Quote:
Originally Posted by BruceWilkie
Excellent reply Tom. Part of the planning should also include type fuel intended. Intercooling and water injection are part of the picture. If pump gas, the practical/probable pressure ratio has to be taken into consideration when choosing the turbo. If for example you set an arbitrary boost psi of say 15 , you need to choose a turbo that can meet the mass flow requirements of the HP desired at that psi level while staying out of surge zone or getting into choke.
I'll also add that you wont need maximum bore size or stroke to acheive/exceed your goal. (Or turn very high rpm for that matter).
I like your goal though. I'm not looking for your ET level with my build but I too like driving my car. Would love to drive all the way to Norwalk run some respectable numbers and drive home. Turbo gives the motor that flexability. The real challenge for me will be keeping the chassis combo flexible enough for a 1000 mile round trip and still be able to run quick numbers.
Good luck with your project I'll be following it closely.
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Agree the Surge Zone, see compressor map for HP76 , can be pretty far to the right on some larger turbos. Fortunately if you look at the HP76 (see link above) you will see that at 10 psi of boost (bottom red horizontal line on the map) you are well to the right of the surge line at as little as 25 lbs per minute of airflow (250 horsepower). Any Pontiac will make well over 250 hp at 10 psi of boost due to their cubic inch size. So the only surge that you might get is if you sized the compressor by-pass valves too small and can't dump the air fast enough when the throttle blade is slammed shut on a quick back-out of the throttle. The wastegate will not help you much there in the first 100 milliseconds of the throttle blade being closed. A GOOD compressor by-pass valve will open in about 32 milliseconds.
It turns out that this guy has one of the best CBVs out there:
http://www.spike.com/video-clips/cw7...mpressor-surge
Great video explaining the difference between a bad and a good CBV valve in his video.
Tom Vaught
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"Engineers do stuff for reasons" Tom Vaught
Despite small distractions, there are those who will go Forward, Learning, Sharing Knowledge, Doing what they can to help others move forward.
Last edited by Tom Vaught; 11-11-2011 at 06:36 PM.
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