• Registered: 2019-12-29
  • Posts: 38

Topic: How to trick our turbo into blowing harder

We got motivated to better understand why so many folks are blowing by us on the straights, so we got a dyno run on our crappy Lemons car. It was a great experience lining up behind the highly tuned C8 vette for our turn with our screeching brakes. I'm pretty sure they would get out of our way on the track.

We have a 2005 GM Ecotech B207R (LK9), with a Mitsubishi TD04L-14T stock turbo.

Our air/fuel ratio is at about 13.1 up to 3500 RPM (with boost about 15), then dips to be rich (maybe 12, with boost of 12) then after 4500 dips again (maybe 11, boost of just above 10).

Clearly a bigger turbo would help push more air at higher RPM, though have the lag issues at the lower end. So not clear that is a win overall.

From some chat around the garage, it seems folks typically get much better than this - i.e. more boost after 3500, and higher max boost, perhaps closer to 17.

It was suggested the boost control valve may be worn / old and try replacing that. Is this a thing?

I also found a video https://youtu.be/csa9A5lZZok with a smoke machine to find some leaks with o-rings, gaskets, etc.  No clue where we could borrow / rent / buy one of those some machines though.

Anyone else running one of these engines turbos and open to sharing what they are seeing, and how they tuned it up?

Thoughts on what we should / could look at for testing / investigating more is greatly appreciated.

  • From: Newport News, VA
  • Registered: 2015-12-23
  • Posts: 620

Re: How to trick our turbo into blowing harder

It's not your car or engine, but they talk about that turbo:
https://www.clubwrx.net/threads/turbo-i … etc.16541/

That guy
  • From: Tustin, CA
  • Registered: 2010-12-30
  • Posts: 3,275

Re: How to trick our turbo into blowing harder

Here's your Lemons grade smoke tester.
This
https://www.harborfreight.com/multi-use … 63144.html

With a cheap cigar on the intake side.  The exhaust hose shoved/taped into a HF glove finger and the opening stretched over the throttle body.

1990 RX7 "Mazdarita"  1964 Sunbeam Imp (IOE 2013 Sears Pointless) 2002 Jaguar x-type (Winner C-Class 2021 Sears Pointless)
Gone bye-bye
1994 Jaguar XJ12 (Winner C-Class 2013 Sears Pointless)  1980 Rover SD1 (I Got Screwed 2014 Return of Lemonites)

4 Reply by fleming95 (edited by fleming95 2021-05-16 01:47 AM)

  • Registered: 2009-06-10
  • Posts: 558

Re: How to trick our turbo into blowing harder

In a Saab 9-3?

<edit - yes - saw your old posts>

Stock boost pressure sounds to be about 12psi.
Had you pulled down T8Suite to measure and tune with?
I'm sure you can find commanded vs. actual boost there. 
And retune for E85 if you want power and more time in the pits...

Also, try repurposing a radiator pressure test set from Autozone to test the BPV?

My rookie ideas are that if you're running stock tuning then the boost could be curtailed by design to keep output torque at the design limit for the transmission even if the stock turbo and plumbing has excess capacity.

  • Registered: 2013-11-15
  • Posts: 669

Re: How to trick our turbo into blowing harder

Do you a have an AFR meter?  Before you start messing with your boost, you want to make sure you have one of those so you don't melt your pistons.  Once you start turning it up, you may start running out of fuel or injector capability.  Once you start hitting boost, your AFRs should start dropping.  The numbers you have are similar to mine in my Volvo.

You should check for boost leaks first.  Every pipe, hose and connection from the turbo to the intake, and to the head.  Maybe intercooler leak?

Do you have any exhaust leaks between the head and the turbo?  That could keep the the little spiny wheels in the turbo from making that sweet boost.

After you have verified you don't have leaks you can start trying to up the boost with a different wastegate actuator or just put a cheap manual boost controller on like this:

https://www.amazon.com/dp/B001J6766A/re … &psc=1

Team whatever_racecar #745 Volvo wagon
  • From: Antioch, IL
  • Registered: 2016-06-08
  • Posts: 101

Re: How to trick our turbo into blowing harder

Just add another turbo.

  • Mr.Yuck
  • Mr.Yuck
  • Lemons Staff Stalker
  • Offline
  • From: Brookeville, Md.
  • Registered: 2013-12-09
  • Posts: 1,012

Re: How to trick our turbo into blowing harder

Boost is a measure of resistance. It is more important that the air gets in and out efficiently. You can hang a bigger turbo on it, but see no gain.

"get up and get your grandma outta here"
  • From: SF Bay Area
  • Registered: 2012-01-06
  • Posts: 721

Re: How to trick our turbo into blowing harder

Several utoob vids for DIY Smoke Tester are available.
Here is one, https://youtu.be/PIpMprjaitA

Capt. Delinquent Racing
RUST-TITE XR4Ti - '21 ARSE-FREEZE-APALOOZA  I Got Screwed
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'17 Vodden the Hell - (No) Hope for the Future Award, '08 AMP Survivor, '08 ARSE-FREEZE-APALOOZA Mega-Cheater