Hemi History - 331-A11 Hemi-powered Kurtis Indy Roadster

Discussion of the 331-354-392 HEMIs.

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Hemi History - 331-A11 Hemi-powered Kurtis Indy Roadster

Post by mart » Sat Oct 08, 2011 9:11 am

http://www.moparmagazine.com/2008/sept- ... _hemi.html

Mopar Magazine - Sept. 2008

Too Much Hemi

Story By: Roger Meiners

It was fall 1952 and big things were happening on the bricks at the Indianapolis Speedway. Chrysler dealer Roger Walcott’s new Kurtis-Kraft Indy Roadster was going faster than he could have dreamed. Faster than anyone could have dreamed. The reason for the astounding speed? The 400 horsepower FirePower HEMI® V8 that Chrysler’s engineers developed to run in the 1953 Indy 500.

What Walcott didn’t know was that the frightening speed of this new rocket ship would spell disaster for both his team and Chrysler.

Earlier that year the AAA Contest Board approved a rules change that would allow stock block engines displacing up to 335 cubic inch displacement (cid) to run against pure racing engines that were limited to 4.5 Liters (274.4 cid). Chrysler’s 331 cid HEMI fit nicely into the formula, as did most of America’s new overhead valve V8s. Chrysler took one look at the new rules and jumped right in. The engineers already had a HEMI racing engine—developed for the Cunningham sports car team. It was to dominate the road courses of America that year and earn respect at the 24 Hours of Le Mans.

Joe Freeman, an automotive historian and author, resurrected the Kurtis-HEMI test car pictured in the top photo. The car was entered as the No. 25 Wolcott Special in the 1953 Indy 500 with George Connor driving. The car averaged 134.35 mph in a simulated 500-mile test at the Indianapolis Speedway. The existing 500-mile record was 128.922 mph, set by Troy Ruttman earlier that year.

The company gave engineers John Plattner and Don Moore the go-ahead to start a test program on a special version of the HEMI engine for the Speedway. Designated the A311, the program included fuel injection, 12.5:1 compression, big valves and a roller cam to achieve over 400 horsepower on alcohol at a relatively safe 5,200 rpm. Big horsepower produced high speeds while the slow engine speed ensured that the engine would live for 500 miles.

Roger Walcott had ordered one of the revolutionary new Kurtis roadsters to carry the new FirePower HEMI engine. The roadster design was a big improvement over the standard oval track racer. The new car was lower and wider and, in the case of the Offy, the engine could be offset to the left allowing the driveshaft to pass next to rather than underneath the driver, so he could sit lower. The roadster handled better than the standard upright car, had reduced tire wear and was easier to drive fast. The Kurtis roadster was also the first Indy car to benefit from wind tunnel testing. Bill Vukovich piloted one known as the Fuel Injection Special in the 1952 500 and dueled with Troy Ruttman for the lead during the entire race before a steering malfunction put him into the wall with nine laps to go.

Firestone sponsored the fall 1952 test for Walcott’s Kurtis-Chrysler at the Speedway. Drivers Joe James and Joe Sostillio completed 577 laps (1442.5 miles) at well above the official 500-mile race record of 128.922 mph set by Troy Ruttman earlier that year. The HEMI-powered Kurtis covered a simulated 500-mile race including pit stops at an average speed of 134.35 mph, easily turning lap after lap at 137 mph and reaching speeds of 170 on the straights. An Indy 500 win was almost a certainty for 1953 if all went well.

But all was not to go well. This big success was also Walcott’s and Chrysler’s big mistake. They did it all in public, not realizing that the news would alarm the Indy establishment, with its huge investment in Offenhauser racing engines. Faced with extinction at the hands of the new stock-block HEMI, the entrenched teams lobbied hard. After months of controversy the AAA caved, and in February 1953 took away Chrysler’s advantage by reducing the stock-block displacement limit to 4.5 Liters, the same as pure racing engines. The result: no more 400 hp for the HEMI.

Chrysler’s program was now the one facing extinction, but the company decided to go for it anyway, with only a little more than three months until the race. Plattner and Moore managed to get more than 350 horsepower out of a smaller 271 cid HEMI V8 by turning it faster—5800 rpm at the power peak with 6,500 rpm available from beefed-up engine internals. But the engine did not pull as well out of the turns, reducing straightaway speed. They tried gearing the car for 7,000 rpm on the straights, but lap speeds were down 4 to 5 mph.

When racers gathered at the Brickyard in May, 1953, Roger Walcott brought two of the cars and Murell Belanger, another Chrysler dealer brought one. But the crash program didn’t work. They failed to qualify. The race went on without them and Bill Vukovich won it in the The Fuel Injection Special. He did it again in 1954 and was leading the race in 1955 when he was involved in an accident that claimed his life.

The Chrysler HEMI didn’t get a chance to win the 500, but it had certainly scared the competition. They knew they couldn’t beat the HEMI on the track, so they ran from it to the AAA boardroom.

All was not lost for the Chrysler Indy HEMI, though, because the Firestone Tire Company saw an opportunity to test its racing tires using the original 331 cid version of the engine to achieve higher speeds than were possible with a standard 270 Offy. Firestone reasoned that such hyper-speed testing would give their racing tires a significant margin of safety.

In late 1953, Frank Kurtis delivered another KK500 roadster chassis for the A311 HEMI, which, according to Automobile Quarterly magazine, was now producing 447 horsepower. Ray Nichels managed the test car team and Indy regular Sam Hanks was hired as the first test driver.

Hanks and Nichels brought the Firestone Kurtis-HEMI to the grand opening of Chrysler’s new Chelsea Proving Grounds in June 1954. Three other Indy stars and their cars were also invited; Ruttman, Jimmy Bryan, and the quick-lapping Jack McGrath, all in Offy-powered machines. During the event, McGrath had a fast lap of 179.386 mph, which blew away the existing world mark of 148.17 established in 1928 by Leon Duray with a supercharged Miller at the Packard Proving Grounds in Romeo, Mich.Ruttman clocked 174.554 and Bryan did 166.342 in an upright dirt car.

Then on June 30, Hanks brought out the HEMI-powered Firestone test car and worked up to record laps over 180 mph before putting the hammer down to set an new world record speed of 182.554 mph. The mark would stand for many years, an indication of what might have been at Indy.


1) "Chrysler President Ed Quinn and Vp Engineering James Zeder pose with the final version of Indy HEMI engine that was used in the qualifying attempts in May 1953."
http://www.moparmagazine.com/assets/ima ... /tmh_1.jpg

2) "The Indy test car that astounded the Speedway establishment in October 1952"
http://www.moparmagazine.com/assets/ima ... /tmh_2.jpg

3) "Joe Freeman, an automotive historian and author, resurrected the Kurtis-HEMI test car pictured in the top photo. The car was entered as the No. 25 Wolcott Special in the 1953 Indy 500 with George Connor driving."
http://www.moparmagazine.com/assets/ima ... /tmh_3.jpg

4) "The A311-3-EX2 engine in the Kurtis-Kraft 500A test car, October 1952. The car averaged 134.35 mph in a simulated 500-mile test at the Indianapolis Speedway. The existing 500-mile record was 128.922 mph, set by Troy Ruttman earlier that year." http://www.moparmagazine.com/assets/ima ... /tmh_4.jpg

"The A311-3-EX2 version of the fuel-injected 331 cid HEMI produced over 400 hp on methanol and was used in the fall 1952 test at the Brickyard." http://www.moparmagazine.com/assets/ima ... /tmh_5.jpg

6) "An early A311-3 engine with four single-throat carburetors on a log-type manifold such as used in the 1952 Cunningham C2R road racing car. The engine produced over 300 hp. Chrysler Engineering VP James Zeder described this engine in an October 1952 Society of Automotive Engineers paper." http://www.moparmagazine.com/assets/images

7) "Engine A311-EX1, the first fuel-injected HEMI. This early development photo is dated June 1952" http://www.moparmagazine.com/assets/ima ... /tmh_7.jpg

8 ) "The final version of the Indy HEMI, A311-6. Reduced to 271 cu. in. by the AAA. It lost so much performance that it couldn’t qualify for the race." http://www.moparmagazine.com/assets/ima ... /tmh_8.jpg

9) "Ray Nichels (standing) and Sam Hanks display the Firestone tire test car in a California hotel lobby. Hanks set the world closed-course speed record in this car at the grand opening of Chrysler’s new Chelsea Proving Grounds on June 30, 1954." http://www.moparmagazine.com/assets/ima ... /tmh_9.jpg

10) "The Chrysler HEMI-Powered Kurtis-Kraft 500A roadster at Indy in May 1953." http://www.moparmagazine.com/assets/ima ... h_main.jpg

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Re: Hemi History - 331-A11 Hemi-powered Kurtis Indy Roadster

Post by DavidBraley » Sat Oct 08, 2011 2:40 pm


Thank you so much for sharing that! What a great article. :wink:
Horsepower determines how fast you hit the wall. Torque determines the size of the hole you make. Holzwarth's Law

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Re: Hemi History - 331-A11 Hemi-powered Kurtis Indy Roadster

Post by budmspeeco » Sat Mar 24, 2012 11:35 pm

I am assuming the heads used were traditional earliest hemi heads with the smaller round exhaust ports since it was 1952/53, and not having the water crossover ports in the front. Guess they DO make some power :o . Or maybe Chrysler was experimenting with a revised design for the early intake/oval exhaust ports of the now legendary "555" heads :-? . I also don't understand why the rocker covers had the stock clearance dimple configuration in the middle on some and the middle AND bottom on others. I would have loved to see the covers off those motors for a few minutes!!! :roll: Photo 1 has what appears to be 5 on the bottom and the original ones in the middle. # 5 has the traditional 4 in the center of the covers; #6 dual sets again; *#s 8 & 9 the duals again. Chrysler may have also been tooled up for the elimination of the extended bell housing block by then but probably wanted to use the existing stock by mid '54. "mart", where DID you get all this secret info? :wink: Buddy :D
'48 anglia

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