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Looks like I definitely need bigger turbo's. No big shock there. Also started running out of fuel above 6k. I couldn't add enough fuel with the rtek 2.0 not that it matter's, I'll be changing the setup over the winter. I was just curious as to what kind of power this setup was capable of. Hp was still climbing when I let off at 6k.
338whp @ 6k
286lb/ft of tq
I'll try to post the sheet tomorrow. The #'s are rather dissapointing but not surprising since these turbo's aren't efficient over 10-12psi.
Last edited by brent clement; Oct 17, 2007 at 11:10 PM.
Actually Brent I think that is Good!(I have no idea WTF I am talking about!!.lol!).But the Good thing about it is that It will always Give GKarmadi something to shoot for,and if you Keep Ugrading,then you will have a Repeated Customer,Over and Over again!.(just kidding there G!.).I am slowly Getting My Car converted to go TURBO".The Financial Report as I see it puts me somewhere in the 2015 year range!..so book me in for a Rebuild!.I know you do Good work!
I'm quiet curious, can you post the dyno sheet? Depending on where you made the power, perhaps it's less the size of the turbos, but what's in it that you might want to change (?).
Most likely going to upgrade to either a set of gt25's or gt28's along with some mods to the engine internally. I built this block in a hurry so I didn't get a chance to do some of the mods I like.That and I'll most likely be going high comp again.
Funny thing is I now have to pull the turbo's anyway, stopped making boost last week. I get the feeling I may have been running on one turbo and it finally died last week. Rather unlikely for both of them to die simultaneously with out something catastrophic happening. Hard to say though, we'll see what I find when I get around to pulling it apart. Might not happen til early next yr. Here's the dyno chart, it's the baseline run so the #'s are a bit lower for hp but it never changed much.
I'm quiet curious, can you post the dyno sheet? Depending on where you made the power, perhaps it's less the size of the turbos, but what's in it that you might want to change (?).
I just realized what your getting at. That's definitely possible. I think the hotside's are too restrictive. Won't know til I install a pressure guage though.
I'm by no means a dyno chart expert, but your peak torque is made very high and is very flat. The peak torque is the opposite of where I would have expected it for twin turbos. Your power looks like it still has a way to go at 6k where the most recent graph stops.
It looks to me like your engine is just waking up , rather than crapping out. You say that the turbos "aren't efficient above 10-12psi." Are you sure? I'm not trying to be a jerk, but my car with a only a custom 2.5" exhaust made about the same torque from say 3500rpm down, so I question how much you're spooling the twin turbos at that point. I wonder if the opposite isn't true, that your setup isn't more comparable to a big single.
Your right at the moment it does seem very similar to a big single, atleast before it stopped making boost.LOL.
The torque below 3500 is definitely no surprise, since mid summer it started only making more than 7-8psi at about 3500-4k. That's why the #'s down low aren't impressive. Your also right about the engine waking up, above 5k it just starts to go nuts. The porting is really large. If one of the turbo's was damaged last yr (which I beleive it was, rather hard to say for sure though) than it would explain a lot. When I was running the high comp engine on the same set up it made 7psi at about 2k and pulled far harder right from 1500rpm up. I blew that engine when a primary injector failed and had to build the current engine in a hurry to make it to a show. I just hoped for the best (that the turbo's were ok) and when I tuned the new engine I assumed that it was sluggish down low due to the drop in compression going from s4 na to s4 t2 rotors. I know a good part of the loss in response under 3k is due to the lower compression, however there's a really good chance that one of the turbo's was no longer working properly and the other one just finally failed. Stock t25's are definately not efficient above 12psi. They simply aren't designed for it. I wasnt able to find a dyno chart however all the 240 guys say the same thing so I beleive it to be true. Not to mention the hot side is most likely a restriction at higher rpm's. There's just so many different possibilities and so little time and money to research it all. That's why most people stick with big singles. I don't really have a bunch of people to compare twin set ups with and get information on what the best sizing is. I used the t25's simply because they're cheap and easily available. Not really the best way to choose turbo's but so far it's been fun.
BTW, I don't think anything you've said is offensive. They're all good points. I have a lot of decisions to make over the winter. Twins again? or big single? High comp?(most likely)
I'm not trying to be a jerk, but my car with a only a custom 2.5" exhaust made about the same torque from say 3500rpm down, so I question how much you're spooling the twin turbos at that point. I wonder if the opposite isn't true, that your setup isn't more comparable to a big single.
