Need some specs on a 91 L98.......
#1
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Need some specs on a 91 L98.......
Just for comparison reasons I need to know
a) what is the stock compression ratio for a Speed Density L98? I heard anywhere from 9.3:1-9.7:1
b) what are the stock L98 cam specs? I have a new comp cam with these specs and want to know how much more radical I'm getting.
Lift @.050- .500 intake .510 Exhaust
duration- 210 intake 220 exhaust
lobe seperation- 114
This cam is recommended for my blower setup and is good to 5800rpm.
I need these numbers to plug into DD2000 too so I can get some comparisons. Thanks!
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L98 w/ ATI ProCharger P600B 9psi, 2 core intercooler. (New L98 coming soon)
Pro-Built Stage 3 700-R4 w/ Continental 2400 stall TC
C5 wheels and tires.
92 Firebird Convertible- L03, 700-R4
Bone Stock
Me, my car and I
"Speed kills but it makes me feel alive" - White Zombie
Crazy street-racing idiot member of the All-Powerful Nor-Cal crew.
a) what is the stock compression ratio for a Speed Density L98? I heard anywhere from 9.3:1-9.7:1
b) what are the stock L98 cam specs? I have a new comp cam with these specs and want to know how much more radical I'm getting.
Lift @.050- .500 intake .510 Exhaust
duration- 210 intake 220 exhaust
lobe seperation- 114
This cam is recommended for my blower setup and is good to 5800rpm.
I need these numbers to plug into DD2000 too so I can get some comparisons. Thanks!
------------------
L98 w/ ATI ProCharger P600B 9psi, 2 core intercooler. (New L98 coming soon)
Pro-Built Stage 3 700-R4 w/ Continental 2400 stall TC
C5 wheels and tires.
92 Firebird Convertible- L03, 700-R4
Bone Stock
Me, my car and I
"Speed kills but it makes me feel alive" - White Zombie
Crazy street-racing idiot member of the All-Powerful Nor-Cal crew.
#2
Moderator
iTrader: (1)
I've heard on here the speed density L98's got a bump in compression to 9.7:1 or so. The cam specs are in the cam tech article on here. Its 203/207, .413"/.428", 114 LSA, or so...
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West Coast GM Shootout 2001!
1991 Camaro Z28
5.7L 5-Speed (originally 305)
13.25 @ 107.18 MPH
Southern California
Member: SoCal 3rd Gen F-Bodies
Webmaster: SoCal F-Bodies
-=ICON Motorsports=-
------------------
West Coast GM Shootout 2001!
1991 Camaro Z28
5.7L 5-Speed (originally 305)
13.25 @ 107.18 MPH
Southern California
Member: SoCal 3rd Gen F-Bodies
Webmaster: SoCal F-Bodies
-=ICON Motorsports=-
#3
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Join Date: Aug 1999
Location: Winnipeg,MB,Canada
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Car: 1991 GTA
Engine: L98 350
Transmission: 4L60
Here is the specs I have for 1991's
4.9L (VIN B) 9.5:1
5.0L (VIN E & F) 9.3:1
5.7L (VIN 7) 9.8:1
5.7L (VIN 8) 10.25:1
Darrell
1991 GTA L98
Canada
4.9L (VIN B) 9.5:1
5.0L (VIN E & F) 9.3:1
5.7L (VIN 7) 9.8:1
5.7L (VIN 8) 10.25:1
Darrell
1991 GTA L98
Canada
#5
Member
9.8:1 sounds pretty high with cast iron heads for a factory setting, I never knew it was that high. Does GM require 92 octane for the 90-92 TPI F-bodies???
Does anyone know what the piston deck height was set at on these motors? Also the compressed head gasket thickness? Trying to figure what the stock "quench" height was.
Thanks
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Dave Zelinka
Does anyone know what the piston deck height was set at on these motors? Also the compressed head gasket thickness? Trying to figure what the stock "quench" height was.
Thanks
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Dave Zelinka
#6
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Join Date: Jul 1999
Location: The Bone Yard
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Car: Death Mobile
Engine: 666 c.i.
According to my 1991 GM shop manual for Firebirds, the L98 had 9.75:1 with 64cc heads. And yes, the manual recommends premium fuel. Oh, and all L98s have a VIN #8 in the 8th digit. There is no "7" to my knowledge.
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