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Discussion Starter #2
Does the precision moderator on here have any input on this ? Do they even have one for this turbo?
 

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Their turbo's are pricey, because they are proven to be performers, which everyone knows. I think most people who are familiar with turbo's and the function, can usually decide if a turbo is going to work for them based on the wheel sizes, and hp range they are looking to make. There's also other things that affect turbo's from spool, to power range, back pressure and flow, so maps only are so useful. A car setup poorly will be a poor performer regardless of the map
 

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Discussion Starter #6
Im just trying to figure out how to get the most out of my turbo with my small motor. its been a challange to say the least getting it to where it is now . Precision spec'd it for me but im just not sure why it doesn't spool all that well from a start. Its great from a roll though.. But im looking for more..
 

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Really depends on the details of the engine, tune, and turbo setup. Many things can contribute to slow spool, that's why it's very important to know what works and what doesnt when putting a turbo car together. Too big of hot side piping will reduce spool on the pressure side. Too restrictive exhaust setup after the turbo can hurt spool. Too long of piping runs can hurt spool(remote mount), many variables just in the turbo kit alone. In the end though, if you have a small motor, and trying to make big power, there will be only so small of a turbo you can go to get there. Larger turbos will be more laggy, but not the soul contributor that will affect that. Dont even know if you are talking about a stick or auto car. The wrong converter in a auto car can affect how a turbo responds. I'm sure if you break down a lot more details, plenty of guys on here would be happy to chim in
 

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Discussion Starter #8
Its 9.7 to 1 and has a 4.090 bore and 3.75 stroke 4 cyl.

580 lift 242 at .050 , 114.

Auto with a contnental converter 9.5". Ive had it loose and tight . The only way it holds the power is tight. When its loose it spools but blows threw the converter. Tight it holds good but lose the spool factor..i only spin it to 6500 rpm . So its tough to balance . I do have a long feed hot side pipe to the turbo.which i know is hurting spool. but i cant change that.
 

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Garrett and Borg have compressor and turbine maps because they are the only ones that ACTUAL have a development and engineering department that DEVELOPS new turbos. Everyone else makes a Chinese copy and tries to sell if for the same price as Garrett and Borg.
 

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Ok I'm not a precision guy ... But that statement is weak

Indeed it takes alot of money to map a compressor and turbine, and why you only see Garrett, Borg, ect provide this


But saying there is no R/D is ridiculous

They are testing/building off of CFD, and that flow modeling gets better and more accurate by the day

Garrett is doing the same.... They can just test actual vs theoretical CFD
 

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And the 6870 is a beast among other more common "68s" because of the large compressor exducer and the large turbine backed to it
 

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Discussion Starter #15
Cheapest and easiest to try is a smaller turbine housing. 6500rpm is a pretty low top line though.
Especially for a unit like a 6870 on a smaller motor

I tried a 6466, it was alittle better but not the fix. .

Only reason i got the 6870 was because Precision spec'd it for me after i told them the power i was after..
 

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Discussion Starter #17
I wish i could but the way my computer is set up i cant. Ive tried ..

The primaries are 1 7/8" with a 2 1/2" collector on the passanger side. From there a 2 1/2" pipe goes across the front of the engine then up and back to the turbo on the driver side. From the collector to the turbo its around 3' or so. I know thats alot of the problem but i wanted to balance the engine bay weight . my engine is half of a V8. So theres a big empty space to utilize where the other half should be. lol
 

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In my humble opinion, your hot side piping sizing has little, if anything to do with lazy spooling.
Describe in detail how you spool it and what it is doing. Include rpm.
Is this a street car? Anything to know about the converter?
 

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Roughly what kind of hp and what is rpm operating range? Where is spool the most problem? From a dead stop?
 

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What are you doing with your tune when you're trying to spool? Adding fuel? Leaning it out? changing the spark advance up or down? Coating the exhaust with Swaintech and wrapping the exhaust will surely help a lot. It'll make a night and day difference in keeping your exhaust temps up to help spool the turbo. If you're looking to max out the potential of a turbo, make sure you're measuring back pressure. Between discharge temps, boost and back pressure, you won't need a compressor map to know where the end of its real potential is.
 
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