Track test and review of the ND-chassis Mazda MX-5 Cup Car

Think back to the first time you saw a high-definition TV image. (Young people, just play along for a few minutes.) Television until that point had shown us amazing concepts, narratives and events, but once we saw those first high-resolution images, we realized we had never seen true beauty. 

Sure, we were seeing the same tales and news and programming …

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Not related to the article itself but if I click on either the Read the rest of the story or the view original article links the resulting page is weirdly formatted with no left margin at all.  This is on the latest version of Firefox.

Our website is in the middle of a minor update today. See if clearing your cache helps. I had the same issue, and clearing my cache made things look normal again. I’m on a Mac with Safari. 

David S. Wallens said:

Our website is in the middle of a minor update today. See if clearing your cache helps. I had the same issue, and clearing my cache made things look normal again. I’m on a Mac with Safari. 

Editorial Director, Grassroots Motorsports & Classic Motorsports

That fixed it.  Thanks.

Good review!

It would be interesting to get a list of all the components that got upgraded on the MX-5 Cup since it was originally introduced, and why. Not just the Flis cars, but also the Long Road-built ones. They were considerably less expensive at introduction ($53,000 in 2015, equivalent to $70k today), but also used a stock (sealed) gearbox and stock brakes. Also, for anyone tracking an ND, there are some good documents around the Cup cars regarding maintenance/upgrades. 

Keith Tanner said:

Good review!

It would be interesting to get a list of all the components that got upgraded on the MX-5 Cup since it was originally introduced, and why. Not just the Flis cars, but also the Long Road-built ones. They were considerably less expensive at introduction ($53,000 in 2015, equivalent to $70k today), but also used a stock (sealed) gearbox and stock brakes. Also, for anyone tracking an ND, there are some good documents around the Cup cars regarding maintenance/upgrades. 

Yeah this sounds like an interesting followup with the Flis crew.

One thing I'll say about the current state of th cars is the current cage is an absolute beat. It's ridiculously overbuilt, but somehow still retains great ingress and egress and plenty of room to work inside. It's also symmetrical, meaning that the RHD and LHD Cup cars use the same cage. It's got to be the single largest labor factor in the car. The sheer number of bars and triangulations and reinforcement plates is just nuts. There's got to be a quarter mile of welds in there.

BTW, Mazda Motorsports lists those shocks as a $1569/corner replacement cost.

Interestingly, they're inverted and very short compared to stock. This is based on the pictures in the published homologation document from 2019, the most recent one available. 7" springs front and rear, while we use 10"/12" for front/rear.

I know when we went to the SADEV sequentials in SRF, the cost of the transmission alone was $13k.  I can't imagine the MX5 one being that different, it may even be more expensive give the front engine layout.  That could explain a lot of the cost.

The guy at the local Mazda shop said that when they started the series they basically had to show up to races with bandoliers of stock transmissions strapped across their body.

In reply to ShinnyGroove (Forum Supporter) :

The EMCO gears and case studs seemed to help, but I can see how Mazda wanted a zero tolerance policy on failures.

It looks like the MX5 Cup car has essentially the same lap time as Andy Hollis' 2019 ND2...assuming that's the 'GRM Project Car' listed.

I find that interesting since, IIRC, Andy's car is usually testing on 200TW tires (245s on a 17x9 wheel) while the cup car is on narrower slicks. Between the two cars, you could probably argue that the suspension, brakes, and power output are close enough that they're not huge factor. If anything, I'd think the cup car would have more power with a catless header and midpipe and the standalone ECU. I'm not sure if it would be any lighter with the full cage but I'd bet it's a lot stiffer.

I run SCCA TT (T4) in an ND2 with all of the typical mods (similar to Andy's car) and have always wondered how it would compare to a cup car around the same track with drivers and conditions being equal.

I suspect there are two other factors: the "we are testing someone else's $100,000 racecar" factor mentioned in the article and weight. That cage doesn't come without some penalty. And of course, weather conditions may have varied.

More importantly, you cannot race Andy's car in MX-5 Global Cup against top level drivers :)

It would be interesting to see the data overlaid to see if there were differences.

JG Pasterjak said:

Keith Tanner said:

Good review!

It would be interesting to get a list of all the components that got upgraded on the MX-5 Cup since it was originally introduced, and why. Not just the Flis cars, but also the Long Road-built ones. They were considerably less expensive at introduction ($53,000 in 2015, equivalent to $70k today), but also used a stock (sealed) gearbox and stock brakes. Also, for anyone tracking an ND, there are some good documents around the Cup cars regarding maintenance/upgrades. 

Yeah this sounds like an interesting followup with the Flis crew.

One thing I'll say about the current state of th cars is the current cage is an absolute beat. It's ridiculously overbuilt, but somehow still retains great ingress and egress and plenty of room to work inside. It's also symmetrical, meaning that the RHD and LHD Cup cars use the same cage. It's got to be the single largest labor factor in the car. The sheer number of bars and triangulations and reinforcement plates is just nuts. There's got to be a quarter mile of welds in there.

Keith Tanner said:

It would be interesting to see the data overlaid to see if there were differences.

Yeah, I suspect there are other factors too.  Global MX-5 cup cars do 1:36 at Laguna, which is pretty fast.  AFAIK Andy hasn't run his car there, but I would be surprised if it's that fast.  (Spec Miata record is something like 1:45)

This car may be a bit up on power compared to Andy's, and my theorized extra weight would punish the car more at the FIRM than it would at Laguna. I think they run hardtops much of the time as well, which would help.

I'm remembering now that I talked briefly to a MX-5 Cup car driver at High Plains here in Colorado a while back. He drove in the series off and on so it was the real deal. I asked him what times they ran in that car at HPR and he thought (?) it was in the 2:02 range. My ND2 on skinny (for an ND) 215/45-17 Kumho V730s with me driving (C+/B- driver) currently does 2:09s. That seemed like a reasonable gap considering the difference in driver skill and car preparation.

FWIW, I built my car to emulate the cup car so it has essentially the same mods (although different brands...AP Racing brakes, Xida suspension, etc.) including some of the 'other' mods such as the under car cooling diffuser. Of course, I don't have a full cage (4 point bar only) or trans and diff coolers, and am still running catted exhaust with a mild off the shelf tune.  It weighs just under 2600lbs with me in it in full race gear and a nearly full tank of gas (according to SCCA scales) and dynoed at 172 corrected at the wheels before the tune...I'm guessing it may be around 180 now.

Good article BTW. If I ever come into an extra $100k, a cup car is at the top of my list.

In reply to FarmerTed :

I'd recommend a trans cooler, BTW. I've datalogged sustained 300F temps on one of our cars. With the cooler, it drops to nearly 200F even with a turbo car running non-stop for 7 hours at Laguna Seca. I believe that's a factor in the transmission failures.

The Global Cup cars have always run trans and diff coolers - I saw a Laguna race where one of the diff cooler pumps failed and that car fell way off the lead pack due to the decreased efficiency in the diff. At least it didn't grenade.

FarmerTed said:

It looks like the MX5 Cup car has essentially the same lap time as Andy Hollis' 2019 ND2...assuming that's the 'GRM Project Car' listed.

I find that interesting since, IIRC, Andy's car is usually testing on 200TW tires (245s on a 17x9 wheel) while the cup car is on narrower slicks. Between the two cars, you could probably argue that the suspension, brakes, and power output are close enough that they're not huge factor. If anything, I'd think the cup car would have more power with a catless header and midpipe and the standalone ECU. I'm not sure if it would be any lighter with the full cage but I'd bet it's a lot stiffer.

I run SCCA TT (T4) in an ND2 with all of the typical mods (similar to Andy's car) and have always wondered how it would compare to a cup car around the same track with drivers and conditions being equal.

For anyone that's interested, you can read more about the work Andy has done on his ND here:

Sorting: How we made an ND Miata 11 seconds faster

It's still a GRM+ exclusive for a few more months, though I'll share this tidbit of info:

Our Triple Threat runs right with a full-race MX-5 Cup car at the FIRM, but the data shows differences. Cornering speeds are similar as our wider wheels and tires overcome our harder compound. While the race car posts faster speeds down the straights, a lower weight allows us to make up time through the curbs of the esses and in some brake zones. 

As Colin mentioned, Andy did do a bit of data analysis oh his MX-5 data at the FIRM vs my Cup car data in a current GRM+/upcoming print magazine story, but I can provide a bit more perspective on the time discrepancy here. Or, rather on the lack of discrepancy.

The best time for Andy's MX-5 at the FIRM is with him driving—a car he's run thousands of laps in for years—and with constant tweaking of alignment and suspension settings to achieve the ideal lap on fresh tires. My lap represents about a dozen laps in a longtime friend's $100,000 car that they hope to use as a promotional tool to sell to actual customers for said $100,000 pricetag. The Cup car was also on a pretty smoked set of 2023-spec tires, as the new rubber had not yet been delivered.

Interestingly, though, on a recent trip to the FIRM there were a couple Cup cars with actual Cup drivers driving and they were only putting a tenth or two on me, so we appear to have gotten pretty close to the threshold for the platform.

So, why isn't is faster? Well, one reason is compliance. One of the sections of the FIRM where it's easy to make up a lot of time in an otherwise unremarkable car is the "esses," which is really just a bumpy straight as the fast line through is just to straight-line through the curbs. A good compliant car with a reasonable amount of travel soaks up those curbs, while stiffer race cars—even ones with awesome shocks—can struggle a bit there compared to the smooth parts of the track. 

Then I think you have to consider the mission here. The Cup cars have been built primarily to be raceable, indestructible and easy on consumables instead of the fastest version of the Miata capable. 

Keith Tanner said:

 I think they run hardtops much of the time as well, which would help.

I thought the ND global MX-5 cup cars didn't have hardtops?

In reply to codrus (Forum Supporter) :

There's mention of the brackets in the documentation, and I've seen them for sale with the tops. They may not race them regularly, I could have been wrong about that. 

Looking further, it may be to allow them to race in other series that require it. 

I'm so old that when I first met him, Troy was too young to drive and raced a go cart.

Since this one popped back up...

I actually think there's a bit more in my ND at The FIRM...cuz JG has that local knowledge and I'm a bit of a wuss in two "scary" places.

Here's that data log comparo of the two cars from the story linked above.

See the first divergence around the 600-800' mark?  That's the kink in the back straight.  JG has gobs of time driving everything under the sun through there, so he has supreme confidence on exactly when to turn in, how much speed to bleed, and how much of the flat track-out concrete can be used without going agro.  Me, not so much.  So I bleed off a little more entry speed, and focus on getting back to power as soon as I can see the exit.  The FIRM is dead flat so most turns are blind in a low slung car.

I'm also holding gear there, banging the limiter into the braking zone.  If I was quicker through the kink, I'd need to upshift.  Double-whammy, that one.

Similarly in the the banked turn, I am always a bit "lost".  I overbrake the entry cuz "risk/reward".  And then It just feels a little vague to me as to when I can start to roll throttle and end up at the very edge of the track-out on exit.  That's the bit just prior to the 2000' mark.

The compliance through the esses that JG spoke of earlier is around 1400'.  It's basically a third gear autocross  with curbs.  I'm still WOT through the first couple, and then just ease off the gas through the last one before hard on the brakes for the pin turn.  Suspension soaks up the bumps.

Of note is the benefit of the SADEV sequential in the Cup car versus my traditional shifting.  Look at the 1600' mark for a good example (and a particularly slow shift on my part).

In reply to Keith Tanner :

Do you happen to know the stroke f&r, and how they compare to the Fox?

They're racing on an oval this weekend at Martinsville. 

Trevor2458 said:

In reply to Keith Tanner :

Do you happen to know the stroke f&r, and how they compare to the Fox?

I know the Fox stroke, but not the Penskes.