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[Blumlein 88]

IMHO: only fun with a Quaife ATB limited slip & a few other things upgrades 225-300 HP would be about right, I think (I have a friend who turboed his)

ND2 MiataSpeed/Edelbrock E-Force Supercharger - 2019+ MAZDA MX-5

From $ 6,450



ACT 16-17 Mazda MX-5 Miata ND HD/Perf Street Sprung Clutch Kit

Regular price $ 1,160 Sale price $ 921.99

Sale

https://www.miataspeed.com/collecti...percharger-no-tune-2016-mazda-mx-5-nd-miata-1


Other wise, they are just another (of many) decent handling cars.

Nope you are wrong. Nothing wrong with the improvements you list. I understand the idea some people have of not abiding by having the same thing as everyone else so leave nothing stock. But the car is fun just like it is without doing anything.

One thing I see repeatedly with people who insist on modifications is loosing sight of why and spending money, time, effort to improve something when they could have just purchased a different car that was more capable. I've been like that at times, a couple of my friends are my father was till his last day on earth. He couldn't even leave his lawn mower un-modded. You do get the experience of improving something which is a different kind of fun. However, the idea you have to do it is wrong. The idea if it is just like thousands of others being a problem is not a problem in my mind.

 

[BeeKay]

In what way is wanting to get where you are going quickly (and safely) a "maturity deficit". (Yes, I know there are people who are unsafe about it and I would agree with you if you said that those people have "maturity deficit").
When I drove from Stuttgart to Salzburg mostly going 257 KPH, my mother was mostly asleep in the passenger seat and in no way was I driving unsafely.
Speed (in & of itself) does not equate with being an unsafe driver in any way, shape or form.
Excessive speed for the conditions is not "speed in & of itself", as it is at the expense of 'safe & prudent', a part of safety.
Most of the time (in non congested areas, on well maintained roads) a speed limit is just a revenue raising device for the government, the judges, the police, the lawyers and most of all: the insurance companies. So it is an un-Holly collusion of governmental and corporate greed and is not at all about safety.

This is an underlying misconception of freedom and what are public roads built for. It’s not fun for the few but safe and reliable infrastructure for the many. Speed and speeding, as we are in a science based forum is the single most reason for lots of casualties in public traffic. Another misconception is that German Autobahnen are unrestricted. It’s only a small number and this hardly changed over decades. For speed enthusiasts there is the Green Hell - (aka Nürburgring, just to named the most famous one). Developing conspiracy theories about us the the evil authorities also isn’t helpful nor based on any facts. There is a 100% option not to be fined. Stick to the rules (StVO or traffic code) and everyone gets safely and without tickets from A to B. What is what the infrastructure was built for.
Btw - even on unrestricted Autobahnen the recommended speed is 130km/h. Always. It’s your decision to max out to whatever your car is able to. Any accident your high speed is found to be a contributing factor and you find yourself in court. Any form of reckless driving (“Autorennen”) with someone getting killed and the subject you deal with is murder.

 

[Mikig]

Miata, one of the few “Cars” with a capital C still present on the roads today. No matter the year or version, always fun, right and balanced. If your desire is to drive, few cars give you the same feeling, of ease, of usability…

 

[Mikig]

This is an underlying misconception of freedom and what are public roads built for. It’s not fun for the few but safe and reliable infrastructure for the many. Speed and speeding, as we are in a science based forum is the single most reason for lots of casualties in public traffic. Another misconception is that German Autobahnen are unrestricted. It’s only a small number and this hardly changed over decades. For speed enthusiasts there is the Green Hell - (aka Nürburgring, just to named the most famous one). Developing conspiracy theories about us the the evil authorities also isn’t helpful nor based on any facts. There is a 100% option not to be fined. Stick to the rules (StVO or traffic code) and everyone gets safely and without tickets from A to B. What is what the infrastructure was built for.
Btw - even on unrestricted Autobahnen the recommended speed is 130km/h. Always. It’s your decision to max out to whatever your car is able to. Any accident your high speed is found to be a contributing factor and you find yourself in court. Any form of reckless driving (“Autorennen”) with someone getting killed and the subject you deal with is murder.

your reasoning is flawless, however, when you are little and you make the noise of a car on your bicycle, you spend days reading about cars, you watch every race on TV, you go to the racetrack on Sunday, you mess around with RC cars with engines, when you get your driving license it is clear that speed, driving and the emotion of "sporty" driving take over you! then I always say, I got my driving license 30 years ago, a period in which you could indulge in some "lewdness" behind the wheel; less traffic, already safe cars, drivers generally much more careful without the omnipresent smartphone in hand, and already adequate roads. Today it is a different story, in terms of the number of cars on the road and the number of idiots who look into a screen instead of looking at a road...

 

[EJ3]

This is an underlying misconception of freedom and what are public roads built for. It’s not fun for the few but safe and reliable infrastructure for the many. Speed and speeding, as we are in a science based forum is the single most reason for lots of casualties in public traffic. Another misconception is that German Autobahnen are unrestricted. It’s only a small number and this hardly changed over decades. For speed enthusiasts there is the Green Hell - (aka Nürburgring, just to named the most famous one). Developing conspiracy theories about us the the evil authorities also isn’t helpful nor based on any facts. There is a 100% option not to be fined. Stick to the rules (StVO or traffic code) and everyone gets safely and without tickets from A to B. What is what the infrastructure was built for.
Btw - even on unrestricted Autobahnen the recommended speed is 130km/h. Always. It’s your decision to max out to whatever your car is able to. Any accident your high speed is found to be a contributing factor and you find yourself in court. Any form of reckless driving (“Autorennen”) with someone getting killed and the subject you deal with is murder.

First, I am not talking about fun. There are many local tracks to go do that if I considered anything about driving to be fun.
I am talking about people just going from place to place in an efficiently safe, reasonable amount of time.
The theory has been proven on numerous occasions in the United States based on lawsuits won. (by the corruption involved (also shortening the red lights from the recommended 4 seconds to 3.7 seconds [or less) because catching people running red lights even where they were not was a revenue raising device.
Where I live, red light cameras have been banned for this reason. Also, the law here says that you are supposed to go to the middle of the intersection if you have a green light and wait for the traffic to clear to make your left turn. If you follow the law & have a red light camera, you will get a ticket because the oncoming traffic will not clear until they have a yellow light & you will be instituting your turn after or during when the light is red.
Please do not be facetious and claim that there is not, never has been nor can there ever be corruption with the speed control systems (as I have personally subpoenaed the equipment it's calibration records and beaten court cases related to speeding).
At one time the suggested speeds where 140 KPH but they have been slowed down to 130 KPH to corelate with the speed that an EV gets its maximum fuel efficiency.
My personal vehicle get's it's maximum fuel efficiency at 153 KPH.
Now, since we are being scientific here, I have the list for the USA (where I live) of the order in which things cause traffic accidents (hint: speed is not in the top 4):

1. Distracted driving
2. Drunk or drugged driving
3. Poor weather conditions
4. Reckless driving and road rage
5. Speeding
6. Disobeying red and yellow lights
7. Running stop signs
8. Improper turns
9. Road hazards
10. Drowsy driving

 

[EJ3]

Nope you are wrong. Nothing wrong with the improvements you list. I understand the idea some people have of not abiding by having the same thing as everyone else so leave nothing stock. But the car is fun just like it is without doing anything.

One thing I see repeatedly with people who insist on modifications is loosing sight of why and spending money, time, effort to improve something when they could have just purchased a different car that was more capable. I've been like that at times, a couple of my friends are my father was till his last day on earth. He couldn't even leave his lawn mower un-modded. You do get the experience of improving something which is a different kind of fun. However, the idea you have to do it is wrong. The idea if it is just like thousands of others being a problem is not a problem in my mind.

I have never left any engine or motorized thing stock in my life. The brand new Subaru at my home got lifted 2" before it got home, a set of intake blocks (makes the intake runners longer and a K&N Typhoon cold air setup). This increased torque 23 ft lb & HP 20. And fuel economy by 1/2 mile to a gallon.
For this vehicle, I will leave it at that (primarily because the CVT trans cannot handle much more torque than that) for performance.
But, for longevity I will add a filter onto the trans cooler output line & a larger trans cooler.
And an engine oil by-pass filter onto the engine oil system that filters down to 3 microns instead of the 25 microns that the stock filter catches.
If your Miata were mine, I would start with the reliability things a better (but only moderately louder exhaust and a computer tune from a well respected tuner.
They seem to find 5-10 % better power, fuel economy & drivability with every tune they do.
The sooner you do that, the more efficient & fun to drive it will be for longer.

 

[Blumlein 88]

My personal vehicle get's it's maximum fuel efficiency at 153 KPH.

What vehicle is this? Almost all vehicles other than diesels get the best mileage (are you defining efficiency differently from MPG?) between 40-50 mph.

Also what would you consider the maximum reasonably safe speed on public roads? Yes it will depend upon many things. I think it probably doesn't extend to 153 kph (95 or so mph).

I also don't agree that speeding is the #1 cause of accidents or death. Once back in the 1970s a university study of it pegged it as #13. Drunk driving was #1 and running stop signs was #2 and turning left was #3. Various things change and it varies from location to location. Almost every such study pegs rates of accidents to be about double at night vs daytime with night time having lower traffic density.

 

[EJ3]

What vehicle is this? Almost all vehicles other than diesels get the best mileage (are you defining efficiency differently from MPG?) between 40-50 mph.

Also what would you consider the maximum reasonably safe speed on public roads? Yes it will depend upon many things. I think it probably doesn't extend to 153 kph (95 or so mph).

I also don't agree that speeding is the #1 cause of accidents or death. Once back in the 1970s a university study of it pegged it as #13. Drunk driving was #1 and running stop signs was #2 and turning left was #3. Various things change and it varies from location to location. Almost every such study pegs rates of accidents to be about double at night vs daytime with night time having lower traffic density.

Th vehicle is a 1979 Pontiac Trans Am with a built (by me) Factory 800 CFM Quadrajet carburetor, tuned by me, that makes 473 HP and 455 ft lb torque with factory 1979 emission heads ported by me and meets California1982 emission standards without the catalytic convertor (aside from the visual because of no catalytic convertor) and will meet 1996 emissions (including the evaporative emissions standard that was not in the earlier standards) with a pair of cats in place (but then it does not meet the visual inspection because 2 cats (one on each side at the exhaust for that bank of cylinders each bank of cylinders are there instead of one). The car uses a Doug Nash 5 speed (5th is not an overdrive, it is 1:1) and 3:08 final drive. This puts the car at it's flattest part of the torque peak between 85 MPH & 100 MPH. In this zone the car gets 21.7 MPG. At 55 MPH it gets 18 MPG at 115 MPH it gets 18 MPG.
Would you like more information? A lot of testing has been done on this car. I was a quality control person for the Porsche factory from 1983-1989 and bought this car in 1985.
Maximum safe speed is highly dependent upon where, when & what conditions & the car one is in.
In general the USA National Highway Traffic Safety Commission (NHTSC) recommends to decide this way:

The 85th Percentile​

Decisions about rational speed limits are based in part on something called a speed study. During the speed study, data is collected at select locations along the roadway. This data is then analyzed to identify the 85th percentile—the speed at which 85 percent of the people drove at or below during ideal conditions.

The 85th percentile speed is typically used as a starting point for setting a rational limit and is considered to be the maximum safe speed for that location.

Is supposedly how the speed limits are set (of course they always round down when the actually abide by this).

In Montana they had unlimited (they called it "as fast as you think is sane & reasonable" so the police had come up with some justification for pulling you over) in many areas during the day but, due to abuse (people seeing just how fast they could go) and they have since lowered it to 80 MPH.
They do have a law that I think should be everywhere, though:
Montana Code 61-8-303,

A vehicle subject to the speed limits imposed in subsection (1) may exceed the speed limits imposed in subsection (1) by 10 miles an hour in order to overtake and pass a vehicle and return safely to the right-hand lane under the following circumstances:
(a) while traveling on a two-lane road; and
(b) in a designated passing zone.

In Texas there are a lot of areas of 85 MPH.
I will say, that I believe that there are places (away from populated areas) that should be unlimited: in places like Montana, Nevada, Texas and some others.

I believe that if this was actually followed everywhere, there would be some places that actually would have slower speed limits but more that would have higher speed limits (by 5-10 MPH in both cases). But that there would be some that were also 15-30 MPH higher (on interstates away from & between populated areas where the speed limits are already 70 MPH or more.
Americans had the first street legal production car to go over 200 MPH in 1977: The world's fastest street-legal sports car in 1977. Car & Driver reported this (Kelmark Toronado GT) as the “Fastest documented speed ever attained by a street machine”, clocked at 202.7 by Car & Driver at the former Transportation Research Center in Ohio (now a part of Honda's US test facility). This proved the cars advanced aerodynamic and performance capabilities.
To put this accomplishment into perspective one should consider that it took Ferrari until March 1987 to come out with a 200 mph street legal sports car, the Ferrari F40. The F40 was a low production volume special which was not a mainstream Ferrari. Just a few months later Road and Track tested several specialty sports cars. The Ruf CTR Porsche 911 Yellow Bird and the Koenig RS Porsche 911; which, broke 200 mph. These two ran at 211 and 201 mph, respectively. Again, these were low volume custom sports cars. In these same tests, which were completed by Road and Track, with Le Mans winning Paul Frere and Formula One champ Phil Hill driving, the Ferrari Testarossa, Lamborghini Countach 5000S and AMG Hammer Mercedes-Benz 300E all FAILED to break 200 mph.

Then, of course there is night driving and you are now light dependent. Mine (and they are a bit higher powered but not as bright as some newest truck headlights) have a reflective range of 9800 feet. At that distance, I can see the reflection of a stop sign OR that there is something (such as a deer) in the road out there.
That is a whole 'nother ball of wax for "to fast for conditions" & perhaps "reckless driving".
As is bad weather (particularly since America allows some really horrid tires to be on the road).

I'm thinking that the first 4 on the list should be heavily worked on (as they are 2/3 of the accidents).

1. Distracted driving
2. Drunk or drugged driving
3. Poor weather conditions (Tires, anyone, also perhaps 10 less MPH [at least in city traffic], rather than 5)
4. Reckless driving and road rage

Street Legal cars that can top 300 MPH on a public road:
Bugatti Chiron Super Sport 300+ (yep the 300+ is part of it's name) (French/German?) 304.773 mph
Hennessey Venom F5 coupe (USA) 307 MPH
2006 Ford GT (USA) (This car IS A DAILY DRIVER) 310.8 mph
Koenigsegg Jesko Absolut (Sweden) 330 mph.

 

[Count Dacula]

I was in Daytona over the winter...

 

[Blumlein 88]

Th vehicle is a 1979 Pontiac Trans Am with a built (by me) Factory 800 CFM Quadrajet carburetor, tuned by me, that makes 473 HP and 455 ft lb torque with factory 1979 emission heads ported by me and meets California1982 emission standards without the catalytic convertor (aside from the visual because of no catalytic convertor) and will meet 1996 emissions (including the evaporative emissions standard that was not in the earlier standards) with a pair of cats in place (but then it does not meet the visual inspection because 2 cats (one on each side at the exhaust for that bank of cylinders each bank of cylinders are there instead of one). The car uses a Doug Nash 5 speed (5th is not an overdrive, it is 1:1) and 3:08 final drive. This puts the car at it's flattest part of the torque peak between 85 MPH & 100 MPH. In this zone the car gets 21.7 MPG. At 55 MPH it gets 18 MPG at 115 MPH it gets 18 MPG.
Would you like more information? A lot of testing has been done on this car. I was a quality control person for the Porsche factory from 1983-1989 and bought this car in 1985.
Maximum safe speed is highly dependent upon where, when & what conditions & the car one is in.
In general the USA National Highway Traffic Safety Commission (NHTSC) recommends to decide this way:

The 85th Percentile​

Decisions about rational speed limits are based in part on something called a speed study. During the speed study, data is collected at select locations along the roadway. This data is then analyzed to identify the 85th percentile—the speed at which 85 percent of the people drove at or below during ideal conditions.

The 85th percentile speed is typically used as a starting point for setting a rational limit and is considered to be the maximum safe speed for that location.

Is supposedly how the speed limits are set (of course they always round down when the actually abide by this).

In Montana they had unlimited (they called it "as fast as you think is sane & reasonable" so the police had come up with some justification for pulling you over) in many areas during the day but, due to abuse (people seeing just how fast they could go) and they have since lowered it to 80 MPH.
They do have a law that I think should be everywhere, though:
Montana Code 61-8-303,

In Texas there are a lot of areas of 85 MPH.
I will say, that I believe that there are places (away from populated areas) that should be unlimited: in places like Montana, Nevada, Texas and some others.

I believe that if this was actually followed everywhere, there would be some places that actually would have slower speed limits but more that would have higher speed limits (by 5-10 MPH in both cases). But that there would be some that were also 15-30 MPH higher (on interstates away from & between populated areas where the speed limits are already 70 MPH or more.
Americans had the first street legal production car to go over 200 MPH in 1977: The world's fastest street-legal sports car in 1977. Car & Driver reported this (Kelmark Toronado GT) as the “Fastest documented speed ever attained by a street machine”, clocked at 202.7 by Car & Driver at the former Transportation Research Center in Ohio (now a part of Honda's US test facility). This proved the cars advanced aerodynamic and performance capabilities.
To put this accomplishment into perspective one should consider that it took Ferrari until March 1987 to come out with a 200 mph street legal sports car, the Ferrari F40. The F40 was a low production volume special which was not a mainstream Ferrari. Just a few months later Road and Track tested several specialty sports cars. The Ruf CTR Porsche 911 Yellow Bird and the Koenig RS Porsche 911; which, broke 200 mph. These two ran at 211 and 201 mph, respectively. Again, these were low volume custom sports cars. In these same tests, which were completed by Road and Track, with Le Mans winning Paul Frere and Formula One champ Phil Hill driving, the Ferrari Testarossa, Lamborghini Countach 5000S and AMG Hammer Mercedes-Benz 300E all FAILED to break 200 mph.

Then, of course there is night driving and you are now light dependent. Mine (and they are a bit higher powered but not as bright as some newest truck headlights) have a reflective range of 9800 feet. At that distance, I can see the reflection of a stop sign OR that there is something (such as a deer) in the road out there.
That is a whole 'nother ball of wax for "to fast for conditions" & perhaps "reckless driving".
As is bad weather (particularly since America allows some really horrid tires to be on the road).

I'm thinking that the first 4 on the list should be heavily worked on (as they are 2/3 of the accidents).

1. Distracted driving
2. Drunk or drugged driving
3. Poor weather conditions (Tires, anyone, also perhaps 10 less MPH [at least in city traffic], rather than 5)
4. Reckless driving and road rage

Street Legal cars that can top 300 MPH on a public road:
Bugatti Chiron Super Sport 300+ (yep the 300+ is part of it's name) (French/German?) 304.773 mph
Hennessey Venom F5 coupe (USA) 307 MPH
2006 Ford GT (USA) (This car IS A DAILY DRIVER) 310.8 mph
Koenigsegg Jesko Absolut (Sweden) 330 mph.

Yes I want to know more about the Trans Am because frankly I don't believe it. It doesn't add up with the physics of the engine and automobiles.

Been aware of the 85th percentile rule for many years. Wished more places would actually use it to set limits.

The rest I have no idea what it is supposed to be about. The fact you can make a car that goes 200 or 300 mph in no ways makes it a safe speed to go on public highways. My own ideas which are fairly simple are that somewhere around 85 mph is probably about as fast as you normally could consider a reasonably safe speed. Definitions of "reasonably safe" would enter into it of course. Primarily based upon visual acuity, braking ability and reaction times. One could make other interpretations of those facts. There is one simulation from a few years ago where someone estimated the maximum speed at which a car passing modern crash standards could crash with some chance of survivability into a solid object. Like a brick wall. If memory serves it was somewhere around 66 mph. 0% survivability. So picking a single number involves some assumptions which aren't going to be perfect. I don't see any place where it makes sense that would be 200 mph.

As for seeing that stop sign or deer at 9800 ft I doubt it. You might see a reflective stop sign in some sense. If deer is looking the other way you wouldn't. First you have to have a road with that much visibility of nearly 2 miles. It cannot be hazy. And after all of that, you don't have the visual acuity to see what it is (probably not even that it is there) at those distances. 1 moa the approximate visual acuity of healthy eyesight is over 30 inches at that range. With you and/or objects in motion it is more like 3 times that. At night even with very bright lights you are fooling yourself to think you'll see it on a highway driving.

 

[EJ3]

Yes I want to know more about the Trans Am because frankly I don't believe it. It doesn't add up with the physics of the engine and automobiles.

Been aware of the 85th percentile rule for many years. Wished more places would actually use it to set limits.

The rest I have no idea what it is supposed to be about. The fact you can make a car that goes 200 or 300 mph in no ways makes it a safe speed to go on public highways. My own ideas which are fairly simple are that somewhere around 85 mph is probably about as fast as you normally could consider a reasonably safe speed. Definitions of "reasonably safe" would enter into it of course. Primarily based upon visual acuity, braking ability and reaction times. One could make other interpretations of those facts. There is one simulation from a few years ago where someone estimated the maximum speed at which a car passing modern crash standards could crash with some chance of survivability into a solid object. Like a brick wall. If memory serves it was somewhere around 66 mph. 0% survivability. So picking a single number involves some assumptions which aren't going to be perfect. I don't see any place where it makes sense that would be 200 mph.

As for seeing that stop sign or deer at 9800 ft I doubt it. You might see a reflective stop sign in some sense. If deer is looking the other way you wouldn't. First you have to have a road with that much visibility of nearly 2 miles. It cannot be hazy. And after all of that, you don't have the visual acuity to see what it is probably not even that it is there at those distances. 1 moa the approximate visual acuity of healthy eyesight is over 30 inches at that range. With you and/or objects in motion it is more like 3 times that. At night even with very bright lights you are fooling yourself to think you'll see it on a highway driving.

The closer you are to the torque peak at light throttle the better your fuel economy will be. If you have to give it more throttle to stay there, than you're fuel economy will drop even though you are at your torque peak.
This is has been demonstrated using identical GMC motorhomes with Oldmobile 455 & 403 Engines. with various final drive gear ratios and various engine states of tune & bolt on modifications. the gear ratios used were 3.07 (original factory), 3.21, 3.42.
Some engines had been modified with camshafts & roller lifter with aluminum heads that gave them a 7% better peak torque and extended that peak torque (vua having a plateau in the torque curve rather than a peak. (Much like my not so powerful but fun Pontiac engine). The broader torque curve vehicle got about the same 10.3 MPG in the 60-70 MPH range (3.21 final drive) because it had a better torque in the speed range (None of the other vehicles exceeded 9.9 MPG and the 403 engines did worse, no matter the gear ratio, due to having less torque at peak & less average torque under the torque curve.

Are you also aware of this formula for the YELLOW traffic signal?:

I am also actually a formerly certified (for 12 years Automotive Master Certified Technician in both automobiles and heavy duty trucks.
And if you have not personally done tests like this, you can believe your physics all you want.
Exactly why NASCAR did not hire engineers until they built their own engineering program at Clemson University.
Because most engineers tell people what can't be done. But they don't usually come up with "How it can be done".
Which is what most of us in this field are about,

I have 2 PHD's.
But I know how to use both of my Post Hole Digger's

 

[EJ3]

What vehicle is this? Almost all vehicles other than diesels get the best mileage (are you defining efficiency differently from MPG?) between 40-50 mph.

OK, here is an all aluminum (heads and block) gas engine that has a diesel like torque curve.
When you have much more than enough power to overcome the "pushing through the air" problem:
Power final / Power initial) = Vel final / Vel initial) ^3

Power final = Power initial x 2^3

Power final= Power initial x 8

And you have this much power:

At what speed will your best fuel economy be?

 

[Blumlein 88]

The closer you are to the torque peak at light throttle the better your fuel economy will be. If you have to give it more throttle to stay there, than you're fuel economy will drop even though you are at your torque peak.
This is has been demonstrated using identical GMC motorhomes with Oldmobile 455 & 403 Engines. with various final drive gear ratios and various engine states of tune & bolt on modifications. the gear ratios used were 3.07 (original factory), 3.21, 3.42.
Some engines had been modified with camshafts & roller lifter with aluminum heads that gave them a 7% better peak torque and extended that peak torque (vua having a plateau in the torque curve rather than a peak. (Much like my not so powerful but fun Pontiac engine). The broader torque curve vehicle got about the same 10.3 MPG in the 60-70 MPH range (3.21 final drive) because it had a better torque in the speed range (None of the other vehicles exceeded 9.9 MPG and the 403 engines did worse, no matter the gear ratio, due to having less torque at peak & less average torque under the torque curve.

Are you also aware of this formula for the YELLOW traffic signal?:
View attachment 436828
I am also actually a formerly certified (for 12 years Automotive Master Certified Technician in both automobiles and heavy duty trucks.
And if you have not personally done tests like this, you can believe your physics all you want.
Exactly why NASCAR did not hire engineers until they built their own engineering program at Clemson University.
Because most engineers tell people what can't be done. But they don't usually come up with "How it can be done".
Which is what most of us in this field are about,

I have 2 PHD's.
But I know how to use both of my Post Hole Digger's

Was not aware the ITE had a formal thing called a "yellow interval". It is however exactly the same as what I came up with for time to come to a stop. You then have to determine how far you traveled once you have that. Which is also a simple formula.

The part about the motorhomes doesn't tell me much. I also have my doubts that it is impossible to get a 403 to get better mileage than a 455 (noting that you didn't claim that only that none of those tested did). Aiming for minimum throttle is not always maximum mileage. The less open the throttle the lower the thermal efficiency of a gasoline engine. NASCAR guys cannot beat that (except by storing away extra gasoline somewhere other than the tank in the car).

What you are saying in that your Tran Am's best mileage was 95 mph is that using more or less 5 times the horsepower vs 45 mph, that it nevertheless had enough of a thermal efficiency advantage to get better gas mileage at those speeds. That would be highly unlikely unless it was some very peaky, very high horsepower engine that would make it a drivability nightmare on regular streets. By your accounts it was a fairly tame engine with a rather flattened torque curve.

 

[EJ3]

Was not aware the ITE had a formal thing called a "yellow interval". It is however exactly the same as what I came up with for time to come to a stop. You then have to determine how far you traveled once you have that. Which is also a simple formula.

The part about the motorhomes doesn't tell me much. I also have my doubts that it is impossible to get a 403 to get better mileage than a 455 (noting that you didn't claim that only that none of those tested did). Aiming for minimum throttle is not always maximum mileage. The less open the throttle the lower the thermal efficiency of a gasoline engine. NASCAR guys cannot beat that (except by storing away extra gasoline somewhere other than the tank in the car).

What you are saying in that your Tran Am's best mileage was 95 mph is that using more or less 5 times the horsepower vs 45 mph, that it nevertheless had enough of a thermal efficiency advantage to get better gas mileage at those speeds. That would be highly unlikely unless it was some very peaky, very high horsepower engine that would make it a drivability nightmare on regular streets. By your accounts it was a fairly tame engine with a rather flattened torque curve.

I checked my records: The best fuel economy of the Trans Am is actually the same between 80 MPH & 90 MPH (21.7 MPG). At 55 MPH it is 18 MPG & at 110 MPH it is 18 MPG. 380 ft Lbs. of torque at 2200 RPM, 455 ft lbs torque at 3800 RPM, 380 ft lbs torque at 5000 RPM. 330 ft lbs torque at 5600 RPM"
I build engines to make torque & let the HP fall where it may.
Dealing with 5 of each in the same motorhomes produced from 1974-1978 With the 455's being from the 78 & earlier models & the 403's being from te early 77 models through the end of production. The stock 403 Oldsmobile (in proper tune) in motorhome use never came close to the fuel economy of a stock Oldsmobile.
Nor did ay of the modified ones even reach the torque level of a stock 455. Even when they had an advantageous final drive gear ratio
The GMC factory new what they were doing putting 455's into them until there were no more 455's available.
Many of these people's engines had issues carburetor not tuned correctly, a vacuum leak, the distributor mechanical advance mot working or the other way around, the vacuum advance not working.
Only 1 of each was 100% correctly functional.
But, it is simple: the 403 in proper factory tune, could not make enough torque at 50-60 MPH to hold that speed without dipping deeper into the throttle than the higher torque 455. Hence, unless you put it into a motorhome with less frontal area, it loses the economy war at that speed.
It may do better at lower speeds but going down the interstate at less than 60 is not a good thing. And having some torque in reserve for hills is a good thing.
Not to mention that many of these folks also tow a car when they are RVing. That can add up to dangerous levels of lack of acceleration and speed.
Particularly on grades.
All but one of these RV's where over their GVW rating by more than 1000 LBs.
And, because most RV's do a fair amount of just sitting, they go downhill without folks thinking about it.
This is the scenario that a diesel excels at because: there is a lot less to go wrong whether sitting or going. But also: they aren't cheap.

 

[Blumlein 88]

I checked my records: The best fuel economy of the Trans Am is actually the same between 80 MPH & 90 MPH (21.7 MPG). At 55 MPH it is 18 MPG & at 110 MPH it is 18 MPG. 380 ft Lbs. of torque at 2200 RPM, 455 ft lbs torque at 3800 RPM, 380 ft lbs torque at 5000 RPM. 330 ft lbs torque at 5600 RPM"
I build engines to make torque & let the HP fall where it may.
Dealing with 5 of each in the same motorhomes produced from 1974-1978 With the 455's being from the 78 & earlier models & the 403's being from te early 77 models through the end of production. The stock 403 Oldsmobile (in proper tune) in motorhome use never came close to the fuel economy of a stock Oldsmobile.
Nor did ay of the modified ones even reach the torque level of a stock 455. Even when they had an advantageous final drive gear ratio
The GMC factory new what they were doing putting 455's into them until there were no more 455's available.
Many of these people's engines had issues carburetor not tuned correctly, a vacuum leak, the distributor mechanical advance mot working or the other way around, the vacuum advance not working.
Only 1 of each was 100% correctly functional.
But, it is simple: the 403 in proper factory tune, could not make enough torque at 50-60 MPH to hold that speed without dipping deeper into the throttle than the higher torque 455. Hence, unless you put it into a motorhome with less frontal area, it loses the economy war at that speed.
It may do better at lower speeds but going down the interstate at less than 60 is not a good thing. And having some torque in reserve for hills is a good thing.
Not to mention that many of these folks also tow a car when they are RVing. That can add up to dangerous levels of lack of acceleration and speed.
Particularly on grades.
All but one of these RV's where over their GVW rating by more than 1000 LBs.
And, because most RV's do a fair amount of just sitting, they go downhill without folks thinking about it.
This is the scenario that a diesel excels at because: there is a lot less to go wrong whether sitting or going. But also: they aren't cheap.

You are now mixing in lots of things beyond fuel economy. No doubt I would want a 455 in a motorhome. Your explanations of dipping into the throttle with the smaller engine etc don't show anything useful. For instance just for fuel economy, the smaller engine with the throttle closer to wide open will be more thermally efficient. It will get better mileage than a more powerful larger engine with the throttle less open. At an extreme a 4 cylinder barely able to reach 70 mph would get better mileage on the flat. Might not get you up hills, accelerate or tow cars very well at all, but would get better mileage. Why do you think some modern engines cut off cylinders? It is like having your 8 cylinder engine for getting up to speed and a 4 cylinder one for cruising once speed is attained.

 

[Blumlein 88]

OK, here is an all aluminum (heads and block) gas engine that has a diesel like torque curve.
When you have much more than enough power to overcome the "pushing through the air" problem:
Power final / Power initial) = Vel final / Vel initial) ^3

Power final = Power initial x 2^3

Power final= Power initial x 8

And you have this much power:
View attachment 436846
At what speed will your best fuel economy be?

I cannot read that image very well even blown up. It looks to be from an engine running wide open. So it won't tell me what the best speed for fuel economy is directly. Nor would it do so at partial throttle unless I know the parameters of the vehicle it is in. Best MPG in a motorhome vs a Trans am are likely to differ for the same engine though I haven't worked thru the requirements of motorhomes. So maybe closer than I expect in terms of most economical speed.

In my estimations of the power at different speeds I made ballpark estimations for rolling frictional drag and aerodynamic drag. Aero drag is power in a cube function versus velocity. Frictional and rolling is close enough to proportional to speed for basic estimations.

 

[EJ3]

You are now mixing in lots of things beyond fuel economy. No doubt I would want a 455 in a motorhome. Your explanations of dipping into the throttle with the smaller engine etc don't show anything useful. For instance just for fuel economy, the smaller engine with the throttle closer to wide open will be more thermally efficient. It will get better mileage than a more powerful larger engine with the throttle less open. At an extreme a 4 cylinder barely able to reach 70 mph would get better mileage on the flat. Might not get you up hills, accelerate or tow cars very well at all, but would get better mileage. Why do you think some modern engines cut off cylinders? It is like having your 8 cylinder engine for getting up to speed and a 4 cylinder one for cruising once speed is attained.

But EMPIRICAL testing shows that the smaller engine does not.
Ahm: fuel efficiency for the vehicles intended use. That incudes normal driving & towing with a load (people & gear on board).
Things that change the whole scenario:
But here are some other things that do not happen until you are going a few miles an hour over 60 that are happening (even with the 3.07 gearing).

Some ways to improve things on these
GMC Motorhomes tested via a wind tunnel were reported to have a drag coefficient of 0.31, which is typical of modern sedans (although offset by the large frontal area.

The Original stock torque converter had a stall of 2200 RPMs. (Lock the brakes and step on the gas and the RPMs go to 2200 with the coach not moving.) While torque converters without lockup clutches don't ever quit slipping, the stock unit is built to slip at 2100. That would be 62 MPH, so drive 64.

Manny's Switch Pitch will lower that stall to about 1600, unless in Switch which places it at about 2600. The tighter torque converter is very responsive, even without lower gears. (Wouldn't want to try to maneuver into a steep camping site with it and a 3.07.) The last big trip I got 10.7 mpg (with 3.42 gears), not towing. That was pump vs. actual miles traveled for 5400 miles. We were from CA to Washington to Montana to Canada to the Dakotas to Iowa and then home, so lots of variety. (Towing I seem to be more around 9.6, but I do it so seldom I only have 1200 miles experience since the switch pitch was installed.)

Also, with EBL, you need a Vehicle Speed Sensor? The VSS allows the EBL to go into Highway Mode with is usually called Lean Cruise. The EBL will cut back on the air/fuel from 14.7:1 to 16.4:1 and at the same time advance the spark 4+ degrees. (These are according to settings but these are good averages.)

Each time the coach goes into Lean Cruise, the instant MPG goes up 1 MPG. VSS may be one of the cheaper items to help realize your mpg possibilities.

With some more EBL tuning you will break the 10 mpg limit most of the time, regardless of the final drive

He does not know why he gest better HWY fuel economy with a lower geared final drive. The 403 is now properly tuned and, due to the much steeper final drive, is making more torque at the wheels. But the engine is turning more RPM per mile & may or may not last as long. Lighter load, lasts longer, more RPM, lasts less long.
Maybe it's a toss up?

Ray Erspamer​

Apr 16, 2013, 1:58:49 PM
to [email protected]
Not sure if there is any scientific data out there. Here is our
experience......

We have the 403 engine and when we purchased the coach it had a 3:46 final
drive. Performance was good and mileage was about 8.9 mpg.

After I wrecked the final drive I replaced it with a 3:70, mileage improved,
performance is outstanding. As of last trip and fill the average was 9.3 mpg.
I typically run about 70 MPH on the highways.

Along with the 3:70 final drive we have the Patterson Ignition System and I've
had the Quadrajet carb rebuilt by Patterson.
Ray
Ray & Lisa
78 Royale "Great Lakes Eagle"
Center Kitchen TZE368V101144
Wauwatosa, Wisconsin 53226
Email: [email protected]
414-745-3188
Web Site: http://ray-lisa.page.tl/

 

[Blumlein 88]

Devil is in the details of all testing including empirical. The data from Ray & Lisa is not enough to conclude much other than when he switched final gears his mileage improved. Did he take the same trips the same places, did he drive a little differently due to how the gearing and engine interacted etc etc etc? We are now a long way from what is the most economical speed for an automobile.

 

[ErVikingo]

Very nice 968! My 911 Carrera from 1988 (G50 gearbox) was a bit neglected since quite a few years but then I had a huge maintenance done on it: it was still, after 37 years, on its first clutch (!) and the mechanic confirmed it. New oil lines, new fuel lines, braking system entirely redone, new clutch, a few oil leak fixed, new tires ofc, etc. Quite the bill but totally worth it.

Now I'm enjoying it (but only when there's no rain / no salt, no risk of rain). I don't wash the car with water: I don't care about "swirls" on the paint or whatnots, that car doesn't see a drop of water anymore now.

Immensely fun to drive. It's 37 years old now and I have it since 26 years (and it went 4x in value since I bought it in 1999 which is always fun too!)

View attachment 436351

Love it! Here are their grandpa and older brother! my 78 (3.2!) and my 69 S

 

[Willem]

OK, it came from the Hedin Automotive Group (and it looks pretty good). But what is it?

The new all electric Renault 5.