Going for big boost on a forged 5.3
09-04-2009, 01:54 PM
#21
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Just tune for e85 and dont worry about it. You will have to run more boost to make same power on a lower compression motor as to running same boost level on higher compression.
09-04-2009, 04:41 PM
#22
2nd that. The 243's are so expensive because they flow so much better than the LS1 and LM7 heads. The 317's have the same ports and flow as the 243's but the big chamber turns most people off unless they are going boosted (as in your application). They are so cheap because there are a million sets around.
Cylinder Valve Lift in Inches
Head .200 .300 .350 .400 .450 .500 .550 .600
LS1 137 187 207 223 228 237 242 243
LS6 156 204 225 243 257 267 275 278
Go with the 317's.
Rick
Cylinder Valve Lift in Inches
Head .200 .300 .350 .400 .450 .500 .550 .600
LS1 137 187 207 223 228 237 242 243
LS6 156 204 225 243 257 267 275 278
Go with the 317's.
Rick
Actualy you dont gain a whole lot by rasing compression 1 point 2.2% hp gain or somthin like that which is only 10hp even if i went from 9.5:1 to 15:1 which is impossible for a boost motor I only get like a 10% gain.... I think these guys are right tellin me to get 315s
09-05-2009, 06:58 PM
#25
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Compression is worth more than you would guess. Low compression makes for doggy response when not in boost. With only running 15psi I wouldn't recomend going any lower than 9.5:1. You're probably better with it at 12psi and 10.5:1. Look at the numbers LQ9's, L76's, L92's, and LS3's make with boost.
09-05-2009, 07:53 PM
#26
Compression is worth more than you would guess. Low compression makes for doggy response when not in boost. With only running 15psi I wouldn't recomend going any lower than 9.5:1. You're probably better with it at 12psi and 10.5:1. Look at the numbers LQ9's, L76's, L92's, and LS3's make with boost.
09-05-2009, 08:47 PM
#27
Compression is worth more than you would guess. Low compression makes for doggy response when not in boost. With only running 15psi I wouldn't recomend going any lower than 9.5:1. You're probably better with it at 12psi and 10.5:1. Look at the numbers LQ9's, L76's, L92's, and LS3's make with boost.
I was just going by a chart i found that siad you get about 1-2% gain by raising compression 1 point then my pulley size is limited by the compression....
So it doesnt make sense to me to have high compression and get 20hp maybe from the compression increase and run a bigger pulley im still up in the air about which heads to gets everyones tellin me different things... I still might get the 317s and have them milled a lil or a tiny gasket
Last edited by 06chevy5.3; 09-05-2009 at 08:56 PM. Reason: added more
09-06-2009, 08:49 PM
#28
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look at this way bob you can make the same hp horsepower with that compression ratio with on now with the same pulley your at now. also 1BADAZZSS has a point you want to go bigger injectors already just tune it for e 85. i bet you and money will make more power with e 85 than 93.
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