HP for 4.7 underrated?

[v8Toilet]

Bradley

I got those statistics from Car and Driver magazine. I also had my doors blown off by two Duramax deisels at the drag strip, they were modified though.

On the S2000 the first four transmission gear ratios are 4% lower. The article even states that the improvements in the acceleration are due to better low-end torque. It’s the whole plight of the article!

Torque is what the engine actually produces. Horsepower is just a mathematical calculation know as HP = torque * RPM / 5252. The longer the engine can maintain torque as the RPM increases the more horsepower it makes. If the Torque curve drops off too fast than so does the horsepower. If the engine makes allot of torque only in the upper RPM than it also has allot of horsepower as is the case with the GM Vortec 4800 V8. Typically a diesel engine can only rev to 3000-3500 RPM max so they don’t produce allot of horsepower unless the torque is sky high.

Another example that is a great one for you is the case with the new Toyota 4 runner. The V8 makes 235 HP and 320 ft. lbs. of torque and the new 4.0-liter V6 makes 245 HP and 282 ft. lbs of torque. The V8 has the five speed transmission but the V6 has VVT-I and is lighter in weight. If you test drive both the V8 feels a whole lot faster.

Another example is the case with an extended cab GM full size truck with the Vortec 4800 engine compared to the Toyota Tundra. Both have similar engines yet the Vortec makes 270 horsepower while the I-force only makes 245 horsepower but the Vortec 4800 makes 285 ft. lbs. of torque and the I-force makes 315 ft. lbs or torque at a lower RPM; 4000 vs. 3400. The Toyota Tundra will out accelerate the GM full size truck with the Vortec 4800 engine. I don’t have the exact specifications but If you pick up an older vehicle publication you’ll see what I mean. During my dyno run on the dynamometer I put down 271 ft. lbs. of torque and a 2002 Vortec 4800 put down just 241 ft. lbs. of torque.

[Bradley]

V8 Toilet,

I agree when you modify gearing on a given vehicle it changes it performance, I was talking about vehicles in pure stock form running against each other. You are comparing modified trucks Vs stock ones, I believe Motor Trend also did an article on the 6.0 liter GMC Truck modified with a supercharger, intercooled, and computer enhancement with factory all wheel drive, the 0 to 60 time was Phenomenal for a truck of that size and weight I believe it hit the century mark in the quarter mile, and with all wheel drive the pull from stand still was awesome. Talking about low end acceleration I believe your Tundra if only modified with a gear change would have let you win the race over the modified Duramax.

[Agent WD-40]

http://vettenet.org/torquehp.html <--worth a read. Sums it up nicely.

[Bradley]

I can put it this way It really makes no difference, if you have a turbo diesel Ford, chevy, Dodge, Take 2 unloaded Trucks one with a gas engine stock with near the same displacement, the diesel may have a higher torque rating and peak at 1600 RPM, that also means it will not be able to wind up and produce any top end Horse power,and will accelerate less over the RPM range than a gas engine with less initial torque, and torgue spread over the RPM range. A gas engine with a Peak at 3200 RPM will wind up much higher , the gas engine will take advantage of the gear ratio through out the RPM range, where as the Diesel will peak out at low RPMs and not be as good for useing the broader range of gearing, loaded with a lot of weight the diesel will be running its sweet zone and out pull the gas engine. If you modify both engines the gas engine can put out more total hp and TQ than the diesel, the gas engine will need more fuel to do the same amount of work and the wear on the gas engine will be greater.

[UsE_To_RoCk]

I obviously know nothing about engines, but what I feel seperates the Tundra V8 from the competitors is that it's a DOHC unlike most which are OHV or maybe a SOHC, when the cam switchover happens you get a nice kick or something. Also We get more valves, exhaust and Intake wise, so the over all engine probably feels more responsive....but I'm just guessing and trying to contribute something. Also The Tundra is lighter than pretty much all the other trucks in it class so that would also make a difference.