Simanaitis Says

On cars, old, new and future; science & technology; vintage airplanes, computer flight simulation of them; Sherlockiana; our English language; travel; and other stuff


AUTOMOTIVE SPORTSMAN John Cobb’s directive to Thompson & Taylor Ltd. was clear: Build a car to set records at the 2 3/4-mile Brooklands circuit. Chief engineer Reid Railton responded with one of the most fabulous machines of that or any other era: the 1933 Napier-Railton.


I’m bigger than the average bear; but the Napier-Railton is bigger yet. Image by John Lamm.

Here in Part 1 are technical details of this 24.0-liter Napier-engine giant. Part 2 will summarize its activities, both as a record-breaker and in a surprisingly varied later life.


The Napier Lion engine is a “broad-arrow” design, not quite a W (in the sense of twin V’s as in VW-Audi’s W-12. Note its primary and yoked connected rods.

By 1933, the Napier Lion aircraft engine was already legendary. It had powered the Supermarine Sea Lion II and S.5 in Schneider Cup victories in 1922 and 1927, respectively (, The engine’s “broad-arrow” 12-cylinder configuration has three banks of four cylinders each, one bank vertical, the other two at 60 degrees to it.


With the Lion’s camshaft hardware removed, one bank’s four valves per cylinder are visible. Note also the robust crankshaft with one of its triad con rods.

Each bank has twin overhead camshafts actuating four valves per cylinder. Each cylinder has a bore of 139.7 mm (5 1/2 in.) and (approximate) stroke of 130.2 mm (5 1/8 in.); displacement is a tad less than 23,948 cc.

This hedge is traced to the Lion’s double-yoke connecting rods. A central master rod connects each vertical piston to a four-throw crankshaft running on roller bearings.


The Lion’s double-yoke con rods give it an oddity of displacement. Image from

Link rods connect each master rod to its outlying pistons, both of which have slightly diminished stroke.

Exhaust ports of impressive size lead to what in some venues were twelve stubby open exhausts. It’s part of Napier-Railton lore that these were shielded from Cobb’s eyes during night endurance runs. Also, for placating Brookland’s Weybridge neighbors and as fitted today, three oversize Brooklands silencers with their traditional fishtail endtips are part of the Napier-Railton’s exhaust system.


Three of these “silencers” don’t actually perform a great deal of silencing. Image by John Lamm.

The engine delivers its massive torque—perhaps 1200 lb.-ft. at 1800 rpm—to an evidently sturdy three-speed Moss gearbox. The latter has non-syncho ratios selected through a gated shift lever to the driver’s left. Directly next to this is a fly-off handbrake.


Everything about the Napier-Railton is oversize.

An oversize steering wheel is the width of the generously dimensioned cockpit (John Cobb was a big guy). The seat and pedals are offset slightly to the right. Pedals are classically aligned, with the accelerator in the middle and brake on its right, the point being to promote heel-and-toe downshifts of that crash box.

The Napier-Railton rides on 6.75/7.00-21 tires, not overly wide but certainly tall for any era. Its axles, front and rear, are straightforward beams. Front springs are semi-elliptic; those at the rear are stacked pairs of these.


The front wheels are sans brakes. Note the friction shock absorber, one of a pair on each side. Image by John Lamm.

Braking wasn’t an important aspect of Brooklands, so only rear drums were fitted. Today, the Napier-Railton has massive disc brakes in back, a fitment made in one of the car’s reincarnations to be recounted in Part 2.

The aluminum bodywork is by Gurney Nutting, one of England’s famous coachbuilders. Its widow’s-peak nose, side-bonnet nacelles covering the cylinder heads and boat tail make it more than minimalist.


The Napier-Railton’s proportions are so well realized that its size is deceptive. Image by Dave Rogers at the Brooklands Museum ( where the car resides as part of the permanent collection.

The Napier-Railton is one of the most purposeful automobiles ever conceived and constructed. Part 2 summarizes its activities, everything from record-breaking at Brooklands, Montlhéry and Bonneville, to postwar testing, to Hollywood stardom, to one of the most memorable drives of my life. ds

© Dennis Simanaitis,, 2013

One comment on “NAPIER-RAILTON, PART 1

  1. Bill Urban
    August 1, 2013

    More than a race car, this is a juggernaut. What did it weigh?

    I am reminded of related Phillip Smith and John C. Morrison comments. In their book they recalled the Brooklands authorities more apt description of their expansion chamber: “. . . to their credit they called it a receiver” (not silencer). And of the fishtail: ” . . . a most effective adjunct to silencing [ ] and a matter for regret that it is a victim of current fashion” (written in the sixties).

    Only rear brakes? Amazing related fact – until the seventies the same was true of truck-tractors for gross weights into the seventy thousand lb. range!

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.


This entry was posted on July 29, 2013 by in Classic Bits and tagged , , , .
%d bloggers like this: