 






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