Least expensive L98 performance upgrade?
Thread Starter
Instructor
Joined: Mar 2017
Posts: 223
Likes: 15
From: Ijamsville Maryland
Thanks in advance. I just bought a very nice, all stock '89 convertible with the L98 engine and it comes with the factory original restrictive exhaust and emission controls. I got the car for my wife and as much as she loves it, she also (thankfully) is just frugal enough to let me indulge in my passion for cars, but otherwise keeps a pretty tight rein on the accounts. Good for me as we'd be eating cat food when I retire if not for her. Then again, I may have a much bigger car collection if not. Anyway, I am hoping to see the best ideas for squeezing a bit more power from the stock configuration. Chip? Cold air box? I wouldn't want to spend any more than absolutely neccessary right off the bat as the car has a couple of immediate issues that I need to spend some $$ on. All ideas are appreciated!
Last edited by Highlander1732; Jun 1, 2017 at 07:47 AM. Reason: correct information
Team Owner
Joined: Oct 2004
Posts: 81,241
Likes: 3,063
From: altered state
St. Jude Donor '05
Regear it to 3.45 max; will make it feel night and day different; a 2500ish stall converter, cheap headers, leave the rest alone its not worth it
Keep your cats if you can theres almost 0 power difference;leave the stock exhaust on there too. Any trans shop can do up a converter some s-10s and monte carlo SS had them
Its not super cheap but the car will feel way better, wont make it any louder either
TPI modding is a lot to spend and little to gain;unless youre a great wrench, can source parts or port yourself is not worth it
You have a nice low mi car keep it tight, everything working and enjoy.
Did all the free mods, little intake stuff, catback, looking back waste of money. Lots of work/time and was only a tad faster.
Keep your cats if you can theres almost 0 power difference;leave the stock exhaust on there too. Any trans shop can do up a converter some s-10s and monte carlo SS had them
Its not super cheap but the car will feel way better, wont make it any louder either
TPI modding is a lot to spend and little to gain;unless youre a great wrench, can source parts or port yourself is not worth it
You have a nice low mi car keep it tight, everything working and enjoy.
Did all the free mods, little intake stuff, catback, looking back waste of money. Lots of work/time and was only a tad faster.
Last edited by cv67; Jun 2, 2017 at 07:41 PM.
Navigator
Joined: May 2020
Posts: 9
Likes: 1
proper air in your tires................well you said cheapest....................
Next cheapest, drive alone.........every 100 lbs you shave off is a 1/10 second down the quarter.
Never fill up more than half tank
If you don;t drive it all that much, keeps you filling it all the time, but you have fresh gas all the time.
Get rid of those heads.
Put better heads on it and open up the factory exhaust manifolds at each head port and you will think you have headers.
Go from 58cc heads to 62 cc or 64 cc heads, and advance the timing.
get 91 factory convertible mufflers.
both pipes work, and still relatively quiet with no drone
use a 160 degree thermostat....won't make it run cooler, but will circulate water sooner
go 2 steps cooler spark plugs
check the gaps on your plugs
Change your rockers to 1.6 and shave the drippers off your rocker covers inside them
take the water hose off your throttle body
add an oil cooler and make sure you have a power steering cooler.
Less heat under the hood makes it go faster.
make sure the air filter duct clamps are tight
use a low restriction air filter.
Use a truck oil filter. they hold more oil and more oil is cooler oil
use synthetic oil
put synthetic fluid in the trans and the rear end.
you will be surprised at the power you recover after you do some of this stuff
Next cheapest, drive alone.........every 100 lbs you shave off is a 1/10 second down the quarter.
Never fill up more than half tank
If you don;t drive it all that much, keeps you filling it all the time, but you have fresh gas all the time.
Get rid of those heads.
Put better heads on it and open up the factory exhaust manifolds at each head port and you will think you have headers.
Go from 58cc heads to 62 cc or 64 cc heads, and advance the timing.
get 91 factory convertible mufflers.
both pipes work, and still relatively quiet with no drone
use a 160 degree thermostat....won't make it run cooler, but will circulate water sooner
go 2 steps cooler spark plugs
check the gaps on your plugs
Change your rockers to 1.6 and shave the drippers off your rocker covers inside them
take the water hose off your throttle body
add an oil cooler and make sure you have a power steering cooler.
Less heat under the hood makes it go faster.
make sure the air filter duct clamps are tight
use a low restriction air filter.
Use a truck oil filter. they hold more oil and more oil is cooler oil
use synthetic oil
put synthetic fluid in the trans and the rear end.
you will be surprised at the power you recover after you do some of this stuff
Last edited by Todd Brugh; Jun 11, 2020 at 10:31 AM.
Melting Slicks
Joined: Dec 2008
Posts: 2,772
Likes: 64
From: Mystic CT
If you do gears and a good tune up it will be a nicer car. If you start hacking and cutting do it on salvage yard parts and store the originals so it can be made stock again. Worst mod I made was cat back exhaust. No need for cold plugs cold thermostat etc. Enjoy the car for what it is a touring car.
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Team Owner
Joined: Oct 2004
Posts: 81,241
Likes: 3,063
From: altered state
St. Jude Donor '05
Catback...agree there. I once spent about 1200 on high flow cats, mail order 2.5 exh etc i dont know if it helped it a full tenth in the 1/4.
Go to a muffler shop those systems are basic short and cheap. More for sound than anything else.
Live and learn
Back when these cars were new guys used to port stock heads, intakes, add a 1.6 roller tip rocker and call it good. Some cammed them most didnt. OEM reliable and did help noticeably, most warranties were intact as noone checked to see if a die grinder was taken to anything.
Same witha converter but with that gear I wouldnt.
Go to a muffler shop those systems are basic short and cheap. More for sound than anything else.
Live and learn
Back when these cars were new guys used to port stock heads, intakes, add a 1.6 roller tip rocker and call it good. Some cammed them most didnt. OEM reliable and did help noticeably, most warranties were intact as noone checked to see if a die grinder was taken to anything.
Same witha converter but with that gear I wouldnt.