I'm not extremely well versed with engines, but I know a little... and I'm wondering.. the S2000 has a 2.2 liter, 4 banger where our ol TSX is a 2.4 liter, 4 banger... difference is S2000 = 240HP/ 161 lb-ft torque where our TSX is 200HP/166 lb-ft torque...

here is the engine comparison, there are only a FEW differences..


First number is TSX the second the S2000 differences are in bold

2004 Acura TSX 6-speed MT 2004 Honda S2000 6-spd MT

Engine & Transmission

Engine Name 2.4L I4 2.2L I4 TSX wins

Cylinders 4 4

Valves 16 16

Valves Configuration DOHC DOHC

Displacement CC 2354 2157 TSX wins

Bore X Stroke 3.43 X 3.90 3.43 X 3.57 S2000 wins

Compression Ratio 10.5:1 11.0:1 S2000 wins barely

Horsepower 200 240

Horsepower RPM 6800 7800 S2000 wins

Torque Ft. Lbs. 166 161 TSX wins

Torque RPM 4500 6500 S2000 Wins

Fuel System Multi-Port Fuel Injected Multi-Port Fuel Injected

Engine Location Front Front

Driveline Front Wheel Drive Rear Wheel Drive

Transmission Speeds 6 6

Transmission Auto/Manual Manual Manual

Transmission Overdrive Y Y

Final Drive Ratio 4.70 4.10



So I ask you, does the extra RPM and shorter stroke really make the 40 extra HP? Or is the TSX engine's power hiding somewhere

 

It's the extra RPM capacity and the extra compression ratio that the S2000 has that give it the advantage in peak power production.

 

I could understand the RPM factor, but .5 more on the compression ratio?

 

The RPM capacity is the biggest factor. For example, compare the power outputs of the two engines when both are at 6800 RPM. You'll notice they're a lot closer. After 6800, the TSX engine redlines (at 7100) and the S2000 still has a lot more revs to work with.

 

10 HP of the 40 HP difference between the two engines is due to compression ratio. 4.8% higher compression ratio=4.8% more oxygen molecules=4.8% more power at full throttle.

 

Also, cam design and spark timing account for variations in power. There are also variations in the intake manifold design as well as exhaust system design which will account for a small bit of the power.

Plus, the S2000 motor is a different series (engine code is F20C) from the TSX motor (K24A4...I think, please correct me if I'm wrong, folks). These two motors are designed with two different applications in mind so they will have various design characteristics that allow them to better suit their purposes.

 

Not exactly. A 4.8% bump in displacement would allow you 4.8% more Oxygen, but CR isn't the same thing. CR is related to power output by cycle efficiency which = 1 - (1/CR^(gamma-1)) where gamma is the specific heat ratio (Cp/Cv) of the intake air. Increasing CR from 10.5:1 to 11:1 translates to about a 1% increase in power.

I thought the same thing originally, but I was wrong so I had to delete that post.

 

HP is directly related to RPM (hp = torque*rpm/5252) so yes the extra rpms (and the shorter stroke which helps allows it these extra rpms) has everything to do with the extra power.

By pure torque numbers the TSX's extra displacement is nearly offset by the S2000's extra compression. So its almost a wash there (161 vs 166).

If the TSX could somehow rev as nearly as high as the S2000, it could easily equal the S2000's HP numbers. The problem is the very long stroke of the TSX makes this veryhard to do, safely.

What would be nice, if we had octane levels to support it, is raise the compression in the TSX and inturn increase its torque. Then maybe slightly increase RPMs.

 

Even nicer would be boring the cylinders and keeing the same redline. Mmmmm....torque.