Performance question.
Thread Starter
2nd Gear
Joined: Mar 2017
Posts: 2
Likes: 0
Performance question.
I have 1989 l98 motor in my Corvette and was told by a performance shop that if I did anything to my motor that I would have to get the computer tuned Everytime. Is this true? I am new to the Corvette "thing". Thank you in advance.
Drifting
Joined: Dec 2012
Posts: 1,504
Likes: 73
From: Georgetown TX
not true, I also have 89. Re-tune if you change cam or heads or intake manifold or change the size of injectors. Stuff mostly on the intake of fuel and air side of engine
change exhaust or most things on exhaust side of engine, you most likely won't need to retune
there are probably some exceptions, but someone else on this forum with more knowledge then I will have to jump in
Last edited by mlm0; Mar 11, 2017 at 11:02 PM.
Team Owner
Joined: Jul 2004
Posts: 28,502
Likes: 3,302
From: Hartford WI
Yes, it's true. No, it's false. As my instructor used to say "It depends". If the shop doesn't know that, run away from them. I suspect they really don't want you as a customer with your old junk which is why they told you that. You have a MAF system which is more adaptable to modifications. If I were to do it, I'd make sure I get the most bang for the buck. I'd do the intake and exhaust manifold and then dyno tune. That will maximize it for a while till you do the next batch. So say you did heads and cam, you can retune. If I were to do headers, I'd let the system work. Sure, it won't be the best it can be but such is life. A dyno tune is about $600 and up.
Le Mans Master
Joined: Jun 2009
Posts: 6,528
Likes: 752
From: South Dakota
Even some small changes can work better with a tune. On my '87 I did flowmaster mufflers and a TPI airfoil with the result that the tune had a little stumble in it at low speeds. I put a SLP chip in and it fixed it. Even though these were very small changes, the factory programming did not like it. Later it even worked when I put the 1.6 ratio rockers on with the SLP chip.
Your system is different from my '87, but how far and how well the system can adjust depends on how much change there is. My guess is that minor changes (like air cleaners or catback exhausts) will probably work ok without a tune. Bigger changes (cam, heads, headers) will run better with a tune.
Good luck.
Team Owner
Joined: Jul 2004
Posts: 28,502
Likes: 3,302
From: Hartford WI
How much of a change is being made? Most changes will need some adjustments to the air/fuel/spark for best performance. The stock engine controls can handle some slight changes and the MAF systems are a little more forgiving of some changes.
Even some small changes can work better with a tune. On my '87 I did flowmaster mufflers and a TPI airfoil with the result that the tune had a little stumble in it at low speeds. I put a SLP chip in and it fixed it. Even though these were very small changes, the factory programming did not like it. Later it even worked when I put the 1.6 ratio rockers on with the SLP chip.
Your system is different from my '87, but how far and how well the system can adjust depends on how much change there is. My guess is that minor changes (like air cleaners or catback exhausts) will probably work ok without a tune. Bigger changes (cam, heads, headers) will run better with a tune.
Even some small changes can work better with a tune. On my '87 I did flowmaster mufflers and a TPI airfoil with the result that the tune had a little stumble in it at low speeds. I put a SLP chip in and it fixed it. Even though these were very small changes, the factory programming did not like it. Later it even worked when I put the 1.6 ratio rockers on with the SLP chip.
Your system is different from my '87, but how far and how well the system can adjust depends on how much change there is. My guess is that minor changes (like air cleaners or catback exhausts) will probably work ok without a tune. Bigger changes (cam, heads, headers) will run better with a tune.
Not sure if it works better or it is a placebo effect. Again, I have yet to see a dyno sheet and I am not a believer in the SOTP dyno. Mufflers shouldn't do much since the choke point is usually in the exhaust manifolds and thus the weakest point. I have little doubt it is NOT the airfoil that adds anything. I'd go as far as to say that if you got a real tune on the dyno, you'd pick up a little more power and it can be made as good as it gets.
On my 91 F-body it worked ok with Superram and Tri-Y headers. It just was much better (forgot any dyno info if given) after Lingenfelter tuned it.
Le Mans Master
Joined: Jun 2009
Posts: 6,528
Likes: 752
From: South Dakota
True but whether that slight change is worth a dyno tune is a different story. 100% stock can be improved on but at what cost? A dyno tune is about $600 and up. The off shelf chips are either "guess a tune" or not much change made. Several people have taken apart the program and besides turning on the fans a little earlier, little to nothing has been changed.
Not sure if it works better or it is a placebo effect. Again, I have yet to see a dyno sheet and I am not a believer in the SOTP dyno. Mufflers shouldn't do much since the choke point is usually in the exhaust manifolds and thus the weakest point. I have little doubt it is NOT the airfoil that adds anything. I'd go as far as to say that if you got a real tune on the dyno, you'd pick up a little more power and it can be made as good as it gets.
On my 91 F-body it worked ok with Superram and Tri-Y headers. It just was much better (forgot any dyno info if given) after Lingenfelter tuned it.
Not sure if it works better or it is a placebo effect. Again, I have yet to see a dyno sheet and I am not a believer in the SOTP dyno. Mufflers shouldn't do much since the choke point is usually in the exhaust manifolds and thus the weakest point. I have little doubt it is NOT the airfoil that adds anything. I'd go as far as to say that if you got a real tune on the dyno, you'd pick up a little more power and it can be made as good as it gets.
On my 91 F-body it worked ok with Superram and Tri-Y headers. It just was much better (forgot any dyno info if given) after Lingenfelter tuned it.
I agree that there is very little to be gained with a chip only.
I agree that the SOTP dyno is not accurate. In my case, there was no SOTP improvement in performance other than the chip cured a stumble at low throttle low rpm, so it did do something good for mine.
I agree the airfoil does very little, but it does do something. It changed airflow enough so that I had a low rpm stumble. In testing airfoils there is usually almost no hp gained, but the flow tests do show a slight improvement. Bang for the buck is terrible, almost no gain for the cost.
Like we both said, "depends". How much change the OP makes will determine whether he needs a new tune.
Team Owner
Joined: Sep 2001
Posts: 62,183
Likes: 1,740
From: Athens AL
C7 of the Year - Unmodified Finalist 2021
C4 of Year Finalist (performance mods) 2019
Its not entirely true, but it does depend on how radical each change is to the engine.
Heads by themselves? Maybe, it would be better with one.
Intake system? depends how radical, but if staying TPI-style, not really needed. If going SuperRam/Miniram, then yeah it'll benefit.
Header/exhaust by themselves? No not really.
Cam? Probably need to retune. I usually recommend anyone just budget for the chip when you decide to swap the cam out. It must be a custom chip, no hyperjunk.
As stated, the MAF can adjust and the car will run fine with more minor things and bolt-ons. If you're only going to do a few and call the car finished, then it would be good to get the chip done after theyre all done, but it will probably be fine without it.
When you get into the motor, definitely budget for a custom chip when its all finished.
Heads by themselves? Maybe, it would be better with one.
Intake system? depends how radical, but if staying TPI-style, not really needed. If going SuperRam/Miniram, then yeah it'll benefit.
Header/exhaust by themselves? No not really.
Cam? Probably need to retune. I usually recommend anyone just budget for the chip when you decide to swap the cam out. It must be a custom chip, no hyperjunk.
As stated, the MAF can adjust and the car will run fine with more minor things and bolt-ons. If you're only going to do a few and call the car finished, then it would be good to get the chip done after theyre all done, but it will probably be fine without it.
When you get into the motor, definitely budget for a custom chip when its all finished.
Team Owner
Joined: Oct 2004
Posts: 81,241
Likes: 3,063
From: altered state
St. Jude Donor '05
If you decide to do it make sure that car is in absolute perfect running order
Many get tunes that have other issues, then complain the tuner ripped them off . A tune wont fix a vaccum leak bad sensor etc
Many get tunes that have other issues, then complain the tuner ripped them off . A tune wont fix a vaccum leak bad sensor etc
Last edited by cv67; Mar 13, 2017 at 03:09 PM.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
5 Best & 5 Worst Corvette Daily Drivers
Joe Kucinski
The Headlights of Every Corvette Generation Explained
Joe Kucinski
5 Best & 5 Most Overrated Corvette Track Packages of All Time!
Joe Kucinski
Every 2027 Corvette Engine Explained
Joe Kucinski
Designer Imagines A Corvette That Looks More Like a Corvette Than the Corvette
Verdad Gallardo
10 Ugly Corvettes That We Still Kinda Love
Joe Kucinski
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
Pro
Joined: Dec 2004
Posts: 597
Likes: 24
I have a 93 with a vortech on it. Just installed long tubes, cat deletes, x-pipe and mid pipes. Didn't get a tune. Runs just fine. Maybe would get a little more HP with the tune but not enough to spend 600 bucks. Saving that for more drastic changes.
Team Owner
Joined: Jul 2004
Posts: 28,502
Likes: 3,302
From: Hartford WI
If you decide to do it make sure that car is in absolute perfect running order
Many get tunes that have other issues, then complain the tuner ripped them off when they had problems the other time that hampered them from the beginning. vacuum or exh leaks for example
Many get tunes that have other issues, then complain the tuner ripped them off when they had problems the other time that hampered them from the beginning. vacuum or exh leaks for example
Team Owner
Joined: Jul 2004
Posts: 28,502
Likes: 3,302
From: Hartford WI
It isn't just about getting a few more HP. Sometimes the engine has problem spots that show up on doing diagnostic work. If it is an issue of 20 HP more, maybe not worth it. OTOH, to spend the money to power it up and not $600 to make sure it is running right, per diagnostic equipment and cheaping out with a "runs just fine" SOTP hope and prayers is kinda "penny wise, pound foolish" IMO.
Pro
Joined: Dec 2004
Posts: 597
Likes: 24
It isn't just about getting a few more HP. Sometimes the engine has problem spots that show up on doing diagnostic work. If it is an issue of 20 HP more, maybe not worth it. OTOH, to spend the money to power it up and not $600 to make sure it is running right, per diagnostic equipment and cheaping out with a "runs just fine" SOTP hope and prayers is kinda "penny wise, pound foolish" IMO.
Would you tune a stock car if it wasn't giving you any issues? No. Now add headers. Running the same? Yes. Tune? No. My installer does custom builds on many vettes and has a dyno and tuning and he didn't think it needed a tune afterwards so I'm not sweating it.
Team Owner
Joined: Jul 2004
Posts: 28,502
Likes: 3,302
From: Hartford WI
Depending on the future. If that is all it will be, hell yes. If I was doing headers and intake, I'd wait for it to be done. LPE did mine and on a blind test, it was way different. Only reason I would feel better with a tune is you mentioned that you had a Vortech which mane me think blown. It can run without a tribute NOT if it is my car.
Pro
Joined: Dec 2004
Posts: 597
Likes: 24
Depending on the future. If that is all it will be, hell yes. If I was doing headers and intake, I'd wait for it to be done. LPE did mine and on a blind test, it was way different. Only reason I would feel better with a tune is you mentioned that you had a Vortech which mane me think blown. It can run without a tribute NOT if it is my car.
It's tuned for the vortech. I'm thinking of going meth injection next. Of course I'll tune for that. I guess you are saying if I was stopping at headers then you would tune. I agree with that but I'm not stopping lol.
Last edited by Natrlone93; Mar 13, 2017 at 03:19 PM.
Team Owner
Joined: Jul 2004
Posts: 28,502
Likes: 3,302
From: Hartford WI
Yes. But there never is stopping, is there? At least as long as you have money