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Is it all in the Cylinder Heads?

Discussion in 'The Coffee Shop ~ Chit Chat' started by Big_Mike, Aug 27, 2012.

  1. Big_Mike

    Big_Mike Member 100 Posts

    850 horsepower. That's a HUGE amount of output especially from a NASCAR engine that is within the range of 351 to 358 cubic inches of displacement (last time I checked that was the legal range listed in the rule book). How is that much power produced from an engine roughly the size of a 5.7 liter production car engine? While learning about racing engines, I was told to consider an internal combustion engine as an air pump. It gets pumped in (with this case, naturally inducted) and gets pumped out. Okay, simple enough. I was further told that so much goes into the intricate design of things like the intake manifold, headers, and ultimately the cylinder heads.

    The cylinder heads contain most of the valvetrain (minus the camshaft which is in the block, OHV design). So all that power from a pushrod engine? Really cool, especially since some OHC engine fanatics snicker at the mere mention of the pushrod predecessors. And on top of that, its naturally aspirated! Until a recent change to fuel injection, one would raise the hood and see that bolted atop the intake manifold was a four barrel Holley carburetor. Now, that is awesome, getting that much out of an engine and having it last the length of a race. Even those who don't like NASCAR hopefully respect that. I enjoy the technical side of it. There truly are some bright individuals out there who think up this stuff. This brings up the question, "Is it all in the cylinder heads?"

    Also please note that the horsepower rating could be more by now, but the last I checked, 850 was what I read as a figure.

    Any comments are welcome... :)
  2. RayVoy

    RayVoy Active Member 2 Years 1000 Posts

    All things considered, from an efficiency perspective, the engine produces that kind of hp because it can rev to 9000 and higher.

    Big rpm = big hp

    And, I could be wrong, but I think the hp is closer to 750
  3. Big_Mike

    Big_Mike Member 100 Posts

    Well, it depends on set up and intended purpose (short track, road course, superspeedway, 1.5 mile tracks)... But yeah, most NASCAR engines are set up around 9000 RPM. At one time I heard some experimenting was done around the 10000 range, but longevity issues led to that being stopped. As for the horsepower, one thing I neglected to mention was that engine builders are often very secretive with exact figures. But I do recall reading in an issue of Car and Driver that the horsepower was at 850. Granted, it was a couple years ago. Best I remember it was a Toyota "stock car" being discussed. Maybe one day I can find it in my collection of old magazines... LOL
  4. moogvo

    moogvo Epic Member 5+ Years 1000 Posts

    It isn't just the heads. It is the cam, bore and stroke, type of pistons, etc. All of the internals play a role right down the the engine oil.

    Back in the first season of GearZ, Stacey built a project called the "Banshee"; a mid 90s Mazda Miata with a small block Ford 302 V8. If I recall correctly, the engine's horsepower is rated at some insane number near 650.

    There is a LOT more than heads that went into the build, though. here is a link to the project page with a list of parts and videos of the build:

    http://staceydavid.com/projects/banshee
  5. ahmitchell1

    ahmitchell1 Rockstar 4 Years ROTM Winner 1000 Posts

    Your horsepower numbers for NASCAR are very close to correct. Like every one else is saying, it's the combination of parts working together to make the power. There are so many ways to get more power out of a motor. With our truck our heads are actually very good. Ls7 heads are almost identical to the 6.0 vortex heads. With NASCAR motors you have to think of how precisely they are made compared to street motors,Every part is machined to exact specs. They also have a very radical cams and very tunable ignition system. These motors are tuned perfectly to produce that much power. You can build a motor like that for your car but you won't enjoy it on the street and it will be needing a rebuild often
  6. Big_Mike

    Big_Mike Member 100 Posts

    I think I remember seeing that build. That is a slick ride! Dang screamin'! Appreciate you bringing that up.
  7. Big_Mike

    Big_Mike Member 100 Posts

    And I did realize before this post that there's more to an engine than just the cylinder heads. Compression is important as well! And so many other things as mentioned above. I was meaning to stress the importance of "breathing" for the engine. I just enjoy learning about that technology. And yeah, I wouldn't want an engine like that in a daily driver. Anyone know what octane of fuel those engines require? Thanks for the replies!!!
  8. ahmitchell1

    ahmitchell1 Rockstar 4 Years ROTM Winner 1000 Posts

    98 octane. 260gtx
  9. moogvo

    moogvo Epic Member 5+ Years 1000 Posts

    Stacey did an incredible job on the car. Fit and finish are amazing. The car looks like it came from the factory that way. He pays excruciating attention to the details in his builds. Nugent's bronco came out amazing and the cougar is coming along well too. I tried to talk him out of the shur track but he won't give it up...
  10. Big_Mike

    Big_Mike Member 100 Posts

    Much obliged.

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