GAC Posted February 1, 2006 Share Posted February 1, 2006 Greg and all, I've talked to a couple folks that had a legitimate question. If it's already been answered, I apologize for the duplicate nature of this topic. Basically we all now know that any car with 650 crank hp is going to have to run in TTR. That being said, how are you going to determine this? Dyno sheets alone won't tell you anything unless you have a good process in place. You have factors such as type of dyno, individual dyno variances, correction factor standards, different individual vehicle drivetrain losses due to many things, but most importantly 2WD vs. AWD. A Dynojet vs. a Dynapak vs. a Mustang all read quite differently. An AWD drivetrain generally sucks up more power getting to the ground than a 2WD drivetrain. So those who have asked me are now curious...what's the process to determine if a 500 whp or a 550 whp or a 600 whp car are to be considered as producing 650 at the crank? Quote Link to comment Share on other sites More sharing options...
National Staff Greg G. Posted February 2, 2006 National Staff Share Posted February 2, 2006 I guess the question is what is the "industry standard" for assumed drivetrain horsepower losses measured on a chassis dyno. I'm thinking that 20-25% for AWD, and 10-15% for RWD/FWD sounds about right. I guess the question is whether to take the conservative higher number or use the lower number. Using the lower number, it would be pretty safe to assume that any AWD car with a chassis dyno of over 520 hp, is making over 650hp. And any non-AWD with over 585hp to the wheels is making over 650 hp. The more consevative numbers yield 488hp and 553hp. I think it is fair to go with the less conservative numbers. So, let's call it: over 520 hp to the wheels for an AWD, and over 585 to the wheels for a non-AWD. Quote Link to comment Share on other sites More sharing options...
GAC Posted February 2, 2006 Author Share Posted February 2, 2006 Greg, My car will never see the light of even 200 CRANK hp. That said, people will just dyno their cars on a non-Dynojet dyno to lower the whp numbers. Dynojets, though seemingly the most common, read higher than just about any other dyno I've seen. Quote Link to comment Share on other sites More sharing options...
National Staff Greg G. Posted February 2, 2006 National Staff Share Posted February 2, 2006 2WD dyno testing should be on a Dynojet 248 or 224 with SAE correction. We could use the certified American Iron dyno shops. AWD cars will have to use what is available. Drivers are cautioned that any car using dyno numbers for classing purposes (some engine swaps will require dyno numbers to classify due to lack of data or hybrid motors), will be subject to dyno testing at any time. I wouldn't be surprised to see a mobile AWD dyno at the Nationals Quote Link to comment Share on other sites More sharing options...
FocusTed Posted February 2, 2006 Share Posted February 2, 2006 I wouldn't be surprised to see a mobile AWD dyno at the Nationals Mobile Dyno Units??? Cool Quote Link to comment Share on other sites More sharing options...
GAC Posted February 2, 2006 Author Share Posted February 2, 2006 I wouldn't be surprised to see a mobile AWD dyno at the Nationals Mobile Dyno Units??? Cool I think that's COOL too!! Quote Link to comment Share on other sites More sharing options...
I-Speed USA Posted February 4, 2006 Share Posted February 4, 2006 I guess the question is what is the "industry standard" for assumed drivetrain horsepower losses measured on a chassis dyno. I'm thinking that 20-25% for AWD, and 10-15% for RWD/FWD sounds about right. I guess the question is whether to take the conservative higher number or use the lower number. Using the lower number, it would be pretty safe to assume that any AWD car with a chassis dyno of over 520 hp, is making over 650hp. And any non-AWD with over 585hp to the wheels is making over 650 hp. The more consevative numbers yield 488hp and 553hp. I think it is fair to go with the less conservative numbers. So, let's call it: over 520 hp to the wheels for an AWD, and over 585 to the wheels for a non-AWD. Hi Greg, As a Dynapack Dyno operator it is very hard to set a standard correction value for one car let alone multiple cars, especially from location to location. We currently tune only Subaru's and have come up with a correction values that works well for our applications in our local environment but have seen these correction change from location to locations. How you pre-determine the correction factor and drive train ratios will have an affect on the final output and to keep things fair between one type of car is a job that will take some time. Then to keep it fair between an infinite selection of vehicles is, to put it lightly, tough. In addition to all this SAE correction values can also change depending on the weather, and as for forced induction vehicles this will have a much different impact than on NA vehicles. Can this be considered fair or not? Where as not using SAE corrections will not give a close estimate of how much power a car is really making if the weather conditions have changed from point A to point B. I have tuned cars at 6000 feet and while they might make over 650 horsepower there, when they are then run at sea Level, they may be quite a bit higher or lower depending on drive train ratios and SAE correction factors. This applies for both NA and Forced Induction vehicles. What I am trying to point out is how do you judge whether a car is over the mark or not? Thank you for your time, William T. Knose Jr. Lead Programmer Crawford Performance/I-Speed USA Quote Link to comment Share on other sites More sharing options...
National Staff Greg G. Posted February 4, 2006 National Staff Share Posted February 4, 2006 I agree that the method is not perfect, but do you have any better idea? American Iron has been using similar dyno testing (albiet NA cars) for years to try and equalize different models, all across the country. I guess my final determination comes down to: If I pull a car out of pre-grid, and put it on a dyno (whatever track I'm at, with whatever weather conditions there are, using SAE correction), and it goes over the limit, then it's non-compliant. So, I would say that an owner needs to give himself a nice "just in case" cushion to avoid disqualification. It would be up to the owner and builder how much they think they would need. I really can't think of a much better way to separate out the "super" unlimited street cars from the lower hp "unlimited" street cars. And, I already know that anything that Crawford builds for my good friend's STi racecar is going to be over 650 hp anyway He's not going to be able to restain himself when you guys offer him the big juice. All of you guys have just gotten too good--making 650-800 hp with 4 cylinder engines in street and converted street to race cars...... I'm always open to ideas that make the program more fair. The intent is to limit the hp in the TTU group, and anything goes in TTR. There is already an Evo back east with about 700+ hp that is going to run in TTR. I'd love to see the Evo's and STi's clean up on the Vipers, Ferraris, and Corvettes. Quote Link to comment Share on other sites More sharing options...
GAC Posted February 4, 2006 Author Share Posted February 4, 2006 I'd love to see the Evo's and STi's clean up on the Vipers, Ferraris, and Corvettes. I'll second that! I also agree that whatever system is decided upon, every competitor that is going to run in TTU that is close to the 650 crank hp number should leave a decent-sized "just in case" cushion, as Greg says. Bill's had a tremendous number of cars on the dyno, and is a good resource. Perhaps he can come up with a more fair system. The dyno system is easier for AI because all the cars are N/A and they're all 2WD. F/I cars are a different ball of wax when it comes to weather conditions and power. And AWD cars...sheesh, talk about complicated drivetrain loss estimates coupled with tons of different kinds of AWD dynos! Quote Link to comment Share on other sites More sharing options...
I-Speed USA Posted February 4, 2006 Share Posted February 4, 2006 Greg, Thank you for the time to answer my question, I would have to say this is a tough one and I am always up for a good challenge. I have a few ideas running around in my head, though I need to actually sit down, write them out and work through them to make sure they will actually work. I have one question: Why are you comparing every car based on horsepower? How would this make it fair? Just seeing if there is maybe another option to compare vehicles. I'd love to see the Evo's and STi's clean up on the Vipers, Ferraris, and Corvettes. Agreed, I would love to see the little 4 cylinders beat up on some slightly larger engines. Thanks, William T. Knose Jr. Lead Programmer Crawford Performance/I-Speed USA P.S. I will pm you about more questions I have in regards to rules. Quote Link to comment Share on other sites More sharing options...
Kerry Posted February 5, 2006 Share Posted February 5, 2006 Nevermind. Quote Link to comment Share on other sites More sharing options...
MustGoFaster Posted February 5, 2006 Share Posted February 5, 2006 Just as a suggestion, why not skip the crank HP part and just specify WHP? I don’t think many guys with AWD cars would mind having a slightly lower limit than FWD or RWD if you think there would be an issue with AWD cars of the same WHP being over powering. Looks like you guys might be on this path already. That still leaves you with Dyno variations and all, but it takes out one of the factors. One thing you could do with dyno differences is have a couple of base cars (preferably NA for better consistency) run on both dyno’s and come up with a correction factor to account for dyno differences. As for weather and turbo cars and ease of cheating. Yeah, that will be a fun one to figure out. Lock boxes on boost controllers? Maybe… Quote Link to comment Share on other sites More sharing options...
Members Shawn M. Posted February 5, 2006 Members Share Posted February 5, 2006 Just as a suggestion, why not skip the crank HP part and just specify WHP? Im thinking WHP to weight ratio has to come into play here somehow. Quote Link to comment Share on other sites More sharing options...
GAC Posted February 5, 2006 Author Share Posted February 5, 2006 Just as a suggestion, why not skip the crank HP part and just specify WHP? Im thinking WHP to weight ratio has to come into play here somehow. I think I agree here Shawn. I like the way GTS does it: weight/(whp+wtq/2). Quote Link to comment Share on other sites More sharing options...
National Staff Greg G. Posted February 5, 2006 National Staff Share Posted February 5, 2006 Wt/hp ratio does come into play. Almost none of these cars will weigh more than 4000#. So at 650hp, their wt/hp ratio will be less than 6:1. Quote Link to comment Share on other sites More sharing options...
Kerry Posted February 6, 2006 Share Posted February 6, 2006 Im thinking WHP to weight ratio has to come into play here somehow. That sounds familiar. Quote Link to comment Share on other sites More sharing options...
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