didnt they find that out when cars kept crashing on super bumpy courses, losing all their aero mid turn and stuff? Some undertrays will even have an air pocket right behind the bumper to reduce that effect. I cant recall it but they have a term for that.... aero lock out or something.

 

The stock design actually has that air pocket and Mitsubishi published some tech papers on it.

I think you could mount the splitter flat (i.e., parallel to the ground), leaving a gap at the front of the bumper, without too much ill effect. As long as the splitter merges with the front undertray, any air that makes it between the splitter and the bumper, will just join the rest of the air in the engine bay. To make sure that the air is forced up into the engine bay and out towards the hood vent, you could add an air scoop to the top of your splitter inside the engine bay to force air up in front of the block. If you haven't already, and it it doesn't cost points, I'd also remove the vented aluminum cover in the hood vent to allow you to push more air through it.

Barring an actual wing, ideally you'd want a splitter that blocks off airflow in front of the tires, but lets air through the middle of the chassis, something like:

__/------\__

l8r)

 

I'm not sure we have to worry too much about that air pocket as we're not producing or relying on a shxt load of downforce. I built my splitter with just a flat bottom and a small cutout for my exhaust to not melt my alumilite. This next winter I want to make a nice full flat bottom undertray from front to back.

 

No. Changing bumpers gets into the black whole area of aero mod pts for TT. Basically any part that is different from stock counts for points; so black hole.

My bumper isn't the SE - it's the base model as is. And I'm pretty sure since the SE isn't called out for a different base class than my base IX, you have to take pts for everything that's not offered on the 'base package'. That'd include aero changes, including 4pts for that little wicker on the rear wing as it's modifying the rear wing.

 

Can you adjust the attitude of the bumper cover with respect to the chassis? So basically remount the cover with it pointing more down?

You might send Paul Gerrard (Chronohunter) a PM and ask for his input given your choices - he knows some about the tradoffs in splitter design.

 

^ Having met Nate and seen him drive, I have nothing but respect for what he has done with an Evo IX in TTA. He has worked the point system until he has figured it out as well as anybody I have seen in an Evo. And he drives it VERY well.

BUT, I went to TTS (even though as of now I am not competitive) mostly because this stuff gives me a headache. I can pretty much plot a straight line path between where my car is and where it needs to be as a competitive TTS car (driver mods needed as well ). As these last several posts show, the TTA-F points system can become 'complicated'.

 

i forgot the rule read "add, replace,modify"...i thought maybe there might be a loophole along the lines of using a part off a same base class car. but you definitely would know better than me!

 

Great weekend at Putnam Park!

Friday I did the Enduro in a Miata, check out the writeup here: http://boomn29.blogspot.com/2012/05/...um-finish.html

Sat/Sun I ran the Evo in TTA with old R6 tires and tons of points to spare - and ended up with 1st both days. I'll have writeups pics and vid to come. There were a few issues but was able to work through them. I can say the combination of a taller tire (1" taller) and a longer 4th gear compared to running this track last year is NOT optimal! lol. But still solid times. Stay tuned...

 

I have traqmate data from the Enduro in the Miata. Comparing the data is interesting.

Comparing 2 Laps
5.11.2012 - 1:24.7 - Miata (Blue line)
5.12.2012 - 1:17.0 - 929 Evo (Black line)

• Max speed: 107 vs 134 --> lol...
• Min speed: 47 vs 46 --> Very close!
• Max brake: 1.07 vs 1.35 --> Brake less in the Miata!
• Time Braking: 9.9 vs 16.2 --> Brake less in the Miata!

Synopsis; Miata vs Evo:
Overall looking at the data, the cornering G's were pretty close on level track. But when the track was angled the extra power of the Evo created more G's due to the ability to acclerate through the turns.
I braked really in the same spots, just not nearly as hard in the Miata. This was mostly due to the fact it did NOT have ABS and I was paranoid about locking up and flat-spotting a tire. This is the area I could gain time; including a bit of trail-braking probably.



And comparing that same Evo lap above to a lap from 2011 under similar conditions but running wider stickier tires:
5.14.2012 - 1:16.7 - 929 Evo - 255 A6's - (Red line)
5.12.2012 - 1:17.0 - 929 Evo - 245 R6's - (Black line)

• Max speed: 131 vs 134 --> Bit better this year; pushing harder!
• Min speed: 42 vs 46 --> Bit better this year; pushing harder!
• Max brake: 1.31 vs 1.35 --> Bit better this year; pushing harder!
• Time Braking: 12.7 vs 16.2 --> Ouch...Had to brake earlier & MORE with not as grippy/wide tires

Synopsis 2011 vs 2012 Evo:
Nearly identical laptimes, but from memory the 1:16.7 from 2011 was maybe 8/10's a lap at best whereas the 1:17.0 from this year was a 10/10's lap. I had a lot less tire this year and I had to work to get a similar time and never had a better one - whereas 2011 my next session I dropped over a second to a 1:15.7 (no data though).
Anyways, the biggest thing that stands out is the amount of time spent braking and when I started it. This year with less tire I had to let off earlier and brake earlier to slow the car. My cornering speeds were pretty similar but the car was definitely more work to control (8/10's lap vs 10/10's lap like I mentioned). I netted more cornering G's last year, I think due to the grippier tires allowing a much quicker transition from L to R in the tighter turns - meaning more instant w/o slides. I think the ACD Tuning really helped control the car when the tires were starting to heat-cycle out; and the Buschur tune is nice and smooth and easily modulated with the right foot - all good. The only thing that was violent was later in the weekend when I was dropping tires and sliding more; I'll try to do the same data comparo on that. It's nice to have the data backup what I felt in the car.

 

Cool comparison! I just ordered up a traqmate as well...excited to play with it during suspension setup and the like.

Dave

 

Traqmate is WIN!

 

I've been liking mine. And, Nathan has been a big help in showing me what to look for and comparing our laps together.

Congrats on the weekend also! Sounds like the enduro was fun.

 

I started running a traqmate this season and it is such a valuable tool to have. I wish I got one a lot sooner...

 

I've had mine since like 2007. So I've got a good record of how pathetically slow I used to be back on stock suspension and whatnot! lol.

 

Putnam Park - Saturday 5-12-2012. 1st in TTA!




After running the Enduro on Friday afternoon, I awoke at 6:45am Saturday tired and sore. I was sore in different area than I usually am on track weekends. Being I turned probably 4x the amount of laps in a single session that I ever had before, my whole body ached some. But especially a knot in the middle of my back from a seat that wasn't holding me in very well laterally and my triceps as the Miata's don't have power steering. I still had to unload and unpack the car, and do some prep but that was about it. I will say when I slid over the cage to drop into the driver's seat of the Evo - it felt plush! I really do like my seat, it's got a lot of cushion and sits low (took forever to get it where I like it) and has a ton of lateral support both for my legs and my back.

Our warmup wasn't until after 10am so it was relaxed. For the warmup I lined up around grip spot #3 I think and after waiting 1 lap for things to come up to temp I put down an easy 1:17.9 to earn #2 in grid. I then went to tech and got weighed since I still had no solid idea of what the car weighed post-cage. It came in at 3198 lbs; which was about 50 lbs over what I was claiming for the day so I was pretty happy with that given the current fuel load.

Session 2 was at noon and I made no changes and fired a 1:17.0 which slotted me first in class and first overall. I hit traffic very quickly as there were 44 cars in TT on Putnam's 1.7 mile course. Also someone nailed the hay bails in the final turn so we had a few sitting on the exit of T10 which was right in the line - and after 2 laps of that I seen the double yellow. I was probably going 130mph when I seen it, closing in on 2 lower classed car probably going 95-100mph but I made the passes safely before the flagstand and tucked in behind the traffic. Oddly though that traffic was another car giving pointby's that was off pace. By the time I realized it I'd been re-passed by a few cars - I think this confused some cars as other passing from other cars ensued and only 1 was called in for passing under double-yellow.

For S3 I made a few small tweaks and ran a best of 1:17.2 but the car was really starting to slide at this point. Wasn't sure if it was the heat - sunny and around 85 - or the tires giving up. I figured a bit of both. I know I was starting to drop 1-2 tires into the dirt in multiple corners on exit as the car just wouldn't hold and would slide. It made 'catching' the slides a bit interesting and fun but I knew this wasn't going to be faster. I was also given the pleasure of the 'meatball' flag and when I came in was told my exhaust was rubbing and throwing sparks. This shocked me as there was no audible difference. When I got back to my paddock spot I seen the brace by the rear axle had broken and it was hanging low and would need a bandaid! I recently had another bracket re-welded and perhaps with that being tighter, me dropped tires and that rear brace being rewelded back in 2009 - the extra pressure caused it to break again. Either way I had 2 hours to fix it, and with my idea and some help from Hoops (thx man) it was pretty simple.



For S4 I adjusted the suspension a touch to try and aid rotation/grip assuming things would be worse if the tires were the problem. I had my answer in the first lap; it was the tires! I ran 3 hard laps right around 1:18.3 until I hit traffic, then I played for another 1-2 and drifted. I actually had a few people ask who left the drift marks in certain turns as I was at least having fun! At this point I new the tires were shot, having 12-16 Heatcyles each. Also good news was that our exhaust fixed had held up just fine. My time from S2 would hold to land me 1st place in TTA - but 1.3 seconds off my record from 2011 when I was on wider stickier rubber.

Vid from Sat; A lap each from Sessions 2 & 3 from different angles:

http://www.youtube.com/watch?v=SDU4h2m1810[/video]