Road Racing Thread

[skeeters_keeper]

I can't believe how quickly you leave him in the straights! I'd expect his power/weight ratio to be better if he is putting down 350whp

Amazing driving! Looks like so much fun... I really want to get in on some of that!

[Advancedynamix]

I can't believe how quickly you leave him in the straights! I'd expect his power/weight ratio to be better if he is putting down 350whp

Amazing driving! Looks like so much fun... I really want to get in on some of that!

Power to weight is better on the Miata, but the parasitic loss of RWD is dramatic. He is running a Rockland tranzilla (basically a beefy t56) and wide racing slicks. Also, the Miata is fully caged (it's a fully race prepped car) and wide body, so it's not exactly like a typical miata+200HP.

Lighweight FWD cars have a huge advantage over RWD because adding HP doesn't necessarily mean adding extra resistance and weight to the car. I run 185mm 13" tires, which roll very easy, and a G series transmission isn't drastically bulkier or harder to spin than an E-series. If you were to drive that Miata on 185mm wide tires, it would be scary.

[FestYboy]

Charlie, i'm thinking of a passive rear steer mod for tight courses... thoughts? (thinking of initial turn in and less steering input because the car will want to turn that much more) and it's a simple bolt on taking advantage of the festy rear beam design.

[eurotiva]

I watched it all, and that stang must have felt bad

[Advancedynamix]

Charlie, i'm thinking of a passive rear steer mod for tight courses... thoughts? (thinking of initial turn in and less steering input because the car will want to turn that much more) and it's a simple bolt on taking advantage of the festy rear beam design.

Yeah, the Festiva already has that built in. I find that a little toe out in the rear will also help turn in. Make sure you have over 2 degrees of negative camber in the rear before trying toe out otherwise the car is scary at speed ( the back will float around badly over bumps when under power.

[Advancedynamix]

I watched it all, and that stang must have felt bad

It's really hard to make out, but you can see a very rare sticker on the bottom left of my rear window. I've heard it adds 10hp.

[FestYboy]

Yeah, the Festiva already has that built in. I find that a little toe out in the rear will also help turn in. Make sure you have over 2 degrees of negative camber in the rear before trying toe out otherwise the car is scary at speed ( the back will float around badly over bumps when under power.

well, that's the thing... i'm NOT a fan of a static toe out in the rear of short cars... makes them twitchy, but if you were able to induce the toe out durring the weight transfer of turn in, the effort and steeering angle required should drop as the rear will automaticly want to rotate in that direction... all it would take is a little flick (just thinking out loud here). i'm figuring a bolt in strutbar type configuration, but at the rearmost part of the rear beam (maybe add an extention for more leverage), that way it can be removed for the longer faster courses, or tention could be placed on it to effect a total toe adjustment...

oh, and were you able to try the "other" mod that was sent your way?

[Advancedynamix]

Not yet, but bump steer hasn't been a problem. Toe out in the rear is scary with less than 2 degrees negative camber, with more than -2 degrees it isn't noticeable going straight, but helps turn in when the car is leaned into the tire. The beam has the perfect amount of flex from the factory to be very predictable and crisp in turns, once body roll is under control with appropriate shock lengths. The track I raced last weekend is excellent for overall setup because it has everything from tight switchbacks to a very high speed straight, full power sweeper and a nice carousel. At the end of the long straight we are traveling between 130-140mph, and the carousel is 90-100mph corner in Tweak. The car is stable and confident pushing the limits through this section, I push the car till it drifts through the apex at around 90-95 mph. Proof of the cars stability with toe out. It's all in the negative camber, I'm running -2.5 degrees front and rear.

Actually, if the car wanted to rotate any more than it does now,I would be slower, because I couldn't carry as much corner speed into the turns.
I think you will find the response and turn in you desire, Arty, through moving the vehicle weight bias forward. This is a enormous advantage in both turn in response and stability. The best way I have found to do this is by moving the engine and tranny forward. A heavier engine also helps, so you might as well put a bigger lump in there. On my next track Festiva, I'm going to move the engine even further forward than I did with Tweak. Abandoning the false principles of 50/50 weight bias will help any chassis tuner to create a faster car. I passed a well driven lotus exige over the weekend and the driver tried to follow my line, he nearly spun off the track. The lotus had more rubber on the ground and a nearly ideal chassis setup according to common theory. The lotus couldn't hold corner speed like the Festiva, even though both cars were within 50 lbs of each other.

[Advancedynamix]

Okay, you mustang fans should like this. The black Fox body chasing me is a tube chassis car with the engine repositioned rearward and the front wheels moved forward. It was crazy fast through the corners for a mustang. Before I passed the stang I enjoyed watching it drift nearly every curve on the track. One of the best parts of this sport is watching all the different cars being driven hard.

http://youtu.be/SUo7q7TrScA

[kumalaba]

mad skills charlie! car set up & driving!

[Motoxpress]

That's it Charlie shoe them the Festiva awesomeness!!

[Advancedynamix]

Here is the Miata that was chasing me around in the video. It's registered, but not a street car, as it gets trailered to and from the track and never sees public roads.

[tripod808]

The best way I have found to do this is by moving the engine and tranny forward. A heavier engine also helps, so you might as well put a bigger lump in there. On my next track Festiva, I'm going to move the engine even further forward than I did with Tweak. Abandoning the false principles of 50/50 weight bias will help any chassis tuner to create a faster car.

I'm guessing you fabricated some engine and transmission mounts to accomplish this. What other challenges did you encounter when you moved the drive train forward?

[Advancedynamix]

I'm guessing you fabricated some engine and transmission mounts to accomplish this. What other challenges did you encounter when you moved the drive train forward?

Yeah, I am using a G series transmission from a Mercury Capri xr2, which requires custom mounts and also requires a more forward positioned mounting to clear the steering rack. With the engine moved 2" further forward compared to the b3/E-series the turbo inlet interferes with the stock radiator. This wasn't a huge deal for me because I wanted to make my own front lower radiator support anyway, so I designed it to utilize a double row aluminum radiator for a honda civic (super cheap and plentiful). That was the only problem. On my next build I plan to move the engine even further forward.
For pictures of my lower radiator support and where the engine sits in the bay, CLICK HERE.

[jawbraeka]

Hey advance, have you seen my thread on the sephia mount? Would you consider as an exercise of interest for me to try that as it looks rather close to the passenger mount and where the placement is of your custom mount. Itd also answer a lot of questions about B6/G series fitment for me that I have and can foot the bill for the mounts needed to buy and mail them, unless you want to get some and I Can fix you up for them? Either way..

To cut down on search time, its a 1998 kia sephia rear Engine bracket and a 2001 kia Rio passenger mount..

I'll get a photo to show you placement.