Emissions Tuning Fundamentals: PEMS & Combination Dynos

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PEMS & Combination Dynos

09.28

00:00	While the equipment we're going to cover in this module may be out of your budget for purchase, renting lab time from a test facility is something that is much more achievable.
00:09	Whether you'll be using the equipment yourself or shipping a test vehicle off to have a lab handle it, it's helpful to be familiar with what's out there.
00:17	Before we talk about certification level emissions equipment, there's a class of devices that falls between VMAS and a full emissions lab.
00:25	Called PEMS, the acronym simply stands for Portable Emissions Measurement System.
00:31	But these are very advanced tools.
00:33	To avoid a potential spot of confusion, the same acronym PEMS is also used for Predictive Emissions Monitoring Systems.
00:40	So if you search for PEMS, you may find a mix of both items.
00:44	Rather than measuring emissions, the predictive system uses non emission vehicle data combined with computer modelling to infer predicted emissions.
00:52	This is beyond the scope of this course and isn't a budget friendly solution at this time so we're going to focus on the portable emissions systems, PEMS.
01:02	If you've been in the Los Angeles area or anywhere vehicle manufacturers test vehicles before release, you may have seen a big box hanging off the back of a vehicle and perhaps a big tube connected to the tailpipe.
01:13	Unlike VMAS which is a single product, PEMS comes in different sizes and shapes and from various manufacturers.
01:20	Generally in the $200-400, 000 range by the time you include a device to record the data, many of these portable systems have lab grade sensors.
01:31	Since they're meant for on road use, the test environment isn't as controlled as a dyno cell but the quality of instrumentation is still very high.
01:39	If you combine a quality PEMS system with ambient conditions that meet the window allowed for certification testing and you have a test track available so that you can drive an emissions drive cycle unencumbered, results should be within a few percent of lab testing.
01:53	In fact AVL, which is one of the leading manufacturers of emissions testing equipment, has tested their PEMS in a lab on a dyno alongside their stationary lab equipment and achieved almost identical results.
02:05	The opportunity with PEMS is the ability to collect accurate results on the road, track or standard dyno without the full multi million dollar investment to build a lab.
02:16	In practice, because you can't certify a product using PEMS data at this time, the value comes in the form of preparation for a certification test at a third party lab.
02:26	Renting a system for a day as a final pre test before certification testing might be a cost effective approach if rental is available in your area of course.
02:36	On the other hand, some emissions labs like SEMA Garages facilities allow SEMA members to perform R &D testing in the actual certification lab.
02:45	If you're in an area where certification labs perhaps require a two day minimum rental but you can rent a PEMS for a few hours at a far lower cost, PEMS may be your better option.
02:55	And now it's time to cover off certification grade stationary lab equipment.
03:00	Like PEMS, there are several brands and models out there but when it comes to lab grade emissions analysers, the biggest names are AVL and Horiba.
03:08	At this level, there are no inexpensive options so labs generally use one of these two.
03:14	Both brands are accepted by CARB and the EPA as well as regulatory bodies in Europe, Asia and other areas.
03:21	While some users have a preference between brands, the level of accuracy from either is of course excellent.
03:27	Beyond the equipment present, a good lab will have excellent staff.
03:31	This is critical because a lab is only as good as its maintenance and operators.
03:36	A lab can have all of the right equipment but lose their approval with CARB due to lack of maintenance, improper procedures or equipment failure.
03:44	As a heads up, CARB's posted list of approved labs is a few years out of date at the moment.
03:50	Before you spend money on lab time, do your homework.
03:53	Contact the regulatory bodies that you want to satisfy and make sure that they'll accept results from the lab that you plan to use.
03:59	Back to the equipment side of things, emission lab bench systems are combined with a constant volume sampling system called CVS for short.
04:07	This is critical to achieving accurate mass based measurements.
04:11	As we mentioned earlier, certification standards are based on grams of emissions per mile.
04:16	The CVS system controls the flow of exhaust gas out of the vehicle to where it's sampled and dilutes it in a controlled fashion.
04:23	This is all specified in emissions test regulations so AVL and Horiba ensure that their systems are in compliance.
04:30	One common emissions drive cycle called FTP75 has 3 distinct phases and emissions from each phase of the test are captured in their own bag for final analysis at the end of the test.
04:41	When reviewing FTP75 test data, you may hear someone talk about what happened during the first bag.
04:48	In that case, they're referring to the first phase of the test which includes a cold engine start.
04:53	Both AVL and Horiba also produce emissions dynos which meet the key requirement, an electric dynamometer that has a single roller with a nominal diameter of 48 inches.
05:03	When they say electric dynamometer, they mean it has an electric motor capable of driving the dyno and a means of applying resistance, whether it's the motor or an eddy current retarder.
05:14	Certification testing also requires certification fuel.
05:18	The fuel is specific to the vehicle being tested and labs are set up to remove standard fuel and replace it with certification fuel for testing.
05:27	The regulations on testing are extensive and even specify how much fuel vapour is present in the charcoal canister so labs have equipment to purge and load canisters too.
05:37	They also have various control gases used to calibrate sensor systems, particulate matter measurement equipment and much more.
05:44	Certification testing involves gathering exhaust samples while driving, then measuring those samples and calculating results after the drive cycle has ended.
05:53	While this is fine for certification, it's not ideal for R&D.
05:57	During R&D you generally want to see emissions data as it's happening rather than just getting a summary at the end.
06:04	A certification test summary will tell you which gases you failed on due to excessive readings but you won't have any idea what the engine was doing that caused the issue because you aren't allowed to data log during a certification test.
06:17	In many cases an engine ran great for most of a test but under a few conditions it performed poorly.
06:23	In order to determine what happened when, you need what's called a modal test.
06:28	During modal testing you can see emissions almost in real time due to a relatively low delay time and at the end you get a data log of the entire test.
06:37	That data log can be synced up with a data log of engine monitors taken using an OBD2 logging device.
06:43	It's generally easiest to use vehicle speed to sync the two up since the vehicle and dyno both know what speed they're going.
06:49	All tests start from a stationary position so we can simply match up when the vehicle starts moving.
06:55	At this point we've talked about expensive equipment that you'll likely be renting time on rather than purchasing.
07:00	This is for 2 reasons and the first being cost.
07:03	It costs about $2 million USD to commission an emissions lab, dyno, analysers and CVS column, dyno cell and control room build out, particulate matter measurement and charcoal canister loading equipment.
07:16	That doesn't get into the space required, time to build, permitting etc so it's a very large and costly undertaking.
07:23	Then when the build is complete it still requires a skilled team of personnel to operate as well as costly maintenance.
07:30	The other main reason more companies don't have full certification grade equipment is that you can't self certify in the USA and this may be the case in other countries as well.
07:41	What we mean by that is that if you're a manufacturer or tuner and you build an amazing facility with the same equipment used for certification, that data can't be used to achieve a CARB EO for your products.
07:53	Due to situations where vehicle manufacturers and others have deceived regulators, that privilege was lost so certification testing for CARB EOs must happen at a third party lab approved by CARB.
08:05	For some companies it still makes sense to build a certification lab for internal testing because it allows them to know if they're fully prepared to pass a certification test at a third party location.
08:16	Where time to market is critical and the budget is there, this can absolutely make sense.
08:22	Getting time in a third party lab sometimes requires scheduling well in advance and one failed test attempt can set a project release back significantly.
08:30	Before moving on, let's take a moment to review these big money options.
08:34	Portable emissions measurement systems or PEMS for short, use lab grade or near lab grade sensors and gather very accurate data in a mobile form factor.
08:44	PEMS aren't currently an option for certification but their high level of accuracy still makes them valuable for R&D.
08:51	Building, operating and maintaining certification grade emissions lab is a multi million dollar effort and self certification is not allowed in the US.
09:00	If you're looking to certify physical products or calibrations, choosing the right lab is about great equipment, great staff, equipment that meets your test vehicle's specific needs and confirming that regulators will accept that lab's results as valid.
09:14	Beyond that, if you're curious enough, you can dive deep into the regulations which detail the nitty gritty technical requirements in operation of lab grade emissions equipment.