This is for those who know how all the numbers add up. I was filling up both cars today at the gas station and had a thought. My Intrepid has a 3.2L V6, the LS a 3.9L V8. I understand a 3.9L V6 would have the same displacement as a 3.9L V8. So in theory could a 3.9L V6 be built to create the same power specs as a 3.9L V8 but with better mpg or would the V8 always have more potential with hp and torque ? The new Infiniti M series uses a 3.5L V6 that puts out 280 hp and 270 ft-lbs but doesnt get better mpg than the 280 hp LS. How are all the numbers relevent to power output ?
Engine displacement question
- Thread starter Fla02LS
- Start date
I guess that is some sound logic. Using your Ferrari example, the 360 Modena uses a 3.6L V8 with a 11:1 compression and puts out 400 hp. The Acura RL uses a 3.5L V6 with a 11:1 compression and puts out 300 hp yet gets comparable mileage to the LS.
2001LS8Sport
Dedicated LVC Member
Fla02LS...there are so many other variables involved with your scenario that it's just about impossible to answer. Engineers discoverd a few years ago that a 3.25 inch bore was the optimum for emissions and combustion control. That was with current head technology at the time and is the biggest reason Ford went to modular motors. Their whole idea was to use an optimum bore and stack on cylinders. Little things like where to place the top ring land on the piston can make a big difference. Cam timing, combustion chamber design, swirl capabilities, compression, intended use of the engine, are all major players. You are comparing apples to oranges. Acura's 3.2L VTEC is another good example of a V6 that gets good mileage and good performance. Ford's 4.0 SOHC V6 is a much larger displacement, but doesn't perform near as well on paper...but is a much better choice in a heavier vehicle due to it's torque capabilities. There are some very small motors in this world that make some incredible hp...and some very large motors that don't.
Jim Henderson
Dedicated LVC Member
Yeah all kinds of variables.
In general, all things being equal, a 6 with the same displacement as an 8 will porbably have higher torque since the cylinders are bigger. The 8 probably has the edge on horsepower since it is eaier to make an 8 have even firing cycles. I think I read most sixes are uneven so they have problems with smooth(ie high RPM) power in comparison to a 8 of equal size.
But variables change the whole picture. I have seen engines that you can hide in your hand that make something like 15 hp at some ridiculous RPM. And there there are the typically very large engines in airplanes that put out very little hp at low RPM. SO all depends on what you designed the engine to do and what cost you were willing to pay.
I will say that I had a chebby prior to the LS. The chebby had the 350/5.7L LT1 engine in it making 260hp and 330ft#s. The LS is a much smaller engine and makes 280 hp and I forget but less torque. The chebby had more off the line kick bootie while the LS is better once you get up to freeway speed.
Also experience of the SS bunch was that the much touted but creampuff Mercury Marauder while on paper should kick the SS here and gone, never really could get out of it's own way. THe Marauder had something like a 4.6L engine with somerwhere upwards of 300hp, but they didn't have any low RPM torque which is what a heavy car like the Marauder/clownvic. SO while an engine may make a lot of horse power, it may not be good in certain applications.
I ramble,
Jim Henderson
In general, all things being equal, a 6 with the same displacement as an 8 will porbably have higher torque since the cylinders are bigger. The 8 probably has the edge on horsepower since it is eaier to make an 8 have even firing cycles. I think I read most sixes are uneven so they have problems with smooth(ie high RPM) power in comparison to a 8 of equal size.
But variables change the whole picture. I have seen engines that you can hide in your hand that make something like 15 hp at some ridiculous RPM. And there there are the typically very large engines in airplanes that put out very little hp at low RPM. SO all depends on what you designed the engine to do and what cost you were willing to pay.
I will say that I had a chebby prior to the LS. The chebby had the 350/5.7L LT1 engine in it making 260hp and 330ft#s. The LS is a much smaller engine and makes 280 hp and I forget but less torque. The chebby had more off the line kick bootie while the LS is better once you get up to freeway speed.
Also experience of the SS bunch was that the much touted but creampuff Mercury Marauder while on paper should kick the SS here and gone, never really could get out of it's own way. THe Marauder had something like a 4.6L engine with somerwhere upwards of 300hp, but they didn't have any low RPM torque which is what a heavy car like the Marauder/clownvic. SO while an engine may make a lot of horse power, it may not be good in certain applications.
I ramble,
Jim Henderson
bufordtpisser
Dedicated LVC Member
Just remember this.................
Torque gets your car moving, HP keeps it moving. The torque is used to overcome the initial getting the mass moving issue, and the HP keeps it moving after it has reached its torque peak.
Torque gets your car moving, HP keeps it moving. The torque is used to overcome the initial getting the mass moving issue, and the HP keeps it moving after it has reached its torque peak.
NickLS
Dedicated LVC Member
so what is the displacement in cubic inches (cu. in.) does the LS have?
GWL
Dedicated LVC Member
3.9L = 237.9926 Cu. In.NickLS said:
NickLS
Dedicated LVC Member
AH CRAP!!!! And here I am a Mech. Eng. and that COMPLETELY didn't even occur to me. Thanks GWL for reassuring that I picked the right career field.
Sorry folks, for the obvious question that I should have figured out.
Sorry folks, for the obvious question that I should have figured out.