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DIY Turbo Discussion greddy on a 1.8? homebrew kit?

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Old 07-11-2007, 10:48 PM   #21
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Quote:
Originally Posted by magnamx-5 View Post
dude there is one for sale that just needs the harness made in the for sale section. https://www.miataturbo.net/forums/sh...ad.php?t=11188 i agree MS is very nice.
:( its not the same. Id really like to put it together myself.
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Old 07-16-2007, 06:03 PM   #22
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Question:

Why do people put airfilters onto the two connections on the valve cover? I know they are crankcase vents but why miniature air filters, and where do I get them.
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Old 07-16-2007, 09:04 PM   #23
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What do you guys think of the knockoff chinese turbos?
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Old 07-17-2007, 01:02 AM   #24
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Markp put down nearly 300rwhp on either a GT30 or a GT32 knockoff Chinacharger. If you want it to last, though, it's not worth it. You can get a rebuildable SR20 T25 from the 240SX/SR20 forums for $150, or a brand-new Garrett T25 from eBay for $250.

The two connections on the valve cover are the breather and the PCV. There's some argument on the PCV, but it's best IMO to just leave it hooked up. Get a PCV valve from a Mazda 323GTX at your dealer; it's a direct swap and it has metal internals, vs the plastic internals. SamNavy will tell you about plastic internal PCV valves doing bad things to motors. :gay:

The other one is the breather, the one next to the oil cap. You can either throw a filter on it, or plumb it back into the intake before the turbocharger. If you ever blow a ring, though, it's going to POUR oil into your intake and turbo and make a real mess. I just have a filter on it.
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Old 07-17-2007, 10:30 AM   #25
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Very good to know about rings blowing.

This is a question I asked y8s, about his car. Basically asked what role does compressor size play when making power.

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Originally Posted by y8s View Post
right around 4200 is where I hit max boost. it depends on the gear of course.

compressor size has a lot to do with top end. boost pressure is a small part. imagine a 10 foot pipe with 2 psi vs. a garden hose with 2 psi flowing into a pool. which supplies more water?

Matt
What an awesome analogy.

So my next question is - Which is safer for the engine, 250hp @ 9psi or 250hp @ 14psi?
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Old 07-17-2007, 12:23 PM   #26
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forget hp... lets ask "which is better, 225 ft lbs at 9 psi or 225 ft-lbs at 14 psi?"

torque is a little easier to understand in terms of the forces involved inside your engine. think of your crank as a torque wrench and the piston as your arm. the force of the piston at 225 ft-lbs is the same no matter what boost you run. 225 lbs of force per foot of lever arm. in our case it's half the stroke dimension. which I forget. and it's averaged over four cylinders by your flywheel blah blah blah

but anyway, the force pushing down on the piston at a given torque number is the same no matter what boost you're at. in reality, if the two scenarios are equal for all other variables*, i'd guess 225 ft-lbs is 225 ft-lbs and neither is significantly worse.

however!

the question really is "can the turbo supply enough CFM at X psi to get you Y ft-lbs at redline? and how hot will that air be?" if the 9psi turbo is more efficient than the 14 psi turbo at the target airflow.... you get cooler air/fuel charges and all the benefits that go with that.

*unlikely.
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Old 07-17-2007, 01:41 PM   #27
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That makes a lot of sense.

Im guessing people dont attach small turbines to big compressors because the small turbine will run out of power to get the large compressor going fast enough to produce a required boost?

Im guessing thats why you got a 2871. Somewhat small turbine(larger then T25) and much larger compressor.
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Old 07-17-2007, 02:59 PM   #28
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Thread jack/

i noticed that sam asked a TMIC question which got me thinking: I have access to a free wrx TMIC for my DIY setup. If i route the IC hotside IC piping under the radiator, cant i just use the wrx intercooler (as a fmic obviously) in reverse pretty easily. I will look up pictures but being a tmic,its a pretty thick core and I think this idea might work.

any ideas?

-dan
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Old 07-17-2007, 03:08 PM   #29
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Quote:
Originally Posted by Saml01 View Post
That makes a lot of sense.

Im guessing people dont attach small turbines to big compressors because the small turbine will run out of power to get the large compressor going fast enough to produce a required boost?

Im guessing thats why you got a 2871. Somewhat small turbine(larger then T25) and much larger compressor.
Mine's a 2876 actually.

And you can have too big a turbine with too small a compressor too...
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Old 07-17-2007, 06:06 PM   #30
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What size is begi's downpipe by default if I don't specify the diameter?

Can I for example, get a 3 inch downpipe made up but utilize my factory exhaust from the cat-back until I make money to get it fully 3 inch?
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Old 07-17-2007, 06:26 PM   #31
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Turbo, close-up
http://smg.photobucket.com/albums/v7...t=DSCN0432.jpg

Can someone please tell me what kind of connection for the oil that is. I have never seen anything like it, it has a bolt and a tube.
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Old 07-17-2007, 10:49 PM   #32
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That's not for oil, that's for water. The oil inlet is directly under the wastegate actuator rod. The oil outlet is on the opposite side of the turbo as the inlet.

The other two ports on either side of the turbo are for water in/out. That particular fitting is a simple banjo barb with a hose attached via a hose clamp, like so:



Check the pic below:
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My intel gathering thread.-dscn0432-small-.jpg  
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Old 07-19-2007, 02:13 PM   #33
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Is there any positives or negatives to using this kind of connection? I cant see very well but is the same kind of connection being used on the oil line?
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Old 07-19-2007, 03:57 PM   #34
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I wouldn't use it on the oil return, and some would argue that you'll get restricted flow, but lots of guys use banjo fittings with no ill effects.
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Old 07-25-2007, 08:29 PM   #35
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Is it necessary to send a turbo to get balanced after it has been rebuilt?
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