question about V6

[louisiana ridgeline]

Well i dont know much about engines so maybe someone can help me. Why is the hp and torque diff. in the RL, Pilot, and new Accord? They all have the same 3.5 V6 engine. My second question: Will the weight of the RL strain and affect the reliabilty of the V6 engine?

[shovelhd]

The engines have the same displacement, 3.5L, but they are not the same engines. Each one is purposely built for its intended use.

[hofffam]

An engine is so much more than pistons, crank, and connecting rods.

Some basic parameters are set by the bore and stroke, but the fuel delivery system and the breathing (intake/exhaust) control just about everything else.

The Accord and RL have the same bore and stroke but have different compression ratios, different redlines, and of course different hp and torque. The 08 Accord is also a newer engine - it has 2nd generation VCM. The valve train is probably signficantly different from the RL. We don't know for sure, but it wouldn't suprise me if the RL's internals are sturdier - maybe heavier crank for instance - that cause the drop in redline.

[McRidgeline]

Yep and, in general, HP engines have a larger bore and smaller stroke while torque engines have smaller bores and larger strokes. Thus, they generally turn lower RPM's but have gobs O'Torque with the larger cranks/bores. Hot Rodders sometime refer to this difference as 'short block' vs. 'big block.'

(Very general description here; as stated in other replies, compression and 'volumetric efficiency' have their affects as well)

Thus, engines with same or similar displacements have have very different HP/Torque values.

[djeaux]

Another way to put it is that the engine in an Accord isn't designed for pulling or carrying loads & can be set up for horsepower. A light SUV or minivan can split the difference, and a truck needs more emphasis on torque.

Unless you're planning to throw some serious overloading on your Ridgeline, engine "strain" isn't likely to be a factor. But do remember that this is a light truck. If you need to tow 5 or 6 tons on a regular basis, you're probably better served to get a V8 dually something or the other.

[VIRUDEBWOY]

Here are some of the engine stats below. I'm actually working with my buddy on his truck on acquiring the intake manifold and camshaft from the RL/TL or if I can get the orginal cam specs from honda/acura then I can have Crower grind me a cam with the same lift / duration or maybe add some more lift /duration, however it's still a work in progress. This truck will be only street driven so no towing at all for us...

Found in:
2009+ Honda Accord
Engine SOHC i-VTEC® V-6 with VCM/SOHC VTEC®
V-6
Displacement 3471cc (3.5-liter)
Compression ratio 10.5:1
Horsepower** @ rpm 268 @ 6200
Torque** @ rpm (lb-ft.) 248 @ 5000

Found in:
Honda Ridgeline
Displacement: 3471 cc
Compression: 10.0:1
Power: 247 hp @ 5750 rpm
Torque: 245 ft-lb @ 4500 rpm
Redline: 6300 rpm
Bore: 89 mm
Stroke: 93 mm
Valvetrain: 24-Valve SOHC VTEC

Found in:
2005+ Acura RL, 2007+ Acura TL Type-S
Displacement: 3471 cc
Compression: 11.0:1
Power: RL: 290 hp @ 6200 rpm (SAE corrected)
TL-S: 286 hp @ 6200 rpm (SAE corrected)
Torque: 256 ft-lb @ 5000 rpm
Redline: 6800 rpm
Bore: 89 mm
Stroke: 93 mm
Valvetrain: 24-Valve SOHC VTEC

[arteegee]

Originally Posted by McRidgeline

Hot Rodders sometime refer to this difference as 'short block' vs. 'big block.'

Huh???????????

[Kodiak]

All these engines are different.

The Ridgeline uses a switch valve in the intake manifold to boost mid-range torque. The Pilot does not use this hardware. Additionally, the Ridgeline uses an riser under the intake manifold for better low end torque (this part is shared by the Pilot). Neither of these parts are on the 2008 Accord which is the new generation of V6 (also installed in the 2008 Odyssey).

The 2008 Odyssey and 2008Accord both have VCM which uses the VTEC to kill cylinders while cruising. This comes at the expense of top end power. The Ridgeline uses the VTEC for high valve lift for better top end. The new Accord and Top trim Odysseys use VCM-2 which runs in 3 cylinder or 4 cylinder mode to expand the operation range of VCM (more torque). The 05-07 Odyssey did not function in 4 cylinder mode. This achieves better real world fuel economy (at higher speed that people actually drive at).

All of these engine are also dependent on the specific installation to the body which results in different intake and exhaust flow rates. This affects HP also (even the same engine installed in two different vehicles will likely be rated differently).

I hope this is helpful.

[McRidgeline]

Quote:
Originally Posted by McRidgeline
Hot Rodders sometime refer to this difference as 'short block' vs. 'big block.'


Huh???????????


It was a general statement regarding the nomencalture of V8 selections Hot Rodders sometimes use/discuss. I kept my post very general given that the question on the initial post didn't imply a lot of engine knowledge. Thus, I was just trying to convey that two engines could have the same displacement, but very differernt HP and torque output.

[DoctorJ]

Originally Posted by McRidgeline

Hot Rodders sometime refer to this difference as 'short block' vs. 'big block.'

The jargon is:
long block vs short block
and
small block vs big block.