Staight 4 engine animation

An animation of a straight / inline 4 engine. Two piston pairs, and firing every 180 degrees. Nothing too exciting here, but this is one of the most common types of engine.

Category:

Autos & Vehicles

Tags:

• engine
• animation
• straight
• inline

[suburbanator91]

I see that this crank set up is used on all inline 4's. Why not make it so 1& 2 are at TDC, 3 & 4 is at BDC. Wouldn' that better rotationally balance the crank and thus not require the used of couner balance shafts? Cause I know with this setup counter balnce shafts are needed. Has that been tried before, if someone has an answer to this that would be awsome!!!

[TheRenalicious]

@suburbanator91 This crank setup is balanced in 1st order harmonics, meaning if you draw a line down the middle (between pistons 2 & 3) both sides are doing the same thing. Balance shafts are used to reduce 2nd order harmonics. Draw a line at mid stroke along the length of the engine, and you'll find that pistons traveling upwards have moved a different distance than the pistons traveling downwards. Than crank you propose would tear the engine apart quickly.

[lewp91]

@norfolkdash9 there would be a huge spike in torque every 180deg with no power to bring the pistons back up. these only fire one cylinder every 180 deg.. to fire all 4 you have to rotate the engine twice (720deg). this way you have the pairs (outer 2 and inner 2) are on opposite strokes, when 1 is on power stroke 4 is on induction. if they ran at the same time there would be twice the draw of air, making less power due to the air restrictions from the inlet manifold and tract sizing. :)

[Eyzi96]

@norfolkdash9 there would be a big chance of misfire, i guess.

[richarddr1234]

@thesupra97 you really emphasized "low powered". Just an observation

[thesupra97]

this one is found in the majority onf low powered Japanase sports cars I.E. honda Civic Hyundai Accent (Korean) and Toyota Celica

[TheEMIR95]

Despite that i hate the straight 4 , i have to admit straight 4 are the most successfull engines in the history of Humanity

[norfolkdash9]

So how come they don't make pistons 1 and 4 fire at the same time and pistons 2 and 3 at the same time? Would that cause unbalance or less torque?

[suburbanator91]

@TheRenalicious, thanks, I iunderstand it a bit better now. I looked at a crosspalne V8 crank & how on the front view of it's animation you get 4 points 90 degrees from each other insted of just 2 points 180 degrees from eachother like this I4. What would hapeen using a crank like that for an I-4. The real question I guess I should ask is that is there an alternate set up that can be used besides this one, maybe one that can take care of both 1st & 2nd order harmonics like you can w/ a V6 & V10

[OzzInter]

MOST four cylinder engines have a 1-3-4-2 firing order.

Some FORD inline fours used a 1-2-4-3 firing order.