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DIY Turbo Discussion greddy on a 1.8? homebrew kit?

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Old 03-21-2010, 12:06 AM   #21
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Quote:
Originally Posted by Mr_SARS View Post
Have you considered disconnecting the compressor outlet of the turbo to the intercooler piping???
That could cause the turbo to overspin and die
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Old 03-21-2010, 12:11 AM   #22
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Originally Posted by Full_Tilt_Boogie View Post
That could cause the turbo to overspin and die
Even with the internal wastegate wired open?

I never thought that there would be enough backpressure from the compressor outlet side to significantly slow down the wheel.
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Old 03-21-2010, 12:12 AM   #23
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This is going nowhere.

You cant just have a big *** hole in your intake plumbing for two reasons. First (which was pointed out to me before) is that the turbo might overspin if you get on it what with basically no pressure ratio to worry about. Second, if you are running an AFM, then suddenly you have more air going into the intake then the AFM is reading under vacuum, unless you place the afm right off the TB or something. IF you do go under boost slightly with the AFM in operation and you have a huge hole, then you will run pig rich and possibly just plain stall out.

Cheap FMU and wired open WG FTW. 3 psig is very low even for these cars and a bit more fuel will do the trick. If you want, set the base timing down a bit too in order to be super paranoid safe.
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Old 03-21-2010, 01:26 AM   #24
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Quote:
Originally Posted by thirdgen View Post
Dude just disconnect the wastegate actuator from the gate and wire the gate open...do you really need a picture???

Not sure who you are talking to about this one as I was just asking if there was any other factors I should be considering when doing this. :(


But for the rest, I'm just going to wire the wastegate open and retard the timing slightly. The original injectors I have (which isn't original per se)for the car is somewhere between 230-305's not too sure. But it should be fine.


Actually, I'm quite glad I made this thread. I personally didn't even think about the pressure differences causing a turbo to overspin and fubaring the turbo.

Thanks boys. Discussion closed!
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Old 03-21-2010, 10:32 AM   #25
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From a guy with personal experience doing this with a cast Begi manifold and SR20det T25.

Unless you REALLY dig into the throttle above 4k, you won't be building any boost with a wired-open wastegate until 4th gear... and even in 4th/5th, you can be careful and make sure it stays at ~0. ****, you can drive a hi-strung turbo car out of boost all day with everything working perfectly. The problem is that you're now so ******* slow it's dangerous to drive. Getting on the freeway, where you may need to actually give it some gas to keep from getting run down will definitely build a psi or two... and that's enough on a stock fuel system to hurt something.

On the other hand, every once in awhile, some dude will come here saying he's been boosting his bone-stock fuel system/ecu for months and gives us all **** for bowing down to the man and buying **** we don't need.

If this was for a day or two and you could stay off the freeway, I'd say no problem, but not for weeks on end. Don't chance it.
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Old 03-21-2010, 02:48 PM   #26
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ballbearing turbos in the same size (as in the OP's sitch) they will spool ALOT harder than the SR t25.

he should be able to make boost no problems.
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Old 03-21-2010, 03:34 PM   #27
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Quote:
Originally Posted by shlammed View Post
ballbearing turbos in the same size (as in the OP's sitch) they will spool ALOT harder than the SR t25.

he should be able to make boost no problems.
dude, no they ******* dont.
A ball bearing turbo spools faster but were talking like 5%.

When I first got my car together I had ridiculous boost creep, with the wastegate hooked up it would creep to 15 psi fast as ****, and would have continued to climb if I didnt let off.
Yet, I drove around for 5 months, with the wastegate disconnected, and never had a problem staying out of boost.

Stay out of the throttle, and youll be fine.

/thread

next person to post is a super homo fagatron
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Old 03-21-2010, 04:04 PM   #28
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^^^
rofl couldnt resist.
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Old 03-21-2010, 05:03 PM   #29
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haha dude it doesnt matter if you have quadruple ball bearing chra and a tiny wg, if its wired open you will have to be TRYING to build boost to do so. just drive like a NORMAL person: keep your foot light and dont wait till figgin 5k to shift gears.....simple and easy...
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