Turbo Boost spool up comparison 15g vs 16T

Vazfx16 · Post by **Vazfx16** » 13 Jun 2016, 16:21

Hi Folks, I have been stalking around here for a while, and wanted to contribute by sharing my latest mod. I have swapped the 15g turbo (1994 Volvo 850 Turbo Wagon) with a 16t, 3" down pipe, 3" cat, and 3" exhaust. The video allows you to see the increase in boost and spool up.

Post by **Clemens** » 14 Jun 2016, 14:55

Hard to belive this alone makes such a difference. Thanks for sharing

Sommerfeldt · Post by **Sommerfeldt** » 14 Jun 2016, 16:03

The 3" setup w/ 16T is my future goal for the wagon as well. Nice to see that it makes such a difference.

- S

Post by **matthew1** » 14 Jun 2016, 16:37

For 1997 and earlier 5-cylinder turbos, a cheap manual boost controller will provide 17-18 psi.

https://www.matthewsvolvosite.com/forums ... =5&t=11494

Post by **hausmeister** » 20 Jun 2016, 02:47

Imo this has less to do with the 16t than with the Exhaust and wastegate setting...

Sommerfeldt · Post by **Sommerfeldt** » 20 Jun 2016, 06:23

hausmeister wrote:Imo this has less to do with the 16t than with the Exhaust and wastegate setting...

My understanding has always been that the 15g and 16t turbos are pretty much the same turbo, with the same overall performance, but the 16t is a popular "upgrade" because the 16t is better in the midrange? The video seems to back that up, as far as I can tell.

- S

Post by **hausmeister** » 21 Jun 2016, 05:17

I'm sure the 16t is better, but...
I have recently swapped in an R manifold and a TME catback on my car with still the stock DP and 15G. (not finished yet)
But in comparison to before the turbo spool is way faster and quickly builds pressure up to half a bar. I had to set the wastegate back to low factory default otherwise it can't regulate the boost... With the low setting it is laggy, but I don't get much overboost.
I don't think there is aynthing wrong - just that the ecu does not seem able to cope with it

So my point is, the 15G also benefits very much from improved exhaust, and If you don't upgrade it then the 16t alone probably will not be much better.
Just my opinion based on my car...

Edit: the problem with regulating boost might be something else and not from the upgrades, I'm still trying to find that out

Sommerfeldt · Post by **Sommerfeldt** » 21 Jun 2016, 05:55

I like those results - certainly better not to swap the turbo, if new exhaust and manifold can do the same. With an MBC like matt says, it should be a very nice setup. What was the "redline" for your WG experiments?

Btw, with a new MAF, the T5 is down to 9.8 now. :O

- S

Vazfx16 · Post by **Vazfx16** » 23 Jun 2016, 11:28

Thanks Folks,
Some very good comments.
Here are my observations about the 16T upgrade:
1. The 16t may not be huge change to flow, but there still a significant difference
a. Compressor map for 15G:

b. Compressor map for 16T:

2. The other aspect that most likely improves the boost performance is the exhaust outlet on the 16t. It is considerably bigger than the 15G, so is most likely flowing a lot more
3. Down pipe on the 15G – based on visual inspection – is a major bottleneck
4. 3” exhaust is a benefit…and would be a benefit for the 15G also, but not at the same level as the 16T – due to the 15G’s restrictive exhaust outlet.
5. I can’t say how much the Japan manifold has helped, but it’s outlet is larger than the stock outlet, which allows for better flow when coupled with the 16T
The next thing I did was added a manual boost controller. This upgrade really changed the behavior of the engine. The engine will now spool up to max boost with WOT. Why is this good you might ask…well it give access to lots of torque without needing to floor the car. Kind of reminds me of driving my LS1 power BMW Touring. The need of full throttle is saved for when you really need it.

The engine will now boost to 20psi if I don't manage the throttle a bit.

Here is a link to my latest comparison:

Sommerfeldt · Post by **Sommerfeldt** » 23 Jun 2016, 11:37

I like that - I have no idea how to read those charts, but your explanation's good.

One thing - you say (and the video shows) full boost pressure without WOT. From the video, it's pretty clear that it builds quickly with the MBC. As Robert (rspi) has also pointed out on a few occasions, high boost at low RPMs is a clear engine-killer (well, a rod-bender, I suppose). How do you feel about that?

- S