OK, me and my friend are having an argument over which gets better mileage, high or low compression ratios. I'm saying turbo engines get bad mileage because of low compression even if you drive them out of boost and its not a big enough turbo to cause alot of backpressure. He says compression doesnt matter at all in terms of mileage. What i want to know is, does anyone know of any real tested proof/evidence that higher compression=better mileage given that the car has a tune towards fuel economy over performance (i.e. a j spec family car motor). I'm pretty sure a higher compression will net a better fuel economy because i know a dude who put a j spec camry engine in his MR2 with 10.5:1 ratio (maybe higher, not sure) in place of his blown (not supercharged, as in blown up, not functional) N/A stock engine and his mileage is ridiculously good, even when he gets on it alot.
Bottom line: given the tune is biased toward fuel economy for both cases, should a high compression engine net a better fuel economy than a lower compression engine? please give links, etc. to back this up because i doubt my friend will believe it on replies alone.
P.S. i mean for a naturally aspirated engine, of course
Last edited by neogeon : Dec 26th, 2005 at 12:01 AM.
High compression. I dont have a link but its just common sense, higher compression makes more power from the same mixture of air and gas. That means that for the same milage, a higher compression motor will make more power than a low compression engine. Conversely, if only x amount of horse power is needed to produce speed y, then the high compression motor will acheive it using less gas in a more efficient manor.
see, thats what i said, it seemed like just common sense to me, the only reason all cars dont have high compression is because the pistons are WAAAY harder to machine because of all the intricate designes to give them the higher compression, and also the fact you have to run a higher octane gas to have higher compression. As a side note, does anyone agree with me that if you put a reasonable sized turbo (nothing huge) and you stay out of boost with stock compression ratio that fuel mileage will only decrease slightly if at all?
Of course when your car is being forced fed tons of air by a turbo it's gonna start using more gas... Unless your goal is to blow up the engine. I agree with you, staying out of boost will get you close to the same gas mileage as an N/A of the same car.
see, thats what i said, it seemed like just common sense to me, the only reason all cars dont have high compression is because the pistons are WAAAY harder to machine because of all the intricate designes to give them the higher compression, and also the fact you have to run a higher octane gas to have higher compression. As a side note, does anyone agree with me that if you put a reasonable sized turbo (nothing huge) and you stay out of boost with stock compression ratio that fuel mileage will only decrease slightly if at all?
Many people here have boosted at the stock compression level and when you stay out of boost, the fuel milage is the same as stock.
The arguement started when he made an over generalized comment that cars with low compression get bad gas mileage simply because they have low compression. His research? "The Kia Rio has low compression and gets bad gas mileage." This statement alone mad me cry that night. After giving numerous example in which a car (with similar weight, engine etc) got better gas mileage than a car with high compression he insisted on arguing.
In a perfectly unrealistic world, if a company built 2 motors, both 2 liter inline 4's. One with 8:1 compression and one with 11:1 compression. Tuned and optimized both gas mileage then yes, the one with high compression would get better gas mileage. But in the real world the 11:1 car would not be a gas sipping car, but rather a sporty car (ala RSX-S).
Now lets look at the situation realistically, you swap out your 8:1 pistons for 11:1. Better gas mileage? mmm no because you haven't had it tuned. So you bring it to get tuned. Now realistically how many shops are going to retune every map in your ECU? all 11ty thousand maps? not many eh? SO you settle for a "incomplete" tune and be on your way. Better gas mileage yet? nope
The bottom line is you cannot look at a car say "Its got 8:1 compression so it gets bad gas mileage" which is exactly what this kid was doing.
As for the turbo comment, THAT argument started when he said turbocharged cars get bad gas mileage because they have lower compression than NA cars. Again, I beat my head against the wall
Before anyone responds in his defense, remember this is the kid that..
1) thinks a diesel engine is better suited for drag racing because it makes more torque, even mentioned swapping one
2) Tried to tell me what MY car (2004 civic VP) runs, said it was in the 17's. When I pulled out a timeslip for 16.7 stock, he immediately said the tracks timing equipment was off and that my car SHOULD run 17s
ok
engines are based on the concept of Boyle's Law in which basicly states that when you compress a gass its pressure doubles and its temp will rise the more you compress it
example: deisiels do not use spark plugs they use very high compression to fire the a/f mixture
higher compression means bigger bang and more heat which turns the crank
lower compression means less heat and less power turning the crank
an engine turns heat energy into rotary energy and that is all it does
more heat more turning and you need heat in the form of fuel
what maters is how well the fuel is burned on each stroke and a better compressed mix which is more atomized will burn better
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I's scratches ma hea' den sniff it.
Last edited by Captain Obvious : Dec 30th, 2005 at 03:48 AM.
in reply to got boost????'s slandering of my character, i would like to state all 4 of his comments are ABSOLUTELY FALSE. The diesel comment was made because i think its cool that modern techology is allowing diesel pickups to have ridiculous power and id like to make a fast diesel car to surprise people, the ultimate sleeper in other words, but i certainly never mentioned swapping one into my car if thats what he means, and he is also the one that said torque is what made cars fast, so he is absolutely contradicting a previous argument about torque and horsepower to begin with, i know full well that especially in drag horsepower is what matters first and foremost and coincidentally torque is usually a part of that. I dont even know what hes talking about with the civic, he must have been arguing with himself, i never saw a timeslip, ever, plus, who cares, a 16.7 quarter mile is like chevy silverado/suburban slow, maybe slower, and thats embarassing to drive a car that slow. As for the e-brake drifting, i have FWD, its not like im gonna do power drifting, and for a spec v e-brake drifting is all but impossible because the handbrake isnt very strong and stops the car long before it locks up the wheels (like the R34 GTR skyline e-brake on Gran Turismo 3 if you want to see what i mean). but the specific thing he is refering to is an INERTIAL drift i told him about that i guess he is jealous because he cant pull one off because the spec v has a suspension setup that allows the back end to slip before the front whereas im sure his civic enjoys nice smoky front tire understeer. And as for racing on asphalt, why would i LIKE racing on asphalt? Spec V has enough traction problems in 1st gear on very high grip cement, why the hell would i want to spin all the way through first on some half assed grainy/sandy asphalt against a car with a taller first gear or an AWD and get completely dominated because of a low first gear ratio?
As for the rest of the argument:
the kia rio was just an example i threw out there, not a first and last example like hes trying to make it seem. And the argument did begin in reference to turbocharging, it went something like this:
I said he would be better off getting a new spec v and turbocharging it for the same price as a new civic si (shoe car, no, not show, shoe, like it looks like one) and be waaay faster. He said "if you go turbo, your gas mileage goes to shit" which is true, but only because, i argued, when in boost you use alot more fuel and when out of boost and in most cases you have lowered your compression and are not being effecient. Already stated on here, however, is people that added turbo to stock internals and reported near stock fuel economy, which means NOT GOING TO SHIT, which right then and there has already proved him wrong. He's just mad because this is like the eleventy billionth argument ive won so he tries to change what the argument is about to make me seem wrong/dumb/mislead when i am really nothing of the sort.
Thanks for reading this LOOOONG post and please respond to who you think is right, thanks.
ok
engines are based on the concept of Boyle's Law in which basicly states that when you compress a gass its pressure doubles and its temp will rise the more you compress it
example: deisiels do not use spark plugs they use very high compression to fire the a/f mixture
higher compression means bigger bang and more heat which turns the crank
lower compression means less heat and less power turning the crank
an engine turns heat energy into rotary energy and that is all it does
more heat more turning and you need heat in the form of fuel
what maters is how well the fuel is burned on each stroke and a better compressed mix which is more atomized will burn better
i just noticed one thing and its probably a typo, an engine doesnt turn HEAT energy into rotary energy, it turns MECHANICAL energy from expanding gas into rotary energy, but the gas will expand more powerfully if compressed more and more heat will result as a byproduct.
in reply to got boost????'s slandering of my character, i would like to state all 4 of his comments are ABSOLUTELY FALSE. The diesel comment was made because i think its cool that modern techology is allowing diesel pickups to have ridiculous power and id like to make a fast diesel car to surprise people, the ultimate sleeper in other words, but i certainly never mentioned swapping one into my car if thats what he means, and he is also the one that said torque is what made cars fast, so he is absolutely contradicting a previous argument about torque and horsepower to begin with, i know full well that especially in drag horsepower is what matters first and foremost and coincidentally torque is usually a part of that. I dont even know what hes talking about with the civic, he must have been arguing with himself, i never saw a timeslip, ever, plus, who cares, a 16.7 quarter mile is like chevy silverado/suburban slow, maybe slower, and thats embarassing to drive a car that slow. As for the e-brake drifting, i have FWD, its not like im gonna do power drifting, and for a spec v e-brake drifting is all but impossible because the handbrake isnt very strong and stops the car long before it locks up the wheels (like the R34 GTR skyline e-brake on Gran Turismo 3 if you want to see what i mean). but the specific thing he is refering to is an INERTIAL drift i told him about that i guess he is jealous because he cant pull one off because the spec v has a suspension setup that allows the back end to slip before the front whereas im sure his civic enjoys nice smoky front tire understeer. And as for racing on asphalt, why would i LIKE racing on asphalt? Spec V has enough traction problems in 1st gear on very high grip cement, why the hell would i want to spin all the way through first on some half assed grainy/sandy asphalt against a car with a taller first gear or an AWD and get completely dominated because of a low first gear ratio?
As for the rest of the argument:
the kia rio was just an example i threw out there, not a first and last example like hes trying to make it seem. And the argument did begin in reference to turbocharging, it went something like this:
I said he would be better off getting a new spec v and turbocharging it for the same price as a new civic si (shoe car, no, not show, shoe, like it looks like one) and be waaay faster. He said "if you go turbo, your gas mileage goes to shit" which is true, but only because, i argued, when in boost you use alot more fuel and when out of boost and in most cases you have lowered your compression and are not being effecient. Already stated on here, however, is people that added turbo to stock internals and reported near stock fuel economy, which means NOT GOING TO SHIT, which right then and there has already proved him wrong. He's just mad because this is like the eleventy billionth argument ive won so he tries to change what the argument is about to make me seem wrong/dumb/mislead when i am really nothing of the sort.
Thanks for reading this LOOOONG post and please respond to who you think is right, thanks.
Fucking typical, make dumbass comments and they deny it up and down. Yes you did say disel engines are superior for drag racing, we were sitting in econ when you said it. Yes you did tell me the track equipment was off and my car should run in the 17s, despite the 16.7 timeslip, that was the day after you got drunk and passed out on the couch. Yes you did tell Shaun and I about your drifting around girard park on numerous occasions. And yes you did say you don't like racing on asphalt when you raced that EG6.
As for your Kia Rio comment, I asked you for proof as to why you though low compression cars get bad gas mileage, and the ONLY example you gave was the Kia Rio, great fucking research.
As for the rest of the argument, you know damn well that I'm looking at a NEW car WITH A WARRENTY, so why you even would bring up getting a turbo'd spec V is beyond me. And my argument is still valid in regards to turbochargers and gas mileage. You don't spend thousands on a turbo kit to drive it around like an old lady. Out of boost, you'll get slightly worse gas mileage and in boost you'll get drastically worse gas mileage depending on the tune and the boost. And this is not the 11ty billionth argument Ive lost, this is the 11ty billionth arguement you try to bullshit your way out of instead sucking it up and moving on.
Last edited by Got Boost??? : Dec 30th, 2005 at 06:01 PM.
OK, me and my friend are having an argument over which gets better mileage, high or low compression ratios. I'm saying turbo engines get bad mileage because of low compression even if you drive them out of boost and its not a big enough turbo to cause alot of backpressure. He says compression doesnt matter at all in terms of mileage. What i want to know is, does anyone know of any real tested proof/evidence that higher compression=better mileage given that the car has a tune towards fuel economy over performance (i.e. a j spec family car motor). I'm pretty sure a higher compression will net a better fuel economy because i know a dude who put a j spec camry engine in his MR2 with 10.5:1 ratio (maybe higher, not sure) in place of his blown (not supercharged, as in blown up, not functional) N/A stock engine and his mileage is ridiculously good, even when he gets on it alot.
Bottom line: given the tune is biased toward fuel economy for both cases, should a high compression engine net a better fuel economy than a lower compression engine? please give links, etc. to back this up because i doubt my friend will believe it on replies alone.
P.S. i mean for a naturally aspirated engine, of course
and i'm the one that got yelled at by the mods for smart ass comments outside of offtopic for saying "3 fast 3 furious called, they want their DVD extras back" and this dude just calls either me...or the other guy, not sure a dumbass and its OK?
P.S. Abmerop18, go drink some liquid plumbr and save the world from another annoying douchebag we dont need.
P.S.S. now i see this is your first post, i probably know you, or you ARE got boost ???, but go fuck yourself anyway
Fucking typical, make dumbass comments and they deny it up and down. Yes you did say disel engines are superior for drag racing, we were sitting in econ when you said it. Yes you did tell me the track equipment was off and my car should run in the 17s, despite the 16.7 timeslip, that was the day after you got drunk and passed out on the couch. Yes you did tell Shaun and I about your drifting around girard park on numerous occasions. And yes you did say you don't like racing on asphalt when you raced that EG6.
As for your Kia Rio comment, I asked you for proof as to why you though low compression cars get bad gas mileage, and the ONLY example you gave was the Kia Rio, great fucking research.
As for the rest of the argument, you know damn well that I'm looking at a NEW car WITH A WARRENTY, so why you even would bring up getting a turbo'd spec V is beyond me. And my argument is still valid in regards to turbochargers and gas mileage. You don't spend thousands on a turbo kit to drive it around like an old lady. Out of boost, you'll get slightly worse gas mileage and in boost you'll get drastically worse gas mileage depending on the tune and the boost. And this is not the 11ty billionth argument Ive lost, this is the 11ty billionth arguement you try to bullshit your way out of instead sucking it up and moving on.
I think the quote should read:
"i dont read what you say at all and im arguing stuff already addressed and i try to change arguments into something else to be right"
again, your just lying with what you made up in your head. I never said diesel was SUPERIOR for drag racing, if anything i said ROAD RACING if there is a horsepower limit where a diesel 500 hp would make thousands of lbft of torque whereas a NA gas would make probably about 500 lb ft and the added torque would help keep it in the power band, douche. Even if you did show me the timeslip, it still doesnt matter, 16.7 is slow and not worth bragging about and personally i would be emarrased to own such a slow car, and besides, i also asked you what day new years was that day, i was in no condition to be making statements about timing equipment. Also, i did tell you about drifting around girard park, but they were INERTIAL DRIFTS if you read the previous statement dumbass, i will bet you 10 bucks my parking brake wont even lock up enough to drift, i used it earlier tonight because i was coming to a stop and im so used to doing it i did it around 30 mph not thinking and all i did was slowly come to a stop and never once were my wheels locked till i came to a stop, in fact i had to use the brake pedal because i was braking so slowly, ill admit it, the spec v handbrake=teh sux, its just barely enough to hold on a steep hill, which is all it needs to be. And again, i already explained why i hate asphalt if your read douche. And finally, warranty never came into the picture until now, just suddenly bringing it in to defend yourself, and actually i read one post about a guy that kept his warranty even with turbo, but you dont need turbo to be faster than a civic si POS anyway. And this IS the eleventy billionth argument youve tried to change the point until you are arguing something unrelated or bring in something not previously part of the argument (warranty) to try to be right.
Last edited by neogeon : Dec 30th, 2005 at 11:18 PM.
This thread should be called...I'm gonna bitch at my friend because of a misunderstanding...
WHAT A WASTE OF FORUM MATERIAL!!
POST MATURE OR DON'T...damn I read the first 5 posts thinking you would have some nice scientific data but instead you are all just arguing like little bitches after that
SO POST LOGICALLY LIKE MATURE PEOPLE OR STFU!!!
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I'm sorry, I didn't quit catch that line of bull that just plopped from your mouth
This thread should be called...I'm gonna bitch at my friend because of a misunderstanding...
WHAT A WASTE OF FORUM MATERIAL!!
POST MATURE OR DON'T...damn I read the first 5 posts thinking you would have some nice scientific data but instead you are all just arguing like little bitches after that
SO POST LOGICALLY LIKE MATURE PEOPLE OR STFU!!!
well it was intelligent until my friend got on (just made an account to try to discount my input) and at this point we may procede with intellectual pursuits.
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