[QUOTE=XclusiveAutosports,Jul 27 2006, 06:36 PM] I can only speak from experience, and I have a GT3071R and I really like this set up because it doesn't spool so quickly that i'm boosting everytime I press the gas, but is spools quick enough that turbo lag is almost non-existant.

 

Actually a turbo can be custom built for a specific engine if the work is done to figure it out; UR did this. The turbo I have on my car from UR is custom and was built specifically for the S and it's power band; you can not go out and just buy it off the shelf.
I believe that's the reason why some people are having small issues with just buying the Gt35R off the shelf and not doing their homework and figuring out the correct maps for the S.

 

What issues are people having? And what's so special about the turbo you have? This stuff isn't rocket science. You either have a small exhaust wheel (fast spool) or a larger one (slower spool with less shaft speed). Asmall compressor wheel (fast spool) or a larger one (I bet you can guess what goes in here). There definitly is a trick to getting the right size turbo, but it's application driven, meaning that what I want from my car may be differant than what you want from your car. UR had a specific goal in mind when they had that turbo made. And it wasn't for a 500HP monster. So of course at lower boost levels it's going to preform better than a GT35R. But start cranking up the boost and I garentee that it will fall on it's face.

I'm not trying to start a flaming war about what one company sells verse another, I'm just saying that no two kits will untilize the same turbo in the same way.

 

Hey Brian, what do you think my GT3071 will be efficent too in terms of whp? I'll be doing the 2mm headgasket in the next few weeks and was just wondering what I should expect when I turn up the boost. Thanks.

 

ah hem... this WAS my thread.


Can someone answer this question?

 

Anything no-ball bearing will be alot cheaper than a duel BB turbo. Before anyone can recommend a turbo things like manifold, downpipe flange, internal or external wastegate need to be known.

 

Depends on the amount of pressure you plan on running and the amount of power you want.

Here's the best way to go about the turbo sizing/efficantcy thing. First decide how much HP you want. Look at other simular set-ups and figure out how much boost it will take to get that HP. You can then plot on a compressor map and see if what you efficantcy will be. For Example, say you wanted 400HP. I know a GT1 kit puts out around 18HP per psi of boost. So you'd need around 11psi (gauge pressure not absolute) to get that. Now look at the map here http://www.turbobygarrett.com/turbobygarre...1R_700382_3.htm . For every 100HP you want, you need appx. 10 lbs/m of air. So you'd neeed appx 40lbs/m. Now plot that with the absolute pressure used (11psi + 14psi = 1.8bar) and that gives you the efficantcy of the turbo. In this example, we are getting really close to the surge line.

 

I was planning on making the turbo the first purchase and then the manifold.

I didn't really have a HP goal, but more of a reliability and drive ability goal. But since HP since to be on the fore front then I would have to say around 350whp since that is what most people I know are doing with the comptech.

 

I was talking to a budy tonight and he said that a T3/T4 or something that is not BB would spool slower for me, which is something I would want so I am not boosting when I pull out. I am not sweating the turbo lag thing and I can always upgrade someday if it ever starts to bother me. But as of now I am not concerned.

 

Why not just buy a kit then? If you don't have alot of experance with turbos then you are better off getting a kit and then building on it.