New guy with 2 projects

[GrantB]

Hello, i just found this site this morning and all i can say is WOW. I see alot of awesome builds going on and alot of knowledge in here.

My name is Grant and i actually just moved to the South Bay area from Indianapolis.

I have a NOS Tiernay TT10. Its a replacement turbine so i believe it has 0 operational hours on it, looks brand new. I plan on making an ecu for it from an arduino some time soon and using it to power a pit cart.

I have plans to build a "hypercharger" with a Borg Warner s480 or something similar. A hypercharger is basically a turbine with 2 combustors. One is a traditional combustor, and the other one is an internal combustion engine. The goal is to have full boost on tap for the internal combustion engine at all rpm's so there is zero lag. I think i have solved alot of the possible issues in my head but im sure there will be ALOT of challenges. Since this project will be used at around 14k feet i'd appreciate any feedback on a large turbo 80mm plus with a high pressure ratio.

I am also currently trying to setup a Kitamura MyCenter 4 to help with my projects. Its a nice 3 axis mill and like always have bit off more than i can chew lol.

Thanks for the space,
Grant

[racket]

Hi Grant

Welcome to the Group :-)

Sounds like an interesting project you've started .

When you say "80mm plus" are we talking inducer or exducer on the comp , we generally talk inducers here ??.

What sort of pressure ratio are you after ??

Cheers
John

[GrantB]

Yes the inducer.

Somewhere around 5:1 is nice any lower than this and im worried it won't be able to make enough pressure for my Internal combustion engine. I also admit im kind of new to the non automotive type turbos, not many make that much pressure from what i have seen.

[racket]

Hi Grant

5:1 is a very high PR ................that ~60 psi of boost , you running a diesel IC engine ................the Garrett GT5533R will run to that pressure only because of its 47 Trim configuration, but at a poor 68% efficiency , most automotive turbos have comps with >50 Trims and will struggle to get to any more than 4:1 .

I notice you want to use this at 14,000 ft , 9.1 deg F and 8.63 psia , sounds like you're interested in Pikes Peak ........................turbos can be "flogged" at altitude , ~5.3% lower rpm will produce the same PR as at sea level .

So will this application require "full boost" at sea level with a consistent PR , or is it going to have a "linear" PR but consistent boost pressure in psia . ....................with sea level rated horsepower up to the14,000 ft critical altitude .

What horsepower at 14,000 ft ??

Cheers
John

[GrantB]

Well you don't beat around the bush do you! Yes this is for my hillclimb car. I feel like the current cars leave some room for improvement in their approach to making power. My idea is to choose a turbo that will provide plenty of pressure all the way to the peak for the power i want and use a secondary combustor to keep it lit.

I probably don't need 5:1 PR with the motor im building but it helps keep my options open i feel. Im shooting for 800hp at the peak and probably a little more at lower altitudes. I think the turbo will be able to produce more boost than the engine will need so the ecu(arduino) will regulate the boost based on the intake manifold pressure.

Thank you for the interest.

[racket]

Hi Grant

LOL...................this is a no crap Site :-)

Ok , 800 hp at 14,000 ft , assuming the "usual" 10hp/lb/min thats 80 lbs/min of air , the GT5533R will do that nicely at sea level at a 3:1 PR , but at 14,000 ft with air density at ~20 cu ft/lb rather than the ~13.3 cu ft/lb at sea level , or ~66% density , that'll mean you'll be needing an "unadjusted flow" of ~121 lbs/min at say 5:1 PR , the GT55 will do that as well .

You probably need to get some info on aircraft turbocharging to double check the numbers , and to see if theres other "variables" that could impact on the horsepower development, but as a rough guide the GT5533R should do what you want .....................at the very worst you might need to reduce the inducer size a tad and sleeve the shroud to lower the mass and move it a bit further away from the surge line .

Cheers
John

[GrantB]

Wow, never looked at the gt55r graphs before!. That is a nice looking turbo. Just checked the price and its up there.

So lets say i need 80lbs/min and at sea level it requires 30psi or roughly a 3:1 pressure ratio. At 14k feet i understand that i would need 30psi at 4:1 pressure ratio(30/.66=45 psi adjusted) which would still be 80lbs/min? A 1:1 RP is atmospheric pressure correct? Im a little confused by my numbers not matching up with yours. I will have to do some more reading on the subject.

And since both the IC and combustor will have electronic throttles(just like the MTU hypercharged tank) the combustor throttle will close based on turbine rpm and boost pressure. This should keep me clear of the surge line i would think. If Turbine rpm's are held(with the combustor throttle) at 87k rpm and boost pressure stays at 30psi relitive (so between 3-5:1 based on altitude) i should be able to stay far away from the surge line correct? Actually i can probably even adjust the turbine rpm by the atmospheric pressure to stay closer to the sweet spot. I really need to re draw my setup and my controls i had in mind.


No need to reply you have already been a big help. And as you can probably guess im trying to convince myself to go with the BW s480 based on price. According to my math it will work but its probably off lol.

[racket]

Hi Grant

We need need to work in absolute pressures not "boost" gauge pressures , so 3:1 =3 X 14.7psia = 44.1 psia , 5:1 at 8.63psia = 5 X 8.63 = 43.15 psia , but because of the lower temps at altitude the density coming out of the comp will be higher ...............these are only rough numbers to get in the ballpark .

As long as the absolute pressure going into the engine stays the same and neglecting slight density differences due to the charge temperature , the mass flow across the engine stays the same and so does the horsepower and the engines cylinder pressures .

A lot of aircraft supercharging works on supplying a set "inches of Hg" absolute to the engine to maintain sea level horsepower to a critical altitude , generally where the supercharger can't supply any more compression, and from that altitude power drops as the aircraft climbs higher .

The pilot might set sea level "inches of Hg " ~30 inches on the throttle gauge with no supercharge , and as the aircraft climbs the controls adjust the supercharger to maintain 30 inches and sea level horsepower .

Do a Google for aircraft supercharging :-)

Cheers
John

[GrantB]

Ok, i have been doing alot of reading and i may be contacting you John for some dimensions for my combustor. I started modeling the combustor but i think its probably going to be to narrow at 3in for the flame tube. But i have been to busy with work and school to do to much research. I will start a new thread for this engine when i get some good info or content like actual progress lol.

And it seems like there are alot of turbine karts around here. I need one too so im going to probably lengthen my laydown enduro kart and put my Tiernay Turbine on it. I will have to work out the clutch and ecu but other than that everything else should be straightforward. I will start a new thread for that soon.

This site is great, lots of great info!

[racket]

Hi Grant

The Tiernay will give you some good experience with turbine behaviour before embarking on your much more complex build :-)

We'll be here when you need some feedback on the flametube .

Cheers
John