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(74 votes) Published: Sep 11, 2007 6:38 p.m. In 3 Favorites Lists Viewed 475 times
Ok this is some advanced stuff. And im talking really advanced.
This First Installment will be about intake manifolds. The design of your intake manifold on your car isnt just made to look pretty or mean looking, it is usually designed that way for a reason.
Notice the differences between the following aftermarket manifolds. #1
#2
Different Intake manifolds are meant for different powerbands. The main parts of a car’s intake manifold are as follows:
#1)The Restrictor. This is attached to a throttle body which controls engine throttle to change the amount of air being sucked into the motor. It attaches to a MAF sensor and then continues to the air filter. The restrictor only needs to be big enough to suck in the correct amount of air for the number of pistons firing at one time.
#2)The Plenum. This is one big chamber which branches the 1 intake-air pipe (restrictor) into individual pipes for each cylinder. This area slows down the intake air in order to increase the air’s pressure which gives a stronger driving force into the combustion chambers within the engine.
#3)Primary Intake Runners. These deliver the air from the plenum into each individual cylinder. The fuel is usually injected from a common fuel rail on each one of these pipes.
The design of an intake manifold will change where in the powerband all of the power will be and how much power there will be at each end.
FORCED INDUCTION:
The first Intake Manifold Shown above has short runners and a large plenum. These types of manifolds are great for engines that use a turbocharger or supercharger (forced induction). They also are used in engines from the factory that want great low-end torque. They have a large plenum and short runners. The reason why the manifold is designed like this is so that it can keep the velocity of the air constant while keeping a high density. Cooler air means denser air. However denser air can sometimes be compressed air which is hot air. This is why "Cold Air Intakes" give different types of performance gains.
A turbocharger or supercharger compresses the intake air as to provide more air to burn more fuel in the engine for more power. Turbochargers require intercoolers to cool down the air in order to keep it dense and to run more efficiently. Having a small intake plenum and long runners on a turbo will slow down the velocity of the intake air but will only give a power gain in the high rpm where the turbo is already kicking in. This is bad. Having short intake runners and a large plenum will reduce space under the hood of the car, keep the velocity of the air high and constant, keep the density of the air high but cool in temperature and is better for forced induction applications.
NORMALLY ASPIRATED (NON TURBO/FORCED INDUCTION):
High Torque in the low endHaving high torque in the low end but keeping high hp in the midrange and good throttle response at all rpm is done with an intake manifold that has a small plenum and short runners. The plenum will still slow down the intake air to increase density at low rpm, but it helps to keep down vacuum at idle and low rpm to make the engine work less in the first half of the powerband. This gives a quick launch, snappy throttle response and quick acceleration. If your intake manifold resembles one like this, you will notice that your powerband is very even and smooth and doesnt spike really high at any point.
These motors can still acheive high hp numbers but when the intake air is flowing alot faster through the manifold at high rpm, there isnt enough plenum and runner space to slow down the air enough to give it the density to get maximum power at high rpm.
High Hp in the high end This is done with long intake runners and a small or large plenum. These motors will have a tougher time accelerating in the low rpm range because the air is slowed down so much that the engine lacks the air velocity to really get a good bang at low rpm. Theres more vacuum in the intake manifold at idle and low rpm but once the engine revs up, the air is slowed down enough to keep the velocity just right so it rushes in fast enought to fill the combustion chamber but it slows down enough to pressurize and become more dense.
WHAT KIND OF INTAKE MANIFOLD IS RIGHT FOR ME?
It all depends on what you have for a camshaft, ignition timing, cam timing and where you want the power.
An engine with a fairly mild camshaft (ex. 260 degrees) that has the cam timing advanced a few degrees is already built for low end torque. If you want to balance out the powerband to get a little more power at higher rpms than you could use a coping saw to modify your existing manifold to custom weld in pipe to make longer runners.
An engine with a really HOT cam (ex. 288 degrees), retarded cam timing, and a really open exhaust is generally built for more power up high. To get the best of this power, you could use a manifold with long runners or if you wanted to balance out the power to get more of a powerband for better launches lower in the powerband than you could use a coping saw and a welder to remove some space out of your intake runners.
Some people have no idea how their engine is designed and dont realize the correlation between cams, intake manifolds, exhaust systems and cam timing. They just bolt together the easiest to find performance parts without doing their research. Sometimes mixing parts from "street" cars with "race" cars will give better performance numbers than building a motor with all "race" parts.
Dont just install a 288 degree cam without realizing that your engine is tuned for more power in lower rpms. This will actually reduce available power and your car will slow down noticeably.
My Jetta has a cold-air intake system on it. The entire engine is built so that it is extremely fast when running in fairly cold weather (under 55 degrees F). In 75 degree heat, my car could run a 14 second quarter mile. In 50 degree heat, it could run the same quarter mile in 13.4 seconds because it relies on colder intake air temperatures to increase air density but keep the velocity high.
Have fun with your car but talk to trained professionals before you ruin your motor.
Sep 11, 2007 6:46 pm - Haha i dont need a new manifold for my 92’ Cherokee :) Lulz i have a K&N cold air intake I made Increased the over all performance.. it only cost me like 60 bucks :)
hake an egg on making you own cold air induction system but over all i give you 5 stars :)
Sep 11, 2007 6:48 pm - The bmw 325e and the 325i are both 2.5 litre motors. One is about 130 hp, the other is 160. The 325e revs to 4500 rpm, the 325i revs way beyond that. The 325e has more torque at lower rpm but the 325 has more power at high rpm. The 325e has an intake manifold designed for more torque while the 325i has an intake manifold designed for high-end power.
Sep 11, 2007 6:49 pm - oh yeah, i made an egg on making your own cold air intake system. I made it a couple months ago. here it is. http://www.rotteneggs.com r3/show/se/211637.html
Sep 11, 2007 6:52 pm - A K&N drop in filter will give better fuel economy and a little bit of throttle response increase but you wont get power increases until you reduce intake restriction in the MAF sensor box, filter box, throttle body and vacuum system. My DIY CAI egg tells you how to get the power increase. Simply installing a K&N doesnt make it into a cold air intake system and the filter will only reduce intake vacuum by like 0.0469KPa.
Sep 11, 2007 6:57 pm - its funny because any time i bring my car to a drag strip, i always look at other dudes cars and ive seen honda civics with these little short intake manifolds. I ask the guys what kind of cams theyre running and theyre like OH, IM RUNNIN A 292 with an adjustable cam gear retarded at -6 degrees. They have all sorts of goodies on their car and under the hood, it looks like they can beat me. The fact that their intake manifold contradicts the rest of their motor allows me to pass them in 2nd gear.
Sep 11, 2007 7:31 pm - Every egg of yours is filled with personal anecdotes, ment to add to your badass fast car rep. "i can pass them in second gear" was pricless.
No more need to stroke your e-cock, we are growing tired of it.
Sep 11, 2007 7:33 pm - Dude mine Isnt a Boxed air filter i made mine out of A K&N cone and Radiator piping :)But anyways you should right a complete egg on a simple tune up Changing oil spark plugs rotor ect
Sep 11, 2007 10:01 pm - to lazy to read it all, but the begining is well writen, 5zerz
Sep 12, 2007 2:53 am - fuck off alle mussen sturben all of chickgriddles eggs are good all yours suck look at them all none are rated high enough to get a rating...u suck...ams why do u hate every 1 chickgriddles this is another good egg 5 and favs...ams go fuck ur sister
Sep 12, 2007 3:25 am - 5 and favs dude , another great egg..
ams gtfo -no one likes you
here are some examples taken from your eggs or replys to your comments-
Quote:
Makel-how did this get into the directory it sucks!
duderdas-fuck you ^ no one likes you on re so continue screwing your sister elsewhere
slowslow-5* because Alle_Mussen_Little_Gay_Bi ch Fucks himself and his sister every night
i hate allemussensturben -
Pointless much? *2
MhF4LiFe-Well thanks for letting me earn egg points by rating everything you have a 0
_______-fuckin 0
DArkNEss-1144-your a fuckin pussy ...
Sep 12, 2007 9:36 pm - they arent personal anectdotes. I am not in the least bit egotistical and why should i give a fuck whether people online think my car is fast? They are examples used to prove a point or back up the information i provided with stronger evidence.
Sep 13, 2007 2:27 am - I’m starting to wander about Alle’s constant need to speak of "e-cocks" nice egg though. 5 star of course.
btw, just kiddin alle... stroke away.
Sep 13, 2007 12:27 pm - doesn’t the 325e have a 2.7L in it? Or did you do an enigine swap? anyway 5*s because this is a sweet egg and I got a 325es myself:]
Sep 13, 2007 9:05 pm - it has a 2.5 I6. They dont rev that high, they only rev to 4500 rpm. Jetta GLs rev to about 7200 and a GLI will rev to about 6800.
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