ran in to a "500hp Civic"
11-04-2007, 10:47 PM
#41
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100hp/liter NA engines are annoying to drive. First, for a given displacement your limited to about 11-12 bar bmep.. so scale that to whatever displacment you want and that will be your peak torque.
Second, to get the "power" on the limited torque, your only option is to spin the crap out of the engine.
This does 2 things, 1. places the power in an unusable area (nobodys going to be in the 8krpm range unless racing..) and 2. induces more engine friction than nessecary. This is why honda spent lots of money to make smaller crank and main bearing diameters..
GM doesnt do this because outside of pushing the car to its limits, the normal person would rather have torque in the 2-3krpm range and not need to rev the engine to 7krpm+ just to be near peak power.. I would rather have high BMEP than high power.. and the only way to do this (oem) is Forced induction!! if you find another way.. let me know..
now if you have 100hp/liter NA below 6krpm.. let me know...
I dont know about you, but i'd rather cruise on the freeway and be able to have 2500 revs or less and still have enough torque to accelerate without downshifting... When your talking engines and specific power output.. forced induction will always win and should. Nobody wants to drive a 111lb-ft engine that makes 240hp every day.. i'd rather have a 200lb-ft engine that makes 205hp..
Second, to get the "power" on the limited torque, your only option is to spin the crap out of the engine.
This does 2 things, 1. places the power in an unusable area (nobodys going to be in the 8krpm range unless racing..) and 2. induces more engine friction than nessecary. This is why honda spent lots of money to make smaller crank and main bearing diameters..
GM doesnt do this because outside of pushing the car to its limits, the normal person would rather have torque in the 2-3krpm range and not need to rev the engine to 7krpm+ just to be near peak power.. I would rather have high BMEP than high power.. and the only way to do this (oem) is Forced induction!! if you find another way.. let me know..
now if you have 100hp/liter NA below 6krpm.. let me know...
I dont know about you, but i'd rather cruise on the freeway and be able to have 2500 revs or less and still have enough torque to accelerate without downshifting... When your talking engines and specific power output.. forced induction will always win and should. Nobody wants to drive a 111lb-ft engine that makes 240hp every day.. i'd rather have a 200lb-ft engine that makes 205hp..
i was not saying it would be PERFOECT FOR EVERYBODY... BUT I WAS SAYING IT WOULD BE INTERESTING TO SEE THE TECHNOLOGY IMPLICATED TO SEE HOW IT WORKED...
ALSO TO SEE WHAT GM COULD DO IF THEY PUT THE RESEARCH INTO PUTTING DOHC CYL HEADS ON THE LS MOTOR
11-05-2007, 11:06 PM
#42
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As far as this guy learning his lesson. i would have to disagree. I hope they never learn they're lesson. That way I have something to laugh at every night I drive down the road. GM definately under rate's they're stuff. My friend and myself both have 06 Z06 Vette's. yes everyone Know's they are
LS7's rated for 505hp. Well Truth His dyno'd 537 at the crank. Mine went 549 with an astonishing 440 to the tires. Gotta love that American HP.
LS7's rated for 505hp. Well Truth His dyno'd 537 at the crank. Mine went 549 with an astonishing 440 to the tires. Gotta love that American HP.
11-06-2007, 10:10 PM
#43
GM doesnt need to do the research.. they could easily build an engine thats capable of your targets, however, there is no reason to. Its not part of thier targets. Fuel economy per hp (generic terminology) is thier goal. The pushrod engine does amazingly well and goes to show that any design can still be optimized.
Technology would be implimenting pneumatic valvesprings in production engines and revving them to 18krpm.. that would get you 200hp/L. But like i said, its not the focus of GM. People are going to buy fuel efficient engines with equal or better horsepower than their previous vehicle. having Torque is what most people consider "powerful" and that would go against everything for them to just make a high strung, uneconomical (word?), small engine.
either way.. i'd rather have 100hp/L and have peak torque at 1500-2000rpm and not have to rev past 6-6.5krpm.. and to do that.. it requires forced induction no matter how you slice it.
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