Ronnieroadster
Well-known member
Here's my two cents to add to this post in regards to chamber design. In Brian's post above he writes Now if we raise the roof that'll improve the breathing but have the adverse effect of lowering the c/r. And asks the question Or will it? Here's my answer to Brian's important question its a long answer but hopefully will give everyone more information to think about.
What I have found each time I opened up the combustion chamber in our race flathead engines to increase breathing engine output increased. The static compression ratio would be lower. BUT would this reduce power output ? Since we run a blower on the race engine the effect of better breathing and reduced compression actually improved the power out put.
Since many of you reading this would likely not run a blower I'm sure you will ask what would happen with just carburetor's. I can answer this with the results from an experiment we did August 2024 at Speedweek.
In 2024 At Speedweek after we established two blown flathead records well over 200 MPH we removed the blower and in its place installed a two deuce tunnel ram intake I fabricated from aluminum tubing. The two barrel carbs were Holley's the type used on the tri power set ups from the muscle car era in the sixtys. They were pretty much stock factory style replacement carbs.
Driving the race car was rookie Carly Moody a young female who has a great desire to be able to drive a car on the salt. Our blower records set that year varied between 211 and 219 MPH.
Carly set a record as well with the two deuce combination at 158.767 top speed on one run was just shy of 160 MPH. On the time slip there's additional details as follows outside air temp for the runs were 101 degrees with a density altitude of 7777 feet. Density altitude means not much air engines need to breath just like us the thankfully the increased port flow idea in our flathead engine without the blower allowed the engine to still make power turning 5500 RPM during the entire three mile run.
Think about that for a moment this was not a purpose built high compression flathead engine. It was the same low COMPRESION and HIGH port flow breathing engine used for our blower.
The way I see it port flow is far more important in a flathead than compression.
Ronnieroadster
An added note if interested I can add the details in a separate post from our experience this year at Bonneville Speed Week setting two more records this time running an 8BA block with ARDUN overhead valve Heads. Same experiment as above with the blower and then remove blower and run with two deuces.
What I have found each time I opened up the combustion chamber in our race flathead engines to increase breathing engine output increased. The static compression ratio would be lower. BUT would this reduce power output ? Since we run a blower on the race engine the effect of better breathing and reduced compression actually improved the power out put.
Since many of you reading this would likely not run a blower I'm sure you will ask what would happen with just carburetor's. I can answer this with the results from an experiment we did August 2024 at Speedweek.
In 2024 At Speedweek after we established two blown flathead records well over 200 MPH we removed the blower and in its place installed a two deuce tunnel ram intake I fabricated from aluminum tubing. The two barrel carbs were Holley's the type used on the tri power set ups from the muscle car era in the sixtys. They were pretty much stock factory style replacement carbs.
Driving the race car was rookie Carly Moody a young female who has a great desire to be able to drive a car on the salt. Our blower records set that year varied between 211 and 219 MPH.
Carly set a record as well with the two deuce combination at 158.767 top speed on one run was just shy of 160 MPH. On the time slip there's additional details as follows outside air temp for the runs were 101 degrees with a density altitude of 7777 feet. Density altitude means not much air engines need to breath just like us the thankfully the increased port flow idea in our flathead engine without the blower allowed the engine to still make power turning 5500 RPM during the entire three mile run.
Think about that for a moment this was not a purpose built high compression flathead engine. It was the same low COMPRESION and HIGH port flow breathing engine used for our blower.
The way I see it port flow is far more important in a flathead than compression.
Ronnieroadster
An added note if interested I can add the details in a separate post from our experience this year at Bonneville Speed Week setting two more records this time running an 8BA block with ARDUN overhead valve Heads. Same experiment as above with the blower and then remove blower and run with two deuces.
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