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hello first of thank you for helping me tune my car so far.
my sey up: Vw Golf mk2 with a r32 engine and a self made turbo kit. borg warner k29 turbo and turbo smart bov and waste gates. mac 3 port boost valve and a vems ecu controlling it all. i made 570 bhp on the dyno at 70% duty cycle and about 17psi of boost.i plan to push tjs set up alot further next year. i have to be car full as the engine is stock apart from a head spacer to lower compression and arp rod and head bolts. i have a straight cut dog gearbox and wavetrac lsd.
i only use my car for drag racing.
my question is what should i be looking for in my data log to help improve my 1/4 mile times?
i data log every single time i go up the strip which is great as it helps me work out problems but i feel like i am missing something.
thank you sam
i am not sure what you mean?
Well there is a bunch of data you can revise with data logs for improve the performance of a drag car but it all depend on the system and sensors you have installed on your car, the possibilities are very varied, for example suspension travel, sterring wheel movement , clutch spin , a lot of temperatures and pressures data as well and many more info that help tune your car and engine to improve performance .
But it requiered special sensors and systems, one data that is very interesting and usefull without invest in extra sensors is analize your rpm at each shift looking at your throttel position sensor signal to detect when you do the shifts , looking at your rpm in each shift and the rpm when you are crossing the 1/4 mile and comparing with the dyno sheet data you are able to figure if you are using the full potential of the engine on the quarter mile , for example if you are shifting at 6500 and crossing the quarter mile at 7000 rpm and you dyno sheet say that your max hp is at 7500 rpm then you know that your are not using the full potencial of your engine and have some homework to do, maybe changing to a higher final drive ratio or less wheel circunference that way your are going to use the engine more close to the full potencial , the perfect should be shifting and crossing the quarter at some( 5-10%) rpm more than the rpm at max hp , but the perfect is not always possible and it all depends on the overall car setup too, but it pay a lot of dividends if you achieve to use your engine as close to full potencial .
Another thing very usefull in drag racing is looking at car speed vs traction wheel speed , you need wheel speed sensor on the traction wheels and vehicle speed sensor or non traction wheel speed sensor that way you could figure wheel spin and then compare if your changes in tyre pressure ,suspension settings ,launch rpm, boost in first gear etc make less or more wheel spin , improving or not traction , that way you are going to improve the first 60 feets , very important in drag racing, maybe the data logging system of your ecu could perform those calculations with the proper sensors, if not there are some basic data loggers on the market that can do that .
When you get to the point that a drag car has more power available than the track can take then the main aspects I'm analysing in a log file is how well hooked up the car was and where I can add power (boost), or alternatively where I need to remove power. This should come after checking the engine vitals however to ensure that everything is mechanically sound. If you can analyse driven wheel speed vs non-drive then this will give you wheel slip, however wheel spin is normally easy to spot with spikes or flares in the rpm trace.
Another aspect that's vital to getting the best out of a drag run is the launch. What you're looking for here is whether the car bogged down when the clutch was released, or alternatively broke into wheel spin. Both will hamper your 60' times and affect the rest of your run.
This is all great information and I think I have been along the right lines I just now need to apply what I have been looking at and test.
I also think I need to get an ECU with more inputs as I have ran out on mine and I'd like to log alot more stuff.
Thank you for the help
I like to look at heat soak. If you have a manifold temperature sensor or even a sensor in the airbox, see how hot the air charge temperatures are getting. For example, are they consistent between runs? Also look at boost control. Is it spiking when you don't want it to? Can you make it come on boost harder safely, or dial back boost to increase traction?