Compression is supposed to increase efficiency right?

Why do the Acura RSX and RSX Type-S put out the same torque (Sport Compact Car, July '01), despite over a point increase in compression?

 

it depends on the stroke and a bunch of other stuff.
its a BIG LONG equasion for compression, look
CR: (cylinder volume + head combustion chamber volume + deck clearance displacement + headgasket displacement +/- piston displacement)
*divided by*
(head combustion chamber volume + deck clearance displacement + headgasket displacement +/- piston displacement)

as for torque its displacment of the engine (e.g. 1.6l, 1.8l) i think its how far the piston moves on the down stroke. the longer the stroke the more torque
someone correct me if im wrong.



[Modified by KAMiN, 3:51 AM 1/26/2002]

 

Up to a point, a higher compression ratio will give you higher fuel efficiency and power at the expense of exhaust emissions.

I haven't seen the article, but I assume the engine with the higher CR had more HP. That's not the same as torque. They're related, but it's not a one-to-one relationship.

 

torque also has to do w/ distance. that's y rwd cars usually have more torque than fwd cars. it depends on the distance from the motor to the wheels

 

What? How does the distance from the tranny to the rear diff, have ANYTHING to do with how much Torque your engine puts out?

Torque is defined as the moment of a force; the measure of a force's tendency to produce torsion and rotation about an axis, equal to the vector product of the radius vector from the axis of rotation to the point of application of the force and the force vector.

So again, I ask how does a rear axle provide more torque to an engine?

 

Other way around: There will be a loss of torque/hp in a rwd because you have turn the drive shaft ,not to mention rear diff then axles.

 

A properly worked/tuned high-compression engine can have emissions just as clean, or cleaner than a similar engine of lower compression.


[Modified by 94gsr, 7:25 AM 1/26/2002]

 

haha - yes, two cars with the same engine, one fwd and the other rwd; the rwd will have less power "to the wheels".

rwd cars usually have more torque than fwd because they usually have bigger engines.

As to why the two rsx's have similar peak torque outputs eludes me. they have the same bottom end don't they? Just a differently set up intake, head and exhaust perhaps? But if you think about it, the '94+ gsr vs. the ls make almost the same torque peak # from almost the same displacement and almost the same r/s ratio and almost a point difference in compression. Displacement must then be the key. this just really makes me believe that vtec is a gimmic, a gimmic to take advantage of gearing. Albeit a gimmic that works.

I would guess (from what i hear) that if you put all these cars on a dyno, stock, then you'd find out honda's factory #'s are a lie.

 

I understand all the things about torque and horsepower and such. But since how the two engines are very close to each other, I would think a point increase in CR would result in a torque increase all across the rpm range.

True, the type S has more power, but given how it's got the same torque it seems to me like the only reason it's got more power is becasue they spin the engine faster. In which case I have to ask why did they increase the compression?