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PostPosted: Tue Nov 29, 2016 2:01 am 
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So, since it'll be TTB no more, but E46 M3 needs to find a new home.

Since I'm new to the modification factor scheme and power/weight classing, is this correct:

2004 BMW M3 (E46) Coupe; base class is "ST" (from PT rules)
3385lbs ~ 285hp (unconfirmed) = 11.9

Modification factors:
+0.1 Vehicle weight >3300lbs
+0.3 Tire size 255
+0.4 OEM Aero
= 11.9 + 0.1 + 0.3 + 0.4 = 12.7 = ST4

In TTB, I was pretty tight on points on my still street driven car and could not consider Aero.
However, assuming that the ST rules will be the same/similar for TT, it seems like I would basically NEED Aero to be competitive with the car to get me closer to the 12.0 (aero would get me to 12.3 then).

So if my calculation and assumptions are correct, I'll need to throw money at the car to remain competitive.
TTC does not seem to be an option for an E46 M3 with decent tires.

Correct?
Also, any news on TT rules for 2017? :)


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PostPosted: Tue Nov 29, 2016 7:56 am 
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I don't have a good answer for you, but I've come to tell you it's average hp for the ratio and not your peak hp :D

Max hp + 3 highest hp data points 500rpm apart, divide by 4 = Avg hp

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PostPosted: Tue Nov 29, 2016 1:29 pm 
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Yes, understood.
So that will make it even worse....

My power/weight ratio will be so high that I would have to seriously throw money at the problem to try to make the car faster. Loose 300lbs somehow? Add 50hp? Big brakes, Aero, Lexan windows, carbon everything?

Remember, this car is still street driven and had a great home in TTB.
TTC is not an option (car's base class is "ST"). So, where do I go from here?


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PostPosted: Tue Nov 29, 2016 5:10 pm 
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Sounds like your options are lose weight or adopt the aero.

Another idea is to reduce your tire size to 245, and run A7's.
Can you really not loose any weight at all? Even 50-75lbs will help. Do you have a passenger seat?
Do you have any way of adding power reasonably?

TT rules and ST rules are the same.


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PostPosted: Tue Nov 29, 2016 11:02 pm 
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Loosing weight would be hard, given the fact the car is still street driven. Yes, it has a passenger seat and I'd like to keep it. But of course, as I said, carbon everything (hood, roof, trunk, fenders etc.), Lexan windows, wire harness reduction etc. would help, but most would be $$$. 50 lbs sounds tough if you ask me at this point.

Would love Aero on track, but again, front splitter will be annoying getting to/from the track. But it would seem it's a must have if there's really no option outside of TT4 for the E46 M3 (which doesn't seem like there is).

For power, no, a naturally aspirated engine, California Carb legal means that coming by 50 HP would be $$$ as well.

*sigh* the more I think about it, the more I think I'm screwed for 2017...
If cost saving was the motivation for the rule changes, it really doesn't seem to apply.


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PostPosted: Mon Dec 26, 2016 10:16 am 
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int2str wrote:
Also, any news on TT rules for 2017? :)

As others have said, the ST4/TT4 rules are the same and they have been out for a month now. :)

I'd get your car dyno'd before you look any further at classing. Once you know that (average power) number you can look at weights and see where your car fits best.

I suspect your E46 M3 might be better off in TT3 with OEM aero and a 275mm tire. I don't see how an E46 M3 stays in TT4 unless they add a lot of ballast or cut avg power. I could be wrong.

Image

Going to TT-Number class aero limits is a big jump in costs and loses a lot of steetability. I'm juggling that decision now with my TTD E46 330Ci above.

Image

But even as a shop owner that does this sort of zero work, it's expensive and time consuming to take a car to the limits of the aero rules for TT# classes. I've done it and it took 2 seasons of changes, testing, and work to get the aero bits dialed in right.

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PostPosted: Mon Dec 26, 2016 10:34 am 
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TT3 is for the well built E46 M3's in my region if you want to remain competitive. TT4 is an easy fit and should have you near the front of the class if you work everything out well. You can pretty easily get another 10-20whp if your setup peak is only around 285whp now. From what I understand, the base is 12. If you are running 255-275 you get to gain .3 which brings you to 11.7. Add another .5 for OEM aero and weight and that gets you to 11.2. You would need to get to an avg whp of about 302 which means a peak I would guess around 315-320 at 3385lbs. With just a better tune alone you should be close. I doubt a non-aero e46 M3 would regularly podium in my region in TT4 (Midatlantic), but there's variance across the country.

E46 M3 frankly is one of the easiest cars to get into TT4. All the stock e36 M3's that use to make up TTB are screwed bc the mods take power levels to a point that just aren't attainable. I have an e36 with an S54 I'll do a few events with. But with half of last years TTB cars now too low on power for TT4, I doubt we hit contingency often.


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PostPosted: Wed Dec 28, 2016 5:41 pm 
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I added Aero to my car. Haven't dynoed the car yet.
So still going with the guessed peak figure of 285, here's where it stands:

3385lbs ~ 285hp (unconfirmed) = 11.9
+0.1 Vehicle weight >3300lbs
+0.3 Tire size 255
= 11.9 + 0.1 + 0.3 = 12.3

Also the weight will have gone up now actually.
Will have to try to make it up somehow :(

I really think I will not be able to be competitive in TT4.
Oh well.....

I miss TTB alread :'(


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PostPosted: Thu Dec 29, 2016 12:09 pm 
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int2str wrote:
I really think I will not be able to be competitive in TT4.
Oh well.....I miss TTB alread :'(

You'll probably end up doing better than you think. I moved into TT3 at the beginning of this season, believing I wouldn't be as competitive as I would need to be. I set goals throughout the season and did much better than expected. Being in TT3, raised my level of competitiveness and that made all the difference...plus some changes to the car. All in all, we had a very successful and fun year and feel we're very competitive in TT3. May try our hand at ST3 someday.


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PostPosted: Fri Dec 30, 2016 2:25 pm 
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Alright, time to update this thread.
I was actually quite wrong on the horsepower.
Car is much closer to 12:1 than I thought.

Here's where it's at now:

Weight: 3406 (estimate currently; car was 3386 at last check on scale - before AERO + trailer hitch)
Average HP: 294 (304 peak!)

3406 / 294 = 11.58
+0.2 Vehicle weight >3400lbs (has to be >3400 now.... :( )
+0.3 Tire size 255
=
12.08

So that will actually clamp cost for me a little bit. That means no exhaust or other mods. Though I'll probably do brakes at some point.
And no more weight loss. I'm fine with that.


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