NC Miata Build

[Trimless]

New NC Miata build and attended our first race at Hallett.  Car has stock engine with header, coil overs with non-adjustable shocks, and adjustable sway bars. No other performance mods.  With this configuration we started with a 4 lap penalty in B class.

 

Just curious if anyone is willing to share what we might want to look at in keeping the car competitive and removing enough points to avoid laps?  I've heard there may be a factory coil over set-up that could be considered "factory" and therefore add no points?  All I know of would be the MX5 cup package avalaible from Mazda, but this was certainly not avaliable to customers on dealer sold cars.

 

Any suggestions appreciated!

 

Thanks

[CoachMK21]

@Grant is the NC Master and there is a thread here somewhere with a lot of his "secrets".  

It was good racing with you guys out there.  Car looked fast.  Thankfully our first driver was able to avoid yours on Sunday morning in the exit of turn 3.  The video was, oh $hit worthy.
 

 

Edited May 17, 2022 by CoachMK21
Added video.

[Trimless]

16 minutes ago, CoachMK21 said:

@Grant is the NC Master and there is a thread here somewhere with a lot of his "secrets".  

It was good racing with you guys out there.  Car looked fast.  Thankfully our first driver was able to avoid yours on Sunday morning in the exit of turn 3.  The video was, oh $hit worthy.

 

Thanks I'll look for that thread.  We had no contact all weekend, so all is good!

 

Cheers
 

 

 

[wvumtnbkr]

400 pt vpi

25 pt header

20 pt rear swaybar

20 pt front swaybar 

10pts x 4 coilover springs.

 

400 +25 + 20 + 20 +40 = 505 or only 1 lap.

 

I'd just take off the adjustable rear swaybar and have 15pts for something else!

[Grufton]

31 minutes ago, wvumtnbkr said:

400 pt vpi

435...

[wvumtnbkr]

3 hours ago, Grufton said:

435...

That's not what the calculator says at this minute...

Edited May 17, 2022 by wvumtnbkr

[Team Infiniti]

Woof

[Trimless]

Actually the VPI is  now 435 for the NC.  The calculator has not been updated yet. 

[TimS]

Sadly anything with “adjustable” in the name will cost more points than it’s worth. Removing the Adjustable portion is your best option to reduce points to  zero laps level. Removing Adjustable coil over springs would be my suggestion 

[wvumtnbkr]

I'd go the other way.  Leave the coilovers and remove the adjustable swaybars.  Depending on the philosophy, stiffer springs can help with roll stiffness and negate the need for the swaybars.

 

Either way, it's 40 pts back.  

 

With springs being fairly open, you could do some testing and determine which way is faster!  I bet the laptimes don't change no matter which way you choose to go.

[Trimless]

56 minutes ago, TimS said:

Sadly anything with “adjustable” in the name will cost more points than it’s worth. Removing the Adjustable portion is your best option to reduce points to  zero laps level. Removing Adjustable coil over springs would be my suggestion 

5 minutes ago, wvumtnbkr said:

I'd go the other way.  Leave the coilovers and remove the adjustable swaybars.  Depending on the philosophy, stiffer springs can help with roll stiffness and negate the need for the swaybars.

 

Either way, it's 40 pts back.  

 

With springs being fairly open, you could do some testing and determine which way is faster!  I bet the laptimes don't change no matter which way you choose to go.

I have to agree with this.  While the stock sway bars are crap, the ability to corner weight the car is a greater benefit.  We can use stiffer springs if needed to avoid the SWAY.

Back to 500 points for now!

[turbogrill]

Remove the adjustable swaybars and go bigger on springs.

You can also drill the front sway bar to make it a little stiffer. The club model came with a slightly bigger rear sway. 

The factory sport suspension is a little stiffer but not very interesting but would be 0pts.

 

These are the combos I have seen:

 

1. (I think this is grant)

40 non adjustable shocks

25 header

 

The best you can buy are the Penske Mazdamotorsports. You need to sign up for it. They are pricey at $2000

Bilstein b14 is another option

 

2. Lonestar rallycross (fast team)

40 non adjustable shocks

20 aero

5 pts ??

 

3. Viking chug motorsport (my car)

25 LSD

25 header

10 camber adjuster

5 RX-7 hubs

(0pts cut springs)

 

We are the orange car that had the pit stall in front of you.

 

Edited May 19, 2022 by turbogrill

[Trimless]

Thanks for the replies, much appreciated!

 

[Grant]

Currently I think the ideal NC parts list is:

 

435 VPI

+25 header (RoadsterSport 1.8" Max)

Custom exhaust with two vibrant 17930s. This should get you just under the 96 dB limit.

Ram-air intake with inline airbox

17x10 Konig Hypergram wheels, or if you want to get spendy some custom 15x9.5s which clear the rear spindles

Wilwood brakes with thin, directionally-veined rotors

Front sway bar drilled out to make it slightly stiffer

no rear sway bar

Cut or custom springs to 500/325 lb/in

Race louvers hood vent

Get a new LSD from Mazda and send it off to Walter Motorsports. They'll remove the pinion damper and install stiffer springs to maybe it lasts longer.

Custom Delrin differential bushings

Custom valved stock shocks

+5 RX8 front hubs

Shaved, ported (or Spec MX5) head with a 0.018" cometic gasket (haven't tested this yet)

Custom Spec 3-puck clutch with their aluminum pressure plate

Fidanza flywheel

Walter Motorsports refreshed transmission

My fuel system mods I may post later

 

I'd like to test air dams, but haven't gotten around to it yet. More aggressive aero I'm skeptical about. You're always in traffic (dirty air) in ChampCar, and straight-line speed helps you pass. You should already have faster cornering speeds than the rest of the field. I will only run an air damn if it does not increase drag.

 

If you want to save yourself a lot of money and pain, take 25 points and run the new Mazda Motorsport Torsen LSD. Quaifes are worse than stock but last forever.

 

If you run an air dam but no diff, you have 25 points remaining. An intake manifold (+25) would be nice, but no one makes a good one (the 1goal is garbage; runners are way too short).

 

Like any ChampCar, the most important ingredients are weight reduction and driver training. We'd like to help the ChampCar field get faster, and don't have any secrets.

Edited May 20, 2022 by Grant

[turbogrill]

13 minutes ago, Grant said:

Shaved, ported (or Spec MX5) head with a 0.018" cometic gasket (haven't tested this yet)

 

 

If you want to save yourself a lot of money and pain, take 25 points and run the new Mazda Motorsport Torsen LSD. Quaifes are worse than stock but last forever.

We run the OSGiken LSD. It is supposed to be durable but 

1. Do you think the Rousch SpecMX5 is a CNC ported stock head? If so I guess 0pts? 

2. We run the OSGiken LSD. It is supposed to be durable. Maybe cheaper than mazda motorsports (25pts) 

It's annoying you can't fit coilovers+header+hubs. That would be the easy button.

[Grant]

51 minutes ago, turbogrill said:

1. Do you think the Rousch SpecMX5 is a CNC ported stock head? If so I guess 0pts? 

It is CNC ported.

[wvumtnbkr]

1 hour ago, turbogrill said:

1. Do you think the Rousch SpecMX5 is a CNC ported stock head? If so I guess 0pts? 

2. We run the OSGiken LSD. It is supposed to be durable. Maybe cheaper than mazda motorsports (25pts) 

It's annoying you can't fit coilovers+header+hubs. That would be the easy button.

You could run 2 coilovers and ger most of the benefit.  Or even 3 if you are creatice!

[Grufton]

13 hours ago, Grant said:

Get a new LSD from Mazda and send it off to Walter Motorsports. They'll remove the pinion damper and install stiffer springs to maybe it lasts longer.

 

Custom Delrin differential bushings

I've been wrong before, but I would have expected to be charged points for both of those.

[enginerd]

11 minutes ago, Grufton said:

I've been wrong before, but I would have expected to be charged points for both of those.

Agreed

 

[turbogrill]

From the 0pts:

 

Suspension bushings: OE replacement or

polyurethane/Delrin with OE geometry (OE hole

location/offset, height, thickness)

 

Would the diff bushing change this?

 

[enginerd]

51 minutes ago, turbogrill said:

From the 0pts:

 

Suspension bushings: OE replacement or

polyurethane/Delrin with OE geometry (OE hole

location/offset, height, thickness)

 

Would the diff bushing change this?

He said "custom", which I assume means that it's dimensionally different than stock, otherwise you would just use this (assuming I googled the right mazda parts. Even if this particular link is the wrong part, you get the idea)

 https://www.powerflexusa.com/shop/product/pfr36-411-mazda-miata-mk3-rx8-rear-diff-carrier-bracket-bushing-2244?gclid=Cj0KCQjw-JyUBhCuARIsANUqQ_JTPUwHAHv8Uz0jJQVNWdF3qjrkfMu_bcBh3N88lyE0wfUP__sbH5caAvIxEALw_wcB#attr=643

Edited May 21, 2022 by enginerd

[Grufton]

13 hours ago, turbogrill said:

From the 0pts:

 

Suspension bushings: OE replacement or

polyurethane/Delrin with OE geometry (OE hole

location/offset, height, thickness)

 

Would the diff bushing change this?

 

In my understanding, diff bushings are not suspension bushings (in most cases)

[enginerd]

49 minutes ago, Grufton said:

In my understanding, diff bushings are not suspension bushings (in most cases)

On the e30 they definitely are. The differential is one of 3 mounting points that attach the rear suspension to the frame of the car, and it attaches via a stiff rubber puck. I don't know about miatas.

[Grant]

On 5/20/2022 at 9:50 PM, enginerd said:

He said "custom", which I assume means that it's dimensionally different than stock, otherwise you would just use this (assuming I googled the right mazda parts. Even if this particular link is the wrong part, you get the idea)

 https://www.powerflexusa.com/shop/product/pfr36-411-mazda-miata-mk3-rx8-rear-diff-carrier-bracket-bushing-2244?gclid=Cj0KCQjw-JyUBhCuARIsANUqQ_JTPUwHAHv8Uz0jJQVNWdF3qjrkfMu_bcBh3N88lyE0wfUP__sbH5caAvIxEALw_wcB#attr=643

No, same dimensions as stock. The last set of Powerflex bushings we had in the car fell out when the diff was removed. They'd developed a lot of play. Polyurethane is really a terrible bushing material. I assumed these or Delrin bushings would be zero points. I've got another set of Powerflexes in there now.

You could probably just run the stock stuff. It doesn't look all that great but I bet it lasts longer than polyurethane.

Edited May 22, 2022 by Grant

[CAM]

NC Miata specific question, is it common for the clutch slave cylinder to fail?  During the first event with the teams NC, we went through two clutch slave cylinders and ended early since we did not have a third.  Seems to be a very odd failure.  Was it bad luck or is this a known issue?

 

The clutch would last around an hour before the peddle went to the floor, would come into the pits and bleed the clutch and was fine again for around another hour.  We were using decent fluid that did not boil in the brakes.

 

Thanks in advance for any advice you can share.