Another reason to use a Detector....

[12secGT]

It's in the news today that law makers want State and Local Police Departments to "remove" the 10mph cushion given to speeders on our highways and biways. They said since the limit has gone up in most states, so has the fatality rate. So they use this as the reason to delete the cushion given to drivers. So, if you are driving 65, in a 55, then it's quite possible that you are looking at a speeding ticket!
Get that detector if you haven't already. Maybe some Veil on those headlights! :wink: :shock:

[SmaartAasSaabr]

But the fatality rate has continually GONE DOWN!

[Regis]

Yes, I've heard that too, the fatality rate has gone down. Goes to show what brainwashing governments will do in the name of revenue generation and to try and perpetuate the myths it's all based on.

[crazyVOLVOrob]

But the fatality rate has continually GONE DOWN!but Bush thinks this might save gas...sadly in 4thgear at 55mph I'm not making any boost for my turbo and i make barely any at 60, i have to go at least 70 get a decent level of boost

[N3T_K1LLA]

Regardless of what is done for law, cops still have to 'want' to catch speeders, most of them here are lazy lol.

[EastGermanOlympicJudge]

Link to the article here (http://www.ghsa.org/html/media/pressreleases/2005/061305.html)

[brick]

More stupidity. Even if it were true that the fatality rate had gone up in the last 10 years there are other factors that could be coming into play. Blaming a problem on one variable that hasn't been isolated from the many is an offence worthy of a good old-fashioned flogging. Let's talk about:
-Dramatically increased traffic volume
-The widespread usage of SUVs, which barely existed when the 55mph speed limits were in use.

[synmoo]

But the fatality rate has continually GONE DOWN!but Bush thinks this might save gas...sadly in 4thgear at 55mph I'm not making any boost for my turbo and i make barely any at 60, i have to go at least 70 get a decent level of boost

Less boost you're running the less fuel you're using...

Boost ≠ economy

[SmaartAasSaabr]

But the fatality rate has continually GONE DOWN!but Bush thinks this might save gas...sadly in 4thgear at 55mph I'm not making any boost for my turbo and i make barely any at 60, i have to go at least 70 get a decent level of boost

Less boost you're running the less fuel you're using...

Boost ≠ economy

Ideally your maximum efficiency would be at close to full throttle with no boost (ie naturally aspirated) or a slight amount. Unfortunately this efficiency (ie power for gas) results in a LOT of power and a lot of gas as well. So a smaller motor is in order. But such a gutless motor would be firstly highly dangerous, and burn more gas because you are always working it too hard.

One problem with gasoline Otto-stroke engines (save a certain BMW V12) is the throttle plate. The throttle works by "choking" the motor so it doesn't suck more air and speed up. This dramatically increases the amount of energy you waste just by sucking the air in. This is also the primary reason a diesel powered car gets so much better milage when going around town in light-footed situations.

[SmaartAasSaabr]

What I would be interested in developing would be an electronic throttle and turbocharger boost control that would be integrated. It would first begin by opening the throttle towards WOT, and then start cranking up the boost as more power is required. This would be much more efficient than what you have now, which is as you open the throttle you are pushing air against the throttle one way (via turbo) and are sucking it against the other way (by the pistons). :roll:

[12secGT]

But the fatality rate has continually GONE DOWN!but Bush thinks this might save gas...sadly in 4thgear at 55mph I'm not making any boost for my turbo and i make barely any at 60, i have to go at least 70 get a decent level of boost
Not to get political, I don't think the President has anything to do with this call. It's definitely NOT to save gas, it's to boost state revenue, PERIOD.

[12secGT]

What I would be interested in developing would be an electronic throttle and turbocharger boost control that would be integrated. It would first begin by opening the throttle towards WOT, and then start cranking up the boost as more power is required. This would be much more efficient than what you have now, which is as you open the throttle you are pushing air against the throttle one way (via turbo) and are sucking it against the other way (by the pistons). :roll:You have a point. But understand there is positive/negative vaccum created by every engine; force fed or not. This pressure you talk about happens no matter what config. you are running, (exc. Nitrous). Yes, s/c and t/c engines create more positive pressure in the intake then naturally aspirated engines, tho in the case you've examined, t/c engines have waste gates which bleed off the excess boost. T/c engines are very efficient because they have no parasitic losses because the impeller is spun by exhaust gases. With this, the throttle action (as you step on the gas) will ALWAYS be a few seconds ahead of the increasing turbo boost due to the fact that the impeller is accelerated via the exhaust gases. Hence the term "turbo lag". The exhaust gas can only be sped up by the action of the throttle; open the throttle, creates more HP, increases exhaust velocity. As you open the throttle, the gases speed up, accelerating the impeller in that order. Where you might be more concerned with what you've said is in EXTREME racing conditions where the turbos are super light, boost is 30+psi, and the engine is making in excess of 800hp.
What I would be interested in developing would be an electronic throttle and turbocharger boost control This is actually avail. from co's like HKS. It's nothing new, the import crowd has been running this for years.

[12secGT]

But the fatality rate has continually GONE DOWN!but Bush thinks this might save gas...sadly in 4thgear at 55mph I'm not making any boost for my turbo and i make barely any at 60, i have to go at least 70 get a decent level of boost

Less boost you're running the less fuel you're using...

Boost ≠ economy

Ideally your maximum efficiency would be at close to full throttle with no boost (ie naturally aspirated) or a slight amount. Unfortunately this efficiency (ie power for gas) results in a LOT of power and a lot of gas as well. So a smaller motor is in order. But such a gutless motor would be firstly highly dangerous, and burn more gas because you are always working it too hard.

One problem with gasoline Otto-stroke engines (save a certain BMW V12) is the throttle plate. The throttle works by "choking" the motor so it doesn't suck more air and speed up. This dramatically increases the amount of energy you waste just by sucking the air in. This is also the primary reason a diesel powered car gets so much better milage when going around town in light-footed situations. I don't mean to be a know-it-all, but I just want to clear a few things up for you. Max efficiency can be found anywhere within the rpm range of any given engine. The design holds the key. Max efficiency is based on engine temp, a/f ratio, ambient temp/pressure, and load on the engine. If you are force feeding the engine, then you can't be at full throttle w/o positve boost. It's not possible. Even in nat. asp. engines, the intake pressure is positive at WOT. This pressure is created by the vaccum of the pistons but it's positive due to the opening and closing of the intake/exhaust valves. If it were negative at WOT the engine would stall.
One problem with gasoline Otto-stroke engines (save a certain BMW V12) is the throttle plate. The throttle works by "choking" the motor so it doesn't suck more air and speed up. This dramatically increases the amount of energy you waste just by sucking the air in Ideally, you're correct. But there is a valve on the throttle body called the "Idle Air Bypass". This does JUST THAT; it allows air to be "leaked" through the throttle butterfly (plate) so the engine won't stall under instant closure of the throttle plate. You need to allow the engine to accel and decel because it has to in real-world driving.
Deisel motors get better gas mileage because of it's design. They have a throttle just like gasoline engines. But Diesels run on auto-ignition principles where is the compression ratio is soo high (17 to 1 at least) that it wastes hardly any fuel. At that compression temp how could it.

[brick]

Deisel motors get better gas mileage because of it's design. They have a throttle just like gasoline engines. But Diesels run on auto-ignition principles where is the compression ratio is soo high (17 to 1 at least) that it wastes hardly any fuel. At that compression temp how could it.

Negative. Diesel engines have no throttle. Where gasoline engines regulate air and adjust fuel accordingly, diesel engines adjust fuel metering to change the load. This is due to the fact that diesel will burn over a wider range of equivalence ratios (air-fuel ratios) than gasoline. Ever wonder why diesel engines, especially older models, spew a black cloud of soot under acceleration? It's because the engine management system is dumping in fuel to increase the power output. It doesn't burn cleanly until the RPMs increase (more airflow) or the power load decreases (less fuel flow). This isn't as much of an issue these days because modern engine management systems are better about metering fuel under these conditions.

You're right about the higher compression ratio, though. But it's not about wasted fuel so much as the thermodymanic efficiency of higher ratios.

I should add that you can eliminate the throttle plate on a gasoline engine through the use of variable valve timing and lift (like on the BMW engines.) Using the valves to regulate airflow is much more efficient because if you close a valve before intake-bottom-dead-center the piston does work against the vacuum, but that energy (minus friction losses) is given back on the compression stroke.

[12secGT]

Deisel motors get better gas mileage because of it's design. They have a throttle just like gasoline engines. But Diesels run on auto-ignition principles where is the compression ratio is soo high (17 to 1 at least) that it wastes hardly any fuel. At that compression temp how could it.

Negative. Diesel engines have no throttle. Where gasoline engines regulate air and adjust fuel accordingly, diesel engines adjust fuel metering to change the load. This is due to the fact that diesel will burn over a wider range of equivalence ratios (air-fuel ratios) than gasoline. Ever wonder why diesel engines, especially older models, spew a black cloud of soot under acceleration? It's because the engine management system is dumping in fuel to increase the power output. It doesn't burn cleanly until the RPMs increase (more airflow) or the power load decreases (less fuel flow). This isn't as much of an issue these days because modern engine management systems are better about metering fuel under these conditions.

You're right about the higher compression ratio, though. But it's not about wasted fuel so much as the thermodymanic efficiency of higher ratios.

I should add that you can eliminate the throttle plate on a gasoline engine through the use of variable valve timing and lift (like on the BMW engines.) Using the valves to regulate airflow is much more efficient because if you close a valve before intake-bottom-dead-center the piston does work against the vacuum, but that energy (minus friction losses) is given back on the compression stroke.
Right. Fuel injected gasoline engines have a throttle body to regulate airflow. However, they also have a mass-air meter that determines HOW MUCH air is flowing at any given rpm and load. With the assistance of 02, crank position, knock supression, and a host of other sensors, the fuel that is injected directly to the intake ports can be controlled. As you reduce the throttle demand, the other sensors "see" this and adjust pulse-width hence regulating the fuel delivery. The energy lost to the accel and decel of the engine isn't soley due to the throttle plate per-se, it's because of realworld effects of things like idling and stop and go traffic. Hell, we've all been in that! The achievement for eliminating this may or may not be possible. I guess we'll leave this up to the SAE teams.
The thermo efficiency is true. That is BECAUSE of the high compression ratio.The compressive forces raise cyl. temps soo high that Diesel engines can almost run without glow plugs once the engine is up to operating temps. The flash-point of the diesel fuel (which is essentially like #2 heating oil with combustion additives) is MUCH higher then gasoline. This is why gas engines won't run well with higher compression ratios then say 11/1 or so.
I'm not trying to argue with you man, I just have a ton of exp. racing cars (legally :wink: ) I agree with you. I've learned a bit from you about Diesel engines tho. Good job!

[crazyVOLVOrob]

But the fatality rate has continually GONE DOWN!but Bush thinks this might save gas...sadly in 4thgear at 55mph I'm not making any boost for my turbo and i make barely any at 60, i have to go at least 70 get a decent level of boost

Less boost you're running the less fuel you're using...

Boost ≠ economyWell my findings have shown i get better highway economy 65-75 then going 55-65...i have to prtess the gas pedal less to accelerate around casrs if i have boost

[synmoo]

The VW 1.8L Turbo actually does work in that fashion. Opens the throttle almost completely before requesting any boost. This is easy as the motor is DBW or Drive-by-wire. Both the throttle plate and the wastegate are electoncially controlled by the ECU. Downside to DBW is a slight loss in throttle response on top of the initial turbo lag. Although the lag on the motor isn't bad at all. Full torque is available at 1950rpms and is nearly a perfectly flat curve all the way to redline. A very fun motor to drive.

Also, as someone else mentioned in the thread, the wastegate does not bleed off excess boost pressure... it bleeds off exhaust gas to slow the turbine thus producing less boost AND less of a drag on the exhaust.

[SmaartAasSaabr]

Well my findings have shown i get better highway economy 65-75 then going 55-65...i have to prtess the gas pedal less to accelerate around casrs if i have boost

Sounds about right. Still the engine doesn't know throttle opening and boost. All that matters re: fuel is the amount of fuel going in. More fuel = less milage. More boost = more fuel, more gas pedal = more fuel. So you are likely doing the same thing.


But if you are passing people at 85mi/h then obviously takes less fuel to go that speed when you already are doing 75 than 55.

[crazyVOLVOrob]

Well my findings have shown i get better highway economy 65-75 then going 55-65...i have to prtess the gas pedal less to accelerate around casrs if i have boost

Sounds about right. Still the engine doesn't know throttle opening and boost. All that matters re: fuel is the amount of fuel going in. More fuel = less milage. More boost = more fuel, more gas pedal = more fuel. So you are likely doing the same thing.


But if you are passing people at 85mi/h then obviously takes less fuel to go that speed when you already are doing 75 than 55.
85 is a guaranteed ticket where i drive in upstate NY besides i can't remember the last time i went 85 :shock: most i have gone recently is 75, torque isn't as high at 85 as it is at 75