Gas vs PSD
Hotshot
Joined: Jun 2007
Posts: 10,008
Likes: 7
From: Austin, TX
Don't believe SA Raceway would like for us to do that, but I will talk to them next time I'm there and see if they will let us do that on Grudge Night or something.LOL That would be runny as heck, thats for sure. I should hook some nitrous up on a purge and purge the nitrous at the line with a trailer behind us. No nitrous to the engine, just the purge. haha
Elder User
Joined: May 2010
Posts: 650
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From: WV
lol...Upstate New York is pretty in an Upstate New York kinda' way, but not like Yellowstone...I like WV too, but they need to destroy some DNA strings before I could move there...(Nothing personal JR) Pennsylvania is where this great country started for the most part so it has it's beauties too. Relocate half of the population and I could live there, too. My point is if you grab a vacation book (not the State-sponsored ones) and look at them, 90%+ of the areas they hype minus Hawaii, are above 3000'.
But I work at a goverment facility here, and last year when I was looking for a job, the government was the only place hiring.
I'll move from WV somewhere south in a few years.
Elder User
Joined: Apr 2009
Posts: 685
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From: Spokane, WA
FTE Leadership Emeritus
Joined: Jan 2003
Posts: 161,999
Likes: 75
From: 3rd Rock
That is good stuff!
alright, so I found this site that tells you the pressure at a give altitude. Assuming he's at 7500', that comes to 584 mmHg, or 11.3 psi.
Altitude.org | Altitude air pressure calculator
Now 14.7 - 11.3 = 3.4
3.4 psi loss at 44.7 psia (or 30 psig of boost) is a 7.6% loss of power.
While that may cause some power loss, lets look at compression ratio (another method would have been to look at turbo shaft speed, but they will have about the same result).
So, to compress 14.7 psia of air to 44.7 psia of air, your compression ratio is 44.7/14.7 = 3.05. The compression ratio at 7500' with a pressure of 11.3 and achieving a final pressure of 41.3 psia, your compression ratio will be 41.3/11.3 = 3.65.
This means at that altitude the the turbo has to spin 20% faster to create the same 30 psig boost. That can cause some significant lag.
You add the lag to the fact the engine is producing 7% less power pretty much all the way through boost range, you will have certainly have reduced performance.
Which one has the greater effect? Depends on what your doing. Accelerating the lag will definitively hurt you, climbing a mountain and maintaining speed, the power loss may hurt you more.
Altitude.org | Altitude air pressure calculator
Now 14.7 - 11.3 = 3.4
3.4 psi loss at 44.7 psia (or 30 psig of boost) is a 7.6% loss of power.
While that may cause some power loss, lets look at compression ratio (another method would have been to look at turbo shaft speed, but they will have about the same result).
So, to compress 14.7 psia of air to 44.7 psia of air, your compression ratio is 44.7/14.7 = 3.05. The compression ratio at 7500' with a pressure of 11.3 and achieving a final pressure of 41.3 psia, your compression ratio will be 41.3/11.3 = 3.65.
This means at that altitude the the turbo has to spin 20% faster to create the same 30 psig boost. That can cause some significant lag.
You add the lag to the fact the engine is producing 7% less power pretty much all the way through boost range, you will have certainly have reduced performance.
Which one has the greater effect? Depends on what your doing. Accelerating the lag will definitively hurt you, climbing a mountain and maintaining speed, the power loss may hurt you more.
Elder User
Joined: May 2010
Posts: 650
Likes: 0
From: WV
Easy...
Diesel costs about $2.95-2.85 here, I used $2.85
Gas costs $2.55 for 87
Assume the PSD gets 18 and the V10 15mpg, that's your 3 mpg difference.
So I figured out the cost to run each engine 1 mile in excel, then found how much more it costs to run V10 per mile, and used solver to find the number of miles you have to drive to save $1092 a year (thats the $91 per a month times 12 months). The result looked like this:
PSD = 2.85/18=$0.158 per mile
V10 = 2.55/15=$0.170 per mile
So the V10 costs $0.0117 more per mile than the PSD under those conditions
To save $1092 a year you divide the difference: 1092 $/yr / 0.0117 $/mile = 93,333 miles per year.
I rounded down to 90,000 miles per year.
I assumed you did some sort of math like that to figure out the $91 dollars a month you saved, I just reversed it.
On a side note, I got about 14 mpg on "flat" ground with steady driving out of my V10. At 14 mpg for the V10 and 18 for the PSD (which seem more reasonable to me), you only need to drive 45,000 miles a year to save your $1092 a year.
Diesel costs about $2.95-2.85 here, I used $2.85
Gas costs $2.55 for 87
Assume the PSD gets 18 and the V10 15mpg, that's your 3 mpg difference.
So I figured out the cost to run each engine 1 mile in excel, then found how much more it costs to run V10 per mile, and used solver to find the number of miles you have to drive to save $1092 a year (thats the $91 per a month times 12 months). The result looked like this:
PSD = 2.85/18=$0.158 per mile
V10 = 2.55/15=$0.170 per mile
So the V10 costs $0.0117 more per mile than the PSD under those conditions
To save $1092 a year you divide the difference: 1092 $/yr / 0.0117 $/mile = 93,333 miles per year.
I rounded down to 90,000 miles per year.
I assumed you did some sort of math like that to figure out the $91 dollars a month you saved, I just reversed it.
On a side note, I got about 14 mpg on "flat" ground with steady driving out of my V10. At 14 mpg for the V10 and 18 for the PSD (which seem more reasonable to me), you only need to drive 45,000 miles a year to save your $1092 a year.
Elder User
Joined: May 2010
Posts: 650
Likes: 0
From: WV
That guy has no idea what he's doing. First off you don't put car seats in the back of the extended cabs, that is the exact reason I traded my extended cab in for a crew cab. If he bought the truck new, he had to remove the sticker that says all car seats must go in the front seat of an extended cab. If not, then he should have looked at the manual to see how to install the seat properly as all the car seat manufactures say to do...
THEN, he's getting single digit mpg with it as a DD? Towing yes you will see single digits, as a DD no, sorry you won't. I had the most gas consuming configuration you can get and drove stop and go traffic up and down mountains and still got 10-11 mpg regularly. Back in "flat" Ohio I could 14 mpg with a mix of city/highway, I would like to see what he's doing with the truck to get such bad mpg...
And when was last time you saw a mechanic complaining about how their truck has so many problems? Something seems a miss there...
Besides, he's OBVIOUSLY making a bad choice going from Ford to Chevy
No one said every single gas SD works perfectly. I'm sure there are some gassers out there that have been problematic for there owners, but the percentage of troublesome gassers is far lower than troublesome diesels. I might be willing to even admit, that the troubled diesels maybe the result of people not properly maintaining them... maybe...
Elder User
Joined: May 2010
Posts: 650
Likes: 0
From: WV
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Hotshot
Joined: Mar 2007
Posts: 10,101
Likes: 40
From: Pa
Easy...
Diesel costs about $2.95-2.85 here, I used $2.85
Gas costs $2.55 for 87
Assume the PSD gets 18 and the V10 15mpg, that's your 3 mpg difference.
So I figured out the cost to run each engine 1 mile in excel, then found how much more it costs to run V10 per mile, and used solver to find the number of miles you have to drive to save $1092 a year (thats the $91 per a month times 12 months). The result looked like this:
PSD = 2.85/18=$0.158 per mile
V10 = 2.55/15=$0.170 per mile
So the V10 costs $0.0117 more per mile than the PSD under those conditions
To save $1092 a year you divide the difference: 1092 $/yr / 0.0117 $/mile = 93,333 miles per year.
I rounded down to 90,000 miles per year.
I assumed you did some sort of math like that to figure out the $91 dollars a month you saved, I just reversed it.
On a side note, I got about 14 mpg on "flat" ground with steady driving out of my V10. At 14 mpg for the V10 and 18 for the PSD (which seem more reasonable to me), you only need to drive 45,000 miles a year to save your $1092 a year.
Diesel costs about $2.95-2.85 here, I used $2.85
Gas costs $2.55 for 87
Assume the PSD gets 18 and the V10 15mpg, that's your 3 mpg difference.
So I figured out the cost to run each engine 1 mile in excel, then found how much more it costs to run V10 per mile, and used solver to find the number of miles you have to drive to save $1092 a year (thats the $91 per a month times 12 months). The result looked like this:
PSD = 2.85/18=$0.158 per mile
V10 = 2.55/15=$0.170 per mile
So the V10 costs $0.0117 more per mile than the PSD under those conditions
To save $1092 a year you divide the difference: 1092 $/yr / 0.0117 $/mile = 93,333 miles per year.
I rounded down to 90,000 miles per year.
I assumed you did some sort of math like that to figure out the $91 dollars a month you saved, I just reversed it.
On a side note, I got about 14 mpg on "flat" ground with steady driving out of my V10. At 14 mpg for the V10 and 18 for the PSD (which seem more reasonable to me), you only need to drive 45,000 miles a year to save your $1092 a year.
Elder User
Joined: May 2010
Posts: 650
Likes: 0
From: WV
The thing with trying to figure out stuff like that especially long term works for some and not for others. Fuel cost is different everywhere. Costs $2.52 for 87 and $3.10-$3.20 for diesel local . So there would be no fuel savings for me. Some people just can't comprehend that, as you are seeing.
Trying to figure anything like that out long term is a best guess at best. Everyone knows fuel prices are going to change over the next few years/decades. So all you can do is use what you have, go with it, and hope for the best...
Elder User
Joined: Apr 2009
Posts: 685
Likes: 0
From: Spokane, WA
That guy has no idea what he's doing. First off you don't put car seats in the back of the extended cabs, that is the exact reason I traded my extended cab in for a crew cab. If he bought the truck new, he had to remove the sticker that says all car seats must go in the front seat of an extended cab. If not, then he should have looked at the manual to see how to install the seat properly as all the car seat manufactures say to do...
THEN, he's getting single digit mpg with it as a DD? Towing yes you will see single digits, as a DD no, sorry you won't. I had the most gas consuming configuration you can get and drove stop and go traffic up and down mountains and still got 10-11 mpg regularly. Back in "flat" Ohio I could 14 mpg with a mix of city/highway, I would like to see what he's doing with the truck to get such bad mpg...
And when was last time you saw a mechanic complaining about how their truck has so many problems? Something seems a miss there...
Besides, he's OBVIOUSLY making a bad choice going from Ford to Chevy
No one said every single gas SD works perfectly. I'm sure there are some gassers out there that have been problematic for there owners, but the percentage of troublesome gassers is far lower than troublesome diesels. I might be willing to even admit, that the troubled diesels maybe the result of people not properly maintaining them... maybe...
I know the issues I had with mine were purely related to prior owner not maintaining the cooling system, as in driving thru wheat fields and never checking the fins.
Posting Guru
Joined: Aug 2008
Posts: 2,313
Likes: 0
From: Sunny, Snowy, CO
True 30 psi is 30 psi. And it will have the same number of molecules of oxygen, assuming the same temperature.
I think the bigger issue is that the turbo will have to work hard to create that 30 psi. You will also see increased turbo lag because of the turbo working harder. And since the turbo is working harder, it will probably heat the charge gas up more, which could result in a lower density of air (and hence less oxygen). However, atmospheric temperature are lower (I think) than normal at elevation, so that might be a wash.
But if your truck is at 30 psi at X RPM's in Y gear at Z speed, it will produce the same hp and torque regardless of elevation.
Of course at some point your turbo will be maxed out and your max boost will drop, but I don't think that's an issue.
Also another side note, Ford claims the new twin turbo Ecoboosted F150 will greatly help those living in high climates. When I read that I thought right away of the PSD owners in CO will at least have a smaller option now with boost.
I think the bigger issue is that the turbo will have to work hard to create that 30 psi. You will also see increased turbo lag because of the turbo working harder. And since the turbo is working harder, it will probably heat the charge gas up more, which could result in a lower density of air (and hence less oxygen). However, atmospheric temperature are lower (I think) than normal at elevation, so that might be a wash.
But if your truck is at 30 psi at X RPM's in Y gear at Z speed, it will produce the same hp and torque regardless of elevation.
Of course at some point your turbo will be maxed out and your max boost will drop, but I don't think that's an issue.
Also another side note, Ford claims the new twin turbo Ecoboosted F150 will greatly help those living in high climates. When I read that I thought right away of the PSD owners in CO will at least have a smaller option now with boost.
Elder User
Joined: May 2010
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From: WV
It was, I got a chuckle out of it.
Elder User
Joined: May 2010
Posts: 650
Likes: 0
From: WV
See my next post on that topic. I don't doubt a difference, just were it is coming from.
Elder User
Joined: Apr 2009
Posts: 685
Likes: 0
From: Spokane, WA
JR, I just noticed you sold your V10, is the recent? What's the story? (sorry if I missed it, I obviously haven't read every post).