Theoretically there is a 33% gain with 5 pounds of boost, this assumes no change in air density from heating due to compression (i.e. intercooler). I am going to guess a 25% peak increase in power and torque, but more importantly a much wider powerband which translates in to a greater usable power across the board.
Bolt on turbo kit (3 Viewers)
- Thread starter scottryana
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Theoretically there is a 33% gain with 5 pounds of boost, this assumes no change in air density from heating due to compression (i.e. intercooler). I am going to guess a 25% peak increase in power and torque, but more importantly a much wider powerband which translates in to a greater usable power across the board.
Being from AZ I think that's a fine idea! Maybe a chili roaster while were at it!I need to develope a Turbo Burrito Warmer
- Thread starter
- #2,403
Elevation does not effect a turbo vehicle as long as the turbo is not maxed out (which this one will not be). So the turbo should be able to supply the 5-6psi of boost at all elevations which I have mentioned before is something the SC'r can not do.
To answer the other part of your question we have to take some serious armchair quarterbacking and leniency with the numbers using what is probably fairly close but still all educated guesses.
Guess #1 an average 80 is probably around 5300lbs, and looses 35% in drivetrain loss, with a turbo at 6psi the gain at the crank is likely 70-80hp. So lets call that 5300lbs and 183-189awhp, so approximately 28.5lbs/hp at any elevation.
Now Guess #2, a 200 series is likely around 6400lbs, has 381hp and looses 26% in drivetrain loss, and 3% with every 1000ft of elevation gain.
0ft = 6400lbs / 281awhp = 22.7lbs/hp
1000ft = 6400lbs / 272.5awhp = 23.5lbs/hp
2000ft = 6400lbs / 264awhp = 24.2lbs/hp
3000ft = 6400lbs / 255awhp = 25lbs/hp
4000ft = 6400lbs / 247awhp = 25.9lbs/hp
5000ft = 6400lbs / 238.9awhp = 26.8lbs/hp
6000ft = 6400lbs / 230awhp = 27.8lbs/hp
7000ft = 6400lbs / 221.9awhp = 28.8lb/hp
Soooo with a lot of guessing and estimating and fudging the numbers, not taking into account things like wind resistance, gearing, etc. I would guess the break even point for a turbo 80 to feel like it has the same power to weight as a NA 200 would be in the 6000ft of elevation range.
To answer the other part of your question we have to take some serious armchair quarterbacking and leniency with the numbers using what is probably fairly close but still all educated guesses.
Guess #1 an average 80 is probably around 5300lbs, and looses 35% in drivetrain loss, with a turbo at 6psi the gain at the crank is likely 70-80hp. So lets call that 5300lbs and 183-189awhp, so approximately 28.5lbs/hp at any elevation.
Now Guess #2, a 200 series is likely around 6400lbs, has 381hp and looses 26% in drivetrain loss, and 3% with every 1000ft of elevation gain.
0ft = 6400lbs / 281awhp = 22.7lbs/hp
1000ft = 6400lbs / 272.5awhp = 23.5lbs/hp
2000ft = 6400lbs / 264awhp = 24.2lbs/hp
3000ft = 6400lbs / 255awhp = 25lbs/hp
4000ft = 6400lbs / 247awhp = 25.9lbs/hp
5000ft = 6400lbs / 238.9awhp = 26.8lbs/hp
6000ft = 6400lbs / 230awhp = 27.8lbs/hp
7000ft = 6400lbs / 221.9awhp = 28.8lb/hp
Soooo with a lot of guessing and estimating and fudging the numbers, not taking into account things like wind resistance, gearing, etc. I would guess the break even point for a turbo 80 to feel like it has the same power to weight as a NA 200 would be in the 6000ft of elevation range.
@scottryana and other turbo gurus:
Elevation power loss for naturally aspirated motor is roughly 3% per 1000 ft.
Is it different (less loss per 1000 ft) for the 6-7 psi (?) of this kit?
In other words is there a point going up Vail Pass the turbo 80 will pass a 200?
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HDJdreams
SILVER Star
Thanks!
I am around 5000, so it could be pretty close.
I am around 5000, so it could be pretty close.
jjdeneen918
SILVER Star
Is that a rivet, lower right, of the oil line fitting?!
NLXTACY
Wits' End
Likely button head
So any update on the HP dyno from yesterday?
NLXTACY
Wits' End
You do realize it’s 8:30am right?
alia176
SILVER Star
Joey is still getting his coffee...
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Oh yeah. West Coast time. Been up for hours!
inkpot
SILVER Star
With all this anticipation, you think he can actually sleep?
646.
NLXTACY
Wits' End
NLXTACY
Wits' End
And honestly, I want everyone to be happy with this setup and there to be zero issues. I know it’s damn near impossible but still gotta try
@scottryana and other turbo gurus:
Elevation power loss for naturally aspirated motor is roughly 3% per 1000 ft.
Is it different (less loss per 1000 ft) for the 6-7 psi (?) of this kit?
In other words is there a point going up Vail Pass the turbo 80 will pass a 200?
I don't think there is a point you'll pass a 200 unless you do some creative add-ons to the kit
But turbo essentially removes power loss due to elevation from the equation. Example: say the volume of air moving through the engine at sea level is 10. At high altitude, it might be 7. Even if only running 1psi, a turbo will bring that number back up to 10+ as soon as you have positive manifold pressure. So essentially high-altitude power loss does not exist as long as you're in boost. That is my totally non-scientific explanation, and I'm sure someone else can answer the question better.
:edit: skipped a page, Ryan's post above is the scientific answer
My understanding is that a turbo provides boost relative to the atmospheric pressure, not absolute.
At 6000' the atmospheric pressure is ~11.8psi, so with 6psi of boost = 17.8psi total
At sea level the atmospheric pressure is ~14.7psi, so with 6psi of boost = 20.8psi total
I'm sure there's a way to build a wastegate that compensates for altitude, who knows maybe one already exists... Its been a few years since I sold my turbo vehicles so I'm a bit out of the loop on the newest tech.
No matter what you do... a third of the people will be happy with it. A third of the people will find something to bitch about. It’s that last third you can actually work on.
And honestly, I want everyone to be happy with this setup and there to be zero issues. I know it’s damn near impossible but still gotta try
My understanding is is that the boost pressure is just boost pressure inside of the intake manifold especially against the manual spring wastegate as the spring’s strength doesn’t change based on elevation. Or shouldn’t change much based on external pressure as the valve itself is pretty small.
- Thread starter
- #2,419
This is what would happen with a roots type supercharger since it is only able to compress a percentage of air per revolution so if the air density gets less at altitude you get less absolute pressure at altitude. With a Turbo you are always targeting absolute pressure regardless of altitude, you can get similar results with a centrifugal supercharger but it is still RPM limited by pulleys, while the turbo if it isn't sized to max out at sea level should always be able to spin faster to supply absolute manifold pressure.
The key to this would be to size the turbo for the elevation requirement. For example if I was sizing a turbo that had to run at Pikes Peak and must maintain max boost the entire run. And I needed it to run say 14.7psi at sea level and 14.7psi at 14,000ft. It would absolutely change where I plotted my boost on the compressor map.
You can see this for yourself if you want to play around with BW Matchbot, just pick an engine size, boost level and then change the elevation and you can see how easy it is to end up off the compressor map at altitude.
BorgWarner MatchBot
The key to this would be to size the turbo for the elevation requirement. For example if I was sizing a turbo that had to run at Pikes Peak and must maintain max boost the entire run. And I needed it to run say 14.7psi at sea level and 14.7psi at 14,000ft. It would absolutely change where I plotted my boost on the compressor map.
You can see this for yourself if you want to play around with BW Matchbot, just pick an engine size, boost level and then change the elevation and you can see how easy it is to end up off the compressor map at altitude.
BorgWarner MatchBot
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- Thread starter
- #2,420
And for those of you that are visual learners. Here is what it looks like. This graph is called a compressor map. You want your turbo to operate at the boost, RPM's, elevations and temperatures that will ensure the plots are all on the "island" on the compressor map.
So first map is the Turbo I picked at 75f, 0 ft of elevation and 7psi of boost.
The second map would be the same turbo at 20f and 14000ft with the same boost.
And finally what you would see if you picked a turbo that was too small to provide the boost required this turbo is a size smaller also at 14000ft same boost and temp. You can see the plots clearly off the compressor island.
So first map is the Turbo I picked at 75f, 0 ft of elevation and 7psi of boost.
The second map would be the same turbo at 20f and 14000ft with the same boost.
And finally what you would see if you picked a turbo that was too small to provide the boost required this turbo is a size smaller also at 14000ft same boost and temp. You can see the plots clearly off the compressor island.
