Hi everyone. i've been assigned to work on a non-typical turbo project for a Plug-in Hybrid Electric Vehicle group at my university. To sum up the purpose, when the car is at high altitude and the atm pressure is lowered to possibly 0.6 atm, the turbo will increase pressure back to sea level conditions at 1 atm. At sea level tho, they just want to maintain 1 atm conditions and so they plan to use an alternator to capture the thermal energy of the turbo to electrical energy to store in the large batteries. Ideally, the alternator will be enough to keep the pressure at 1 atm. But, in case it can't, they don't want the boost to rise and damage the engine.

So, i'm wondering how i can limit the intake pressure to a max of about 1.2 atm, which i think is about 3 psi of boost(ususally people want to raise not lower boost). I've read that u can lengthen the wastegate rod(?not sure how exactly) to lower boost but i'm not sure how much adjustment is possilble.

Please give me any solutions u can. Also, please give as many details as u can like how to connect stuff,what parts do i need,etc, cuz I know the basic theory about turbos, but not really good at exactly how everything fits and where to get parts for cheap.

Thx in advance for any help

PS. the engine is a 1.5L Prius engine and the turbo is a Garrett GT1241(not sure wat rating the wastegate is tho) (http://www.turbobygarrett.com/turbob...1-756068_1.pdf)

 

Use an external wastegate with a 3psi spring.

 

do u know where i can get it? most i've seen have at least 6psi

 

egay has some knockoff springs for there knockoff wastegates. just search around and be sure to tell the seller you want a 3 psi spring with the wastegate. there famous to throw in any spring they feel like. not sue how you would regulate the boost at dif. altitudes though

 

i found 3.63 psi ones on ebay but not sure if they fit. any easier cheaper solutions ... ones that can use the existing wastegate on the turbo? does anyone know what wastegate size/rating i have and how to adjust and how much adjustment is possible?

 

that internal wastegate on the turbo isnt made to be dissasembled, so I really wouldnt try it. Just keep an eye out, you can sometimes find knockoff wastegates for less than $50. Using an external gate would mean you would have to have an extra flange for it on the manifold too. If you could get you're wastegate apart without dammaging it you could grind/cut down the spring a little.

 

carb spring.

 

1 ATM = 14.7 ATM

I might be dumb but wouldn't you want more like 5-6 PSI then?

you need to make up .4 ATM when at high altitude which would be 5.88 PSI right?

 

hmm...interesting. yes boost would be 5.88 psi on a pressure gauge at high altitude,but the absolute pressure to the intake manifold would be 1 atm or 14.7 psi.

So i guess my next question is if a wastegate is rated at 6 psi, does that mean whenever the gauge reads 6 psi boost it'll open regardless of what the atmospheric pressure is, or when the absolute pressure is 14.7 + 6 = 20.6 psi?

 

Right. Your problem is the vehicle does not know if it's at sea-level or 5,000 ft. At high altitude this will work exactly how you want it, but there's nothing to stop it from making boost at sea-level (you could always lay off the gas, but that doesn't seem to be the point of your project).