A turbocharged engine is a double-edged sword. Extra energy is available via extra enhance, however so is extra catastrophe.
So, even if you’re vaguely contemplating turbocharging an engine, plan to no less than monitor the opposite elements that can be affected by the extra air. Most notably, this implies keeping track of how a lot gasoline will get blended into that flamable fog being rammed into your cylinders.
The connection between gasoline and air in your engine is multifaceted. On one hand, you could have one thing referred to as the stoichiometric ratio, which is the perfect combination of air and gasoline that, when combustion happens, leads to no leftover gasoline or its catalyst (oxygen, on this case).
[Turbo boost is good, but too much can be bad]
For typical gasoline, on Earth, the place air is about 21% oxygen, that ratio is 14.7 elements air to 1 half gasoline. In fact, totally different gasoline blends and elevations have an effect on this quantity barely, however that’s the baseline.
However that 14.7:1 ratio doesn’t inform the entire story of max potential. See, whilst you could also be burning the entire gasoline at that ratio, secondary results could possibly be robbing the engine of most energy. Full burning of the gasoline means much less atomized liquid gasoline within the combustion chamber, which implies much less cooling of inside combustion surfaces, which implies extra vitality misplaced as warmth, for instance.
Now, each engine is totally different, and most make most energy at some ratio that isn’t the perfect 14.7:1, however this ratio is simply attainable via dyno testing and exact monitoring. When you have a contemporary automobile, the monitoring half is normally so simple as slipping a connector on the OBD port and utilizing some software program or a {hardware} logger to learn the info being despatched to the onboard laptop.
However our 1991 Toyota MR2 Turbo has no such trendy accoutrements, and the manufacturing facility oxygen sensor that sends exhaust information to the onboard laptop is extraordinarily low-resolution.
Time for Some Sensorship
The answer is a correct wide-band oxygen sensor, which normally means the set up of an accompanying in-dash gauge or monitor to maintain observe of the numbers. However we discovered a better resolution that installs in minutes from Performance Electronics. The corporate’s PE-Wideband package consists of a Bosch sensor that connects to a Bluetooth-enabled controller you may monitor by way of an app in your iOS or Android gadget.
The setup simply requires an influence and floor connection, so all of the wiring can keep beneath your hood–or engine cowl, in our case. The unit additionally has CAN inputs and outputs and a 0-5v output to attach it to devoted gauges or your programmable ECU.
Set up on our MR2 was a snap, as we’d simply put in a TCS Motorsports downpipe that we had the foresight to order with an additional oxygen sensor bung already put in. We merely eliminated the plug, put in the brand new sensor, and plugged it into the unit. We have been up and operating inside half-hour. The package additionally comes with a weld-in bung manufactured from delicate metal in the event you don’t have already got an obtainable and prepared bunghole. Stainless bungs can be found as properly.
The app is straightforward to make use of, has real-time monitoring and a few fundamental logging options, and reads AFR both as ratio or lambda. Typical AFR reveals ideally suited as 14.7:1, with decrease numbers–that means extra gasoline per air mass–indicating a “wealthy” situation and better numbers indicating a “lean” situation. Lambda expresses ideally suited stoichiometric ratio as 1, with readings decrease than 1 indicating wealthy and better than 1 indicating lean.
So now that we are able to simply monitor our air/gasoline ratio, what will we do about it? Effectively, first off, it’s good to know that our engine is correctly metering gasoline.
At wide-open throttle, the onboard ECU richens the combination to round 11:1, which implies a variety of unburned gasoline–but additionally a variety of security margin for not producing extra warmth or preignition, which might rapidly kill an engine. As we add enhance and open airflow, making certain the gasoline combination is throughout the protected zone can be extra insurance coverage in opposition to untimely catastrophe.
But when we in the end need to take advantage of energy that we are able to for a given configuration and enhance degree, we’ll want a option to exactly modify that gasoline combination at varied load ranges. Sadly, in contrast to extra trendy ECUs, the MR2’s classic laptop isn’t simply reprogrammable, so we’d want to put in an aftermarket engine administration laptop. For now, although, this setup is a welcome improve.
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An “obtainable and prepared bunghole”? You guys are a riot.
That is a superb article. Thanks.
SV reX mentioned:
An “obtainable and prepared bunghole”? You guys are a riot.
That is a superb article. Thanks.
I might encourage folks to get a knowledge logging system, so that you’re not logging together with your eyes. You have to be driving.
And even on a dyno, a logging system will present you exactly the place the problems are as a substitute of attempting to juggle a/f, engine velocity, and a few load measurement.
I like for the eu to only do all of the work for me and kick into failsafe mode if AFR is not within the applicable window.
alfadriver mentioned:
I might encourage folks to get a knowledge logging system, so that you’re not logging together with your eyes. You have to be driving.
And even on a dyno, a logging system will present you exactly the place the problems are as a substitute of attempting to juggle a/f, engine velocity, and a few load measurement.
Agreed, an AFR gauge is at finest a heat fuzzy, it is not likely helpful by itself. AFR information logged together with RPM, manifold strain, and so on is what you want for tuning.
So far as “failsafe” goes, IME widebands are significantly much less dependable than issues like gasoline pumps and injectors. I favor tuning the automobile with the wideband (on the dyno) after which turning off the automated provisions in order that the pc is utilizing the tuned, known-good gasoline map. It may monitor the AFR and activate a giant crimson warning mild if it thinks issues are going askew, nevertheless it shouldn’t silently “repair” the gasoline combination.
In reply to codrus (Discussion board Supporter) :
It might be very nice if MS had an on board provision for a Bosch sensor. Then I might belief it extra.
I take problem with the assertion, “the stoichiometric ratio, which is the perfect combination of air and gasoline that, when combustion happens, leads to no leftover gasoline or its catalyst (oxygen, on this case).”
It ought to learn : In a excellent combustion occasion, the stoichiometric ratio, which is the perfect combination of air and gasoline that, when combustion happens, leads to no leftover gasoline or its catalyst (oxygen, on this case).
An ideal combustion occasion isn’t obtainable. Take a look at a combustion occasion as a singles mixer with 100 males and 100 females. As an instance the mixer is 95% profitable; leaving 5 males and 5 females unpaired. If you wish to see all of the females paired, you could introduce extra males to the mixer till that occurs.
Identical concept with gasoline/air mixtures. If you need max energy, you need to use all of the oxygen within the cylinder (leaving unburned gasoline). If you need economic system, you need to burn all of the gasoline (leaving unused oxygen). Richer than max energy mixtures present cooling; working to stop extra warmth, detonation and/or preignition.
SV reX mentioned:
An “obtainable and prepared bunghole”? You guys are a riot.
I hit that phrase and instantly thought “JG, proper?” Skimmed again as much as the highest and confirmed.
JG, you’re hilarious. I like studying about vehicles, extra if it is partaking, and superior if it is humorous besides.
I by no means had a turbo automobile so do not know whats obtainable ,
However is there an fool mild swap to mount on the manifold that goes on when you could have extra enhance than the swap is calibrated for ?
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