40 mpg engine build
Sure. Just take the small block early vs late and look at the trends.
Consider how it went and why, then the injection of more technology and how it has gone since.
The early motors like the original 265 cubic inch small block Chevrolet started out with a 3" stroke and a 3 3/4 bore. Oversquare ratio 1.25. Then 283 (they needed a bigger motor) with a 3" stroke and a 3 7/8 bore. Oversquare ratio 1.292. Then the 302 3" stoke and 4" bore (for racing) was oversquare 1.33. Then the push for more displacement out of their old 265 design led to the 327 (1.23 oversquare), the 350 (1.14 oversquare) and ultimately the 400" (1.06 oversquare) version to move the big fat early 70 cars loaded with smog equipment. I don't think any of these changes from the original 265 design were motivated by anything other than the need for a larger displacement engine from the original design. However, in the later years when Chevy needed better gas mileage and less emissions and they were a little more knowledgeable than they were, they chose to create the 305 (1.074 oversquare). They had already designed engines in that displacement area in the past and could have saved a bunch of money by just using the old 302 or the 307, but they knew that the 305 design would have higher combustion efficiency and a better torque curve.
Then came the new LS motors. This was the first pushrod V-8 Gm would design from an absolutely clean slate. By this time they had been studying emission and fuel efficiency very closely with computer technology and inside combustion chamber cameras that simply did not exist before. Armed with their new knowledge and understanding they decided to make the new 350 cubic inch engine with a bore of 3.898 in (99.0 mm) and a stroke of 3.62 in (92 mm). This is an oversquare ratio of 1.077.
When they decided on this ratio, there was nothing to influence them other than reaching their goals of power curve, emissions and durability. You can see the choice they made.
Now since then, there has been other displacements come about for the LS series, but I will offer that they are nothing more than modifications of the original for specific applications. Meaning the desire for more displacement for competitive reasons or less displacement for fuel economy reasons.
Consider how it went and why, then the injection of more technology and how it has gone since.
The early motors like the original 265 cubic inch small block Chevrolet started out with a 3" stroke and a 3 3/4 bore. Oversquare ratio 1.25. Then 283 (they needed a bigger motor) with a 3" stroke and a 3 7/8 bore. Oversquare ratio 1.292. Then the 302 3" stoke and 4" bore (for racing) was oversquare 1.33. Then the push for more displacement out of their old 265 design led to the 327 (1.23 oversquare), the 350 (1.14 oversquare) and ultimately the 400" (1.06 oversquare) version to move the big fat early 70 cars loaded with smog equipment. I don't think any of these changes from the original 265 design were motivated by anything other than the need for a larger displacement engine from the original design. However, in the later years when Chevy needed better gas mileage and less emissions and they were a little more knowledgeable than they were, they chose to create the 305 (1.074 oversquare). They had already designed engines in that displacement area in the past and could have saved a bunch of money by just using the old 302 or the 307, but they knew that the 305 design would have higher combustion efficiency and a better torque curve.
Then came the new LS motors. This was the first pushrod V-8 Gm would design from an absolutely clean slate. By this time they had been studying emission and fuel efficiency very closely with computer technology and inside combustion chamber cameras that simply did not exist before. Armed with their new knowledge and understanding they decided to make the new 350 cubic inch engine with a bore of 3.898 in (99.0 mm) and a stroke of 3.62 in (92 mm). This is an oversquare ratio of 1.077.
When they decided on this ratio, there was nothing to influence them other than reaching their goals of power curve, emissions and durability. You can see the choice they made.
Now since then, there has been other displacements come about for the LS series, but I will offer that they are nothing more than modifications of the original for specific applications. Meaning the desire for more displacement for competitive reasons or less displacement for fuel economy reasons.
I didn't realize that this took off so much, I would have checked it earlier.
To answer a few generic questions:
I am not going to do any recycling exhaust techniques or strange advance engine design. I can be arogant but i'm not that good with engines.
As far as other aero/efficiency concerns. I will be running 215/35/17 eco tires on a set of 7x17in wheels. My track wheels will be 255/35/17 on 9x17 or potentially wider. I am planning on dropping a ton of weight on the car (seats, dash, hood, ac delete, etc.). Switching the old flag mirrors to a close fitting aero/racing mirror. I'm still trying to figure out which way to go with a bumper. I'm debating running a turbo 944 bumper and then designing fiberglass panels to cover the large air intakes on highway but remove them later for power. I will also probably run an underbelly tray and a rear difuser. The gearing will be through a 944 turbo box with an oil cooler. The 5th gear will be a .60 gear from a 5000 audi desiel box. I'm still trying to source it but I'll be at 2100-2200 rpm at 70mph.
To answer a few specific questions.
tonybain42: I'm going to have to disagree with you. I've looked through a lot of ecomodder forums and motorcycle forums and there is no noticable results of lightening the engine internals. I thought the exact same thing but there are many well documented cases of nothing changes. These ecomodders are thorough with their data. That being said. I'm usually lightwieght carillo rods, crank, and pistons but that is more because I want solid, dependable parts.
Metal Muscle: I know its not going to make up for the price of gas but its more environmentally friendly and it gives me bragging rights. I cannot wait to rub it into my Prius driving coworkers that my car gets nearly the same gas milage and i actually enjoy my car. In fact, my car wasn't bought new, it doesn't have a 100 lb lithium battery, and therefore its probably more environmentally efficient.
A 240sx does have a drag coefficient of .31 vs the porsche's .33 but the weights are very close. It actually seams easier and cheaper to drop the porsche's weight for the first 200 lbs or so. (Then the price of porsche body panels gets a little crazy). I also think the porsche is much better looking than the 240sx but to each their own.
BLK95-Z: I don't know if I would subscribe to this. I don't want to be responsible for your boredom. Its going to be about 2 years until I truely get this finished. I still need to get the car running properly before the engine swap. (new front hub, brakes, bumper, dash). Though I'm completely pumped about this project.
speedtigger: I think there was more than gas mileage that influence the progression of GM engines. I know it was a primary goal but I could see power/cost influencing the engine design to sacrifice some mpg's. I'm not saying that your point is wrong but I'm not sure I would believe it by that evidence alone. I'm not trying to offend but its not as solid evidence as I would like.
To answer a few generic questions:
I am not going to do any recycling exhaust techniques or strange advance engine design. I can be arogant but i'm not that good with engines.
As far as other aero/efficiency concerns. I will be running 215/35/17 eco tires on a set of 7x17in wheels. My track wheels will be 255/35/17 on 9x17 or potentially wider. I am planning on dropping a ton of weight on the car (seats, dash, hood, ac delete, etc.). Switching the old flag mirrors to a close fitting aero/racing mirror. I'm still trying to figure out which way to go with a bumper. I'm debating running a turbo 944 bumper and then designing fiberglass panels to cover the large air intakes on highway but remove them later for power. I will also probably run an underbelly tray and a rear difuser. The gearing will be through a 944 turbo box with an oil cooler. The 5th gear will be a .60 gear from a 5000 audi desiel box. I'm still trying to source it but I'll be at 2100-2200 rpm at 70mph.
To answer a few specific questions.
tonybain42: I'm going to have to disagree with you. I've looked through a lot of ecomodder forums and motorcycle forums and there is no noticable results of lightening the engine internals. I thought the exact same thing but there are many well documented cases of nothing changes. These ecomodders are thorough with their data. That being said. I'm usually lightwieght carillo rods, crank, and pistons but that is more because I want solid, dependable parts.
Metal Muscle: I know its not going to make up for the price of gas but its more environmentally friendly and it gives me bragging rights. I cannot wait to rub it into my Prius driving coworkers that my car gets nearly the same gas milage and i actually enjoy my car. In fact, my car wasn't bought new, it doesn't have a 100 lb lithium battery, and therefore its probably more environmentally efficient.
A 240sx does have a drag coefficient of .31 vs the porsche's .33 but the weights are very close. It actually seams easier and cheaper to drop the porsche's weight for the first 200 lbs or so. (Then the price of porsche body panels gets a little crazy). I also think the porsche is much better looking than the 240sx but to each their own.
BLK95-Z: I don't know if I would subscribe to this. I don't want to be responsible for your boredom. Its going to be about 2 years until I truely get this finished. I still need to get the car running properly before the engine swap. (new front hub, brakes, bumper, dash). Though I'm completely pumped about this project.
speedtigger: I think there was more than gas mileage that influence the progression of GM engines. I know it was a primary goal but I could see power/cost influencing the engine design to sacrifice some mpg's. I'm not saying that your point is wrong but I'm not sure I would believe it by that evidence alone. I'm not trying to offend but its not as solid evidence as I would like.
I forgot to address one thing.
The l76 v8 seems to be a ls2 with a few modifications. It has a set of heads that I believe are not the l92's but similar. It does have AFM and VVT but I'm not sure that they both were used. The G8 GT doesn't seem to get very good mpg either. 18/24 as far as I can find. Any ideas of the best G8 GT or L76 forums would be? Who would have more information on them? It seems like someone with the engine must have played around with VVT and AFM at the same time.
This is a slightly vague article that gives a lot of the info on it.
http://www.gmhightechperformance.com...gm_pontiac_g8/
The l76 v8 seems to be a ls2 with a few modifications. It has a set of heads that I believe are not the l92's but similar. It does have AFM and VVT but I'm not sure that they both were used. The G8 GT doesn't seem to get very good mpg either. 18/24 as far as I can find. Any ideas of the best G8 GT or L76 forums would be? Who would have more information on them? It seems like someone with the engine must have played around with VVT and AFM at the same time.
This is a slightly vague article that gives a lot of the info on it.
http://www.gmhightechperformance.com...gm_pontiac_g8/
TECH Addict
Joined: Sep 2009
Posts: 2,481
Likes: 5
From: PA/MD
Another easy thing to look at doing is run a super low gear in the rearend gear (273 or lower), then you can buy a gutted old 4 speed that only has 3 and 4th gears in it and everything else taken out (yes you cab buy them like this)....run the output of your normal tranny to the input of the modded 4 speed, then driveshaft from the modded 4 speed to your rear.
Normal driving you leave the modded 4 speed in 4th to get a 1:1 ratio, then at the track shift and leave the 4 speed in 3rd to effectively give you a higher final gear ratio.
Normal driving you leave the modded 4 speed in 4th to get a 1:1 ratio, then at the track shift and leave the 4 speed in 3rd to effectively give you a higher final gear ratio.
TECH Regular
Joined: Feb 2008
Posts: 458
Likes: 1
From: Keller, Texas
Sure. Just take the small block early vs late and look at the trends.
Consider how it went and why, then the injection of more technology and how it has gone since.
The early motors like the original 265 cubic inch small block Chevrolet started out with a 3" stroke and a 3 3/4 bore. Oversquare ratio 1.25. Then 283 (they needed a bigger motor) with a 3" stroke and a 3 7/8 bore. Oversquare ratio 1.292. Then the 302 3" stoke and 4" bore (for racing) was oversquare 1.33. Then the push for more displacement out of their old 265 design led to the 327 (1.23 oversquare), the 350 (1.14 oversquare) and ultimately the 400" (1.06 oversquare) version to move the big fat early 70 cars loaded with smog equipment. I don't think any of these changes from the original 265 design were motivated by anything other than the need for a larger displacement engine from the original design. However, in the later years when Chevy needed better gas mileage and less emissions and they were a little more knowledgeable than they were, they chose to create the 305 (1.074 oversquare). They had already designed engines in that displacement area in the past and could have saved a bunch of money by just using the old 302 or the 307, but they knew that the 305 design would have higher combustion efficiency and a better torque curve.
Then came the new LS motors. This was the first pushrod V-8 Gm would design from an absolutely clean slate. By this time they had been studying emission and fuel efficiency very closely with computer technology and inside combustion chamber cameras that simply did not exist before. Armed with their new knowledge and understanding they decided to make the new 350 cubic inch engine with a bore of 3.898 in (99.0 mm) and a stroke of 3.62 in (92 mm). This is an oversquare ratio of 1.077.
When they decided on this ratio, there was nothing to influence them other than reaching their goals of power curve, emissions and durability. You can see the choice they made.
Now since then, there has been other displacements come about for the LS series, but I will offer that they are nothing more than modifications of the original for specific applications. Meaning the desire for more displacement for competitive reasons or less displacement for fuel economy reasons.
Consider how it went and why, then the injection of more technology and how it has gone since.
The early motors like the original 265 cubic inch small block Chevrolet started out with a 3" stroke and a 3 3/4 bore. Oversquare ratio 1.25. Then 283 (they needed a bigger motor) with a 3" stroke and a 3 7/8 bore. Oversquare ratio 1.292. Then the 302 3" stoke and 4" bore (for racing) was oversquare 1.33. Then the push for more displacement out of their old 265 design led to the 327 (1.23 oversquare), the 350 (1.14 oversquare) and ultimately the 400" (1.06 oversquare) version to move the big fat early 70 cars loaded with smog equipment. I don't think any of these changes from the original 265 design were motivated by anything other than the need for a larger displacement engine from the original design. However, in the later years when Chevy needed better gas mileage and less emissions and they were a little more knowledgeable than they were, they chose to create the 305 (1.074 oversquare). They had already designed engines in that displacement area in the past and could have saved a bunch of money by just using the old 302 or the 307, but they knew that the 305 design would have higher combustion efficiency and a better torque curve.
Then came the new LS motors. This was the first pushrod V-8 Gm would design from an absolutely clean slate. By this time they had been studying emission and fuel efficiency very closely with computer technology and inside combustion chamber cameras that simply did not exist before. Armed with their new knowledge and understanding they decided to make the new 350 cubic inch engine with a bore of 3.898 in (99.0 mm) and a stroke of 3.62 in (92 mm). This is an oversquare ratio of 1.077.
When they decided on this ratio, there was nothing to influence them other than reaching their goals of power curve, emissions and durability. You can see the choice they made.
Now since then, there has been other displacements come about for the LS series, but I will offer that they are nothing more than modifications of the original for specific applications. Meaning the desire for more displacement for competitive reasons or less displacement for fuel economy reasons.
I think this can be done with out VVT,AFM, or DOD. I drove my 06 c6 6 spd to Houston TX and got 28.6 mpg and the car was bone stock. I did this at 72mph. I have a buddy that has the same car with heads and a mild cam and his car did 32.7 mpg.
If my buddy slowed down to 55mph I could see him getting 35mpg out of his car easy maybe a hair more. Then his car had a 3.42 rear. Drop that gear to something like 2.73 or 2.41 and 37-38mpgs would be in sight. The last 2 mpgs could be acheived from better tuning than what he had. His tune was agressive for racing as we all know. Tune it for economy and those last 2 would be achieved netting 40mpgs!
If my buddy slowed down to 55mph I could see him getting 35mpg out of his car easy maybe a hair more. Then his car had a 3.42 rear. Drop that gear to something like 2.73 or 2.41 and 37-38mpgs would be in sight. The last 2 mpgs could be acheived from better tuning than what he had. His tune was agressive for racing as we all know. Tune it for economy and those last 2 would be achieved netting 40mpgs!
