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Discussion Starter #1
Why was the Chrysler Hemi used in Nitro racing? I have a couple of "Experts" at work claining it was the superior hemi design. Of course explaining to them there was several version of the Hemi doesn't change their minds. The 331/392 and 426 Hemi are completely different engines. I think it was based on the fact that 392 in the early sixties that could be bored and stroked to easily was a big a factor as any other. BBC, Cleavland Fords, Boss 429 are all Semi-Hemi engines from what I understand.
 

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The 392 first appeared in 1957 in the 300C's. It is an extremely heavy and durable engine, able to withstand the rigors of nitromethane and was the engine of choice for these applications. We look back from today with all the aftermarket specialty equipment available and wonder how they did it, but somehow they managed with basically stock blocks.
 

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I'm not a top fuel expert but at the risk of posting the wrong answer:

I believe the cubic inch limit for Top Fuel is 500 CID. Not sure if it was in the sixties, but the wide bore centers of the Hemi and stroke capacity make that limit easily. The Hemi is a robust design that seems well suited for the double whammy of nitromethane and boost.

I think your friends are correct.
IMO, the hemi chamber with centrally located sparkplug(s) evenly distributes the enormous combustion pressure on the piston dome. With a wedge chamber the flame travel goes across the piston.

Other engines have been used for Top fuel, it's just that the Hemi was more successful in the long run, so more racers chose the Hemi. As the class and records got higher, more and more specialized parts had to be developed to keep pace. By the time Top Fuel progressed into this century, Darwin's law weeded out the rest.

There probably isn't many (if any) stock parts on a Top Fuel engine anymore.
Top Fuel is very expensive and limited to a handful of racers, so it's not cost effective to develop parts for other engines...that makes the Hemi the only practical choice these days.
 

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Discussion Starter #4 (Edited)
Thanks for the inputs. I remember a few years back someone developed a newer style blower. It had several hundred fins along the length instead of the twisted rotors. It was much more efficient design; made more power and used much less to turn. It was banned by the NHRA before it made a big impact. They said it would cost the smaller teams to much money to convert over. I think that is one of the main reasons the older style engines are still in use. The NHRA won't let them change based on cost.

The bore and stroke of a 392 is 4.00 x 3.906. I remember reading that a adding a 1/4 inch to the stroke was fairly easy (417). Thats a big jump in cubic inch and nitro fuel burns slow. Starting with 392 CI, strong block and adding a 1/4 of stroke back then would be a major power plant.

Cool quote off a Hemi site
"Now I've been to church and I've been to the drags, and brothers and sisters, for those of you who have never heard a Hemi on nitro, get thee to the drag strip when the Fuel cars are running. Get thee a pit pass, and bring thyself to a Fuel car being tuned up. Listen to the overwhelming sound of what must be the closest thing you can hear in this life to The Sound Of God. Reach out, brothers and sisters, and bask in the glory of the almighty Hemi. For I have heard the Hemi testify. And I believe! Yayass, I believe."
 
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