Considering 2015 racing debut
 

Hi guys,

I want to spend more time on the track so I'm considering to start racing in 2015 and could use some advice. I live in Denmark and the class I'm looking at is called Youngtimer. The class is for 15 years (or older) production cars and it has three sub-classes based on weight/hp.

Basically, I want to start in the lowest sub-class with a low costs > speed mindset and if it grows on me, progress towards the fastest sub-class and speed > low costs.

Class Regulation

For each race there is 20 minutes qualifying and three heats of 15 minutes plus one lap. Standing start.

The three sub-classes are

• > 16.3 Lbs per crank hp
• > 14.1 Lbs per crank hp
• > 9,7 Lbs per crank hp
• Weight is including the driver

Max rim width allowed:

• 1931 - 2151 Lbs: 8”
• 2151 - 2370 Lbs: 8,5”
• > 2370 Lbs: 9”

Tires are unrestricted.

Suspension pretty much no rules except that ground clearance must be at least 2" (disregarding mufflers).

Brakes are pretty much unrestricted too except for no exotic materials.

Engine work, FI and modified exhaust is allowed. No race fuel.

The transmission is limited to 5 speed unless the car was produced with more gears. Diff ratios can be changed. LSD allowed.

It's allowed to strengthen the chassis/construction but not to remove or swap in lighter material. However, non-supportive bodywork can be replaced with lighter material.

Non-OEM front and rear spoilers are allowed as long as they don't breach the top-down silhouette and the rear-spoiler has to be discreet and mix well with the body shape. Rear wings are not allowed unless they were an original option. Wider fenders are allowed up to 100 mm increase in overall vehicle width (approximately 2" per side).

The tracks:

Padborg Park (1.3 miles)
https://www.miataturbo.net/attachmen...1&d=1399296593

Aarhus Classic Race (1.6 miles)
https://www.miataturbo.net/attachmen...1&d=1399296995

Jyllandsringen (1.4 miles)
https://www.miataturbo.net/attachmen...1&d=1399296713

Ring Djursland (1.1 miles)
https://www.miataturbo.net/attachmen...1&d=1399296804

Ring Knutstorp (1.3 miles)
https://www.miataturbo.net/attachmen...1&d=1399297024

The Competition

Here is a heat with the 2013 overall winner. He is starting from the pit lane in this one so you will see him working his way up through the field:


The Plan

So, for the first (cheap) step I'm thinking a '99 with a 6 speed and LSD. '01 Sport brake system, cheap coilovers, a Megasquirt, better cooling, cage, seat, harness, wheel, mild weight reduction, no aero.

Would it be realistic to aim for 2370 Lbs (that's just under 2200 plus driver), allowing 145 crank hp and 9" wheels. What size slicks would make the most sense, keeping in mind that I can widen the fenders 2" per side?

Do you think the MX-5 is a good choice for this class? Any other thoughts?

Cheers,
- Tom

That's going to be expensive.

@ that weight/power, I think the miata is pretty good chassis to do it in. Especially if the restriction is 15 years or older. That puts you right at the 99 miata which is a pretty good platform. I guess the preferred method for a power-to-weight limit is probably VVT with a very wide power band, but I am sure you can manage. There is plenty of info on building engines and turning the power down to get a wider power band.

If brakes are unrestricted, I would definitely NOT go for sport brakes. They are expensive and they aren't really a significant step above the stockers. especially for 15 minute sprints, I would look more to wilwoods (ie lower unsprung weight) or go with whatever is on the 99.

Cheap coilovers? Nope, you need to get something that is top of the line. Choose what you wish, but I (and many here) will tell you that Xidas are definitely worth it.

I think you have the right idea for tires/wheels, but consider that the compound can make a bigger difference than size. low weight/low power cars will probably benefit from running on smaller tires with a sticky compound. There is probably a sweet spot there, but we maybe discussing tenths, not seconds now.

Not sure if you are a "beginner" or not, but unrestricted tires just sounds like an awful experience if you want to win and don't have a lot of money. People build cars (and drivers) around a specific tire. If you are in this for fun, then definitely do this and don't give a shit about the tire stuff.

It sounds like you have a pretty good plan so far, that should be able to be a quick car. If you're stripping the car out of all the non-essentials, you will likely need to add ballast to make the car heavy enough to qualify for 9" wheels.

And on that note, do not flare/widen the car. You can fit 9" wheels just fine under the stock fenders of an NB (just need to roll the fenders a bit so nothing jabs the tires). The narrower car will have less drag.

Looking at the weight/wheel width brackets, I'd wager you could be faster by dropping 300+ lbs and running the 8" wheel, but to really maximize that you'd need lightweight body panels, etc. to try to get down under 2,000 lbs with driver weight included. The cheaper option will be to go heavier car/wider wheel.

-Ryan

I doubt it. Power to weight classes inherently favor heavier, more powerful cars, especially when the heavier cars are given advantages like wider wheels. Heavy cars get more power, and north of 90mph the power matters more than the weight (think aero).

OP is on the right track, but cheap coilovers are a huge mistake. An optimized Miata for that class would have high-end shocks, 9" wheels and 215/580 Hoosier radial slicks, and a built motor with flat power from 5k to 8k.

Look at the tracks and their lengths. They are smaller than Mickey Mouse tracks and low weight always wins over power in these cases.
Heck, you can almost disregard drag completley since time spent above 80mph is very small.

The class looks very similar to the Roadsport C we run in Sweden except the tires and the lower clearance (they get more power out of their untouched engines though).
Getting hold of decent slicks in 15" is not easy, 190/580-15 and 200/580-15 are the dimensions that are available in some German one-make series, but then the compound used is too hard (who cares in spec series).
One way to get started is to use cheaper and longer lasting tires (Rcomps) as a start and then decide. Sure there are many things to change to optimize with slicks but it's not uncommon to win series just by being consistent.
Avon 225/580-15 looks interesting on paper.

Interesting that you use Knutstorp, then there are plenty of times on street legal tires to compare too (slicks only needed to go below 1:10.0, or 1:09.0 if we count that summer with new tarmac) :)

Hankook F200's are available in a 215/580R15 in three compounds

Would it be worth upgrading the 99' 3-channel ABS to the 4-channel from the '01+? Does it bolt right in?

BTW, adjustable brake bias control is also allowed.

- Tom

You should maybe be looking at what the quick autocross guys are doing instead of track cars with courses that small. I would remove as much rotating mass in the drivetrain, wheels, and brakes as possible and let the mass that remains be in the static parts that effect acceleration and braking least. The 949 Racing twin disc clutch and forged connecting rods would be on my list, along with the BHJ damper and Boundary Engineering billet oil pump gears.

Shandelle at V8Roadsters can put together a very lightweight aluminum hat brake package that is larger in diameter than stock but will weigh less and stop better, since you will likely be sprinting from 30-80mph and back to 30mph instead of going 130-50-120-30mph like the big track cars do. Just explain your needs carefully to him. There are different rotor rings to fit the same hats and he can customize them to your special needs.

And Savington is right about the broad, flat horsepower curve.

Be aware of the mass of the tire itself when making a selection, too. I switched from Kuhmo V710 to Avon slicks once when I was autocrossing my RX7 and was much slower just due to the additional mass of that particular Avon with its thick sidewall.

Good luck.

Both are 3channel, one line to the rears. But the 01+ have EBD.
The lines are the same, but the harness is different.

11.75" Mini dynapro setup in front, sport rear disks with stock caliper on brackets, 01+ Master+booster.

Any pointers on what rubber you are aiming for?