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Garrett T25 Turbo Build

Discussion in 'The Garage' started by plattey, Jan 8, 2013.

  1. plattey

    plattey XS650 Addict

    I have been contemplating a turbo build for a while and here's my progress so far. The turbo is a Garrett T25 from a 2nd gen mitsubishi eclipse or eagle talon (same thing, both dsm). This will be a low boost engine (about 5-6psi max), currently higher cr than stock (9.4:1 due to a thinner headgasket and no basegasket) and probably run e85. Leaning towards blow through carb setup, but a draw through setup would eliminate a bov and fuel pump. Since these engines don't create oil pressure like the dsm engines, a separate oil pump and system will be used to keep the turbo journal bearings alive. As for the crank, upgrade the rods and weld the crank and pray that it holds:D

    Here's what I have done so far. The manifold was made from a pair of hacked TT pipes from hoos racing. Mandrel bent 1.75" pipes. All I have is a vintage Forney stick welder so the welds aren't the best to look at but the manifold will get wrapped to keep gas temps up. The manifold had to be split for a slip joint in order to get it on and off the engine.

    Compressor view.jpg

    Turbo and manifold.jpg

    Front brake side view.jpg

    Front view.jpg
    Last edited: Feb 25, 2013
  2. Dead Roman

    Dead Roman XS650 Addict

    Let me know hoe the setup runs when you are finished. Im gonna do the same thing excet suck through, and imma try to hide the turbo under the seat.
  3. Im liking that turbo buil! Also liking you signature!
  4. plattey

    plattey XS650 Addict

  5. jd750ace

    jd750ace Front Toward Enemy

    Interesting stuff Plattey. Don't sweat the welds. If you can do that well stick welding thin-wall tubing, you'll be fine! If I did it, that shit would be a puddle on the floor!
  6. Pov76

    Pov76 XS650 Addict

    I love turbo stuff!!

    Posted via Mobile
  7. Time for some real brakes me thinks,
  8. plattey

    plattey XS650 Addict

    Was able to tackle clocking the turbo last night. Both the turbine and compressor housing are clockable, but with age, heat cycles, and rust, the turbine housing was thoroughly seized to the center housing. Luckily the oil feed and discharge are....uhhhhh almost in a vertical position after mounting the turbo. The compressor side was a pain to clock without a big set of snap ring pliers but was able to clock the compressor housing into a better position. After clocking the compressor housing and re-positioning the wastegate actuator, this is where the build stands so far.
    Jan 9 2013 a.jpg

    Jan 9 2013 b.jpg
    Last edited: Feb 25, 2013
  9. Just thought I'd drop some ideas in here, food for thought:

    The way you currently have the manifold build has the two runners at vastly different lengths...considering the firing order of the xs650, I think it's going to yeild a very funny spool-up pattern. if the pistons didnt travel up and down simultaneously it would be less of a factor, but I'd be doing the best I could to make the runners as close to equal as possible....

    also, I'd try to flip the turbo itself 180* so the exhaust flange faces rearward for a few reasons:

    -having the exhaust outlet facing forward is going to make the downpipe effectively air-cooled.....this will have a detrimental effect on exhaust scavenging, as well as make the heat/cool cycles on the exhaust tubing more extreme....which will cause premature thermal breakdown of the steel. If it were facing backwards the scavenging would be much much improved, which would help the turbo spool faster and lag less, in addition to allowing it to recover quicker from off-throttle during gear changes.

    -Having the compressor face forward with a quality/sturdy cone filter will effectively create a ram-air effect into the compressor wheel as you ride. In addition to that, it will be getting the coldest air possible because it will be ahead of the motor rather than next to it, and colder air is more dense (makes more horsepower)

    I know the elbow on the compressor outlet points the wrong way to flip the turbo around, but you could either cut it and re-weld it 180* around, or cut it off and use a silicone 90* coupler to aim it where you want.

    That's just my $.02 without getting into fueling for it, that's a whole 'nother conversation.

    In the end, what you have mocked up will "work", Just trying to mention ways to improve it ;)
  10. plattey

    plattey XS650 Addict

    Thank you for your insight:) When I tried to find a location to mount the turbo, I wanted to mount it behind the front wheel just like how cowboy3669 (http://thexscafedotcom.wordpress.com/2011/06/23/xs650-cowboy3669-dragracer/) did it. But I didn't want to make the handling any worse than it is so extending the front forks to make room for the turbo wasn't considered. Then I thought about mounting it off to the side as you described: compressor facing forward and turbine facing rearward. Then it just came down to packaging issues between mounting the turbo forward or backward, and mounting the turbo backward made the turbo and the manifolds more compact. As for spooling, I guess we'll have to wait and see.
    To keep the turbo and the downpipe hot and aid in scavenging, would a turbo blanket and exhaust wrap help in that area? I know it's just a band-aid to help the issue, but it would mean that I could keep the current setup.
    Oh, here's a thought to go with the backward theme:laugh:, who was it in the beginning that decided that most motorcycle parallel twins, triples, and fours should have the intake facing rearward and the exhaust facing forward? :laugh:
  11. A turbo blanket and exhaust wrap would help, but like you said it's a bandaid (and rather displeasing aesthetically IMO).

    on the backward theme, in the beginning the exuast was put at the front and the intake at the rear so that the heat from the exhaust is as far away from the rider as possible, and the intakes would see the least turbulant air possible by being enclosed inside the frame behind the bulk of the rest of the bike. The pros of scavenging and colder air are merely multiplied exponentially under boost, which is why I made mention of them....

    I also feel like that t25, while small for a CAR engine, is quite a bit oversized for a bike....

    If I were to boost a bike, I'd go with something like this little guy:

  12. plattey

    plattey XS650 Addict

    I've looked at that turbo too :laugh: The reason I'm using a T25 is pretty much because I have one :laugh: I ported and polished a set of gm3800 heads for a good friend and he paid me with the turbo :)
  13. wannabridin

    wannabridin XS650 Junkie

    i hope you're considering a different air filter. that one doesn't look up to the job at all.

    also be careful if you switch the compressor forward. the ram air effect is true, however if will be quite turbulent air, and while colder, might cause cavitation effects on the compressor blade tips and lower efficiencies. just my $.02
  14. good points....

    I'd want to build some type of duct that mounts to the compressor housing and uses some type of anti-filter-ingestor that would also keep down turbulance of the air....I've seen a few horror stories of cheap cone filters that a turbo sucked apart and ingested (blowing the compressor wheel to smitherines)
  15. bobber_xs

    bobber_xs XS650 Addict

    do you keep the stock wastegate?
    or goin to use external?
  16. plattey

    plattey XS650 Addict

    That's a filter I had laying around....just being used to keep foreign objects out of the compressor for now :laugh: I'm gonna be running a k&n filter or uni foam filter. For now gonna stick with the internal wastegate.

    Cowboy, thank you for your blog, it has been very helpful so far. My questions about your bike are:
    1. In your draw through setup, while the engine is under vaccuum, is oil getting drawn past the compressor oil seal? Or have you built the turbo for the draw through setup?
    2. With oil feed being tapped from the engine, how's the rocker box doing after so many runs? Also, I was thinking of running a separate oil system to feed the turbo. I was thinking of using something like this to pressurize the oil:
    3. Lastly, the bottom end of the engine. Are you running race rods and a welded crank?
    Thanks Cowboy!
  17. plattey

    plattey XS650 Addict

    Oh! Another thought, how bad was the turbo lag on your bike without nitrous? Your current turbo is from a 2.2L ford probe gt engine? I found a compressor map for the ford probe gt turbo but the units are in volumetric flow instead of mass flow. I'll have to crunch some #'s to make the conversion and compare the ford comp map and the t25 map.
  18. That is actually a blog by Vernon Blair he asked some questions and put that together.
    The turbo is just way I took it off the car,no carbon seal. It does pull some oil but not a problem with it being a dragbike. Could be a problem on a street bike.
    The cam and rockers are doing ok. Some of the bigger dragbikes are using a separate system. Thought about it, but the turbos are lasting.
    The crank is welded, but it may be hard to believe but the rods and pistons are stock 447 parts. Even the cam is a stock 447 unit,for now.
    Lag would be a problem without the nitrous,the turbo is for a 2200 cc engine. The bike was set-up with the nitrous from the beginning. So lag is(was) not a problem.
  19. Plattey,

    I don't want to highjack your thread but I thought I would post some inspiration for you.

    My brothers and dad are in the process of building a Land Speed Record (LSR) bike which is plumbed with a turbo.

    You can find his progress on facebook here http://www.facebook.com/MondayLsr and here http://forums.sohc4.net/index.php?topic=114700.0

    My brother Matthew who is doing much of the mechanical work is quite talented and although he is not very familiar with this type of bike; he is quite experienced with turbos and tuning for turbos so he may be able to give you pointers to help guide you if you have questions.

    I'll keep watching to see how your build comes along.


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