Okay, there's a thread on this somewhere already, but I was just looking at the car classification chart for the TT classes and I think we've been doing it wrong.
Here are the charts:
Code:
Time Trials Production Classes by Displacement
TT-1 8.1 - Unlimited
TT-2 5.7 - 8.0
TT-3 4.3 - 5.6
TT-4 3.0 - 4.2
TT-5 2.1 - 2.9
TT-6 0.0 - 2.0
Displacement Multipliers Chart
Diesel x0.50
Rotary x2.00
Stock Turbo x1.50
Other Turbo* x1.75
4 valve/twin cam/VVT** x1.25
Engine Swap*** x1.50
Front Drive x0.90
* Includes altered stock turbo (i.e. ECU, Boost Controller,
Wastegate, BOV), twin turbo and supercharged motors.
** Variable Valve Timing (including but not limited to:
Honda's VTEC and Toyota's VVTi)
*** Does not include update/backdate among models covered by
the same OEM manual.
In the past we were doing things like this:
Scott's WRX:
2.0L (base displacement)
* 1.5 (stock turbo)
* 1.75 (altered stock turbo)
* 1.25 (4 valve, twin cam)
= 6.56L -> TT-2
However, I'm not so sure you can apply the "stock turbo" AND the "other turbo" modifiers. For example my car now has no stock turbo, it's just go an "other turbo". Somehow my displacement just went down!
I guess my question is: does the "stock turbo" multiplier get applied on any car that comes with a turbo? I'm inclined to say no, since a turbo'd 350Z shouldn't get a 400hp motor with less multipliers than an STi simply because the STi came with a turbo to begin with!
Another question: if you've got both DOHC and AVCS, do you have to apply the "4 valve/twin cam/VVT" multiplier twice? Hell, three times for that matter since it's a 4 valve motor too? I honestly don't think that the valvetrain in the STi is so advanced it's worth 1.75 times the motors displacement, but I could be wrong.
Let's take a look at some test cases.
Assuming the "best-case" rules interpretation:
Stock STi:
2.5L (base)
* 1.5 (stock turbo)
* 1.25 (4 valve, DOHC, AVCS)
= 4.69L -> TT-3
sperry's old car:
2.0L (base)
* 1.75 (altered stock turbo)
* 1.25 (4 valve, DOHC)
= 4.38L -> TT-3
sperry's current car:
2.5L (base)
* 1.75 (other turbo)
* 1.25 (4 valve, DOHC)
= 5.47 -> TT-3
Now let's assume the "worst-case":
Stock STi:
2.5L (base)
* 1.5 (stock turbo)
* 1.25 (4 valve)
* 1.25 (DOHC)
* 1.25 (AVCS)
= 7.33L -> TT-2
sperry's old car:
2.0L (base)
* 1.5 (stock turbo)
* 1.75 (altered stock turbo)
* 1.25 (4 valve)
* 1.25 (DOHC)
= 8.20L -> TT-1
sperry's current car:
2.5L (base)
* 1.5 (stock turbo)
* 1.75 (other turbo)
* 1.25 (4 valve)
* 1.25 (DOHC)
* 1.5 (engine swap)
= 15.38L -> TT-1
Okay, what the hell does a 15L motor drive like!
That's so far above and beyond the 8.1L TT-1 minumum, I've gotta think we're over doing it.
Let's do a little deductive reasoning. First we need a car that actually is just straight displacement w/o any fancy multipliers. How about the ubiquitous Corvette. Most came with a Chevy 350 small block. That's 5.7L, 2 valve, pushrods, and that's it. A stock 350 Vette is a TT-2 car based purely on it's base displacement.
Now, MikeK has shown that a bone-stock STi can run down the stock Corvettes in our region at Club Trials. Our worst-case scenario places him in their class, making that a "fair fight". However, I'm inclined to think that a) Mike's car get help at altitude from the turbo over the N/A Vettes, and b) Mike's a better driver with larger than average balls. But I could be convinced that the STi should be classed with the Vettes, stock for stock, in Trials (just don't tell the Vette guys that!)
Now, if we look at my 2.0L car versus a stock STi, the "best-case" senario paints a pretty realistic picture. My tuned WRX really was just a little bit slower than the stock STis. Looking at the "worst-case" I think it's pretty obvious that something's awry. My 2.0 certainly didn't act like it was a liter up on a stock STi!
So, IMO here's the way we should interpret the rules:
- "Stock turbo" and "Other turbo" are mutually exclusive.
- the "4 valve, twin cam, VVT" multiplier needs to be applied for *each* of the items on the car.
The only question left is specific to me: is a 2.5L STi short block considered an "update/backdate" in the context of Trials? We know they're not on the same line in the SCCA Solo2 rulebook. But this mentions the "OEM manual", not the Solo rulebook. IMO the "spirit" of the rule is to add a 1.5 multiplier for people that have dropped a chevy 350 into a Z and the like, whereas putting an STi shortblock into my car is the equivalent of just boring/stroking a 2.0L to 2.5L.
With all that said, here are some cars based on my interpretation of the rules:
Stock STi:
2.5L (base)
* 1.5 (stock turbo)
* 1.25 (4 valve)
* 1.25 (DOHC)
* 1.25 (AVCS)
= 7.33L -> TT-2
sperry's old car:
2.0L (base)
* 1.75 (altered stock turbo)
* 1.25 (4 valve)
* 1.25 (DOHC)
= 5.47L -> TT-3
sperry's new car (swap doesn't count):
2.5L (base)
* 1.75 (other turbo)
* 1.25 (4 valve)
* 1.25 (DOHC)
= 6.84L -> TT-2
sperry's new car (swap does count):
2.5L (base)
* 1.75 (other turbo)
* 1.25 (4 valve)
* 1.25 (DOHC)
* 1.50 (engine swap)
= 10.25L -> TT-1
MattR's car (for comparison's sake):
2.5L (base)
* 1.75 (altered stock turbo)
* 1.25 (4 valve)
* 1.25 (DOHC)
* 1.25 (AVCS)
= 8.55L -> TT-1
Finally, Matt and I were able to get an excemption for the AVCS on Subaru's in order to keep all of the Subarus in the same class. I didn't bother to assume that in these numbers, but that's one more thing to consider.
Thoughts everyone?