Which of these two turbos?

LateApex

Well-known member
Anyone have an opinion on whether the Garrett GT3582R turbo or the Borg-Warner K27 is better?

The compressor map for the K27 looks awesome. Essentially, it has an efficiency island right where I need one.

On the GT3582R, the turbo is bigger than I need but gives me room to grow.

Mostly I'm just wondering if the K27 is too good to be true. On some of the air-cooled Porsche forums, guys are swapping from the K27 to the GT3582R. The K27 is older technology (no ball bearings) and has a smaller inlet (the GT3582R is 4"). They're a little harder to find but Godspeed seems to stock some still. I think the biggest worry is that there was an evolution in the K27 and the older ones are not as good as the newer ones but how do you know which one you're getting?

Any thoughts? Thanks.

P.S.: compressor maps...K27: http://lh3.ggpht.com/__pqkhEfdq8I/SIjGa ... rs-K27.jpg
GT3582R: http://www.turbobygarrett.com/turbobyga ... larged.gif (for a 5.0L engine, too!)
 
Get the Garrett. It's a very good match for the engine, the ball bearing center section means it spools super-fast. If you want something smaller like the K27, look at the GT3076 or similar, or just get the smaller A/R exhaust housing to spool faster, like the GT3563.

I have a GT2871 on my Nissan 240SX, and it spools faster than the stock T25 despite flowing roughly 2/3 more air.
 
Thanks for the input, Wallaka.

Since I'm shopping on e-bay for a $300-$500 turbo, I basically have two options.

The GT35R comes in an A/R on the compressor side that is .70 but on the turbine side can have an A/R of .84 or .63. So, I need to flip a coin, I guess.

Heads = quicker spooling, Tails = more on the top end.

I was intending to get 400 HP out of the beast but I don't know if the cylinder head honestly will support the flow required. It has the big valves and is ported. I also have two Webers on top of a Clifford dual-quad intake. On the exhaust side, I have the late-model EFI manifolds that I plan to route into a flange for the t3 turbo base.

Any ideas on whether that setup (assuming the correct cam) will flow enough to warrant the large A/R on the turbine side?

Thanks much.
 
You'll have to find the table that converts from CM^2 to A/R, I was running a Holset HY35w with 8cm turbine on a 300. As much boost as I wanted at 1700rpm, but at 65mph it sounded like the turbo was about to fly out of the hood!

I have gone to a 12cm^2 HX35W which makes the desired boost around 2200rpm (starts to spool at 1700) and it is quiet on the interstate, well, it does whistle just a tad but its hardly noticeable.
 
Hi, Turbo_B. So, your Holset has an area of 12 square centimeters? That must be what it tapers down to at the center of the turbine, right?

I'll have to find out what my two turbo options use for area, then. It seems like if I know the area of the flange opening, I should be able to calculate the area at the turbine. Is my thinking correct on this?

Thanks, LA
 
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