'98 and up LS1 differences....
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On The Tree
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Joined: Oct 2005
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From: Windsor, Ontario, Canada
'98 and up LS1 differences.... Just curious as to what, if any significant differences there have been through the years to the LS1 engines.... excluding the LS2 of course. And is there any one year in particular that is more advantageous to have than the others? I am wondering because I am currently putting the pieces together to build an LS1, but want to make sure there is no major differences between the years...like a different timing cover or fuel rails for example. I just want to make sure all the pieces I assemble are going to work with one another, I don't want to think I have everything all together ready to build, and find out that a '98 timing cover only fits on a '98 LS1...but everything else i have is for say a 2001. 
Any help here would be most appreciated.... Thanks in advance!
Any help here would be most appreciated.... Thanks in advance!
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Joined: Jun 2003
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The most important difference is the PCM and wiring harness for the 98's compared 99 and up. Up until recently it's been pretty difficult for us less experienced wiring experts to convert a 98 pcm and wiring harness to the 99 and up style.
So why would you want a 99 + PCM vs a 98?
Because its expensive and hard to upgrade and install the pcm and harness. In addition the software to tune the PCM on 98s was only available from LSEdit and within last year HP Tuners and now EFILive (within in last two months). Now we finally have some good software to tune with if you plan on making some serious mods.
But with a 98 you are limited to 1 bar if you go FI because 1 bar is only available for 98', but 2 and three bar is available for 99's + along with custom OS's. I suspect it's doubtful we will get 2 bar because of the major differences in the pcms for the 98 vs the 99 + units.
The 98 heads are perimeter style which require perimeter style valve covers and different coil brackets (new will take about $200 out of your wallet).
The oil pump is suspect, but is easily upgraded.
The gas tank is metal compared to plastic in later years.
The 98 rearend contains an auburn diff vs the better torsen in later years. The torsens were available from SLP for $99 but think the supply is exhausted now.
Steel driveshaft on some 98's but aluminum for later years.
LS6 style intake on later years vs LS1 on 98's.
The upside...there a some very slick 98's around and the price is coming down.
As for the PCM harness, LS Speed has a plug and play harness (they say), but don't know how easy it is to install. If it's fairly cheap and complete (runs all guages including the 98 style temp guage) then I might spring for the kit and upgrade to the 99 style + pcm, since I have FI at about 525 rwhp but will be upgrading to more HP, so will need 2 bar at about 600 +.
Do a search on the 1 bar tuning, some are now finding ways to tune the 98 for FI and still use 1 bar.
So why would you want a 99 + PCM vs a 98?
Because its expensive and hard to upgrade and install the pcm and harness. In addition the software to tune the PCM on 98s was only available from LSEdit and within last year HP Tuners and now EFILive (within in last two months). Now we finally have some good software to tune with if you plan on making some serious mods.
But with a 98 you are limited to 1 bar if you go FI because 1 bar is only available for 98', but 2 and three bar is available for 99's + along with custom OS's. I suspect it's doubtful we will get 2 bar because of the major differences in the pcms for the 98 vs the 99 + units.
The 98 heads are perimeter style which require perimeter style valve covers and different coil brackets (new will take about $200 out of your wallet).
The oil pump is suspect, but is easily upgraded.
The gas tank is metal compared to plastic in later years.
The 98 rearend contains an auburn diff vs the better torsen in later years. The torsens were available from SLP for $99 but think the supply is exhausted now.
Steel driveshaft on some 98's but aluminum for later years.
LS6 style intake on later years vs LS1 on 98's.
The upside...there a some very slick 98's around and the price is coming down.
As for the PCM harness, LS Speed has a plug and play harness (they say), but don't know how easy it is to install. If it's fairly cheap and complete (runs all guages including the 98 style temp guage) then I might spring for the kit and upgrade to the 99 style + pcm, since I have FI at about 525 rwhp but will be upgrading to more HP, so will need 2 bar at about 600 +.
Do a search on the 1 bar tuning, some are now finding ways to tune the 98 for FI and still use 1 bar.
Last edited by dlandsvZ28; Dec 10, 2005 at 08:47 AM.
This link, https://ls1tech.com/forums/showpost....80&postcount=2, can be found in this thread, https://ls1tech.com/forums/new-ls1-owners-newbie-tech/213148-jrp-s-faq-commonly-asked-questions.html, very useful. 
Block Question To my knowledge the 98 blocks have an oilling issues on the top side of the motor, left side I believe and the rod bolts in the 97/98 motors are weaker than the 99 and newer motors.
