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Old 10-31-2019, 12:41 AM   #16
zbrown
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Default Re: Precision 6870 turbo map

Post up pics of what you actually have going on
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Old 10-31-2019, 01:39 AM   #17
HALFanINJUN
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Default Re: Precision 6870 turbo map

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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Old 10-31-2019, 07:57 AM   #18
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Default Re: Precision 6870 turbo map

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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Old 10-31-2019, 08:04 AM   #19
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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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Old 10-31-2019, 09:52 AM   #20
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Default Re: Precision 6870 turbo map

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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Old 10-31-2019, 10:20 AM   #21
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Default Re: Precision 6870 turbo map

Quote:
Originally Posted by Twin-TurboVette View Post
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.
Great points. Does this application use a two step rev limiter and/or a trans brake?
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Old 10-31-2019, 10:25 AM   #22
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Default Re: Precision 6870 turbo map

How effective is the swaintech? Does it keep the exterior of the header considerably cooler? And the hot side of the turbo?
I have a dragster, and my fear is often that a child may touch in the staging lanes. Of course they shouldn't and other cars have headers too. But the turbo stuff seems to retain a bunch of heat. And of course the turbo hot side rusts with any moisture that hits it. I'm leaning toward wraps.
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Old 10-31-2019, 10:35 AM   #23
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Default Re: Precision 6870 turbo map

But when I hear about trouble spooling, I generally think in a couple areas:
-camshaft (larger camshafts make n/a engines lazy down low. When trying to spool, it's basically an n/a engine.)
-Tune: Give then engine what it wants to gain rpm. You need mass to spin that turbo. You won't get the mass without some rpm. So do what it takes to get rpm up. With a two step or trans brake, once you land at your desired staging rpm, if you want to build additional boost, you can pull a bunch of timing and add some fuel. But don't do that while you are trying to build rpm. It will just make it lazy.
-stall converter: Tight converters give you a catch 22. You can't gain rpm until you have power. And you can't make enough power without boost. And you can't make the boost because the engine isn't moving air with rpm. I hear people all the time say "you have to have load on the engine". Well, I get it when talking about stick cars. But with a trans brake or foot brake, you will find the load after you get some rpm. And that additional rpm make it spool quickly.
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Old 10-31-2019, 11:51 AM   #24
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Default Re: Precision 6870 turbo map

Quote:
Originally Posted by tempname View Post
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?
Yes its a street car .
I feel that the lenght of the pipe is some of the isse. Not all of it but some. I say that because i can get 1250*f at the header flang. But just 600*f 10" back from the turbo. I do have the crossover pipe wraped..

There are 2 ways i do it. On the fook break i bounce the peddle up and down trying to keep the car still which never really happens. It always moves. Depending on the weather believe it or not i can get it to spool once and a while. But mostly i cant. So i know its possible. As for the tune. i'll get on my laptop when i do this on the trans break and start taking or adding timing while im trying to get boost. During this im listening and watch rpm for the best settings. I do the same with fuel . I never seem to have luck with this though..

The converter is a 9 1/2" continental, guys name is Chris in California . Hes out of bussness now though.. Its been lose, real lose , tight, half tight now its real tight. I need the setting inbetween where it is now. Chris says if he tried that , it would be back to the last setting. So im kind of out of options with that..

The turbo starts spooling around 2900 rpm . When i get on the converter it goes 2000-2200. So i need another 700 rpm .. If i hold it for like 2-3 seconds it will creep to 2500-2600 and try to make boost . Sometimes ill get a pound or two but buy that time the trannys getting hot. I really only have 2 trys then i have to cool it down..
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Old 10-31-2019, 11:57 AM   #25
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Default Re: Precision 6870 turbo map

Quote:
Originally Posted by Twin-TurboVette View Post
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.
exactly what you said ive tried all of that . The fuel seems to make the most difference. I do have the pipes wrapped.

I plan on checking the back pressure for sure..
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Old 10-31-2019, 02:42 PM   #26
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Sounds to me like you are planning what may influence it the most. Converter
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Old 10-31-2019, 02:44 PM   #27
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Of course mine stalls around 7000
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Old 10-31-2019, 03:08 PM   #28
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Default Re: Precision 6870 turbo map

And still no mention of what turbine housing.....

And are you saying the 6466 was the same ? different ? other ?
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Old 10-31-2019, 03:32 PM   #29
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Default Re: Precision 6870 turbo map

Quote:
Originally Posted by tempname View Post
Sounds to me like you are planning what may influence it the most. Converter
Im not sure i know what yu mean..
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Old 10-31-2019, 03:37 PM   #30
HALFanINJUN
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Default Re: Precision 6870 turbo map

Quote:
Originally Posted by tempname View Post
Of course mine stalls around 7000
Do you have a 4cyl?

Ive been told in the past that the fact that i only go 6500 rpm is going to be a big problem getting the coverter lose enough and hold the power. No balance room for the low hp n/a part vers turbo hp in the end for it to tighten up enough

Last edited by HALFanINJUN; 10-31-2019 at 03:39 PM.
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