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Originally Posted by BLSTIC
First up: I refuse to read 20 pages of replies to see if what I am about to state has already been noted.
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I don't blame you! I thought this thread was over until I checked my e-mails!
Quote:
Originally Posted by BLSTIC
I'm unfamiliar with the numbers and brands you are working with, but it sounds like 'big runners' are, well, big. If they are large diameter, they will lose port energy at low rpm, and this will adversely affect cylinder filling, which adversely affects torque. Whether this is bad for fuel economy depends largely on your cam and whether you are going for a semi-atkinson cycle. More on that one later.
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The TPI intake was designed for the 305 SBC engine and this is why anyone running this intake on the L98 SBC complains about the lack of airflow for high horsepower performance, the large tube runners only allow for a minor increase in airflow without sacrificing low end power production which kicks in at 2000 RPM. However, the overall performance is hardly noticeable by accounts of those who use these intakes with larger runners.
I don't drive my car around town with a high RPM performance mentality, I drive it around with low RPM performance in mind! This is why I have been researching how to increase the fuel efficiency of my LT1 while also increasing the engines performance at low to mid-range RPM which is why the TPI is
PERFECT for my driving style! Since I also want to have fuel mileage comparable to a 6-cylinder engine or maybe to achieve 4-cylinder engine fuel economy, I am looking into hybrid technology as well and how
best to apply it to my application. I want to drive around town and have the full functionality of my V8, but there are areas where hybrid technology can help minimize the fuel consumption from stop-and-go city driving. The age of my car's components is also an added factor as well.
Quote:
Originally Posted by BLSTIC
Long tube headers for low-rpm are unfeasibly long. 60" 4-1 headers are good for a 2500-5500rpm band on a 302-HO. If you intend to try tune lower than that they might not fit. Don't forget that cat converters mess with tuning lengths. If you can (and the length is appropriate) you want to fit a pressure wave termination box immediately before the cat. It simulates open headers for correct collector length tuning but allows connection to the rest of your exhaust. Also, if you're concerned about emissions, make sure your exhaust stays hot til the cat. This might involve wrapping, but heat shields and/or a coating are probably enough.
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I appreciate your comments and I will take the time to look all of these suggestions over. This project is a few years out but there is a TON I need to look into before I commit to overhauling my car into something brand new and definitely
"With the times".
I have been given headaches over how I can use long-tube headers optimized for my power band and still retain the functioning of my catalytic converter and emissions hook-ups. I was planning on modifying my car with self-heating oxygen sensors to address this issue and help with cold-start and warming. I want to use catalytic converters because I am very conscious of emissions pollution,
which is why I am determined to use GEVO Iso-Butanol in my car when the time comes! I am still going to need a catalytic converter to address NOx emissions even though Iso-Butanol burns so much more cleaner than straight gasoline.