supercharger compressor map reading vs pulley size
02-08-2009, 01:14 PM
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supercharger compressor map reading vs pulley size Did any of you guys calculated the correct pulley sizes from the map supplied from vortech for the rpm / cfm you made ?
and was it in the ballpark ?
my combo is a gm derived engine making about 160-170hp without the blower.
it is now spinning 47.500rpm and only making 6psi
when looking at the map should it not be making closer to 10psi ?
and was it in the ballpark ?
my combo is a gm derived engine making about 160-170hp without the blower.
it is now spinning 47.500rpm and only making 6psi
when looking at the map should it not be making closer to 10psi ?
02-08-2009, 10:22 PM
#2
Need more details on your engine setup - displacement, intake, exhaust, cam, CR, blower pulley size, crank pulley size, max rpm, type of use, etc.
Also, are you seeing any rubber dust on the blower or nearby? Belt slip is common when you are trying a new setup.
Jim
Also, are you seeing any rubber dust on the blower or nearby? Belt slip is common when you are trying a new setup.
Jim
02-09-2009, 04:23 AM
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wouldn't belt slip cause the boost not to go up as rpm's would increase ?
i did get some initial belt slip , when i tightened it, boost went up from 3 to about 6 psi.
It's difficult to give accurate engine info, but i will try :
(sorry ls1 guys, to ask it in here, - i do have several ls1 engines too- but this is basically the only forum where there is enough knowledge to het a good answer)
its basically half a chevy 305 (4 pot) with the same port layout and bore / stroke with a reworked head with bigger valves , compression ration 8,2:1
with a mild mechanical race cam.
specs on the cam would be a bit difficult as here in europe they use a different (less good) cam spec. they basically tell a cam by its total degrees of lift WITHOUT the @0.5 lift when done without the @0.5 it's 300 degrees which is basically a middle of the pack race cam, not full race , but with some overlap, with good street manners
but wouldn't you just have to look at the map for about the 300lb/min (the amount of air a 170hp engine would need at a pressure ratio of 1.8 to end up at around 47.000 rpm what i am now making ?
because with 47.000 and 1,5 pressure ratio i would end up with WAAY more flow then the engine could need
i did get some initial belt slip , when i tightened it, boost went up from 3 to about 6 psi.
It's difficult to give accurate engine info, but i will try :
(sorry ls1 guys, to ask it in here, - i do have several ls1 engines too- but this is basically the only forum where there is enough knowledge to het a good answer)
its basically half a chevy 305 (4 pot) with the same port layout and bore / stroke with a reworked head with bigger valves , compression ration 8,2:1
with a mild mechanical race cam.
specs on the cam would be a bit difficult as here in europe they use a different (less good) cam spec. they basically tell a cam by its total degrees of lift WITHOUT the @0.5 lift when done without the @0.5 it's 300 degrees which is basically a middle of the pack race cam, not full race , but with some overlap, with good street manners
but wouldn't you just have to look at the map for about the 300lb/min (the amount of air a 170hp engine would need at a pressure ratio of 1.8 to end up at around 47.000 rpm what i am now making ?
because with 47.000 and 1,5 pressure ratio i would end up with WAAY more flow then the engine could need
