Classic Engine Tech 1967 - 1981 Engine Related

Endurance racing: 305 or 350?

Old 10-26-2018, 02:33 AM
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Question Endurance racing: 305 or 350?

I haven't been able to find the exact answer what I am looking for, so I wanted to share this question. We are building a 2nd gen Camaro (78') to race in the Champcar endurance series. Races can be 8 to 24hrs, with driver changes every 2 hours. We are going to build a new engine but we're not sure on what size to build. (Note, we have to use an engine/block that was available for year of car, so no LS swaps, etc.)


Goals for our engine:
  • Fuel Run: Car can go 2hrs on 20 gallons of 91 pump gas.
  • Reliability: Not over stressing the motor so it can race in several races without issues.

Would you go with a 305 with a smaller displacement to try and save fuel. Or go with a 350 with a 4 bolt main. No matter the build I think we would still run roller cams with a very mild cam. Overall I think our target HP is mid 300. We've seen 5.0 mustangs make a 2hr run with a 18gal fuel cell (so they say). We previously ran a car with a 3.5 V6 with 240hp at almost the exact same mileage. As you can see, we don't have enough data to make a solid guess on what kind of engine combo we should build.


So... We are open to suggestions, questions and ideas!


Thanks!

Last edited by Mike_; 10-26-2018 at 02:48 AM.
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Old 10-27-2018, 11:41 AM
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Re: Endurance racing: 305 or 350?

I would imagine that the fuel consumption is going to be impacted most by how aggressive your cam is. The extra displacement (at not much extra weight) will allow for a milder cam, and should give you mileage. At the end of the day, the quality of your heads and how well your cam is designed will do more for the engine than the difference in displacement. I would swing for the 350 and put money in the heads/cam combo.
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Old 10-28-2018, 08:47 AM
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Re: Endurance racing: 305 or 350?

I would go with a 350 rather than a 305 as long as its permitted. The 350 has more torque so it doesn`t have work as hard. And its easier to come up with that horsepower number or better with a 350,.
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Old 10-30-2018, 10:58 AM
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Re: Endurance racing: 305 or 350?

Probably a good topic to post in the "Autocross and Road Racing....." forum. Not a lot of activity, but there's a member "Feffman" that appears to check in regularly and post info about local events.
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