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Turbo Boost spool up comparison 15g vs 16T

Help, Advice and DIY Tutorials on Volvo's extremely popular car line -- Volvo's 1990s "bread and butter" cars -- powered by the ubiquitous and durable Volvo inline 5-cylinder engine.

1992 - 1997 850, 850 R, 850 T5-R, 850 T5, 850 GLT
1997 - 2000 S70, S70 AWD
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Re: Turbo Boost spool up comparison 15g vs 16T

Post by jblackburn » Thu Jun 23, 2016 11:41 am

Driving a 1994 Turbo (15) compared to my 1998 (16), the first thing I noticed was that the 94 has a LOT more power lower in the RPM range (there's actually something there at 2000 RPM, while the -70 is still struggling to get its fat butt moving).

But yeah, the 16 does feel stronger in the midrange and for sure at the top of the RPM band - it's still pulling strong at redline.
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Re: Turbo Boost spool up comparison 15g vs 16T

Post by Vazfx16 » Thu Jun 23, 2016 12:28 pm

I am worried about high torque production at low rpm, this is why I am managing the throttle. I may end up turning things down, but I have found that if I roll onto the throttle -- instead of a rapid flooring -- boost pressure builds in a more acceptable fashion and hangs out at around 12-15psi. So, I am not doing drag starts yet. I know that womping on the throttle can kill the rods. On the highway is where things are really nice. I can cruise at 1 - 5 psi under slight load. Roll on the throttle, and 10-15psi is generated. I am evaluating and investigating the next direction. Also, I have a wideband O2 sensor to monitor the AFR. I wanted to share this with folks because there is a lot of speculation out there. I was hoping this might add some concreteness to the discussions. I am no expert on flow maps, but based on the comparison of the ones above, the 16t flows more and has the ability to generate pressure at higher speeds --BUT, looks to flow better down low too! The 15G's efficiency is below 2 bar, where as the 16T is efficient up to 2.6 bar at a higher flow rate. All that equals, better power and less heat generated by the compressor.

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Re: Turbo Boost spool up comparison 15g vs 16T

Post by Sommerfeldt » Fri Jun 24, 2016 1:12 am

To be fair, 2 bar is a lot of psi's. But I see what your're saying - more flow = less heat, more power. My personal, ultimate goal is about 18 psi or 1.2 bar, and with a new exhaust, the 15G should be well capable. The 16T will have to move into a holding pattern for my part, me thinks. :)

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Re: Turbo Boost spool up comparison 15g vs 16T

Post by Vazfx16 » Fri Jun 24, 2016 6:58 am

Sommerfeldt wrote:To be fair, 2 bar is a lot of psi's. But I see what your're saying - more flow = less heat, more power...

- S
I am basing the 2 bar on reading the turbo flow map (but, I am not considering the flow rate needed for the engine), and what is possible for the turbo. I am not literally running 2 bar. But, you are getting what I am saying.
Point being. the 16T is a good modification, even though folks say it's not much of an improvement...it really is.

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Re: Turbo Boost spool up comparison 15g vs 16T

Post by hausmeister » Mon Jun 27, 2016 9:37 am

The 16T chart is not working.. http://www.stealth316.com/2-3s-compflowmaps.htm this site has a lot of maps, (not sure about the other content, seems to be about some other car.)

In the video... it is kind of hard to tell without rpm, but to me it seems there is something wrong with the stock setup. The ~7-8psi that it shows before shifting seem too low to me. Also with the 1st upgrade to 16T the boost is all over the place?
Not saying it is bad, just that on my car stock looks different. But it is hard to tell what is correct with the cars being so old and without going through everything to make sure it is working correctly. I had a lot of problems with boost leaks... And I only have my car to go on for comparison..
If I find a video of mine I will edit it in later.
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Re: Turbo Boost spool up comparison 15g vs 16T

Post by Vazfx16 » Mon Jun 27, 2016 10:15 am

All boost leaks where fixed. And all maintenance is up to date. there is nothing wrong with the car. Stock boost on the 850 @8 psi. I would not bet on the accuracy of my aftermarket boost gauge when comparing it to another aftermarket boost gauge. My gauge should only be used when evaluating the changes to my car. Are you running an aftermarket boost gauge? What are your boost numbers? What turbo? What exhaust?

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Re: Turbo Boost spool up comparison 15g vs 16T

Post by hausmeister » Mon Jun 27, 2016 3:00 pm

Like I said, I only have mine as reference, and it might not be the best reference.
It is a stock T5-R, 15G. Most issues were fixed in this older video... but there is always something else with this car. Today I learned that the Cams were off 1-2 notches on the timing belt, most likely because a previous owner botched it or thought it would go faster.

Here is an video of accellerating. Not saying it is fast, but the boost development/curve looks right to me. Everything was stock. The gauge is in bar, so 0.5 and 1 bar in case it is hard to read.




Anyways I don't have much experience with turbo cars, so don't think I'm trying to tell you how it should be. I'm just trying to get a better understanding.
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Re: Turbo Boost spool up comparison 15g vs 16T

Post by Vazfx16 » Mon Jun 27, 2016 4:08 pm

hausmeister wrote: Anyways I don't have much experience with turbo cars, so don't think I'm trying to tell you how it should be. I'm just trying to get a better understanding.
I do appreciate the conversation. All questions and conversation make us better :D
It's hard for me to read your dials, but the car is looks to be making healthy boost. Here is a video I took today. As I noted earlier, I roll on the throttle as to protect the car some. This video is a roll on from a stop...up to 70mph (it's also 98 degrees here...which seems to affect boost)
https://youtu.be/QXN3aZe1iYs

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Re: Turbo Boost spool up comparison 15g vs 16T

Post by Vazfx16 » Mon Jun 27, 2016 4:12 pm

Vazfx16 wrote:
hausmeister wrote: Anyways I don't have much experience with turbo cars, so don't think I'm trying to tell you how it should be. I'm just trying to get a better understanding.
I do appreciate the conversation. All questions and conversation make us better :D
It's hard for me to read your dials, but the car is looks to be making healthy boost. Here is a video I took today. As I noted earlier, I roll on the throttle as to protect the car some. This video is a roll on from a stop...up to 70mph (it's also 98 degrees here...which seems to affect boost)

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