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Discussion Starter · #1 ·
I was on supercars.net today and I have a question about something. Take the 2001 BMW E39 M5 for example, under specs it says the configuration is V8, (which I always though v8 meant 8 cyl's and v6 meant 6 cylinders, etc.) and that the valvetrain is a DOHC 4 valves/ cyl!!!!! So, I guess my question is what exactly does v8, v6, or v4 mean??? And is there even a car with more than 4 valves/ cyl's???? Wow! You think you know something, and then SMACK, you find out you don't!!! :eek:
 

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ferrari makes a 40v V8 and so do other manufacturers...4valves per cylinder is common today...V6, V8, etc. is the # of cylinders...okay?
 

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The V in V8 or V6 stands for the way the engine is shaped. In this case, the engine is in a V configuration where in a V6 config 3 cylinders are on one end and 3 cylinders are on the other end. Most 4 cylinder engines are inline, so you may see them as I4 or just 4 cylinder. There are are also inline 6 cylinders which BMW uses and inline means exactly that. The cylinders are in a straight line. Subaru has thier horizontally opposed engines which are denoted as H4, or at least I have seen it represented as such. As for the valves per cylinder, not all engines have four valves per cylinder and not all engines are DOHC. I'm not sure if car engines have more than four valves per cylinder.
 

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Damn it Lee, I was going to post the same thing! :D

Actually Audi makes an inline 5 also... Don't ask
me how they balance it... :)
 

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Acually its not an inline 5. It is a small degree V, but I just cant rember the exact term right now. It uses one cylinder head.
 

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Volvo had a turbo inline-5 for a while, and I think they played around with a V7. Crazy Swedish.
 

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way back when AUDI had the AUDI 5000 problem, there was an inline-5 engine. they even turbo'd it for their quattro applications (quattro coupe). nowadays, they're probably using VAG's VR5. you know the VR6 minus 1. i believe that everything is in a vee shape and the extra cylinder sticks out somewhere.
and yeah, the VAG 1.8T is a 5v / cylinder job.
hey, even HONDA had an inline-5. it was used in the VIGOR. but, who really cares... it's a honda.

hope this enlightens...
 

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Discussion Starter · #9 ·
So each valve has a cylinder or something???? I mean, can someone pretend I'm 3 yrs. old and break it down to me?
 

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it's the other way around...
each cylinder has 2 valves, intake and exhaust. so at a bare minimum, there will be 2 valves per cylinder.

the valves are actuated one of two ways, cams or pushrods. a cam is basically a rod with 'bumps' on them that 'bump' the valves open as it spins in place. pushrods are like fingers that open up each valve. each valve gets a finger.
most engines these days have cam actuated valves and are known as Over Head Cams or OHC. so a SOHC engine has a Single OverHead Cam, which means only one cam operates the valves. while a DOHC has Dual OverHead Cams operating the valves.

for instance on a SOHC inline-4, you're gonna have minimum 8 valves run by one cam.

the SR20DE is a DOHC 16v design, which means each cylinder gets 4 valves each run by two cams. 4valves X 4cylinders = 16valves. generally, when an even number of valves are present it's split evenly between intake and exhaust duties.
in the instance of an engine with an odd number of valves, i believe that intake gets the extra valve. examples of engines with an odd number of valves are the VAG 1.8T -a DOHC 4 cylinder with 5 valves per cyl & MB's 3.2L V6 - a SOHC V6 with 3 valves per cyl.


does this shed some more light?
 

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simply put. cylinders are the number of 'cylinders in a engine. e.g, v-8, v-6, i-6, i-4. v=v-angle configuration, i=inline configuration. each cylinder has a piston, size of your fist that goes up-down in the cylinder. there are valves, usually one for intake and one for exhust. hi-performance engines use 4-valves per cylinder, which means 2-intake, 2-exchaust, e.g., v-8 with 4-valves per cyl = 48valve.

our sentras have i-4(inline four cylinders), with 4-valves per cylinder(2-intake, two exhaust).

there are also SOHC(single over head cam), and DOHC(double over head cam). each cam drives one bank of valves, which are placed opposite sides of each other(intake one side, exhaust the other) engines utilizing 4-valves per cylinders most often have DOHC, like our sentra 2.0 engines.


got it! if not, go to your local library and look up 'internal cumbustion engine's!!!
 

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for you, fuddaker, quad cam on the lexus is simply 4-cam system, two one each bank of cylinders for the v-8. the 300 models are inline six, utilizing only DOHC.

then you have the VVTi system (varialbe valve timing induction)
 

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lets take this even further (FAQ ME!)

Ok the numbers of valves that you can find in today’s modern engines are 2, 3, 4, &5

2 valves per cylinder
Push Rod engine. In this type of engine (LS1, LT1, ford 351W, 302-5.0L) the cam is located off to the side of the cylinder and can be either belt or chain driven. The cam lobe hits a "push rod" which intern pushes on a "rocker arm". The rocker arm then actuates the valve. 1 intake and i exhaust valve in this setup. 1 cam per side of the engine. Again good low end power, but there is flow issues at higher rpm.

SOCH
Nissan VG30E (and 33E) 84-89 300zx, 85-87 200sx se v6, infinity m30, pathfinder, frontier, quest/villager. This engine is referred to as a SOCH or single overhead cam. This type of set up usually is beneficial to low end power and not all that great for high end due to air flow restrictions. The cam in this vehicle is located above the valve and the "cam lobe" actuated the top of the valve. This set up has 1 intake and one exhaust valve. The intake valve is usually slightly larger than the exhaust, but the can be the same size

3 valve per cylinder SOCH a la Mercedes Benz V8's. The AMG "55" series engine. This has a soch with 2 smaller intake and 1 large exhaust valve. This betters the 2 valve per cylinder design by allowing for greater air flow. It also adds a swirling motion in the cylinder as air is drawn in. This creates a more uniform combustion mixture, yielding a more complete burn.

4 valves per cylinder Nissan SR20DE, KA24DE, VG30DE, VE30E, VQ30DE, Honda DOCH Vtec, MKIV Toyota supra.

2 intake and 2 exhaust valves. In these engines there are 2 cams per side of the "v" or 4 total. There is a dedicated cam for the exhaust and the intake camshaft. Like the SOCH engine, the cam shaft resides right above the valves and directly actuates the valves. These engines have much better breathing at the top end as opposed to their 2 cylinder counter parts. This enables them to rev to ridiculously high rpms and make power up to redline - 9K in many Honda JDM engines.

5 valves per cylinder - 3 intake and 2 exhaust. The intake valves are smaller than the exhaust and the setup looks like a pentagon. Again good top end breathing. This setup can be found in VW/AUDI 1.8T engines.

There have been various number of cylinders that have graced many automobile.
3 cylinder. this has a straight or inline pattern - geo metro, and many of the up coming hybrid vehicles.
4 cylinder. this has a straight or inline pattern - sentra, altima, civic, accord, crv, prelude, camry, carola, sunfire/cavilir, MR2's.
"V4" typical motorcycle engine
5 cylinder - this has a straight or inline pattern. Volvo NA and Turbos, Audi 5000's, Acura Vigor (yes Honda made a strait 5) These engines are not all that hard to balance. Piston motion is generally set off by 72 deg of crank shaft rotation and is counter weighted like many production engines.

6 cylinder this can be either a strait six configuration MKIV supra, Nissan "L" series a la 240, 260, 280Z, datsun 510, BMW M3. This style of engine has been noted to be the most balanced because piston motion is off set by 60 deg of crank shaft rotation. Strait 6's are praised for their smooth revving behavior and good torque/hp #'s

8 cylinder. There were old strait 8's made, but none in recent memory, so i won't talk much about them. Obviously space becomes a consideration with engines like this.

Most common V8 These can be push rod LS1/LT1 Ford 351W and 302. There are SOCH and DOCH versions of the V8. Basically 2 4 cylinders off set by 60 to 90 deg V. Infinity q45, mustang, Firebird/camaro/vette, M5, 7 series bmw.

10 Cylinder - same basic idea as the V8, but with 2 extra cylinders. Found in the viper, Ferrari, possibly new baby Lamborghini, Ford GT90 - (this was 2 duratec V6s laser welded together with the extra cylinders chopped off. quad turbos)

V12 - basically two v6's known for creating obnoxious amounts of power at smaller displacements. Lamborghini, Ferrari, McLearen, Bavarian Motor Workz, Mercedes Benz.

W12 and W18 -Audi/VW/Bugatti the easiest way to think of these engines is 3 4's or 3 straight 6's couples together. I haven’t read all that much about these engines, but they make good power and are well balanced.


Ok now on to engine configuration....

Horizontally opposed almost all FWD cars use this configuration. The engine is turned 90 degrees so that the crank shaft is pointed at one of the front wheels. Most engines rotate clock wise except for old Honda 4's. they rotated counter clock wise...

Boxer style. 4 or 6 or 12 cylinder. Basically the pistons are off set 180 degrees from each other. Subaru, Porsche, Ferrari.


If I made an error above I apologies, but the basics are there....

Want to learn more? search the web!!! The information is out there you just have to find it. Many manufacture web sites have basic engine information

Doc

[Edited by Dr. Mario on 05-19-2001 at 01:56 PM]
 

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oops forgot 2 types of engines

Both are currently used by Mazda. (crazy mazda engieers)

The wankle! aka RX7 motor. This engine does not have pistons, but rotors. I believe most maza configurations are 2 rotor. each rotor has 3 sections to it where combustion can take place. Look for this one on the internet. There is a ton of information on it.

MB also played with it back in the 60's. You may also hear this style of engine refered to as turbine style as it mimics a jet engine. (vaguely though)

THe miller cycle engine. This is currently used in the mellina S. Very interesting. Basicly this engine has an electricly driven supercharger, but not conventally. There is a large portion of the cam shaft duration that overlaps as the supercharger runs. forcins some of the unburn hydrocarbons back into the engine. exhaust valve closes and the cylinder is charged on the up stroke of the pistion with the valve still open until a point just before combustion. Advantages 3L power out of a 2.3L power plant.... good fuel efficency too. Its too bad that mazda doesn't make a 3 or 3.5L version of this engine. they would be producing V8 torque and hp#'s with a v6.

again look this up on the internet. it is easier to see how this one works with pictures rather than my convoluted explanation..

Doc
 

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Discussion Starter · #16 ·
Hey thanks~~~ya'll definately provided great explanations! I have a much better understanding now. I was real confused!
 

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doc, a horizontal oppose engine is a boxer engine. that is because the cylinders are oppose from each other.
the type of combustion engine is named is according to the arrangment of the cylinders from the drivers/pilots view. there are 4 types of engines: inline (i), v type (v), opposed/flat (o, ho), and radio (r).
inline engines can have from 1-8 cyl, and they are arranged in a straight line pattern.
v type can have from 6-12, and are arranged adjacent to each other and they will always have an even # of cyl.
opposed type can have from 4-8, and are arranged opposite to each other and they will always have an even # of cyl.
and radio can range from 5-9, are arranged in a circle.
 
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