swhiteh3 Posted September 15, 2004 Share Posted September 15, 2004 I'll add this topic, even though it does not affect me in AIX. There has been some concern about dyno variabilty. I think this needs to be addressed on this board. My personal feeling is this: As a career powertrain engineer, dyno variability is a fact of life. Correction factors only start to correct for the numerous variables that exist. I think that NASA's position should clarified. There is no "fudge room" in dyno numbers, and dyno numbers, as measured, will be final. The only thing that will justify a re-measurement is the discovery of a problem - discreet enough to be "fixed", with the dyno by the dyno operator. No other official, including NASA officials. Okay, I'm brainstorming out loud, but here's my $0.02..... Discuss. Quote Link to comment Share on other sites More sharing options...
D Algozine Posted September 15, 2004 Share Posted September 15, 2004 I agree with Scott. The dyno at the event is final without any correction factors. If there is going to be dyno checks at the event, it should be set up early. Anyone who decides to push the limits can have there car checked prior to qualifying, otherwise you run the risk of being over and DQ'd. Dave Quote Link to comment Share on other sites More sharing options...
swhiteh3 Posted September 15, 2004 Author Share Posted September 15, 2004 I think it's also important that people understand that even run to run variation can affect horsepower significantly, even on the same dyno and on the same day with the same weather. To minimize (but certainly not eliminate) this, competitors should be allowed 2 (or 3?) pulls, obviously with no changes between these pulls to the car - the competitor is not allowed to touch the car during this process. The competitor can take the chart which is most advantageous to him (i.e. the lowest) but can not mix & match HP and torque for different charts. Quote Link to comment Share on other sites More sharing options...
z28racergirl Posted September 15, 2004 Share Posted September 15, 2004 Right on, I'm glad there's a thread for this. I already said something along these lines in the other dyno thread--I'd like to know ahead of time where the "official" dyno is so I can do my own pulls; again, ahead of time; so the car is legal. No surprises, ya know? I realize there will be fluctuations I can't control. However, I should be in the ballpark (as will others from other parts of the state/country). Since my current co-driver is approx 150 lbs heavier than I (am I really off Jerry? sorry!) I need to know for ballast purposes since we're limited to 100 lbs. Thanks, Christine Quote Link to comment Share on other sites More sharing options...
Guest Posted September 16, 2004 Share Posted September 16, 2004 There are issues with dyno's. Case in point: at Beave Run our car dynoed over 11hp less on day to the next. I know that weather is related but that is what the correction factor is for. If you ask dynojet they will tell you that there is absolutely dyno variance on every machine they make. Some of you will say that each car should run a cushion, well ladies and gents, we do. In fact we run over 100lbs of cushion but that is quickly taken away at a ratio of 9.5lbs:1hp. We need to address the fact that the dyno will not always read the same thing and trying to keep a car legal day to day on the same weekend with no changes to the engine/computer/ignition is like chasing a ghost. This situation occured on the 'official dyno' at the track in a period of less than 14 hours. What happens if I am dynoed before the race and put my car to that weight and then after the race I dyno again and I suddenly gain my mysterious 11hp back? That is over 100lbs. How do you fix that problem mr. Powertrain engineer? Quote Link to comment Share on other sites More sharing options...
racercosmo Posted September 16, 2004 Share Posted September 16, 2004 As long as the dyno is a Dynojet each time, I don't think there should be any problems. If some other type is used, then perhaps there could be a little leeway. Edited because I was on the wrong topic. Quote Link to comment Share on other sites More sharing options...
mwilson7 Posted September 16, 2004 Share Posted September 16, 2004 Well Cosmo at Beaverun we had 2 of 3 cars dyno 9-11 hp and tq difference from day to day with NO changes to the car. The third car had to make a few changes which could have affected the dyno runs. NO one could explain the differences but 11 hp is 99 lbs of weight. Something isn't right with this picture...... Quote Link to comment Share on other sites More sharing options...
tacovini Posted September 16, 2004 Share Posted September 16, 2004 Hopefully folks in the other regions are averaging 3 dyno pulls. Getting a cool, warm and hot pull back to back and averaging the #s gets you almost dead on for repeatability. -=- Todd Quote Link to comment Share on other sites More sharing options...
mwilson7 Posted September 16, 2004 Share Posted September 16, 2004 Hopefully folks in the other regions are averaging 3 dyno pulls. Getting a cool, warm and hot pull back to back and averaging the #s gets you almost dead on for repeatability. -=- Todd That is what EVERYONE was saying at our last event until the numbers came out completely different on Sunday and then no one knew what to say. A corrected 8-11 hp difference on the same dyno from day to day with NO changes on the car is NOT acceptable. Then the issue becomes which number do you weight the car to? I think the dyno to dyno variation will become a bigger deal when regions start having more and more cars closer to the edge. Quote Link to comment Share on other sites More sharing options...
D Algozine Posted September 16, 2004 Share Posted September 16, 2004 It seems most are in agreement that their is a variance from dyno to dyno and even day to day. So, what is the solution? How about don't push the power to weight ratio so close. An 8-11 hp variance is only about 3%. I know that translates into about 100 lbs, but perhaps each driver needs to factor that variable into their numbers. Keep the burden to be legal on the driver, not the series. This is club racing, isn't it? If you expect the AI series to be dead accurate and have corrections, and the means to monitor it all, that requires resources, "money". The more complex the measurements become the more expensive it gets. Qualified people and machines are necessary to maintain such a process. Also, that opens more doors to interpretation, rulings and cheating opportunities. The AI engine is based on a maximum hp & tq to weight ratio that is designed to keep costs down and equall. Don't make the process so complex that drivers become discouraged to race. Drivers who want to push the limits to the very edge will sometimes get burned. What are typical ranges for dynos? And what is the most extreme variance anyone has witnessed? Make this information available to drivers. They should all plan occordingly. If individuals want to push the envelope they run the rist of being DQ'd. Quote Link to comment Share on other sites More sharing options...
onralz Posted September 16, 2004 Share Posted September 16, 2004 A big part of variance is oil and water temperature. This is particularly true with fuel injected cars. At 180 water temp and minimal oil temp my car has 302 rwhp. At 200 degrees water temp and 180 oil the car has 283 rwhp. That is only 20 degrees water temp but 19 hp. There will always be a variance and we the drivers need to be aware of that and not push the envelope. Quote Link to comment Share on other sites More sharing options...
swhiteh3 Posted September 16, 2004 Author Share Posted September 16, 2004 How do you fix that problem mr. Powertrain engineer? Sorry Brian, there is only one way to get around the fact-of-life that is dyno variation........ Some of you will say that each car should run a cushion, well ladies and gents, we do. Unfortunately, you don't run enough of a cushion apparently. I'm not being a wise-ass here, I'm speaking the truth. If you expect to NEVER get DQ'ed for HP/WGT, then you need to run a big cushion. If you can accept occasionally getting DQ'ed because of dyno variation, then go ahead and run tight. If you ask dynojet they will tell you that there is absolutely dyno variance on every machine they make. Do you have a name for this crack-smoker? If this is true, then I have just lost ALL faith in anything that company has ever and will ever make.... Quote Link to comment Share on other sites More sharing options...
Guest Posted September 16, 2004 Share Posted September 16, 2004 Why do we run corrected dyno numbers? The correction factors brings the numbers up or down based on the perfect atmoshperic conditions. Since we are not racing in perfect atmospheric conditions why are we not using the non corrected numbers? The non corrected numbers are what the car is actually making at the track on that day. Example. At Beave Run our car made 319hp CORRECTED for perfect conditions. Our uncorrected number, the number we were actually making that day was only 305. This is based on weather conditions. If the atmospheric module in the dyno is reading wrong or simply miscalibrated it is going to give you/me/we a false reading. The rule is your car may not be over the 9.5:1 during that race. Since we weigh the cars after that race we should be correlating that number to the amount of actual horsepower we are making during that race, not the mythical HP that we could be making in perfect conditions. Using the uncorrected numbers would eliminate one variability of the weather and tell you exactly how much power you are making that day at the track. Thoughts? p.s. Scott, do you think that running over a 100lbs of cushion is not enough? How close do you guys cut weight in the GAC car? Quote Link to comment Share on other sites More sharing options...
swhiteh3 Posted September 16, 2004 Author Share Posted September 16, 2004 The correction factor corrects for SOME of the factors, but only a very small number of them. This correction factor helps (a little) the correlation between the dyno sheet you got to certify the car, and one at the track. Unfortunately, it's only a small step towards making them correlate. Personally, I think being 100lbs over 9.5:1 is just about right. Of course, there is still the possibility of being over, even with that cushion. Sucks, huh? The power in our GAC car is mandated by parts choices, which enforced with tear-downs. If you'd prefer tear-downs to dyno pulls, then lobby for that style of rules - and require everyone to run the same heads, cam, etc. Personally, I don't think that's right for AI/X, and I don't think you do either. (Not being sarcastic, trying to be funny....) So since our GAC car is not mandated to pass 9:1/9.5:1 rules, we cut weight much closer, since the only variation is that of the scales, which are much more accurate than a dyno, especially when you multiply that dyno variation by 9.5! Quote Link to comment Share on other sites More sharing options...
bmw22 Posted September 16, 2004 Share Posted September 16, 2004 Great thread. As the director of GTS Challenge, this topic is very important to me. Our 5 classes are based on weight to power ratios. Unlike AI, we deal with dozens of different cars that are prepped at various levels ranging from Showroom Stock to Speed World Challenge to Grand Am. Now add turbos, superchargers and AWD to the mix and it gets really complicated. This season is our first year with the wiegt/HP based rules and we haven't been very strict witht he enforcement of it simply because we're still learning. We've learned a lot, and will be working hard this off season to put a good system in place for enforcing the rules. I agree with many here that each one of us should prep our cars with a cushion to allow for variables that come into play. To create "variance factors" would almost be impossible to do. Think about all the variables you would have to consider: air temp, barometric pressure, altitude, engine temp, dyno operator technique, differences between dynos. All those factors in an infinite number of combinations could not be summed up into a single scale. However, there is a more useful tool at our disposal and its much easier to use. Trending! I'm sure AI keeps records just like we do in GTS. If there appears to be a trend at a particular event, maybe that should be factored in. If it's an unusally cold day, everyone will have HP numbers higher than usual. If you dyno three cars and the three cars are an average of 4% higher than usual, then allow everyone 4%. This would also apply if a different dyno shows up at the track. This would require a little extra effort from those doing the administration work but it may be a solution. The downside would be if the dyno numbers would be coming in low. If the dyno results were an average of 4% lower, then trending would need to be applied to keep us from dropping weight to take advantage of the low numbers. Another posible solution would be to allow for a slight error. For example, allow an error of +/- 75lbs. If a car proves to be 48 lbs underwieght at post race impound, don't DQ the car, give them the benifit of the doubt. But place the car on probation. To keep the points and not be DQ, the car most meet the proper weight/hp (no +/- 75 lbs) at the next race. If the car is 1 lb under weight, it is DQed from that race and the the previous race. I prefer the margin of error method over the trending method. One thing to keep in mind is that there is no easy, cost effective, perfect solution to the problem. There will always be an exceptional case or two and there is always a way to get around a rule if that's what one would chose to do. I've met many of you AI guys and I don't get the impression that intentional cheating is an issue, nor is it in GTS Challenge. Of course we all want to prep our cars to the limit of the rules, and the thought of intentional slowing down the car for the sake of cushion makes us cringe. The ideal scenario would be to have scales and a dyno at every event. Have NASA and/or sponsors pay the dyno fee for the weekend. Nobody wants to spend $50-150 every weekend just to make sure their car isn't DQ'ed because of variables. Quote Link to comment Share on other sites More sharing options...
swhiteh3 Posted September 16, 2004 Author Share Posted September 16, 2004 Mark- Let me address your two ideas... First, trending. Trending assumes that most of the variation factors are trendable, and even less likely, trendable together. Suffice it to say, they are not. Most of variables occur with the car, and not with the dyno. Oil temp, water temp, trans temp, diff temp, etc, etc, etc are most of what makes the variation. The dyno is only a very small part of it. Second, giving a 75 cushion only serves to create a different line in the sand that people will push. At that point, why not make it 8.5:1hp. Heck, now if I'm on the dyno, instead of just taking my weight and dividing my 9.5, now I have to subtract 75, then divide? Whatever the line in the sand is, it should be firm and fast. IMHO. Quote Link to comment Share on other sites More sharing options...
Black Horse Posted September 16, 2004 Share Posted September 16, 2004 Here is a solution, but I'm now sure how to go about making it practical. You have one car that is not being raced the entire year (Eric?) come to each event. That car is not altered at any way from event to event. This car becomes the "Challenge" to set the inherent Dyno variance. In other words - the challenge car has a 300 HP dyno sheet baseline. At the next it event it dynos at 310 hp - this 3.22% correction allowance would be applied to all the rest of the cars dynoed. Quote Link to comment Share on other sites More sharing options...
bmw22 Posted September 16, 2004 Share Posted September 16, 2004 Scott, the 75 lb cushion isn't drawing a new line. By use of the probation, the original line is still the line that everyone ultimately has to meet. It just allows for a slight error and doesn't punish you for being the victim of an unknown variable. If someone is placed on probation, they must meet the original requirement or be DQ'ed from two events. Probation could be different than what I said. It could last for 3 events or even the entire season. If at anytime during the probation the car is under weight, it is DQ for that race and the race of the original infraction. The +/- 75 wouldn't apply to a car currently under probation. The original requirement would always be the goal, the +/- would only give protection for a one time honest mistake. The goal here is to keep an even playing feild, not to catch cheaters. If someone wants to cheat, they will and no rules can stop them. We do this for fun, and we spend lots of time and money to do it. Being DQ'ed when you honestly thought you were legal just ruins the weekend, pisses us off and starts a lot of crap that no body wants to deal with. I get the impression that nobody is accusing anyone of cheating, but this only affects those that prep to the max. Whatever direction is taken, it shouldn't discourage prepping to the max. Afterall, unless everyone is at the max there will be no level playing field. Our goal in GTS is to create an atmosphere where ever care can compete without creating massive amounts of work and headaches for the administrators. Most importantly, we want it to be fun and safe for all! Quote Link to comment Share on other sites More sharing options...
johnbasf Posted September 17, 2004 Share Posted September 17, 2004 Why do we run corrected dyno numbers? The correction factors brings the numbers up or down based on the perfect atmoshperic conditions. Since we are not racing in perfect atmospheric conditions why are we not using the non corrected numbers? The non corrected numbers are what the car is actually making at the track on that day. Example. At Beave Run our car made 319hp CORRECTED for perfect conditions. Our uncorrected number, the number we were actually making that day was only 305. This is based on weather conditions. If the atmospheric module in the dyno is reading wrong or simply miscalibrated it is going to give you/me/we a false reading. The rule is your car may not be over the 9.5:1 during that race. Since we weigh the cars after that race we should be correlating that number to the amount of actual horsepower we are making during that race, not the mythical HP that we could be making in perfect conditions. Using the uncorrected numbers would eliminate one variability of the weather and tell you exactly how much power you are making that day at the track. Thoughts? p.s. Scott, do you think that running over a 100lbs of cushion is not enough? How close do you guys cut weight in the GAC car? You should only use the uncorrected numbers on the dyno the day of the event. Quote Link to comment Share on other sites More sharing options...
NickS Posted September 21, 2004 Share Posted September 21, 2004 Folks, This post is liable to cross over into multiple '2005 rules' threads. I'm posting here in the Dyno thread as I think its more appropriate here than in the EFI thread.... I raced in CMC for 3 years before I was upgraded to AI earlier this year. As a result, I'd like to think I know a few things about dynos and dynoing race cars so please bear with me while I throw my $0.02's worth in on the subject, after that you can bit bucket the comments if you feel so inclined. I will start this out by saying up front: I don't know jack sh*t about carbs. I have only played with EFI cars and being a professional computer geek I understand them better than carbs so please feel free to jump in and correct me where I'm wrong. A few comments up front: I belive in a zero tolerance on power / weight. As soon as you start allowing a cushion people will eat into it and ask for more. Min weights are min weights. Max power is max power. Max torque is max torque. End of story. If you want a 75lbs cushion then add 75lbs of ballast to you car. Challenge Cars: While this is a noble idea the logistics of finding a challenge car that is acceptable to everyone for each region and making sure that the challenge car is present for each dyno are rather complex and time consuming IMHO. Back to Dynos: Based on my 3 years of racing in CMC as well as been playing around with street cars for 2 years before that and combined with my experience playing with my 'street' car, I believe that Dynojets will produce duplicate results accross the board. What seems to change IMHO, are the engines. Engines are subject to a lot of variables that can affect power and torque numbers, the biggest of which are air density,humidity, fuel quality (eg - octane rating) and ignition advance to name a few. I know that differnet dynos produce repeatable numbers. My old '92 Camaro would produce pretty repeable numbers within a certain tolerance accross all three dynos. The few times the numbers were off I was abel to trace it down something like a burned or marginal plug wire. Based on my experience with impounding other CMC cars as well as helping other CMC drivers sort out engine / power issues. I ran my '92 Camaro on a total of three dynos and all three produced similar numbers as the others. If I recall correctly, I have seen up to a 10hp variation from day to day from the same car on the same dyno. I attribute that to changes in factors like the ones I mentioned earlier. So, I think we're blaming the instrument for giving us readings we don't expect, like and or want. I dont belive that one pull is not enough due to the inconsistencies from engines I mentioned above. I would suggest that AI adapt a similar system that CMC has been using successfully for the last few years. Three dyno pulls at three different water temperatures (I belive that CMC uses 185, 210 and 220 water temperatures) and a minimum oil temp (I would propose 180 or 200 deg). The average of the three horsepower and torque readings of the three pulls is the final reading. Period. Also, like CMC, we should also look at instituting a dyno spec sheet for each car. It should contain roughly the following information: Basic stats on the car, chasiss #, car #, owner, basic engine config as well as: Name and Signature of the dyno operator (This gives the tech inspectors someone to call if they have questions) Basic engine config (eg small block chevy, alum heads, vic jr intake, holley 650 carb, 14" round K&N air filter) Basic exhaust config (eg hooker long tube headers into an X pipe, 2 dynomax mufflers, side exit in front of the rear wheel) Revlimit RPM (if the car has a rev limiter) Any modifications needed to bring the engine within spec, for example throttle body restrictor plates. For Carb cars: carb model jet sizes fuel presssure (if this is even a factor for Carb cars?) degrees of initial ignition advance For EFI cars (this is where things could get a bit complicated): Type of EFI (factory stock, Accel DFI, FAST etc) Fuel pressure with vacumn line disconnected Degrees of initial ignition advance (not applicable to all cars for example LT1 and LS1 camarobirds and Ford ModMotors (I think)) These things will cover the very basic things that people can easily do to a carb or EFI motor to adjust the power levels both up and down at the track, they are also things that can easily be checked at the track in impound with some simple hand tools and a few minutes. It only takes a few min to check fuel pressure and timing and visually inspect the external appearance of the motor, exhaust etc and compare it against what is listed in the dyno sheet. If it doesn't match, the car is in violation plain and simple. Some folks have raised what I think is a valid concern about people altering the PCM programming to reduce the power numbers. I think there are several ways that this can be addressed depending on the type of EFI system being used. Cor computers that require a physical chip swap, using security tape to cover the ALDL port and the PCM cover closed should be sufficient to prevent reprogramming of the PCM. For computers that can be reprogramed via a laptop and a cable there is a bit more of a challenge. Simply physically securing the the computer(s), ALDL and in the case of aftermarket EFI systems, any other interface ports the system uses is not enough. Its sitll possible to splice into the wiring harness to In this case I would propose that each competitor also include a copy of the program loaded in the computer in their car to the tech officials along with a copy of the dyno tech sheets and printouts of the dyno runs. All the tech inspector has to do is pull down a copy of the program in the car and compare it against the one provided with the dyno sheet. If they do not match then the car is in violation. Plain and simple. It doesn't matter if the car dynoed under the limit, if the program in the car does not match the one provided to the tech inspectors then the car is in violation. The slightly tricky point in this whole proposal is how to enforce this. Does this mean we need to turn out tech inspectors into computer geeks? No, I dont' think so. All the tech inspectors need is a laptop, cables and software. I would expect the competitors to be able to provide the cables and a copy of the software needed read the program in the PCM into the laptop. I can only speak for LT1 and LS1 cars, but I would expect that the vairous tuning software packages have the ability to compare two PCM programs and show the differnces between them (note, I am speaking out of my ass here as my only direct experience has been with LT1edit and LS1edit for GM cars. I have not fiddled with anything for the Ford products nor any of the aftermarket EFI systems). So what do we need to do this? A used $500 - 800 laptop and a bit of training for the tech inspectors in each region whichI think are pretty reasonable. Heck, I will volunteer to show folks how to do this with the LT1 and LS1 cars if this makes it into the '05 rules. I'm sure we can get someone to volunteer for the Ford cars and for the few aftermarket EFI systems ou thter e(Accell DFI and FAST come to mind ). Yes, one possible downside to this proposal is that it means that folks will have to redyno their cars when they make changes to the exhaust, jets, and computer but then again, we are all doing this now aren't we? I mean, someone goes from shorty headers to long tubes with an X pipe and no mufflers, I would fully expect that person to redyno their car to verify its not over the limit for their weight. On anothernote, I do realize that this proposal does not take into account forced induction motors. I don't belive there are any competing in AI (Feel free to smack me with a 2x4 if I'm wrong...). If / when there are any forced induction cars the above system should be able to adapt to them. The dyno spec sheet could be expanded to include supercharger / turbo charger type, pulley sizes (if applicable), intercooler type and max boost level. Feel free to flame away... - Nick Camaro Pilot Quote Link to comment Share on other sites More sharing options...
Members Jim P. Posted September 21, 2004 Members Share Posted September 21, 2004 I belive in a zero tolerance on power / weight. As soon as you start allowing a cushion people will eat into it and ask for more. Min weights are min weights. Max power is max power. Max torque is max torque. End of story. If you want a 75lbs cushion then add 75lbs of ballast to you car. My thoughts exactly. Posted as a Director AND a Racer Quote Link to comment Share on other sites More sharing options...
Guest Posted September 21, 2004 Share Posted September 21, 2004 I belive in a zero tolerance on power / weight. As soon as you start allowing a cushion people will eat into it and ask for more. Min weights are min weights. Max power is max power. Max torque is max torque. End of story. If you want a 75lbs cushion then add 75lbs of ballast to you car. My thoughts exactly. Posted as a Director AND a Racer Jim, how would you propose that the series deal with day to day variations of the dyno when there have been no modifications to the vehicle in question? Also, when you say director do you mean regional director (NASA SE) or AI director? Quote Link to comment Share on other sites More sharing options...
NickS Posted September 21, 2004 Share Posted September 21, 2004 I don't belive the variations are from the dyno, they are from the engine. Quote Link to comment Share on other sites More sharing options...
Members Jim P. Posted September 21, 2004 Members Share Posted September 21, 2004 If your car is legal - add/remove ballast to meet the dyno 'du jour' readings - it seems pretty simple to me? Everyone that is dynoed that weekend will have the same issues, so if you are all trying to meet the same standard where is the problem? We haven't even talked about the lunar phases and the effect on gravity (and the weight of the cars! ) It is one of life's little variables: - dyno's will vary - the sun shines sometimes - some people win the lottery - some drivers are better than others - you never know where a hurricance is headed - the outcome of a race is always a toss-up If we are doing this primarily for the FUN of it, how hard is it to understand that everyone's car has to meet a standard? Posted as a Regional Director and a Racer Quote Link to comment Share on other sites More sharing options...
johnbasf Posted September 21, 2004 Share Posted September 21, 2004 If your car is legal - add/remove ballast to meet the dyno 'du jour' readings - it seems pretty simple to me? Everyone that is dynoed that weekend will have the same issues, so if you are all trying to meet the same standard where is the problem? We haven't even talked about the lunar phases and the effect on gravity (and the weight of the cars! ) It is one of life's little variables: - dyno's will vary - the sun shines sometimes - some people win the lottery - some drivers are better than others - you never know where a hurricance is headed - the outcome of a race is always a toss-up If we are doing this primarily for the FUN of it, how hard is it to understand that everyone's car has to meet a standard? Posted as a Regional Director and a Racer Jim, the last time I had my car tuned it varied as much as 8 RWHP. 8rwhp=76lbs, see why the question has come up. If NASA racing is primarily for fun then it should not be called "NASA PRO Racing". Quote Link to comment Share on other sites More sharing options...
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