Ive been thinking, and cannot make up my mind.

[Mr_Joshua101]

lets say you are at 10,000', how much boost pressure would it take to compensate to have the same horsepower as if you were at sea level?
14.7psia is the Standard Atmosphere at sea level. Its 10.1psia at 10,000'. I kinda think it would be 4.6lbs boost to make up for it, but then I lean more toward any positive boost pressure and you are at or above sea level hp. Because NA engines work off vacuum right? So the minute you change from Vacuum to a positive pressure wouldn't you have made the necessary amount of boost to compensate?
I know its a silly question, but I got in an argument with a guy that said its 7lbs for every 5000 feet, and not I cannot stop wondering. Im kinda obsessive about understanding things. So if you could help me out.... Thanks
Josh

 

[sledRevy]

i heard you loose 3% horse power boosted every 1000 feet dont know if its true

 

[snowmanx]

You lose about 3% every 1000 feet for a N/A sled. From all the post I;ve seen on hear, it seems like you lose aobut 1% on a turbo for every 1000'.

I would say you are pretty close on your estimate. An 800 sled at sea level makes 160 HP.

At 10000', a twin 1000 say makes about 190 at 3#, which I don't even know if you can go that low, compensting for my theoretical 1%loss, is still 171 HP at 10000 feet.

That's just my guess, no mathematical equation involve, just an estimate of from the reading I've done on here.

 

[Wheel House Motorsports]

i dont know exactly what the deal is... BUT, i can say that the 7# per 5000 feet is a little off.. i guess.. ill try to make some sense, if it just comes out as jibber jabber, move on.

well, i gave up, i think i could explain to someone in person, but typing out an explenation is DEATH...

 

[canucklehead]

My understanding is 3% for N/A and less for boosted. Here's the math for 10 lbs of boost at sea level and 10lbs at 10k.

Sea level. 14.7 + 10 = 24.7

At 10k. 14.7 loses 3% for every 1k = (10000/1000*.03) = 30% loss

14.7 * .3 = 4.41

so 14.7 - 4.41 = 10.29

Total at 10k is 10.29 + 10 = 20.29

20.29 - 24.7 / 24.7 = 18% loss.

Only 18% loss versus 30% for N/A. The difference changes at all elevations. The other problem with N/A sleds is that they don't have a boost controller.

 

[Mr_Joshua101]

I found this some how on google. I have searched this kinda stuff for months and never seen this sight. But it was the first one in the search this time. It has a pretty logical explanation.

"Does a Turbo lose power with altitude? Yes!

Atmospheric Pressure = 14.5 psi, Boost = 10 psi, Total Pressure = 24.5
Atmospheric Pressure @ 9000 feet = 10.5 psi + Boost of 10 psi = Total 20.5 psi
Approximate Pressure Loss = (24.5 - 20.5) = 4.0 (4.0/24.5) = 16.32 % @ 9,000 feet"

So percentage of boosted hp loss per altitude is directly related to total #s boosted. The more you boost the less you loose percentage wise. According to this guys theory, witch seems rational. Still don't know what you have to do to get the N/A hp numbers from how many ever pounds of boost. Guess I would just have to do the math and find the numbers that equal 14.7psia.

This guy had all kinds of info on his sight. In case you are interested in the charts and what not here is the address.
http://www.2-stroke-porting.com/
his sight is kinda not easy to navigate here is the page where I copied and pasted that math stuff from.
http://www.2-stroke-porting.com/altiden.htm

 

[badass1000]

I did a bunch of reasearch 3 or 4 years ago and it turned up 3% per 1000' na and .3% per 1000' turbo. I know on my na motorcycles it is a huge change from 3000' to sea level. around 3 tenths in a 1/4 mile. Not very much of a change on my turbo motorcycles. I have made my last pass at sea level and first pass at 2,800' with no changes in my boost, fuel controller, and clutch setup and was .04 seconds slower at elevation.
Tired of argueing on all the other posts discussing this. This will be my only post.

Forget all the math. You want proof... cut and paste from a post from VOHK:

That question is so misunderstood and even more likely to have the answer misinterpreted than almost any other question on the forums. The principle consideration when faced with the "to turbo or not to turbo" question is rooted in "actual" or "observed" horsepower. For example a 2009 M8 boasts a 140+ SAE HP rating (SAE is an acronym for Society of Automotive Engineers and as applied to HP was meant to standardize the system of measurement to insure all entities were reporting a comparable number), so at 60 degrees F, 0% humidity and 29.92 inches of mercury (basically death valley on a cold January morning) that M8 will make that power. However that same M8 at my shop on an average fall day made an actual 111.3 HP which when correct to SAE Standards was 140.8. So now consider the same unit with a Boondocker pump gas kit later that same day made 192 actual HP at 7.8 PSI. Of course minor differences in baro and temp were apparent however insignificant to the point. The real issue is a naturally aspirated M8 Ported, piped, with an intake, billet head, v force reeds and whatever else you care to throw at it, will build less than 135 actual HP at altitude though it can be boasted as a 170+ package... That leaves little to the imagination with respect to the "no BS how much horsepower" question. So now consider race gas kits with mild modifications pushing up-wards of 16 PSI capable of 300+ actual HP. Sort of makes you feel silly screwing around with those reeds and heads and whatever else you may have been considering doesn't it? Kind of like that big bore guy that says "turbo bla bla... my 1200 with twins is 230 HP and will smoke one of those pump gas turbos" Not up here it won't! in fact at 12k' it won't even mount a challange... So the core issue is one of altitude, if you ride high don't waste your money on anything else. BD has a chart that loosely illustrates turbo power potential, http://www.boondockers.com/flyers/wh...kit_ac_low.pdf



I believe I read somewhere that his dyno is at 7,000'. In short a stock m8 made 111hp uncorrected on his dyno. Same sled made 192hp uncorrected with 7.8lbs of boost on the same dyno on the same day.

 

[Wheel House Motorsports]

that is a very usefull set of info.. expecially cuz it has uncorrected dyno numbers at elevation. makes good sense of the situation.... actual hp vs observed is the name of the game.

 

[CBX]

lets say you are at 10,000', how much boost pressure would it take to compensate to have the same horsepower as if you were at sea level?
14.7psia is the Standard Atmosphere at sea level. Its 10.1psia at 10,000'. I kinda think it would be 4.6lbs boost to make up for it, but then I lean more toward any positive boost pressure and you are at or above sea level hp. Because NA engines work off vacuum right? So the minute you change from Vacuum to a positive pressure wouldn't you have made the necessary amount of boost to compensate?
I know its a silly question, but I got in an argument with a guy that said its 7lbs for every 5000 feet, and not I cannot stop wondering. Im kinda obsessive about understanding things. So if you could help me out.... Thanks
Josh

Visit http://www.turbobygarrett.com and you'll be able to answer all of your questions.

Here's the thing to remember. A turbo isn't 100% effiecent. If you measure Lbs. of air, the calculations are more exact. PSI of air really isnt that important (it is...kinda) Lbs of air or Mass Air is what really matters.

To answer your question, you would have to take into account how many lbs of air you need at 10k to get the same lbs of air at sea level.

Do a seach under my username and you'll find a topic called intercooler math. It has all of the formula's you'll need to find what your looking for once you know what turbo you have and how efficent it and your plumbing is.

 

[8ooho]

A turbo only adds to atmospheric pressure 10# at sealevel 14.7 +10 =24.7 at 10000 10.3 + 10 = 20.3 same conditions. thats why you can run lower octane at elevation.

 

[Mr_Joshua101]

CBX
Thanks for the info there. there is enough in that article to keep my mind busy for a few hours. Reading all that 101 102 and 103 turbo information on the garrett sight is what got me thinking about this. I was just hoping for an easy answer if I asked the question on here. Actually one of the reasons I asked the question on here is I am wanting to drive something boosted so badly I started a project on a 93 firebird lt1 car. Since it don't look like my kit for my sled will get to me before all the snow melts, I picked up this car to play with. Right now I am trying to figure out how much boost I can run with out getting a dynotune done on the car. I heard that 4lbs is all I could go before the stock computer couldn't deal with it any more.
@ badass1000
That Vohk post you shared is the reason I decided to buy a kit from R&D instead of an 860 kit. I read that whole thread a few times this fall. My question though was how much boost at 10000' does it take to just get to sea level hp. There is no question in my mind that a turbo is the way to go, like vohk was trying to say.
I am still trying to figure my question though. I hope that if I fallow some of the directions that cbx pointed me in, I will find the answer. Unless some one can just tell me.
Thanks for y'alls help so far.
Josh

Visit http://www.turbobygarrett.com and you'll be able to answer all of your questions.

Here's the thing to remember. A turbo isn't 100% effiecent. If you measure Lbs. of air, the calculations are more exact. PSI of air really isnt that important (it is...kinda) Lbs of air or Mass Air is what really matters.

To answer your question, you would have to take into account how many lbs of air you need at 10k to get the same lbs of air at sea level.

Do a seach under my username and you'll find a topic called intercooler math. It has all of the formula's you'll need to find what your looking for once you know what turbo you have and how efficent it and your plumbing is.

 

[8ooho]

Maybe that was blunt but that is what it comes down to. Can you imagine what the temp is going to the carbs? To many variables. No inner cooler? (Heat)

 

[badass1000]

don't mean to sound like a dick, but all I got to say is who cares? I don't. No reason to turn the boost down to make sea level hp at elevation.
I am runing 7.2lbs of boost on pump gas at the elevations I ride at. It makes way more power then any stock sled. Makes more power then any NA xp. Anyone who wants to argue that send me a pm and come ride with me.
Some na xp's may be able to out climb me in deep pow because I am only runing a stock 154 track and stock skid. I would like to try it, but don't know if my sled currently will outclimb a 174x3 xp with a really good runing na engine. I know I outclimb 163 xp's by a good margin with pipe, head, clutched, etc.
if their is a little bit of a run at it or I can get my ground speed up a little before the climb it makes a huge difference. If my ground speed gets down too much (like almost stoped) and I pin it on a steep hill it will just point strait up.
I was going to put a 162x2.5 challenger extreme on it, but by time I totaled up the drivers, track, rails, and tunnel extension it was almost $2000. I would love to do it, but top priority for me is to make sure I get my new turbo bike done. I want to see how deep I can get into the 7's this year and see if I can run 190mph in the 1/4 on a street legal bike I ride around town once in awhile. I have already spent alot on the sled and all new gear this year. Need to quite spending money on the sled and work on the bike.
I got some reed boot girdles from turbo performance, new avid drivers, and manual boost controller. Drivers should be here by the weekend. Can't wait to run 10lbs of boost or more.
I will run 10lbs and 2 gallons of $5.75 a gallon sunoco 105 mon fuel per tank of 91 octane premium. I know big bore guys that run 50/50 and are not even close to a pump gas turbo.
I am just saying that at elevation their is no comparison turbo vs na.

 

[8ooho]

Badass1000 thats cool u have the reliabilty of an 800 at sealevel way more power than a 860 at elevation if setup is right

 

[Mr_Joshua101]

let me explain why I care
I am kinda like you and have moved on from spending on the sled this year.
That TA turbo I am wanting to build has a problem. The PCM for the 93 cars and not flash based. So to run a tuner program on it I have to buy a piggyback chip and an adapter and other stuff to tune the car. I am not sure how to do that as of yet, so I figure the stock map should be able to handle sea level hp.
The reason I asked the question here is because I don't know any turbo car people yet.
Now eventually I will get confident enough to work over the PCM and run 16 psi, but for now I CARE what I can do safely with a stock PCM.
I am like you, if I can run 7lbs then why worry about turning down the boost. But I am not sure, in the care, what I can run.
Sorry that this tread annoyed you, I just didn't think it was a naughty thing to ask a turbo question on a turbo forum.
Thanks again guys
Josh

don't mean to sound like a dick, but all I got to say is who cares? I don't. No reason to turn the boost down to make sea level hp at elevation.
I am runing 7.2lbs of boost on pump gas at the elevations I ride at. It makes way more power then any stock sled. Makes more power then any NA xp. Anyone who wants to argue that send me a pm and come ride with me.
Some na xp's may be able to out climb me in deep pow because I am only runing a stock 154 track and stock skid. I would like to try it, but don't know if my sled currently will outclimb a 174x3 xp with a really good runing na engine. I know I outclimb 163 xp's by a good margin with pipe, head, clutched, etc.
if their is a little bit of a run at it or I can get my ground speed up a little before the climb it makes a huge difference. If my ground speed gets down too much (like almost stoped) and I pin it on a steep hill it will just point strait up.
I was going to put a 162x2.5 challenger extreme on it, but by time I totaled up the drivers, track, rails, and tunnel extension it was almost $2000. I would love to do it, but top priority for me is to make sure I get my new turbo bike done. I want to see how deep I can get into the 7's this year and see if I can run 190mph in the 1/4 on a street legal bike I ride around town once in awhile. I have already spent alot on the sled and all new gear this year. Need to quite spending money on the sled and work on the bike.
I got some reed boot girdles from turbo performance, new avid drivers, and manual boost controller. Drivers should be here by the weekend. Can't wait to run 10lbs of boost or more.
I will run 10lbs and 2 gallons of $5.75 a gallon sunoco 105 mon fuel per tank of 91 octane premium. I know big bore guys that run 50/50 and are not even close to a pump gas turbo.
I am just saying that at elevation their is no comparison turbo vs na.

 

[fredw]

we were out last weekend, with a turbo dragon, turbo nitro, and turbo m8, from what they said all three were running around 10lbs, i had the biggest track othere than m8, he had 174 by 2.5

the na xp with nitrous was quicker and higher on most hills

 

[badass1000]

No problem.
Believe me. The internet is your best friend. Search for some forums on your car and read up. I am sure their will be several posts from people with the same issue as you or make a post and I am sure several will be happy to answere all your questions. Just a quick google search poped these up.

http://camaroforums.com/forum/index.php?

http://www.firebirdnation.com/forums/

http://www.fbodyonline.com/forum/

http://www.ls1lt1.com/forum/index.php

Sounds like a fun project.

let me explain why I care
I am kinda like you and have moved on from spending on the sled this year.
That TA turbo I am wanting to build has a problem. The PCM for the 93 cars and not flash based. So to run a tuner program on it I have to buy a piggyback chip and an adapter and other stuff to tune the car. I am not sure how to do that as of yet, so I figure the stock map should be able to handle sea level hp.
The reason I asked the question here is because I don't know any turbo car people yet.
Now eventually I will get confident enough to work over the PCM and run 16 psi, but for now I CARE what I can do safely with a stock PCM.
I am like you, if I can run 7lbs then why worry about turning down the boost. But I am not sure, in the care, what I can run.
Sorry that this tread annoyed you, I just didn't think it was a naughty thing to ask a turbo question on a turbo forum.
Thanks again guys
Josh

 

[badass1000]

we were out last weekend, with a turbo dragon, turbo nitro, and turbo m8, from what they said all three were running around 10lbs, i had the biggest track othere than m8, he had 174 by 2.5

the na xp with nitrous was quicker and higher on most hills

Sounds cool. I have read alot of your posts and you have alot of time and money in that sled. Sounds like it runs great. What elevation do you ride at and what fuel do you run?

Looking forward to hearing how it runs compared to high roller customs sled if you two get together to ride.