How to boost your boost

flash7210 · **Posted:** Fri Sep 25, 2015 8:33 pm

This is a relatively simple mod that will allow you to dial-in the max boost from your turbo.

What you will need:
1. An actual boost gauge, mechanical type is preferred
2. A 10K ohm variable resistor
3. TorquePro or other application that will allow you to read the MAP sensor
4. A soldering iron

The variable resistor gets spliced into the signal wire from the MAP sensor.
There are four wires going into the sensor. When standing in front of the engine, the signal wire is the one closest to you.
I mounted the resistor on the dash and ran its wires through the firewall.
The variable resistor is wired in as a voltage divider. That is, the splice from the sensor goes to one end of the resistor. The other end of the resistor goes to ground. And the center wiper goes to the splice back to the ECU.

Increasing the resistance lowers the sensed pressure at the MAP sensor.
Sensing lower boost, the ECU will allow the turbo to boost up to a higher pressure.
This is why you need an actual boost gauge. This mod fools with the MAP sensor reading.
To dial it in I used my TorquePro app to get a view of the MAP sensor reading.
With the key on and engine off, I adjusted the resistor till the reading showed between 2-3 vacuum.

Before doing this mod I could inly get 21-22 psi with a stock tune. As viewed by the gauge.
Now I can easily get 24-25 psi and dial in even more if needed.

However, there are some limitations.
I think 25-26 psi is the highest you would want to go under heavy acceleration. Dont want to blow a head gasket.
Too much resistance in this circuit can throw a turbo underboost code and may cause some drivability problems.
Too much boost can put the turbo into an overspeed condition which could destroy the turbo.
More boost does not automatically mean more power. With a diesel engine, more power comes from injecting more fuel.

Let me know if you need more details.

flash7210 · **Posted:** Fri Sep 25, 2015 8:58 pm

Mountainman · **Posted:** Fri Sep 25, 2015 10:51 pm

Really nice, thanks for posting :rockon:

I am really interested in any increase in mileage with this mod, however unlikely because the temptation to drive faster :POPCORN:

Billwill · **Posted:** Sat Sep 26, 2015 4:13 am

This is pretty much what they do with the little Black boxes that you plug in series with the Map sensor to give you more power and supposedly better economy except they usually do not use a variable resistor and charge a fortune for it.

I ordered an Italian make after TonyCRD recommended it....it gave me more power but worse consumption and then blew up after about a month on the open road. I disconnected it so as to get home and threw it away....could not be bothered to open the black box to see what had blown.

This circuit of yours is worth a try provided it is used with caution as you advise and make use of a proper gauge. :wink:

GreenDieselEngineering · **Joined:** Sun Jun 07, 2009 5:10 pm **Posts:** 1111

Increasing boost will decrease fuel economy...all else being equal. To increase the boost you must close the vanes on the turbo, this adds restriction in the exhaust system and overall drive pressure.

To maximize fuel economy requires optimizing the combustion process: boost, injection timing, pilot injection 1 and 2 quantity/timing, fuel pressure, airflow, etc. Do this to minimize CO2 on a full modal emission bench and you will reach the lowest BSFC over the entire engine operating range.

Mountainman · **Posted:** Sat Sep 26, 2015 9:12 am

Thanks Keith, I guess I'll leave it for the max power folks :JEEPIN:

mass-hole · **Posted:** Thu Oct 15, 2015 11:31 pm

flash7210 wrote:

This is a relatively simple mod that will allow you to dial-in the max boost from your turbo.

What you will need:
1. An actual boost gauge, mechanical type is preferred
2. A 10K ohm variable resistor
3. TorquePro or other application that will allow you to read the MAP sensor
4. A soldering iron

The variable resistor gets spliced into the signal wire from the MAP sensor.
There are four wires going into the sensor. When standing in front of the engine, the signal wire is the one closest to you.
I mounted the resistor on the dash and ran its wires through the firewall.
The variable resistor is wired in as a voltage divider. That is, the splice from the sensor goes to one end of the resistor. The other end of the resistor goes to ground. And the center wiper goes to the splice back to the ECU.

Increasing the resistance lowers the sensed pressure at the MAP sensor.
Sensing lower boost, the ECU will allow the turbo to boost up to a higher pressure.
This is why you need an actual boost gauge. This mod fools with the MAP sensor reading.
To dial it in I used my TorquePro app to get a view of the MAP sensor reading.
With the key on and engine off, I adjusted the resistor till the reading showed between 2-3 vacuum.

Before doing this mod I could inly get 21-22 psi with a stock tune. As viewed by the gauge.
Now I can easily get 24-25 psi and dial in even more if needed.

However, there are some limitations.
I think 25-26 psi is the highest you would want to go under heavy acceleration. Dont want to blow a head gasket.
Too much resistance in this circuit can throw a turbo underboost code and may cause some drivability problems.
Too much boost can put the turbo into an overspeed condition which could destroy the turbo.
More boost does not automatically mean more power. With a diesel engine, more power comes from injecting more fuel.

Let me know if you need more details.

Do you also get more boost at idle or does that pretty much stay the same because of exhaust flow?

Sent from my LG-D850 using Tapatalk

flash7210 · **Posted:** Fri Oct 16, 2015 9:07 am

It seems to me that at idle boost is set to HIGH.
At idle, vacuum to the turbo actuator is high.
High vacuum = high boost.
But because exhaust flow at idle is low actual boost will be LOW.

So, even on a stock engine boost is high when accelerating from idle. As you are accelerating the ECU will adjust boost level according to throttle position and engine RPM as sensed by the MAP sensor.

You can bypass all the vacuum control solenoids so that vacuum to the turbo actuator is always high. This will not effect turbo boost at idle. But it will effect turbo boost during acceleration.
Under this condition, turbo boost will continue to increase under acceleration.
The MAP sensor will give the ECU a high boost reading and the ECU will try to adjust boost to a more appropriate level. But because all the vacuum solenoids have been bypassed and the ECU cannot control boost, the ECU will throw a Turbo Overboost code and go into limp mode.

Yeti · **Posted:** Tue Oct 20, 2015 4:36 pm

I think is normal , for a better response

flash7210 · **Posted:** Mon Nov 23, 2015 7:45 pm

Update:

So far, this is working good.
I have it set to where it peaks at 27 psi and hold steady at 24-25 psi under moderate to hard acceleration.
I am using the Yeti stage 2 tune and I think I have found the right ballance of fuel and boost.

Occasionally I will get a MAP sensor code. It must be something loose in my wiring.

Yeti · **Posted:** Tue Nov 24, 2015 11:45 am

if you want I can increase the bost map and limiter without this trick , but 27 psi is really high for our turbo

flash7210 · **Posted:** Tue Nov 24, 2015 8:01 pm

Yes, but it only hits 27 psi for a brief moment and drops to 23 psi.

Yeti · **Posted:** Wed Nov 25, 2015 10:28 am

yes , because there is a limiter at 1300 millibar and you can go only over for the time written in the overboost map , BTW you trick the ECU and the boost rise the 1,58 bar

How to boost your boost

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