gretchen/jason Posted March 1, 2008 Share Posted March 1, 2008 Wasnt sure what thread to use as this is mainly a question about a 383 . I did a short rod 383 5.565 rods forged pistons etc . I have a weiand supercharger and when my 383 was a stock 350 full throttle gave me roughly 7 lbs of boost . I havent quite hit full throttle yet 3/4 is about all but the boost doesnt seem to kick in as quick i hit about 5lbs . Is it the stoke that is changing this from a 350 to a 383 ? Only difference is now im running 3:54 gears instead of the 4:11 gears i had before i can say this though the 383 without even using any boost is a lot more fun then the 350 ever was . main question is does the displacement have any affect on the boost ? Jason Quote Link to comment Share on other sites More sharing options...
jnjdragracing Posted March 1, 2008 Share Posted March 1, 2008 More cubic inches. The more cubes you have the more you have to fill the cylinders. If you want the same boost then you will have to go with a larger bottom pulley or a smaller upper pulley. Hope this helps... We went from a 1-1 ratio to a 2% over then went to 8% over. This was in the last engine. With the new 355cu I went back to the 2% over. I tore up the other 355cu because of detination, cracked the deck and cracked both aluminium heads, but it still ran a 9.40 in the 1/4. John PS: you can go to the bds web site http://www.blowerdriveservice.com/techcharts.php and they have a graph of the pulley ratios / boost ratio for cubic inches as well. Wasnt sure what thread to use as this is mainly a question about a 383 . I did a short rod 383 5.565 rods forged pistons etc . I have a weiand supercharger and when my 383 was a stock 350 full throttle gave me roughly 7 lbs of boost . I havent quite hit full throttle yet 3/4 is about all but the boost doesnt seem to kick in as quick i hit about 5lbs . Is it the stoke that is changing this from a 350 to a 383 ? Only difference is now im running 3:54 gears instead of the 4:11 gears i had before i can say this though the 383 without even using any boost is a lot more fun then the 350 ever was . main question is does the displacement have any affect on the boost ? Jason Quote Link to comment Share on other sites More sharing options...
gretchen/jason Posted March 1, 2008 Author Share Posted March 1, 2008 Makes sense to me now i figured as much but wanted a opinion before i started changing stuff as far as pulley size . Up here at 6,000 ft above sea level im running a 10 -11 lb upper pulley just to get 5-7 lbs of boost so ill see about changine the crank pulley thanks for the info . Jason Quote Link to comment Share on other sites More sharing options...
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