With cheap wideband oxygen sensors being available at low prices, the optimisation of fuel curves has been available to home tuners for a while. The optimisation of timing curves however, has always been a bit of a black art. Knock sensors / headphones provide the ability to make decent approximations but it is still a daunting task for the DIY'r. OEMs and race shops have the ability to use cylinder pressure sensors like Kistler sensors but these are simply out of the price range of DIY'rs and probably a fair amount of performance shops also. I remember a conversation with one of the motorsport guys at my university and the Kistler sensor they were using cost $40k. It also required drilling and tapping the heads in order to mount it. Well, there is another option. Optrand, Inc. have developed a fibre-optic based pressure sensor which can be fitted to a modified standard spark plug. They are accurate to within 1% of conventional head-mounted water-cooled sensors as shown here ----------------------------------------------------------------- You might be wondering exactly how pressure sensors are used to optimise timing curves. By looking at the pressure trace during the cycle we can observe events like knock and preignition. Knock can be seen as a eratic changes in the cylinder pressure. Close up from 'Engine Management Advanced Tuning by Greg Banish Spark ignition that is retarded too far shows up in a late increase in the cylinder pressure as seen here 'Engine Management Advanced Tuning by Greg Banish Ok now for the good curves: 'Engine Management Advanced Tuning by Greg Banish Here one can see the progression towards optimisation of the ignition map in this region. The highest curve has the maximum area under the curve but knock is not yet an issue. Note how the cylinder pressure is maximum just after crank angle of 0 degrees / TDC. ----------------------------------------------- So how much does this shit all cost? If you consider the cost of getting tuning performed by a workshop, these prices are not that bad. With a wideband / EGT / pressure measurement setup you should have everything you need to get your setup tuned perfectly. Because the sensor is mounted to a spark plug I would imagine a group from a similar area might be able to split the costs so these prices become more affordable. I dunno, food for thought?
Photoshop fake In all seriousness Nissan has designed the Z32 ecu and OEM components for their optiimal performance of the Z32.
thats pretty serious stuff. nasa spec !!! i really cant see a application on a road registered car tho . maybe give it 10 years and the prices will come down but i wouldnt hold my breath
No...they designed the maps in the ecu to minimalise wear and warrantee claims, optimal performance is far far away from OEM.
Optimum also regarding AU emissions and notorious greenhouses gases (not that i'm a greeney at heart. As pointed in previous posts, alot of aftermaket ECU's don't transcend much furtherer than stock ECU settings unless higly modified.
I emailed Optrand August 2008, never got a reply, I think they are more interested in Corporate R&D type customers. Latest "news" on there website is 2006, looks a little stale. This is the available alternative. http://www.tfxengine.com/ Email reply August 2008.
Hmmm, it kinda looks like the system that is used on the late model VG30det's, here are a few pics I took of my VG30det i have no idea what it is for but all i know is that the motor had series 2 PTU connectors... My perception is that is is a spark monitoring system, maybe more ???? Wish i has a Cima Manual to decipher WTF these wires are for. In regards to the first post all it looks like is wire attatched to a spark plug, no sensor at the plug.
Hence the reason for this thread. This is a brilliant device that will allow you to really optimise ignition timing to the edge! No way could you advance timing to the point of critical mass with any other means of detection. As we all know, our engines have serious leaning out issues on the rear cyclinders, this device will pick up any such activity instantly. Thanks for this thread Steve, very intersting to know such a product is available.
But how important is it to get 99.9% out of a tune anyway. Its not like we are racing these things. Its going to be hard to justify the cost.
Exactely what i came up with August last year and left it a that. This thread has a bit in it for those interested. http://www.aus300zx.com/forum/showthread.php?t=279164&highlight=worms
Because the plug sensors look like an easy install, where as 6 x EGT needs to be tapped into manifold. Like these: http://www.aus300zx.com/forum/showthread.php?t=276403 Apparently dynos can use software to measure individual cylinder performance.
The primary effect of timing is detonation. The primary effect of AFR is temperature. It would still be possible to use this device and detect no knocking, but still have excess temps if a lean out occurred. Leaning out in the rear cylinders would be best detected by an EGT/WBO in that area, if that is physically possible.
Nothing wrong with EGT sensors but I would think this device will pick up a significant change in cylinder pressure earlier than temperature variation, not to mention way easier to implement. K-Type thermocouples are very accurate but there is a delay between the acutal temperature vs the time the two elements react to output the resistance.
Too broad a statement. Advance your timing, you increase your cylinder pressure, which in turn increases the force on the power stroke. 2 things will happen as you increase cylinder pressure. 1, is the flame front will distort, depending on the fuel will depend on how much pressure increase it will handle before "knock" occurs. 2. Heat. Increased cylinder pressure always results in increased heat. Lean mixtures create heat, which in turn increases cylinder pressure and causes detonation. BUT due to the massive amounts of heat a lean out can cause, your more concerned with pre-ignition due to melting plugs or damaged crowns, than the increase in cylinder pressure. SO, EGT's placed on the runner 5 and 6 are great for tuning timing, but only with WO's to ensure your AFR's are well within spec so the EGT's your measuring are purely from timing advancement.
Yep that's why I was interested in pressure sensors, implementation and cost are the problem. At the moment usage is limited to OEM and R&D people, but this stuff will become stock as emissions standards are driven to new levels, tuning and efficiency will need to follow.
