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Thread: Turbocharged Single 450cc

  1. #31
    Senior Member
    Join Date
    Feb 2004
    Location
    Costa Mesa, CA
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    773
    Any updates?

  2. #32
    I do, I've been meaning to give an update just just busy at work. Give me a few days to get back on here.

  3. #33
    Sorry its been so long. First Kirk I do wanna say Thanks for all your help and I'm not trying to step on your toes with where I went with this build. Again I really appreciate your help.
    Just a little recap with the Tdo4-9b turbo we made 75hp at about 10-11 lbs at 11,500 rpm redline. We thought the turbo was to big because it was hard to spool. We did add an "air box" or "air chamber" to the TB about 8 times the size of the motor so about 200ci-in. That helped a ton with the power band but did nothing for spooling. I do have that chart but cant figure out how to post it here?
    So for a long wile there I was on the look out for a used gt12 never found anything, but then one day I ran across a gt15 for a song so I thought why not. I fabed it up "My fab time is free". This turbo sucked to be honest, 56hp at the same 10-11 lbs redline and the motor just didn't want to rev there. When the bike was first fired up it was pig rich, bad sign. It would barley run. Had to take out fuel everywhere. The gt15 didn't really spool any sooner and was prety much lbs for lbs with the td04 threw the rpm range.
    The motor/dyno guy says he's 99% sure the exhaust side is just to small. Keep in mind he's not a turbo junky, just speaking from the motors he's built. He's very open minded. So this puts me back at with what little info I have found and ppl I have talked with that maybe I do need to go with a gt20 or gt22. They say the "singles" just put out one big pules and theses small turbo turbines just can't flow it? So maybe even the td04-9b is still to small on the exhaust side?
    Kirk after reading this you still think the gt12 is the way to go?
    On a side note my wife and I are expecting our 2nd child. Crossed fingers for a girl

  4. #34
    Senior Member
    Join Date
    Feb 2004
    Location
    Costa Mesa, CA
    Posts
    773
    Cool man, congrats!

    Yeah, without digging into about 30 more questions, I don't know how to help you troubleshoot the system. It's possible that you need a larger turbine side... and that's ok. If you're set on the bigger turbo, there are other ways to mitigate the spool issue. Are you already using a wastegate controller? Have you considered a small shot of nitrous to get the turbo up to speed faster on the bottom end? Ignition retard as a form of anti-lag could help too.

    -Kirk

  5. #35
    Thanks
    To be honest I'm really not set on a larger turbo, everything you have said about the gt12 makes scents to me. But the only change made was the turbo, so if I knew nothing about nothing I'd say the turbo is to small. I mean is it possible that the exhaust side is to small and just cant flow it? Doesn't/isn't one big large exhaust pulse from 432cc require a larger flow/turbo then say a 4 cylinder 432cc motor? I dunno maybe I've done something wrong and its staring us in the face?
    At this time where just using the stock WG sometimes we add a helper spring,most times its worth about 2psi so no wastegate controller. Nitrous isn't something I really care to mess with. Right now we haven't done anything with the Ignition, all stock settings we can tho.

  6. #36
    Hey guys I am in the middle of building my cannondale 450 and have a VZ21 turbo kit I have built.I have some questions on how to tune this the best and what map sensor to use . I have A GP CONTROL TO MAKE THE CHANGES ,AND HAVE 2 725CC INJECTORS FOR IT AND WILL BE RUNNING E85 ETHANOL. I would like to talk to someone that has done this with a cannondale. please call me 619 607-7333 thanks Ike the bajaracer

  7. #37
    It was nice talking with you Ike.

  8. #38
    Just my $0.02 after reading this and now reviving it from the dead is that the single large exhaust pulse is creating a turbine flow/WG control issue from the 'small' turbine. The compressor is spot on by the numbers but the turbine's small size, I think is the issue. It's a case like this where I wonder how an exhause 'plenum' would help to reduce the exhaust pulse strength and make exhaust flow rate through the turbine more linear...of course if you could keep the flow only going toward the turbine

    I'd love to see data of exhaust pressure, turbo speed and pre-intercooler boost pressure for this setup.

    I think a larger turbine A/R, if only it were available, would help a great deal on that GT15 or a for a GT12.

    P.S. You're indication of being fat on the GT15 can be a indicative sign of exhaust restriction. If you can't get it out of the engine, you can't get it in. Bet it was a pretty large shift in manifold pressure ratio.
    Micah McMahan
    Red Bull Powertrains Performance Design Team Leader
    3MI Racing LLC Owner/Engineer
    Former MSI Defense Solutions - Sr. Design Engineer/Project Manager
    Former Roush Yates Engines - Sr. Design & Analysis Engineer
    ODU FSAE 04 member, 05 controls leader, 06 control/ergo/brakes leader, 07 brakes/MC22 turbo engine/Asst Team Leader

  9. #39
    Your right, there is something to do with the large exhaust pulse. When we went to the gt15 from the TD04 we had to lean it way out just to get it to run half way right, right then we knew the exhaust side was way to small.
    At this time I don't have any record of the exhaust psi. We never did measure it with the gt15 only TD04. Looking back at everything and learning more yeah we even had to much with the TD04.
    I'm %90 sure even with the TD04-9b that the 9b comp wheel is enough air for the motor, I'd bet even the gt15 comp wheel is enough. But the WRX TD04-13T exhaust side isn't large/flow enough.
    I think the advice I got from the guy that turbos the Yamaha 700's is right. Gt2252 exhaust side with gt2052 comp side. But I'm not going to throw $1,400 at turbo just to lose it. I've been on the hunt for used ones with no luck.
    A for the exhaust "plenum" Idea I'm not sure where to stand tho take a look at this video,http://www.youtube.com/watch?v=FoYHr...eature=related they made the exhaust way longer then it has to be, and no other turbo mfg. does it this way, they always make it short as possible.

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