Dominic Berry Posted October 18, 2000 Share Posted October 18, 2000 Whilst out in the Seven last night I was wondering what is the quickest way to get to max revs. Just floor the accelerator or gradually (but quickly) apply the right foot? I have no timing equipment but my car (1.6K SS) felt faster applying the power gradually. Is this correct? Does flooring the accelerator just flood the engine? Dominic Link to comment Share on other sites More sharing options...
tgracing Posted October 18, 2000 Share Posted October 18, 2000 pull the clutch and floor the throttle ? tongue.gif Davebo C7 CAR Edited by - davebo on 18 Oct 2000 14:00:31 Link to comment Share on other sites More sharing options...
John Richens Posted October 18, 2000 Share Posted October 18, 2000 Dominic, why didn't you end up at the Plough then...a nice dry night and only a few Sevens in the carpark... Link to comment Share on other sites More sharing options...
Dominic Berry Posted October 18, 2000 Author Share Posted October 18, 2000 Had to barter with the other half just to get a 30 minute run out. Is there a smilie with a thumb print in the middle of it's forehead? Link to comment Share on other sites More sharing options...
EFA Posted October 18, 2000 Share Posted October 18, 2000 Best way to get it all on the road is with a Racelogic box of tricks called Traction control! Yes Domonic - why weren't you at the Plough last night... Link to comment Share on other sites More sharing options...
Dominic Berry Posted October 18, 2000 Author Share Posted October 18, 2000 Traction what? Is that more money? wink.gif Or should I get it painted luminous yellow and not give a sh*t? Link to comment Share on other sites More sharing options...
Mike Bees Posted October 18, 2000 Share Posted October 18, 2000 Dominic - assuming you're not having to control wheelspin then just putting your foot to the floor should work as well as anything else. On a modern computer-controlled fuel-injected engine the ECU will supply the 'best' amount of fuel (and best ignition timing) for the combination of throttle position and rpm. At low rpm you find that you only get extra power up to a certain amount of throttle opening, after which the power stays (more or less) the same however much more you open the throttle. The ECU has this information stored in it and knows the optimum amount of fuel to supply in all conditions. Mike Link to comment Share on other sites More sharing options...
mark.hall Posted October 18, 2000 Share Posted October 18, 2000 thumbsdown.gif smile.gif or of course thumbsdown.gif sad.gif Edited by - mark.hall on 18 Oct 2000 16:40:07 Link to comment Share on other sites More sharing options...
Peter Carmichael Posted October 18, 2000 Share Posted October 18, 2000 If you stomp on the pedal, the ECU may not have enough consideration for acceleration fuelling built in. When you gulp in a lot more air, the first few cycles following will be lean unless more fuel is supplied - this is down to the different paths the fuel takes to get into the cylinder. Injected fuel can: 1. Evaporate off the back of a hot valve. 2. Get sheared into appropriately air suspended droplets in a fast airflow. 3. Wet the inlet tract surface and evaporate slowly from there. Typically (not my figures, but a real shocker and I can refer you to my source), ten times the amount of fuel that is injected in each cycle is just sitting around wetting the inlet tract walls. At steady state, evaporation into the airflow is at the same rate as deposition onto the tract walls. This is a surface process and the rate of transfer depends on the surface area that is wetted. When you increase the air flow rate, if you just injected the steady state mapped fuel figure (more), the greater injected amount would deposit more fuel onto the inlet tract walls than would be evaporating. Eventually a new steady state would be achieved where the wetted wall area would be larger than before and the fuel path via the tract walls would deliver more fuel to the cylinder, along with more fuel following the more direct paths. i.e. in between the two steady states, the mixture in the cylinder would run lean because fuel intended to get into the cylinder would be ending up on the inlet tract walls, with no balancing evaporation back into the airflow. To stop this happening (giving a hesitation on rapid throttle openings), your ECU has to know to supply extra fuel for a short transitional period. This is the ECU performing the same function as acceleration pumps in carbs. A standard production spec ECU like the Rover MEMS may favour underdelivering fuel for the sake of emissions, but the transients will be poor. I have recently seen two k-series Caterhams with MEMS units that were mismatched to the engines and very poor corresponding transients. Mike Bees comments cover another contributing factor. Link to comment Share on other sites More sharing options...
flick Posted October 18, 2000 Share Posted October 18, 2000 Does peter work for Anderson Consulting ??? Link to comment Share on other sites More sharing options...
Red SLR Posted October 18, 2000 Share Posted October 18, 2000 They sponsored Mr Hill no less. I think listening to F1 drivers etc the best acceleration can be found by gradually opening the throttle but in a timely manner. This also works for coming off the brake pedal - rather than just snapping off it you should gradually remove the pressure off the pedal. This all went out of the window for Senna - he stabbed at the throttle violently when he accelerated out of corners - this gave him upto 1 second a lap over the likes of Alasi, Mansell etc. I saw a graph of his accelerator pedal movement over a lap at donnington - it looked like a fine tooth comb. on off on off on off etc. Simon X777CAT Link to comment Share on other sites More sharing options...
Peter Carmichael Posted October 18, 2000 Share Posted October 18, 2000 It has been a while since F1 drivers have had direct mechanical control of their throttles. It is all drive by wire with control strategies preventing the torque build up from being - how shall I put it - inappropriate. Link to comment Share on other sites More sharing options...
Dominic Berry Posted October 19, 2000 Author Share Posted October 19, 2000 So if I understand the theory correctly, the ECU *SHOULD* be able to handle me just stomping on the pedal, but due to inadequacies in the Rover box this may not be the best way - ie the gradual application of the power may indeed be the quickest way to get me going (as I found). Simon, what you were saying... '...the best acceleration can be found by gradually opening the throttle but in a timely manner' was drilled into us by Don Palmer on his Wetter the Better course at MIRA. Everything (accelerate, breake, steer) had to be done smoothly. ie no stomping on anything. This showed itself in faster times aroung the short circuit. Dominic Edited by - dominic berry on 19 Oct 2000 09:42:50 Link to comment Share on other sites More sharing options...
Mike Bees Posted October 19, 2000 Share Posted October 19, 2000 I'm still confused as to whether you're talking about getting the best performance out of the engine, or getting the best acceleration on a traction-limited surface... In respect of engine performance, 'stomping' the pedal to the floor in the space of a few nano-seconds might cause the engine to stumble very briefly, but after that it shouldn't make any difference. Mike Link to comment Share on other sites More sharing options...
mark.hall Posted October 19, 2000 Share Posted October 19, 2000 I seem to find every surface has limited tractionteeth.gif Link to comment Share on other sites More sharing options...
Dominic Berry Posted October 19, 2000 Author Share Posted October 19, 2000 Mike, I'm talking about on a dry road, in 2nd, 4000 rpm, then stomping (or not) on the gas. When I did this a couple of nights ago, the car felt faster when I applied the gas (relatively) slowly. The car is a 1.6SS so the cams are just starting to come in. Traction was not an issue. There may have been no difference in acceleration times - it just *felt* faster. Dominic Dominic Link to comment Share on other sites More sharing options...
EFA Posted October 19, 2000 Share Posted October 19, 2000 Dominic, What tyres does your car have and how old are they??? A 140bhp car should not be spinning the wheels everywhere unless you are dropping the clutch and using too many launch revs. Do you have a limited slip diff??? What ratio?? Does the wheelspin happen when you are going dead straight?? Answer these and we'll be able to help..... Incidental.... All engines will splutter a little if you whack open the throttle when they are not 'on cam'. This is the maechnics of inlet tract velocities, not ECU performance. The Supersport ECU is written for sharp response unlike the ECU in a stock K Series where the enrichment map is written with economy in mind rather than acceleration. Software aside, the ECU and throttle pot can process commands far quicker than any human can detect. Arnie Link to comment Share on other sites More sharing options...
Dominic Berry Posted October 19, 2000 Author Share Posted October 19, 2000 Arnie, You are right, traction/wheelspin are *not* a problem sad.gif (see the previous post). I think you have hit the nail on the head with 'all engines will splutter... when they are not on cam'. As I said the difference felt marginal - or it might just be me talking boll*cks. I'll take you out at the next meeting & show you what I mean (about the acceleration not me talking boll*cks). Dominic Link to comment Share on other sites More sharing options...
Red SLR Posted October 19, 2000 Share Posted October 19, 2000 What has drive by wire throttles got to do with the way Senna drove then??? Dominic - there is only one way to prove the theory - time it. Say 30 to 60 in 2nd. Simon X777CAT Link to comment Share on other sites More sharing options...
Jules Martin Posted October 19, 2000 Share Posted October 19, 2000 Buy an R500, then you can do it anyway you want! unlike that Blackbird piece of crap! Jules Link to comment Share on other sites More sharing options...
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