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jumped the gun on GT2871R turbo


guyz

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After pulling my smoking, blown t3/t4oe garrett turbo unit off my 72 z with 82 l28 et, On some advisement, I went ahead and bought a cx racing gt2871rs ball bearing, billet wheel turbo with an accompanying 3" v band flange and a t2 to t3 adapter. New unit has 60 ar / 53x71 compressor wheels and a 64ar/ 47x54 turbine side. with internal wastegate which I preferred for the simplicity.    Well, now that I own this and have  it in front of me, I'm fearful that this was a hasty and bad move. Turbo seems so small and the biggest corncern is just how much smaller the T2 inlet is and how restrictive this will be.   Thinking I should abandon this install and go to a larger T3 setup, GT3076, GT35r or something similar and just deal with fitting external wastegate etc.  I don't want to go through the whole process for no gain and feel I should just sell the turbo to a 4cylinder guy and start again.  Any concise guidance would be much appreciated.  Re my setup, here's the shortlist...

p90 head stock, 60mm tb, megasquirt, 14point7 wideband (great!), 3'' exhaust with soon to be 3" downpipe, 450cc talon injectors, supercoupe IC with 2.5" piping.

 

Running 15-18 max boost and seeking reliable 350-375 hp 

 

Thanks in advance from  North Vancouver,   :-)

 

 

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With a stock cam,  you won’t be reving the snot out of it.  The small turbo weakness will be in the upper RPM range where it just can’t keep up with the flow of the engine.  As previously said, with the stock cam, you won’t be revving high.  It has the potential to make the power you want. 

 

Id try and run it. Why not.  I’m also in Vancouver so I’d like to see how it turns out. Will probably have torque like a V8 

Edited by HuD 91gt
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If you really think you need a bigger turbo, go ahead and get one. As above, it's your car, make sure you're happy with it.

 

At the same time, Garrett claims this turbo is suitable for 280-475HP and engines 1.8-3.0L, so maybe they know what they're talking about. Keep in mind that these are a pretty significant jump in technology and performance from your old turbo, and you'll probably be surprised with how well it works.

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Consider that people have made 600+ hp on the factory manifold. Ported, yeah, but I think for your goals the inlet restriction will be largely inconsequential. You MIGHT see some issues at high RPM if you can get towards the top of the turbo's pressure ratio map. Otherwise, I bet you won't notice.

 

And keep this in mind... Pressure in the manifold can actually be MUCH higher than inlet boost pressure before significant power is lost.

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Hmm,  it's hard for me to get my head around the substantially smaller area of the T2 adapter and the bottleneck it presents. Do you really think that I'll have better performance all round with good peak output to 6500 rpm or so, than I had with the old school t3/t4? If I'm certain of that I'd forge ahead as I don't really relish the thought of going back to square one on this project.

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