Difference between L98's
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Melting Slicks
Joined: Sep 2003
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Difference between L98's
What is the difference between a 84-89 L-98 and a 90-91 L-98... If any.....It sems like everyone I talk to, that has a little clue,,, says there is a huge difference. I realize the difference of about 20-25 Hp, but is that the only difference?
Team Owner
Joined: Mar 2000
Posts: 83,383
Likes: 87
From: Boston, MA
Re: Difference between L98's (1990CORVETTE)
90 and 91 are Speed Density computer systems while 85-89 are MAF systems.
85-early86 have cast iron cylinder heads. support ~10hp :D
late86-87 have 128 casting Aluminum cylinderh heads. support ~300hp
88-91 L98s have 113 casting or "D-Port" cylinder heads that are the best of the bunch and support ~350hp.
All are 2-bolt mains, but 86-91 are 1 piece rear main seals (correct me if i'm wrong on 86)
85-early86 have cast iron cylinder heads. support ~10hp :D
late86-87 have 128 casting Aluminum cylinderh heads. support ~300hp
88-91 L98s have 113 casting or "D-Port" cylinder heads that are the best of the bunch and support ~350hp.
All are 2-bolt mains, but 86-91 are 1 piece rear main seals (correct me if i'm wrong on 86)
Le Mans Master
Joined: Dec 2002
Posts: 5,270
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From: Seattle Area WA
Re: Difference between L98's (scorp508)
All are 2-bolt mains, but 86-91 are 1 piece rear main seals (correct me if i'm wrong on 86)
Racer
Joined: May 2001
Posts: 407
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From: San Antonio TX
Re: Difference between L98's (1990CORVETTE)
:iagree:
in case you aren't in the speed density vs. mass air flow tidal wave. The MAF sensor can limit the amount of air coming into a highly modified engine, your 90 has no such restriction, so you can go to a 406 with a huge intake and its just a matter of a lot of ECM tuning. The MAF car would have to deal with possible restrictions. Cork and Ski have proven a MAF car is extremely capable too :D
in case you aren't in the speed density vs. mass air flow tidal wave. The MAF sensor can limit the amount of air coming into a highly modified engine, your 90 has no such restriction, so you can go to a 406 with a huge intake and its just a matter of a lot of ECM tuning. The MAF car would have to deal with possible restrictions. Cork and Ski have proven a MAF car is extremely capable too :D
Le Mans Master
Joined: Apr 2000
Posts: 6,341
Likes: 1
From: Shelton CT
Re: Difference between L98's (Raistlin)
'85s have forged bottom end, lot tougher than 86+ L98's, 9-9.5:1 compression with flat top pistons, and yes, the POS iron 'emissions' heads.
:U :U
Also : NO 'Frizbee' and a MAF Burnoff Module (sits next to the ECM), very expensive to replace (IF you find one used).
:U :U
Also : NO 'Frizbee' and a MAF Burnoff Module (sits next to the ECM), very expensive to replace (IF you find one used).
Safety Car
Joined: Nov 2001
Posts: 3,753
Likes: 191
From: Orange County California
Re: Difference between L98's (MrNuke)
91-91 is the most refined of the bunch. You basically have all of th improvements they made over the years. Plus the extra 15 ponies is nice. I have 104K on my 91 and it drives like new (the engine anyway LOL)
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Re: Difference between L98's (scorp508)
Minor differences between cams too between the SD and MAF cars to help smooth out the idle. 89 and back had ever so slightly bigger cams. port heads, or 113s ar4e the same head as found on the ZZ4 crate motor. Compression did get a bump in 90-91 due to piston change...small valve reliefs, hypereurtectic and flatop design as previously mentioned.