2010 Evolution X Team

Tire Selection: Yokohama ADVAN Neova AD08

March 22, 2010 in 2010 Evolution X Team, 2010 One Lap of America, Car Preperation

As the 2010 One Lap of America event approaches, we had to decide on a set of tires to go with on the Evo X. Since the VR4 already had two new Dunlop Starspecs from last year, their decision was to stick with them again this year. Looking at the sizes available for mounting to the 19×9.5″ wheels we found out that the moderately priced Dunlops were not made in the 19″ size we would need, and I didn’t want to compromise by going back down to the stock 18×8.5″ wheels. After comparing all the options it as really down to two choices:  Bridgestone RE11 and Yokohama AD08 tires.

As you can see in the video they are pretty much a dead heat between 1st and 2nd place and depending on what attributes you valued most the test results may be swayed one way or the other. I’ve found that the Evo X’s suspension is already very good at realing in highly responsive tires so that negative effect on wet handling stability shouldn’t be an issue assuming we don’t  make the car handle twitchy at the limits with the new BC Racing ER series coilovers. The last few times I’ve had the car out on the track during wet conditions, I was one of the few cars able to lay down nearly full power on corner exits and still feel comfortable using moderate braking zones adjusted for a wet line depending on what kind of water was pooling on the track.

I won’t have them mounted until the 2nd or 3rd week in April but I can already tell they are going to handle quite a bit better than the Pirelli P-Zero Nero tires I have mounted now. When I went from the stock Yokohama 245/40-18 tires to the Pirelli P-Zero Nero 275/30-19 tire I felt that I made a tradeoff by going with a 15% wider tire that was easily 15% less sticky after several track visits that resulted in a combo that handled about the same but perhaps had a bit better wear rates. I anticipate that these tires will be even stickier than the stock compound and have a wider contact patch which should result in lateral G’s pushing well above the stock .99g mark!

We have 100′ Skidpad testing planned so that we can compare the stock Yokohama tires on stock 18×8.5″ wheels with a stock suspension against the wider Yokohama AD08 tires on 19×9.5″ wheels with Coilover suspension. If there is time we’ll even swap the tires and wheels between the cars to get some more data points to see if the tires or suspension are helping lateral G’s the most. What’s even nicer is that for a limited time there’s a $75 rebate when you buy 4 of these tires from the Tirerack.com before April 30, 2010!

Once we complete the 4500+ miles that we’ll be placing on these tires for the 2010 One Lap of America, Sean and I will give our first hand impressions of daily driving attributes as well how it holds the track at the limits of wet and dry traction so stay tuned!

EvoX – I’m not fat, I’m big boned

March 14, 2010 in 2010 Evolution X Team, 2010 One Lap of America, Car Preperation

So Saturday came and went and we were able to get the suspension on the EvoX a little more dialed in.  A huge thanks goes out the Emery and the guys at Street Tuned Motorsports especially Austin and Ryan as they let us take up their time at the shop on the lift.

After the BC Coilover install and the very basic alignment, we were able to get a very good feel on how the new suspension was going to alter the handling feel over the Eibach spring setup. The car is more compliant, more responsive, and most important,  its easier to predict the dynamics of the car under power, braking, bump and recoil.  So far, we are pretty darn happy with the initial impressions and setup. Over the next coming weeks, we’ll be mapping out the various shock settings to give us a good suspension tune map before we take off for OneLap.

As far as the corner weighting, let’s start off by saying the car is no lightweight.  With Chris as the driver, total weight is in around 3650 give or take a few pounds.  Luckily for us there’s plenty of power on tap to account for it. Regardless we may undergo some attempts at dropping some weight before we take off but for now, it’s a back burner “if we have time” kind of thing.

The corner weighting was pretty straight forward. We were able to use Emery’s scales as well as his lift which made things go a lot faster. With that being said, what we did was time constricted so we did a very modified version of what **should** be done to corner weight a car.  For those with unlimited access, time and resources, ideally you want to start with a completely flat surface, with the shocks and sway bars disconnected, and the ability to move physical weight around the car as needed.  We didn’t really have those options to us so we made to with what we could.  We focused mainly on what the cross balance and left/right balances were.

In its starting, post-install form, the car was front right heavy and right rear light.  That gave us a left-right balance of  46%/54%  which isn’t so good and a crossweight of about 50.8% which is actually pretty damn good. We knew with the EvoX that it would be nose heavy and we were right. The balance was about 58% front/42% rear. As we didn’t have the ability to shift the physical weight around, we’d be focusing on the left-right and crossweight balancing as best we could.

If you want to read a decent primer on suspension geometry/corner weight balancing review the PDF here.

So we started in on the loads/preload/perch heights on the fronts to try to shift the load around a bit.  Getting the fronts done didn’t take too long but that threw us off of the ideal of 50/50 left to right and 50 on the cross weight.  The rears were a bit more of a pain. As you adjust each corner, forces shift back to the other 3 corners in various amounts depending on what functional items are still attached. Focusing on just getting the front close was easier as we somewhat ignored the rears but as we adjusted each rear corner we have to take into account the other corners.  This is the main reason you want to disconnect shocks and swaybars or other weight-shift type applications. You want any transfer be through the body and truly a static corner change.  Swaybars and shocks should be used to manage the rate of dynamic transfer.  So as we adjusted the rear, it altered the other corners in ways that weren’t as directly linear as we would have liked or expected.

But we persevered as we were on a time crunch and were able to get it damn close considering the situation. Below are the final numbers:

Front Left: 1061                                Front Right: 1066

Rear Left: 799                                    Rear Right:  728

Total Weight: 3654

Left/Right Balance: 50.9%/49.1%

Crossweight: 49%/51%

Note: In the picture the input sides are reversed.

So although not perfectly 50% for left-right as well as cross weight balance, it’s definitely much closer to where we want it. The Front to rear there’s not much we can do at the moment without physically moving/removing weight from the overall car.  We also did another camber check although we will be tweaking that as we get the feeling for the car.