help reading compressor maps?
#1
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help reading compressor maps?
looking around here, forcedinductions.com and turbomustangs.com to try and learn me some stuff about turbos
looking to run a 370 LQ9 truck block, 317 heads, 233/233 .585 116 +4 gives me an overlap of 1
9:1 SCR
6.60:1 DCR
turbo would be a T6 GT-47 88 .96 A/R 3" charge pipe, 4" downpipe, 10lb's or so for the street and trying to figure out what rpm I would be at that boost level
here is the air consumption for a 370 ls1
http://www.forcedinductions.com/consumption370.htm
and the T88 compressor map...
http://forcedinductions.com/_derived...tm_txt_t88.gif
PR = 1.68
using
(CID × RPM) ÷3456 = CFM
370x4200 / 3456 = 450 CFM
then multiply for VE
× 0.85 = 445.7 CFM
= 382 CFM turn that into by X 0.69 = 26lb/min
think I'm definitely doing something wrong...that says I'll only be making 4lb's of boost @ 4200rpm?
someone please help the math challenged?
edit: 3.30 rear gear.
Chad
looking to run a 370 LQ9 truck block, 317 heads, 233/233 .585 116 +4 gives me an overlap of 1
9:1 SCR
6.60:1 DCR
turbo would be a T6 GT-47 88 .96 A/R 3" charge pipe, 4" downpipe, 10lb's or so for the street and trying to figure out what rpm I would be at that boost level
here is the air consumption for a 370 ls1
http://www.forcedinductions.com/consumption370.htm
and the T88 compressor map...
http://forcedinductions.com/_derived...tm_txt_t88.gif
PR = 1.68
using
(CID × RPM) ÷3456 = CFM
370x4200 / 3456 = 450 CFM
then multiply for VE
× 0.85 = 445.7 CFM
= 382 CFM turn that into by X 0.69 = 26lb/min
think I'm definitely doing something wrong...that says I'll only be making 4lb's of boost @ 4200rpm?
someone please help the math challenged?
edit: 3.30 rear gear.
Chad
Last edited by Nimitz87; 04-26-2009 at 07:38 PM.
#4
if u were to hit 10 psi at 4200 rpm or sooner u would be close to surging .But thats a big if... most likely u would hit the 10 psi alittle later than 4200 rpm.
#5
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370x5500/ 3456 = 590CFM
x.85 = 501
x .069 = 34 x2.02 = 70lb/min
so looking at the map at a 2.02 PR and 70lb min I'll be at 15lb of boost at 5700rpm but right at the "surge limit" according to the T88 map
unless I'm all screwed up...I thought the 370 and 88mm turbo's were good/common setups?
Chad
#6
FormerVendor
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1st find cfm unboosted (CFMU):
(C.I.D/1726) X (maxRPM/2)= CFMU
2nd find Pressure Ratio (Pr):
(14.7+Desired boost) / 14.7=Pr
3rd find CFM boosted (CFMB):
CFMU X Pr= CFMB
4th convert CFMB to LB/min:
CFMB X .07= (required LB/min)
5th look at the comp map and use your required LB/min and Pr to place yourself on the map, trying to be in the lower right hand corner of the efficiency islands.
I hope this helps,
Rob@modularturbo
(C.I.D/1726) X (maxRPM/2)= CFMU
2nd find Pressure Ratio (Pr):
(14.7+Desired boost) / 14.7=Pr
3rd find CFM boosted (CFMB):
CFMU X Pr= CFMB
4th convert CFMB to LB/min:
CFMB X .07= (required LB/min)
5th look at the comp map and use your required LB/min and Pr to place yourself on the map, trying to be in the lower right hand corner of the efficiency islands.
I hope this helps,
Rob@modularturbo
#7
I don't understand why its so close to surging on the map at pretty much any boost level, here at 15psi
370x5500/ 3456 = 590CFM
x.85 = 501
x .069 = 34 x2.02 = 70lb/min
so looking at the map at a 2.02 PR and 70lb min I'll be at 15lb of boost at 5700rpm but right at the "surge limit" according to the T88 map
unless I'm all screwed up...I thought the 370 and 88mm turbo's were good/common setups?
Chad
370x5500/ 3456 = 590CFM
x.85 = 501
x .069 = 34 x2.02 = 70lb/min
so looking at the map at a 2.02 PR and 70lb min I'll be at 15lb of boost at 5700rpm but right at the "surge limit" according to the T88 map
unless I'm all screwed up...I thought the 370 and 88mm turbo's were good/common setups?
Chad
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#8
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1st find cfm unboosted (CFMU):
(C.I.D/1726) X (maxRPM/2)= CFMU
2nd find Pressure Ratio (Pr):
(14.7+Desired boost) / 14.7=Pr
3rd find CFM boosted (CFMB):
CFMU X Pr= CFMB
4th convert CFMB to LB/min:
CFMB X .07= (required LB/min)
5th look at the comp map and use your required LB/min and Pr to place yourself on the map, trying to be in the lower right hand corner of the efficiency islands.
I hope this helps,
Rob@modularturbo
(C.I.D/1726) X (maxRPM/2)= CFMU
2nd find Pressure Ratio (Pr):
(14.7+Desired boost) / 14.7=Pr
3rd find CFM boosted (CFMB):
CFMU X Pr= CFMB
4th convert CFMB to LB/min:
CFMB X .07= (required LB/min)
5th look at the comp map and use your required LB/min and Pr to place yourself on the map, trying to be in the lower right hand corner of the efficiency islands.
I hope this helps,
Rob@modularturbo
good to know...I knew everyone running this setup couldn't be having those issues.
Chad