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Dyno reclass?


ken o

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What are the benefits to a dyno reclass in TTB-TTF?

 

It seems like a roll of the dice. Some cars can benefit from it while others wouldn't not. If you don't know to request a dyno reclass for a car with a base class your competition with a dyno reclass could have an advantage over you and actually have more points to use in the same class.

 

But why do we really need to reclass a car if the car has a defined base class and all the mods on the car are assigned points. Why would it need a reclass? Why not adjust the base class of the car accordingly to correct the need to reclass?

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The point I think Ken is getting at is why even have the option to dyno re-class a car in the first place? It seems to muddy the water and create more variables that can disrupt the parity that the base class points system is trying to achieve. The only exception being if you make drastic changes to a car like an engine swap. The idea that you can take any car in any state of tune and request a re-class seems to be at odds with all the effort that goes into creating (and adjusting if required) the base class ruleset.

 

It took me about 2 years to fully grasp what a dyno re-class was and even longer to understand if I could benefit from it versus the setup I eventually went with. Because it is something that is looked at on an individual case by case basis it makes it difficult for newcomers or folks that are building out there cars to grasp how it affects them. Would remove the notion of studying the points ruleset to develop your car (what the majority of folks do) or try the mysterious portal of a reclass. Would make setups much more comparable between competitors and I bet would significantly reduce the size of Greg's inbox.

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Recent experience tells me that having a reclass isn't always roses and unicorn farts.

Recent experience tells me that having a reclass isn't always roses and unicorn farts.

 

Ken B, Ive always wondered why a Unicorn's butthole smells different from its farts?

 

Please advise...asap

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I think reclassing each car by power to weight is ultimately the fairest way because different cars respond to engine mods differently. S2K's generally benefit from a reclass because the points we take for intake, header, exhaust, and a tune are not worth the points assessed. Those mods barely increase hp on an S2K. On a car like the STI, it is much better to stick with the points system. They can make 325 whp / 410 wtq on e85 with a stock turbo.

 

Given the same power to weight ratio, a more powerful / heavier car is still at a huge advantage over a lighter / less powerful car at high speed tracks like Road ATL, VIR, etc. due to drag. The more powerful / heavier cars overcome drag better than a similarly sized lighter / less powerful car because the amount of drag between the 2 cars is the same. The current rule set makes it very track dependent whether a particular car and setup will have an advantage.

 

Having to dyno reclass every car would be bad for TT participation though. Most people start doing TT in whatever class their car and mods lands them by simply adding up the points. Having to submit dyno forms would deter newbies.

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Wynn, your point is valid regarding different cars responding to differently to the same mods and different approaches to the same power to weight gives advantages to different cars at different tracks. However I don’t think a dyno reclass solves this issue. Lightweight lower hp cars will be faster at tight tracks, heavier higher hp cars will be faster on straight tracks….and boosted cars can torque fill till their cup runneth over and dominate everywhere. Unless NASA implements success ballast or air restrictors and tweaks them every event it will never be a perfectly equal scenario for every car on every track. Its a tale as old as racing itself and comes back to the frogs and warts argument…do the dance KBrew!

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.and boosted cars can torque fill till their cup runneth over and dominate everywhere.

 

Bahahah, I legitimately laughed at that one. Thank you.

 

While I understand what you're saying,(and Carroll Shelby wouldnt agree with me) torque doesn't win races, horsepower does. There's plenty of examples if you look it up The 2nd place guy in TTB at nationals didn't have a turbo, or anything fancy and still found a way to be only .2 seconds behind a "dominating" turbo car.

 

Unless NASA implements success ballast or air restrictors and tweaks them every event it will never be a perfectly equal scenario for every car on every track. Its a tale as old as racing itself and comes back to the frogs and warts argument…

 

I dont like the idea of success ballast, why should someone be penalized for picking a good car, developing it and driving it well? So when they win they get weight added, to compensate for others who might not have a fully optimized car, or aren't driving it at 100%? Im not directing this at anyone, or saying this has happened, just hypothetical.

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For a max allowable whp of 305, under the current rules both below dyno plots are legal. The only difference is for the blue line the boost controller is turned on. Red is straight off the turbo's actuator. Which would you rather have? Which do you think would result in a faster lap time?

 

Both AI and GTS use wtorque for classification. PT/TT (or ST) does not. Area under the curve is what matters and I GAURENTEE the blue line would produce faster lap times.

 

Oh and it can be had for +4pts boost controller (or 0pts for engine w/ OE pwm valve or 0pts with reclass) and you don't even need a reclass. Not even possible with a smaller displacement NA engine w/ unlimited pts or funds using a reclass.

 

.....Jeremiah is not legitimately laughing now - jk! Had to give you a hard time before I see you this weekend.

 

1993_240sx_AMS__Dyno_01Aug07_BC.jpg

 

I agree with Jeremiah about awards weight. It's appropriate in pro race series where the cars are completely built to the rules and optimized. But in an amateur series especially Time Trials where cars are at different build levels and some are even legitimate street cars, it doesn't make sense.

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Rob, you just love stirring the pot. Lol. To answer your question though, I AM still laughing, I've just added a little head shaking to it.

 

Of course everyone would choose the blue curve! It has a higher number and area under the curve, horsepower number that is!

 

I cant explain it very well, people much smarter than me have a good explanation for why horsepower matters over torque. If I can find it quickly ill post it, but everyone has access to the same information I do, look it up!

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.and boosted cars can torque fill till their cup runneth over and dominate everywhere.

 

Bahahah, I legitimately laughed at that one. Thank you.

 

While I understand what you're saying,(and Carroll Shelby wouldnt agree with me) torque doesn't win races, horsepower does. There's plenty of examples if you look it up The 2nd place guy in TTB at nationals didn't have a turbo, or anything fancy and still found a way to be only .2 seconds behind a "dominating" turbo car.

 

Torque is the only motive force that determines how fast a car is, not horsepower. Horsepower is just a product of torque and revs. Since torque is not accounted for in PT/TT as Rob S pointed out, we really should all be running V6 TDIs (or V10 TDIs for those in the U-3 classes) with 10 speed DCTs. But I digress...

 

I dont like the idea of success ballast, why should someone be penalized for picking a good car, developing it and driving it well?

 

Absolutely agree. Which leads back to those frogs and warts again. Why am I not running a turbo diesel? Cause I don't want to! But its fun to bench race and b*tch about the advantages other cars have over your own. I mentioned success ballast as tongue in cheek. Totally not practical to employ the way touring car & GT series do in Europe do on race by race basis but if adjustments need to be made to base classing for a specific car every now and then so be it. The FRS/BRZ being the latest example.

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Rob, you just love stirring the pot. Lol. To answer your question though, I AM still laughing, I've just added a little head shaking to it.

 

Of course everyone would choose the blue curve! It has a higher number and area under the curve, horsepower number that is!

 

I cant explain it very well, people much smarter than me have a good explanation for why horsepower matters over torque. If I can find it quickly ill post it, but everyone has access to the same information I do, look it up!

 

I know, can't help it!

 

I think you are thinking of the example Dave posted in the GTS forum comparing different types of engines. In my example, the engine, trans and FD are the same. Even if you change the blue line to equal the red at 292.8 whp, the blue line is still superior. The point is the blue line makes the same whp from 4K to redline whereas the red line only at redline. It's +50whp at 4.5Krpm and +30whp at 5Krpm!

 

Don't even look at wtorque. The area under the curve difference for whp from 3.5K to 6Krpm says it all!

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We've gotten a little off topic from the original thread intention, sorry to the OP for that.

 

Rob, its not what I was referring to, but Dave's answer in the Thunder Roadster thread is somewhat still applicable to this discussion. The power gained in that dyno sheet you posted wasn't free though either, 4 points is a lot to spend for most cars. And I'd argue that a well thought out NA car could take advantage of those 4 points with other mods to be just as competitive.

 

Im just curious though, is there a disproportionate amount of turbo cars winning in B-F that would warrant this hate on them? or is it simply a bench racing session where turbo cars are in the crosshairs of non turbo guys? Obviously I have a turbo car and have been fortunate do do well with it, after years of development. But I dont really have a dog in this fight after this year since I most likely won't be competing in B anymore. So im just asking if there currently a large number of turbo cars winning in all classes to deem a change? I dont see it, but maybe I just have my (turbo) blinders on.

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You're asking for two different sets of people to tar & feather you Mr. Turbo AND All-Wheel-Drive. What did you dyno at at Nationals?

 

 

Psh! It won't be anything I haven't heard before! Apparently im a no talent, hack driver who just happens to drive gods gift to racing in the form of a Subaru! LOL.

 

But ill answer your question anyways, as it somewhat makes my point. I won in tt by less than .2 seconds over a 15 year old FIREBIRD with a pushrod V8! Oh, and LOST (gasp!) In pt to that same non turbo, solid rear axle, 3500 lb, pushrod V8, 15 year old FIREBIRD. Sorry about the sarcasm, just making the point that almost any car can win with the right driver/combination.

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We've gotten a little off topic from the original thread intention, sorry to the OP for that.

 

Rob, its not what I was referring to, but Dave's answer in the Thunder Roadster thread is somewhat still applicable to this discussion. The power gained in that dyno sheet you posted wasn't free though either, 4 points is a lot to spend for most cars. And I'd argue that a well thought out NA car could take advantage of those 4 points with other mods to be just as competitive.

 

Im just curious though, is there a disproportionate amount of turbo cars winning in B-F that would warrant this hate on them? or is it simply a bench racing session where turbo cars are in the crosshairs of non turbo guys? Obviously I have a turbo car and have been fortunate do do well with it, after years of development. But I dont really have a dog in this fight after this year since I most likely won't be competing in B anymore. So im just asking if there currently a large number of turbo cars winning in all classes to deem a change? I dont see it, but maybe I just have my (turbo) blinders on.

 

Jeremiah, I'm a huge fan of turbos. I design them as my job. I'm not hating on turbos but merely using it as an example to point out what I see as a potential area for improvement within the current PT, TT and ST rule set.

 

The same thing can occur in ST/TT1-3 with crazy V8 torque builds and detuning.....more wtorque than whp and flat whp curve. I'm sure Greg does some adjusting during PT/TTB-F reclasses (and initial base classing) based on wtorque but two other successful classes (AI and GTS) think wtorque is important enough to include it in the rules. Why not PT, TT and ST? Why not consistency within NASA for "power" calculation to make dyno compliance testing easier?

 

Older cars that don't have boost control solenoid valves need to take the +4pts for aftermarket boost controller. Modern turbo cars with programmable ECU's and boost control solenoid valves like yours don't need to take the +4pts because it's built into the OE system. Tune the stock ECU and the MASSIVE increase in area under the curve is free! NA engines with programmable ECU's will get nowhere near the same increase.

 

Sorry you feel you're in the cross-hairs. That was never my intention. And I never said or implied your success was based on the fact you have a turbo car. I can tell you've worked hard developing your car and driving. But if you want to see my point in action, run your car with the stock tune and a power plateau tune (what most turbo cars run like the blue curve on previous dyno graph), guarantee there is an appreciable difference in laps times and definitely more than an NA engine with a retune.

 

Sorry, OP. I'll stop. I'll bust Jeremiah's chops some more in person this weekend over a beer!

 

Update: I've been beating the "add torque to the rules" drum for quite some time to no eval so I'm sure turbo cars have nothing to worry about.

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Jeremiah, I'm a huge fan of turbos. I design them as my job. I'm not hating on turbos but merely using it as an example to point out what I see as a potential area for improvement within the current PT, TT and ST rule set.

 

The same thing can occur in ST/TT1-3 with crazy V8 torque builds and detuning.....more wtorque than whp and flat whp curve. I'm sure Greg does some adjusting during PT/TTB-F reclasses (and initial base classing) based on wtorque but two other successful classes (AI and GTS) think wtorque is important enough to include it in the rules. Why not PT, TT and ST? Why not consistency within NASA for "power" calculation to make dyno compliance testing easier?

 

Older cars that don't have boost control solenoid valves need to take the +4pts for aftermarket boost controller. Modern turbo cars with programmable ECU's and boost control solenoid valves like yours don't need to take the +4pts because it's built into the OE system. Tune the stock ECU and the MASSIVE increase in area under the curve is free! NA engines with programmable ECU's will get nowhere near the same increase.

 

Sorry you feel you're in the cross-hairs. That was never my intention. And I never said or implied your success was based on the fact you have a turbo car. I can tell you've worked hard developing your car and driving. But if you want to see my point in action, run your car with the stock tune and a power plateau tune (what most turbo cars run like the blue curve on previous dyno graph), guarantee there is an appreciable difference in laps times and definitely more than an NA engine with a retune.

 

Sorry, OP. I'll stop. I'll bust Jeremiah's chops some more in person this weekend over a beer!

 

Update: I've been beating the "add torque to the rules" drum for quite some time to no eval so I'm sure turbo cars have nothing to worry about.

 

Don't want you to stop beating the drum... but my recent (~18 months) dyno reclasses do come with a TQ limit as well as a HP limit. Just a FYI.

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To the OP question: It totally depends on the car. In my case, the reclass would have me running 100lbs heavier all else being equal. So...why would i run it? The car in question simply responds quite well to the ancillary engine mods like intake and exhaust. Also, as we found out now two years in a row the Dyno behaving as it did at the championships can have folks scrambling for new reclasses at a national level event, which i think is quite silly.

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Don't want you to stop beating the drum... but my recent (~18 months) dyno reclasses do come with a TQ limit as well as a HP limit. Just a FYI.

 

...and the mysteries of re-classing continue to be revealed...

 

This is the sort of stuff that needs to be part of the base rule structure including appropriate base classing (i.e. for cars that do/do not respond well to mods) so that everyone has access to the same set of information as to what cars we should/shouldn't be looking to develop, compare against our own, etc. Transparency please!

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Some stuff worth mentioning:

 

-A dyno reclass will put you a good bit from the maximum allowed power to weight ratio for the class. If you were to make a graph - power on one axis and weight on the other, your reclass will fall somewhere on a line that is a fair bit off from the class limits. If you can get above that line with points only, you're better off with points. If you have anything beyond simple engine modifications, though, you're probably stuck with the reclass route. It also makes sense to reclass if you are below that reclass line. You get your engine mods or lightness for "free," which lets you run better tires, aero, suspension, brakes, etc.

 

-Another strategy arises if you can mess with your tune: you can cap your maximum power. Turbo cars get a bad rap because they can easily pull boost off the top and keep a nice meaty power band, but NA cars can use this strategy as well. It's a double edged sword though, because you have to tune as close to the limit as possible, and variation between dynos and tuning conditions is a harsh mistress. (At Mid-Ohio this weekend, 1st place TTE was DQ'd both days for going over on power - even after messing with the tune on Sunday.)

 

-You can't just "add torque." Torque and HP are directly related. (HP = Torque x RPM ÷ 5252.) At 5252 RPM, Torque = hp - this is why the curves always cross each other. This also means that below 5252, the lower the RPM, the higher the rise in torque to increase horsepower. At 1000 RPM, 10 ftlbs of torque gives you about 2 HP. At 5000 RPM that same 10 ftlbs gives you an increase of about 9.5 hp. So when you add a peak torque limitations into the mix, you're adding a linear limitation on horsepower. (Max of 300 ftlb says you can only make 57 hp at 1000 rpm, 171 hp at 3000 rpm, etc.)

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Some stuff worth mentioning:

 

-A dyno reclass will put you a good bit from the maximum allowed power to weight ratio for the class. If you were to make a graph - power on one axis and weight on the other, your reclass will fall somewhere on a line that is a fair bit off from the class limits. If you can get above that line with points only, you're better off with points. If you have anything beyond simple engine modifications, though, you're probably stuck with the reclass route. It also makes sense to reclass if you are below that reclass line. You get your engine mods or lightness for "free," which lets you run better tires, aero, suspension, brakes, etc.

 

Thanks for sharing...but this information is not in the ruleset which is partially the point of the thread.

 

-Another strategy arises if you can mess with your tune: you can cap your maximum power. Turbo cars get a bad rap because they can easily pull boost off the top and keep a nice meaty power band, but NA cars can use this strategy as well.

 

Only large displacement LSx type motors can attempt to replicate torque fill like a turbo car can.

 

-You can't just "add torque." Torque and HP are directly related. (HP = Torque x RPM ÷ 5252.) At 5252 RPM, Torque = hp - this is why the curves always cross each other. This also means that below 5252, the lower the RPM, the higher the rise in torque to increase horsepower. At 1000 RPM, 10 ftlbs of torque gives you about 2 HP. At 5000 RPM that same 10 ftlbs gives you an increase of about 9.5 hp. So when you add a peak torque limitations into the mix, you're adding a linear limitation on horsepower. (Max of 300 ftlb says you can only make 57 hp at 1000 rpm, 171 hp at 3000 rpm, etc.)

 

Not sure I follow your point. Its very simple to account for torque. You limit torque the same way you limit horsepower, either the same max value for each or do an average of each max like GTS does or a separate Tq/Wt ratio like AI does. RPM does not matter...as long as you're under the max limit for each across the rev range you're good.

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Thanks for sharing...but this information is not in the ruleset which is partially the point of the thread.

 

It would be very nice to see a big document with all the reclass details and rules for each car, I agree. Such a document would be the source of endless debate, but at least there would be transparency.

 

I know it's anecdotal, but I will add that turbo cars tend to get a big PTW penalty, probably to account for the "torque fill" factor. A buddy had plans to turbo a Miata, but keep the peak power the same as NA. The reclass weight came back so high that he abandoned the approach.

 

Then take the case of the K swapped Miata - it was slated for TTB, but got bumped up when it came to light that the OEM subframe would not be retained.

 

Again, this stuff is not published anywhere, but probably should be. It would make planning a PT / TT build much easier.

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It's not in the ruleset but anyone getting a reclass and paying any attention at all will quickly realize that dyno reclasses will never put you right at the class adjusted W:P minnimum....

 

One also shouldn't be surprised that changing a subframe will incur a big penalty, that is readily transparent in the ST rules. You would have to assume that it trickles down in any reclass for PT. TT/PT/ST rules are threshold applied. Once you dip a toe, you might as well jump all in....it's that way across the board and always has been. Want to modify your subframe? Might as well go tube chassis. Is that economical, no but its part of the BoP approach, having threshold rules. Otherwise we get into HUGE games of trying to subjectively decide how much faster a particular change would make a car.... It always makes me scratch my head when people, who supposedly have run in this class structure for YEARS are surprised by it.

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Don't get me wrong. I'm not saying this class ruleset couldnt be improved.

 

I would argue that peak torque is a useless number. At best it's a way of sorta measuring, in a simple manner, what we really should be talking about, which is....Area under the usable HP curve!

 

In direct argument to an earlier post in this thread. Torque is not what moves a car. Mechanical engineering 101, Power is what accomplishes propulsion, in this case specifically WHP.

 

So if we wanted to get really accurate and do this properly we would all be talking about dynoing every car, determining what RPM range is used in the gears between say 50 and 150 MPH....then measure area under the curve and normalize for a standard RPM range........

 

Start that conversation with the average "driver" track rat and quickly watch their eyes glaze over....

 

All that said, i would consider it a HUGE step forward if EVERY dyno reclass came with a max peak tq number...

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In direct argument to an earlier post in this thread. Torque is not what moves a car. Mechanical engineering 101, Power is what accomplishes propulsion, in this case specifically WHP.

 

 

Not sure where you got your mechanical engineering degree but horsepower is not a unit of propulsion, it only defines, in a very archaic way, the energy output over time (Watts) of an engine. The ft-lb torque that an engine produces is indeed the foundation for the horsepower equation (TqxRPM/5252) but its the torque that spins the shafts/tires that translates to the propulsive force of the tires on the ground. Horsepower is just window dressing for how quickly the torque is transmitted.

 

If torque is the same between two engines at 100rpm and 10,000rpm it doesn't make a bit of difference how fast whatever is strapped to those engines will go. The engine spinning at 10,000rpm will make a crap ton more horsepower but it won't be any faster. It goes against our caveman like instincts that the faster and louder we rev something the faster it should go.

 

Another example is an electric engine. They basically make all their torque from zero RPMs. If horsepower determines how fast whatever is strapped to an engine will go, then how do we explain the fact that you can boot an electric motor from zero revs and it fires you like you were shot out of a cannon? After all, at zero revs its basically making zero horsepower. Its the torque that moves it!

 

Area under curves is great to analyze where you are dyno tuning but for the sake of an understandable and enforceable ruleset we need to keep it simple and stick to maximums. In an ideal world your typical IC engine would have a flat table for a tq curve at whatever your max tq was restricted to and your power curve climbing linearly up to whatever your max hp limit is. Gear so that your RPMs are always on the flat tq table and you're good to go. But its never that simple. Some engines rev to the moon and make very little torque and some make more torque than hp. The only way to keep the different engines in check and comparable is to limit torque as well as hp. It just so happens that most of the engines we typically run in this game are similar in terms of how they make their tq/hp so just a hp comparison/limit usually works most of the time. But for anything that has potential to make lots of torque at lower revs, electric>turbo diesels>turbo gas/E85 & big blocks...the rulset should account for that somehow. And in some NASA rulsets it already does.

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If torque is the same between two engines at 100rpm and 10,000rpm it doesn't make a bit of difference how fast whatever is strapped to those engines will go. The engine spinning at 10,000rpm will make a crap ton more horsepower but it won't be any faster. It goes against our caveman like instincts that the faster and louder we rev something the faster it should go.

 

By this description, A V6 Mustang that makes 300tq at 2500rpm should be just as fast as a F1 car (circa 2013) making 300ish TQ but 800hp at 18,000rpm.

 

I think you are trying to simplify it a little too far.

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