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Hemi Development Stories

Willem Weertman and the 426 Street Hemi engineWillem Weertman (engine design leader) wrote about the 426 Hemi:

We had been using the wedge-head big block V-8 engine and we weren’t doing very well with it [in racing], we were being outgunned by the very experienced and well-equipped Ford and Chevrolet teams.

Our senior management thought it would be nice for us to win races.  They asked the question “What would it take for use to win a race?”

After a lot of consideration, the engineering response was that we should go back and try to see if we can run our Hemi engine again because we did so well with the first generation Hemis that had come out in 1951 and had been raced in NASCAR and had a tremendous amount of victories. 

The inquiry came to us in engine design, “could we put a Hemi head on top of a raised B (RB) engine?”  That’s when the story started and ended up with our indeed being able to do that and we had engines ready for the 1964 NASCAR race in Daytona Beach and we did extremely well and continued doing well during that season.

When the order came we assigned our best designer to it, with Bob Rareya and me looking over his shoulder.  By making changes to the block we were able to do that job with a brand new set of cylinder heads having machined Hemi chambers that just happened to have the same included valve angle as the 1951 Chrysler Hemi and it worked.  It was quite a program for us; it was a very rushed program and we were extremely happy when it was successful on race day and we blew the competitors off the track.

For more, see our interview with Willem Weertman!

Candymatic

Pete Hagenbuch (engine development engineer) wrote:

I was running valve dynamics (pump-up speed) on one of the 300 letter series engines with the long cross ram intake manifolds. This entailed me being in the performance cell close to the engine but not in line with the prop shaft. The dyno operator was at his console which sort of protected him from flying parts; but not me! As I remember we were going up from 6000 to 6400 rpm when suddenly the room filled with dense white smoke! My operator hit the big red button on his way out with me stepping on his heels.

426 Hemi engine dyno test

When things quieted down a bit we went back in and found a leak had developed between exhaust manifol and cylinder head surface. The exhaust gas was blowing right onto the cork cylinder head cover gasket. When it burned through we had hot gases inside the head cover! Scary!

This one was before my time but it was certainly possible. [I heard that] When the original "Double Rocker" was expanded to 392 cid, a weakness was discovered in the main bearing bulkheads, which would crack leaving the crankshaft to fail eventually. And, at least on lab endurance engines, this lead to unbelievable mayhem. The block would sort of disintegrate spewing out all sorts of parts from pistons and rods to valves and pushrods. Not to mention pieces of the crankshaft. All in all quite spectacular.

You know that basic engine continued to be a favorite with the dragster guys but perhaps you're aware that they all used a "steel girdle" between block and oil pan to hold things together.

street Hemi

Another favorite story I can't prove: John, a good friend of mine who was in the Bearing Group at the time was in an endurance cell listening for some sort of noise in the engine. Our endurance lab at that time (1960s) consisted of six cells, each with two engine running 24/7 (a term that didn't even exist then). Anyway, John's boss was right behind him, between engines, when the exhaust system on one of them just plain broke and fell off. The engine was running 4000 at wide open throttle at the time. Legend has it that John was first out of the room and that his boss had a footprint on his chest due to John's hasty exit.

For more, see our interview with Pete Hagenbuch!

Neil Newman, as interviewed by John Gunnell in Auto Trader (reprinted with permission), remembered one of the major tire companies using a Chrysler-engineed racing car running alcohol fuel to test tires. “Firestone was also building an Indy Car with some form of Hemi engine. An Offy engine would only last 500 miles before it needed to be rebuilt, but the Hemi would last for many more test cycles.” (See the A311 Hemi created for the Indy 500.)

Roger Meiners wrote:

That would be the Firestone Indy car, the Kurtis 500 (500C?) that ran a 331 cubic inch Chrysler FirePower hemispherical engine running fuel injection (Hilborn). The car was put together and maintained by Ray Nichels and driven by Sam Hanks and Pat O’Connor. When the Chrysler Indy project died, Firestone kept going with a later installation for tire testing only. That car also ran laps at Monza before the Race of Two Worlds just to test tires (but set a lap record at 170 mph, with OConnor driving). Hanks set a world closed-course record at Chelsea at 182.55 mph in June 1953. Yes, the Hemi could run all day at speeds faster than an Offy could achieve.

426 Hemi | Hemi History | Hemi Central | Bob Scott's early-Hemi tuning developments

Modern Hemis 5.7 Hemi • SRT 6.1 and 6.46.4 Truck Hemi • Supercharged “Hellcat”
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