NASCAR is one of America’s top-flite motorsports. Despite its “stock car” roots, the series now runs custom-built race cars and bespoke engines that share almost nothing in common with regular road cars. Indeed, a NASCAR Ford Mustang probably has more parts in common with a 1997 Mercedes S-Class than a Ford Mustang road car.
This hilarious state of affairs came to our attention thanks to race mechanic and Autopian contributor Bozi Tatrevic. He’s a skilled pit crew member, and he knows a thing or two about race cars.
Bozi was recently browsing the NASCAR parts database, when he came across something interesting. It concerns the ignition coils approved for use in the top three NASCAR series.
Today I learned that it's legal to use an ignition coil from a Mercedes-Benz SL600 in a NASCAR Cup car. pic.twitter.com/x0EkucNjER
— Bozi Tatarevic (@BoziTatarevic) April 4, 2024
There are just two ignition coils on the NASCAR-approved list. There’s one from McLaren Electronics Systems, and the other is a Bosch part. The latter is listed under part number 0 221 504 001. “It’s part of the NASCAR Parts Database,” Bozi explained to me. “Any part used on a race car in the top three NASCAR series must be submitted to NASCAR for approval and once it is approved it is listed in that database.”
Type that part number into Google, and you’ll find a ton of parts sites selling these coils for around $70 a pop. That’s because they’re commonly used on a whole raft of Mercedes-Benz models!
Known as the P50 ignition coil, you can find these on the Mercedes SL500 and SL600 from the mid-1990s. They used a whole bunch of these coils on their V8 and V12 engines. The same part was also found on multiple S-Class models from 1992 to 1999, and the E420 as well.
As explained in Bosch documents, the P50 ignition coil was designed to mount directly to the cylinder head, in a coil-on-plug configuration. In many applications, it’s used with a long rubber boot connecting it directly to the spark plug. However, the boot is not an integral part of the P50 coil, and it can be used as a small square model with a regular spark plug lead connected to its output terminal instead.
Bozi noted that the coils were approved for NASCAR, but I wanted to see if they were actually being used on actual NASCAR engines. I skipped over distributor-based engines, with the Bosch coils really built for a more modern coil-per-cylinder setup. Looking around, I found photos of the Ford FR9 engines used in NASCAR, and was able to spot the Bosch coils quite easily. In photos from engine builder Roush Yates, they’re mounted in groups of four up near the air intake. From there, spark plug wires extend down to the spark plugs, which are nestled down by the exhaust ports.
It can be a little confusing, as the coils are mounted in square brackets that obscure their form a little. If you want a better look, you can zoom in on this high-res photo from the NASCAR Hall of Fame. Looking closely, you can spot the little plastic tooth on the top of the coil which is characteristic of the Bosch part.
It appears that at least some Chevy engines in NASCAR use the same part and layout, based on pictures from Engine Builder Mag in 2017. I did some research into Toyota’s NASCAR engine program, and I reckon they were using the same coils in 2017.
Amusingly, based on part numbers, it appears that NASCAR only approves the Bosch P50 coil. This would preclude teams from running the Bosch P50-M, which is a specialist motorsport-spec version that is built to better resist damage from vibration. You can actually purchase the race-spec parts allegedly used by the Aston Martin LMP1 race team on eBay. If you prefer to order new, look up part number F 02U V00 869-01.
In any case, it was interesting to see that modern NASCAR engines share a part with classic Mercedes-Benz models. The road car world has moved beyond the P50, but it seems like Bosch has sold plenty to NASCAR teams since the part was approved in 2015.
Image credits: Jeffrey Hayes, CC BY-SA 2.0, Sparesbox, TRD via YouTube Screenshot, RoushYates, Bosch, Mercedes-Benz
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In a bizarre twist….
The Mercedes V8 that won the 1994 Indy 500 was pushrod, so it technically shares more engine design features with the NASCAR Mustang vs an actual 1994 Mercedes SL!
https://en.wikipedia.org/wiki/Mercedes-Benz_500I_engine
^It’s a pretty cool story about how this top secret engine exploited a small rule to win in 1994 only.
What’s the part number of Toyota’s cheating throttle body? /s
Supposedly the front grille of the NASCAR Fusion was the same size as the production model, but I’ve not had the chance to have both Fusion’s in the same room to confirm this.
I would love to see a more filled out list of off the shelf parts like this that are motorsports approved, widely available, and cheap for the quality you get. A Bosch branded P50 coil for a 1997 SL600 is less than $40 on Rockauto.
For another example, the Mk60 ABS system installed on the E46 BMW M3 is allowed in many racing categories as the only non-factory ABS system that can be installed on a car.
OEM parts swapping as an upgrade is my favorite way to mod a car. I’m running BMW E30 front hubs and Toyota Yaris rear hubs as beefy upgrades on my Miata. My fuel pump relay went out and I repinned the electrical connector for a standard square Bosch style relay instead of whatever weird format Ford/Mazda were using in the 90’s. I’m working on that ABS swap as well. When I had been running megasquirt, I installed junkyard LS truck coils trying to diagnose some spark issues, but getting good ones now is apparently more hit or miss as they get older. This seems like it would be the next logical step.
Wait…Yaris hubs are an upgrade over stock Mazda?
Is this perhaps because they were saving weight? I mean, I love the idea, but I didn’t think the Yaris was intended as much more than a cheerful cheap car
They’re thicker and heavier. Stock NA/NB Miata hubs become consumable on cars with high grip track tires. They will eventually crack if used too long and suddenly you’re on three wheels.
This is a big step for NASCAR, not too long ago they were running HEI distributors from 1974.
I was thinking the same thing, noting that they’re still running spark plug wires.
Edit: D’oh – too early/not enough coffee. I guess those aren’t really spark plug wires, right, but rather the electrical connection…
Those are definitely still spark plug wires. An electrical connection carried by a long thin flexible metal piece is….. A wire.
The real question is; in coil-on-plug systems, does the spark plug boot count as a very short and fat sparkplug wire?
I would guess that’s exactly one more part than NASCAR engines — or complete cars, for that matter — have in common with actual production-line Fords, Chevrolets or Toyotas at the local dealers….
I bet you could find the same 10 mm bolt in there somewhere.
I stand corrected!
And the 10mm socket rattling away somewhere in the engine bay….
What? You mean I can’t go into my local dealership and buy a RWD Camry coupe with a V8? My world is shattered
Let’s see an off the shelf Bosch part vs ones from McLaren. Ya they all run the Bosch parts.