Rules for 2013

[Brendan]

Jimmy - Check your email.

[WillM]

Hey Guys,
I know I only do two COM events a year,,, away events at that,,, but PLEASE do not kill the best classing system in the Northeast.
One of the main reasons I fell in love with COM was the run what ya brung nature of the COM Prepared classes.

Screw around with all the other classes all you want but PLEASE leave Prepared alone and let the modified cars continue in a straight fight.
Any time, ANY sanctioning body starts determining the "base class" of a car its a mess. What factors go into that?
Who gets to say what car is better by what amount than another. All 100% subjective. No way to quantify it.
Any driver of an E30 M3 has been fighting that since the car was built.

The beauty of the COM Prepared system is its a straight fight based on cylinders. May the best gun and gun fighter win.
I for one love it... No matter how many times Fred kicks my ass,,, its still better than being beaten by cars with 6 or more cylinders because someone said a certain car was an overdog and started in a high base class.

PLEASE leave Prepared alone.

Jimmy,

This is a discussion I had with a couple of SP and P folks recently, and one I shared with Nick and Paddy this weekend. The magic that makes these two classes work is that we have a good sized group of members who like to tinker with their cars and love the 'run what you brung' approach. I'm one of them! I was concerned that a new set of rules that did not appropriately and fairly deal with these cars would turn long-time members away. That is among LAST things that I think anyone wants to do. I'm intrigued by the possibilities and excitement around the new rules, but not at the expense of alienating a large group of dedicated COM members.

That said, the response and depth of knowledge and commitment that I heard back from Nick and Paddy put my mind at ease. There prototype rule set is not finalized. There isn't going to be any voting or decision making until December, three board meetings from now. In the mean time, and during the October and November board meetings, there will be a lot of discussion and the 'rules team' is dedicated to digging deep and doing things right. I know there is talk and serious consideration for at least one more "super" class (SuperC).

There was a poll that went out today, which went out too soon. Most members have not even seen the proposed new rule set yet! I apologize for the confusion it has caused. I believe the poll will be taken off line / suspended and that page will be replaced with information and documents concerning the new rules. We'll be encouraging members to contact us with questions, feedback, and suggestions. This can be done via email, on these forums, or at our board meetings, the next of which is tomorrow night!

Thanks,

Will

[Brendan]

I know there is talk and serious consideration for at least one more "super" class (SuperC).

I personally would support this. My car is somewhere between T90, T100 and Super B right now, but would get crushed in Super B based on my Power to Weight.

[agrabau]

Bruce, there's a lever arm with a load cell on the dyno that measures newtons of force which is converted into ft lbs.

Hp is a function of that measurement and RPM.

Yes, but the torque curve you supply from your dyno is NOT the torque measured at the wheel! It is much less, by a factor of 3 or 4... an estimate of the engine shaft torque. I suggest your dyno measures actual wheel torque (a twisting rotational force) multiplies by wheel RPM to get wheel horsepower and that is on the horsepower plot. It will be about 85% of the shaft hp due to drive train losses. I further suggest that the displayed torque plot is HP/engine shaft RPM. This calculated value will be the engine shaft torque reduced by the drive train losses so, just like HP, the plotted torque will be less that manufacturer shaft torque by 15%. Right?


No. It's an actual measurement of torque, at the wheel. Not sure what you mean exactly.

By the way, as we know, your dyno that can measure true steady state torque produced by an engine is much more accurate than an "accelerate the mass" dyno. The latter does not take into account the mass of the engine, flywheel, drive train and gears, wheels and tires which is very significant.

Correct. Some dynos are accelerometers. They can only make a mathematical determination of torque based on the acceleration.

Regarding the rules, I think they state that Touring cars should use the manufacturer's shaft HP and torque but in Super classes chassis dyno Hp and torque figures are used. I think all classes should use shaft hp and torque so cars can see the effect of moving from Touring to Super or vice versa. As you say, if you know shaft you can calculate wheel and vice versa.

That would be easy to get around if the car was actually never checked. A stock STI with no parts on it can be tuned to an additional 40whp for example.

[Resolution78]

Bruce, there's a lever arm with a load cell on the dyno that measures newtons of force which is converted into ft lbs.

Hp is a function of that measurement and RPM.

Yes, but the torque curve you supply from your dyno is NOT the torque measured at the wheel! It is much less, by a factor of 3 or 4... an estimate of the engine shaft torque. I suggest your dyno measures actual wheel torque (a twisting rotational force) multiplies by wheel RPM to get wheel horsepower and that is on the horsepower plot. It will be about 85% of the shaft hp due to drive train losses. I further suggest that the displayed torque plot is HP/engine shaft RPM. This calculated value will be the engine shaft torque reduced by the drive train losses so, just like HP, the plotted torque will be less that manufacturer shaft torque by 15%. Right?


No. It's an actual measurement of torque, at the wheel. Not sure what you mean exactly.

By the way, as we know, your dyno that can measure true steady state torque produced by an engine is much more accurate than an "accelerate the mass" dyno. The latter does not take into account the mass of the engine, flywheel, drive train and gears, wheels and tires which is very significant.

Correct. Some dynos are accelerometers. They can only make a mathematical determination of torque based on the acceleration.

Regarding the rules, I think they state that Touring cars should use the manufacturer's shaft HP and torque but in Super classes chassis dyno Hp and torque figures are used. I think all classes should use shaft hp and torque so cars can see the effect of moving from Touring to Super or vice versa. As you say, if you know shaft you can calculate wheel and vice versa.

That would be easy to get around if the car was actually never checked. A stock STI with no parts on it can be tuned to an additional 40whp for example.

a new mustang can pick up around 30 with a flash tune also..... and really there is no way your going to be able to check that..... heck i have reflashed my PCM in the staging lanes at the dragstrip

[brucesallen]

Bruce, there's a lever arm with a load cell on the dyno that measures newtons of force which is converted into ft lbs.

Hp is a function of that measurement and RPM.

Yes, but the torque curve you supply from your dyno is NOT the torque measured at the wheel! It is much less, by a factor of 3 or 4... an estimate of the engine shaft torque. I suggest your dyno measures actual wheel torque (a twisting rotational force) multiplies by wheel RPM to get wheel horsepower and that is on the horsepower plot. It will be about 85% of the shaft hp due to drive train losses. I further suggest that the displayed torque plot is HP/engine shaft RPM. This calculated value will be the engine shaft torque reduced by the drive train losses so, just like HP, the plotted torque will be less that manufacturer shaft torque by 15%. Right?


No. It's an actual measurement of torque, at the wheel. Not sure what you mean exactly.
[/b]

The rear end and transmission are torque multipliers. If the engine makes 300 Hp and 300 Lb/ft torque then there will be 900 lb/ft of torque at the wheels if the transmission is 1:1 and the rear end is 3.00:1. So your dyno displayed torque must be a calculated shaft torque, not wheel torque.

[agrabau]

It doesn't change the power to the ground Bruce. You aren't understanding how it works. It changes the relationship that the engine has with the transmission but not the ultimate torque that the engine produces and not the wheel tq or hp.

The engine outputs torque to the pinion gear (in a simple example) and the pinion/ring gear relationship modifies that torque to the wheels. The missing ingredient is that the speed of the wheels also changes. Changing the gearing modifies the torque output and rpm of the tires at a given speed but not overall. If we graphed road speed on a dyno the charts would look shifted. That would be the only difference.

I hope that helps explain things.



The dyno measures torque at the wheels. It is not making a guess or an extrapolation. It is a load cell that measures torque. Gearing has no affect. We can dyno a car in 1st gear or 2nd gear and derive the same numbers. The pull is very short. That's the only difference.

Alex

[agrabau]

The faster you spin the drivetrain the more friction losses you will encounter so if anything switching to a shorter gear (that also offers more acceleration) might in fact work in the opposite fashion that you suggest, taking some power off the curve due to friction losses and drivetrain inefficiencies.

This loss would be minimal but we're talking specifics here.

[brucesallen]

It doesn't change the power to the ground Bruce. You aren't understanding how it works. It changes the relationship that the engine has with the transmission but not the ultimate torque that the engine produces and not the wheel tq or hp.

The engine outputs torque to the pinion gear (in a simple example) and the pinion/ring gear relationship modifies that torque to the wheels. The missing ingredient is that the speed of the wheels also changes. Changing the gearing modifies the torque output and rpm of the tires at a given speed but not overall. If we graphed road speed on a dyno the charts would look shifted. That would be the only difference.

I hope that helps explain things.



The dyno measures torque at the wheels. It is not making a guess or an extrapolation. It is a load cell that measures torque. Gearing has no affect. We can dyno a car in 1st gear or 2nd gear and derive the same numbers. The pull is very short. That's the only difference.

Alex

I understand that power measurement does not change. It is torque times rpm. If you measure at the wheels, the wheel torque is three times (or whatever the rear end ratio is) the engine shaft torque and the wheel rpm is 1/3 the engine rpm. The torque shown on your dyno sheets is NOT the wheel torque, but the estimate shaft torque.

[Chrispy]

Bruce and Alex, we're getting this thread pretty off topic.

Here's the answer that should keep everyone happy.

Yes, the torque multiplier changes the effective torque at the wheels but the measurement on the dyno drum is always constant since it is divided by velocity. It is neither crankshaft torque or wheel torque, but rather is wheel torque multiplied by gear ratios which effectively gives you crank torque but with all drive-train losses taken into account.

The bottom line is the dyno works in essentially any gear, and if run in shootout mode should be highly comparable to other dyno's of the same make, and with a known drive-train/dyno loss estimate calculating true crank hp/torque within a few percentage points should be possible.

Please lets leave it at that and move back to discussion on actual proposed rules related subject content. Let's please only discuss dyno's again as they relate to rules class calculation.

Thanks!

[dlopilato]

-1 tires 10mm smaller
-2 vrs factory wheight with driver

This all being said I'm def not taking anything off my car next weekend what class should I be running in ????

Also there is nothing in the rules for my tiger racing hood .... It's supposed to help with front end downforce at speed ....???

Sorry but you don't get -1 for being 10mm under, you would get -2 for being 20mm under though. There is a 10mm grace that works in both directions as it sits now.

Not sure about the hood, would have to see it. At worst it might get a 1 point assessment but chances are it is free unless it has widgets sticking out all over.

Remember for this event the new classing system is just for data gathering purposes so don't sweat it too much. Figure T90 for now, and then next year you can decide what you want to do as far as classing.

Got it t90 for now .....

I run the the same Tiger Racing hood (I sell them...RIP Paul Brown) and I don't see any points, nor should there be any. My 07 Mustang comes in at between 98 (T100) and 102 (SB w/13.5 P/W ratio) points, depending on tires and rules interpretation. The dynojet figures are 313hp/291tq SAE corrected. Our vehicle weights should be similar (same base car)...but you have over 120 more hp, factory tuned track-ready suspension...and you class at one to three classes below me?

I'm trading in my car for a Boss 302.

[Chrispy]

I run the the same Tiger Racing hood (I sell them...RIP Paul Brown) and I don't see any points, nor should there be any. My 07 Mustang comes in at between 98 (T100) and 102 (SB w/13.5 P/W ratio) points, depending on tires and rules interpretation. The dynojet figures are 313hp/291tq SAE corrected. Our vehicle weights should be similar (same base car)...but you have over 120 more hp, factory tuned track-ready suspension...and you class at one to three classes below me?

I'm trading in my car for a Boss 302.

David,

Remember that he was on street tires, adding race tires would easily move him to T100 and possibly beyond.

Your base car is 21 points lower (I think it started life as a GT). If you took a lot of points for engine modifications then you are eligible to have your car base points re-calculated. Under that scheme you would take a fixed 11 points for engine mods (recalc base 71.5 - 60.1). You get to choose which is more favorable for you.

Something else that is under consideration is a low power to weight Super Class. This would be an attractive option to the folks like yourself that have highly modified vehicles that find themselves not fitting well in touring. Cars like the Boss and the Corvettes would not be eligible for this class since their power to weight is too high.

[Resolution78]

Like a boss lol ...... Street tires or not the car had a lot more to god than my 1.22 time I drove it to going up the hill in turn 4 in third and I think I can carry a lot more speed threw. Turn 10

I like the new rules .... Seams like you take the time to fit everything in right and your classed pretty well

[dlopilato]

I run the the same Tiger Racing hood (I sell them...RIP Paul Brown) and I don't see any points, nor should there be any. My 07 Mustang comes in at between 98 (T100) and 102 (SB w/13.5 P/W ratio) points, depending on tires and rules interpretation. The dynojet figures are 313hp/291tq SAE corrected. Our vehicle weights should be similar (same base car)...but you have over 120 more hp, factory tuned track-ready suspension...and you class at one to three classes below me?

I'm trading in my car for a Boss 302.

David,

Remember that he was on street tires, adding race tires would easily move him to T100 and possibly beyond.

Your base car is 21 points lower (I think it started life as a GT). If you took a lot of points for engine modifications then you are eligible to have your car base points re-calculated. Under that scheme you would take a fixed 11 points for engine mods (recalc base 71.5 - 60.1). You get to choose which is more favorable for you.

Something else that is under consideration is a low power to weight Super Class. This would be an attractive option to the folks like yourself that have highly modified vehicles that find themselves not fitting well in touring. Cars like the Boss and the Corvettes would not be eligible for this class since their power to weight is too high.

Chris,

I am in favor of the new system. As with any system, not everyone will be happy...for example, my car has a factory optional exhaust (axle-back)...However, I changed it to a different brand, just sound (no advantage) and added headers under the old rules. I did also remove the cats for track. I gained about 15hp on the dyno...but this system is costing me 5 points for 15 hp exhaust update (unfair). It cost 3 points for the cams I added which gave me 40+ hp (fair). I think that an entire exhaust should be worth 2-3 point max. I will submit a rules change for the new rule set to reduce this penalty. So, many will gripe...submit a rules change. If it doesn't pass, live with it.

The Super C makes sense as I would have to add 150+hp to my car, as someone with the exact same car can punch it up to 520hp (200 more than me) and meet the 8.50 ratio for Super B...not gonna happen. So I have a 3700 lb+, 57/43 weight dist, 315 hp car that has a bunch of mods that won ST1 last year, SPA (new engine mods) this year and may now be non-competitive...well, I'll just have to drive the snot out of it!!

Actually, I'm just looking for an excuse to buy a Boss 302

[Chrispy]

Chris,

I am in favor of the new system. As with any system, not everyone will be happy...for example, my car has a factory optional exhaust (axle-back)...However, I changed it to a different brand, just sound (no advantage) and added headers under the old rules. I did also remove the cats for track. I gained about 15hp on the dyno...but this system is costing me 5 points for 15 hp exhaust update (unfair). It cost 3 points for the cams I added which gave me 40+ hp (fair). I think that an entire exhaust should be worth 2-3 point max. I will submit a rules change for the new rule set to reduce this penalty. So, many will gripe...submit a rules change. If it doesn't pass, live with it.

The Super C makes sense as I would have to add 150+hp to my car, as someone with the exact same car can punch it up to 520hp (200 more than me) and meet the 8.50 ratio for Super B...not gonna happen. So I have a 3700 lb+, 57/43 weight dist, 315 hp car that has a bunch of mods that won ST1 last year, SPA (new engine mods) this year and may now be non-competitive...well, I'll just have to drive the snot out of it!!

Actually, I'm just looking for an excuse to buy a Boss 302

Good feedback. The problem with points is that different mods have different results on different cars. For example I could add headers to my car but I would only net 5-10hp and it would be at redline, but a Corvette could do the same and pickup 30hp. Going forward folks get to make the choice whether the points are "worth it" for the results, but like you said the problem is for the people that have already built to the limit of the old rules.

Submitting a rule change request is the way to go. No system is perfect at v1.0 so now is the time to make your voice heard if you have improvements that can be made.