New Horsepower/Torque Curve Shape Rules


This needs a thread of it’s own!

See, Appendix D: Engine Performance


I think its great.


Looks fair enough to me.


Looks great!


Can someone walk through the process here?

From my understanding this would be the process:

  1. Go to impound, get a dyno slip.
  2. RD follows you over to impound
  3. Brings tools and removes intake boot to check for throttle wide open and switch works
  4. Put car on dyno
  5. Set all dyno setting to SAE standards in rule set (does this take into account humidity/etc.?)
  6. Operator sets tire pressure to 36 psi
  7. Open hood?
  8. Run 3 dyno tests

Did I miss anything?


I’ve done this a bunch in my FFR Roadster:

Car in impound, hood taped shut.
Get dyno slip
Go to dyno. Usually sit and wait for a long time.
Tire pressure checked
Car brought up to temp
Dyno operator makes three pulls

I’ve also had the car torn down before the dyno, which makes no sense.

I believe the rules say the car is supposed to be dynoed within 45 minutes of the race. I remember there being an issue about that in the past.


The rule needs to specify hood open or closed. Major issues in AI - CMC - FFR on that exact issue. I believe AI and FFR run hood off, and CMC runs hood on. There was a massive issue on that at Nationals a few years ago, and the rulebooks of all three classes now specify one way or the other.


It says hood up. Then again, I know a few guys that have hood pins, so it would have to be “off” instead of “up.”


Interesting! I certainly appreciates the volunteer efforts of the rulesmakers to help keep the playing field level.

This is a pretty big rule addition - Are the Spec E30 officials planning a press release with more info? I’d certainly appreciate some more background information. And I have a bunch of questions :slight_smile:

Will a fully-built legal motor truly fit under the 163 number? I have a fresh motor that pulled strong at VIR, but I’ve never had it on a dyno. Presumably, I would need to find a local dynojet to find out if I have to run ballast, correct? Also, how much variation we can expect with the dynojet…I wonder how much the “SAE J1349 Rev JUN90” standard is a a true no-shit measurement…Also, the GTS guys have had plenty of issues with their dyno specs, and variances from dyno numbers - any thoughts on how we can avoid the same pitfalls?

Just a couple of early thoughts…thanks for indulging.


The rules/numbers are a good start. We will have another to test in the SE with Fred’s car soon and perhaps Harness’ car. Can’t see any need to do “real” high dollar engine builds as the numbers given can be acomplished by me and my buddies at the shop. Look at Chuck’s, Kelly’s, mine, and Danny’s numbers in the SE discussion of HP to see the results last year.

Dyno results with the #8 car befors I sold it last March (same results from another Bubba the engine assembler endeavor) tell me to add a fan, change the oil and spark plugs, and delete the air cone in order to bring down the HP of the #911 that was strong last January.



Looking forward to seeing this in action.


This looks great, but for even greater cost savings and parity, why not start the weight penalties at 145 or even 140 instead of 155.
Does this mean we will get “free” dyno runs at track?


Only if you podium.


How come torque is mentioned nowhere in the rules. Can I build a 155/165 motor with no weight penalty? Note there are motors out there who have dynoed at nationals with that kind of HP/trq relations.


How does it match the curve?


How do you define “match?” The shape of the line/curve could be identical while have absolute values that are greater than those shown on the representative curve.


If I had any want to bring a car to miller you better bet it will have 150/165. Using a dyno is a great tool, but should NEVER be used for a final say in anything. You have tire pressures set for the rules, but what about the way you strap it down? You can easily have 3-4hp in the way you strap if down.

Rulers do not lie. Whistlers are very consistent.

Also what about the guy with 162hp having to add 140lbs now that car is legal with the HP rules but NON COMPLIANT with the ballast rules of no more ballast than 125lbs. :huh:


I’m not crazy about potentially having to add an additional 140 lbs of ballast after I already have 70 lbs and barely make the 2700 weight minimum.
I don’t think we should be penalized with weight for having a legally built motor that meets the factory specifications. Weight penalties should start ABOVE the 168 HP factory spec. not at 155.9. Those of us with recently built motors are being unfairly penalized by this new rule.
I think this rule is trying to fix something that isn’t broken.


I cant speak for the rules people, but the intent, if I follow, is a cost effective spec class.

Just because you can be 100% legal, spend many many MANY thousands of $$$$ on a motor, doesn’t make it a healthy spec class long term. One shouldn’t have to show up with more than a healthy stock motor, and be competitive by the spirit of any stock limited class.

That is the intent I got from reading the new rules.

What is the eventual cost of a competitive E30 car, if “its legal” with money thrown at the problem? I believe there are more people unable/willing to keep up with the budget war, than are.

That is the long term intent that I see going on here, and I see a healthier long-term E30 presence from it.

I 'spose for much else, you’ll have to reach out to the people that make the rules.

PS: I suppose the joke at the end of the day, is that I’m seeing high 14xhp cars win races cleanly occasionally, so what’s that say about spending more than Pick & Pull wants for a motor and a few gaskets?

Save your $ for BBQ and beer after the race, it lasts longer than the race does. :slight_smile: :slight_smile:


If I’m not mistaken, that factory 168hp spec is at the crank and not the wheels. Allowing for driveline losses and the increases of a more free flowing exhaust, 155.9 at the wheels seems reasonable. It only represents about 7-8 % loss from the crank to the wheels.