Tuning after Headers
 

S O after installing my Long tube headers and SLP claw cold air intake I needed to get my tune tweaked. the day I had it set up car decided to run terrible. running pig rich. well this was due to my lack of knowledge of the make up of 02 sensors. after getting to tuner both 02's turned out to be not working properly. tuner made it at least able to run better then it was on the way there which just would stall at idle in gear. drove it home and did some research as car was running fine prior to header swap and like crap after and going from shorty headers to long tubes, removing cats and adding cai should not have changed that much. I am gonna confess when I removed the 02's from old exhaust I had to put a wrench on them and beat the hell out of the wrench to get them out. well who knew they're ceramic inside and so fragile lol. not me. so I am assuming I broke the internal ceramic causing failure. so I order 2 new 02's and decided to get new injectors and I had to reorder new plugs as the brand new ones got pretty sooted up driving to tuners. so when I go back we are starting with new plugs. maybe I am the only one that didn't know this about 02's but if others don't maybe you can learn from my mistake.
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what kind, size and cost are those wheels on that car? like to see them on a page.

That is Truly One Beautiful Corvette that you have there!

Oxygen Sensors used to be very easy to damage when first came out. I was told that every 50 k miles you replace all of your 02 sensors. O2 sensors are expensive today but what isn't?
Old O2 sensors have a bad habit of getting "Lazy" and developing a Lag in the sensor's ability to rapidly change like it did when it was new. I just installed a digital air/fuel ratio meter on my 1968 C3 dashboard, am looking forward to tuning the engine to run more efficiently and powerfully from a new modern heated O2 sensor that will monitor my Carburetor system and really help to get it tuned properly.

Regards,
Chris a.k.a. ctmccloskey

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Car as I bought it.
Thanks I appreciate the compliment. came a long way from when I got it. new 02's weren't bad $32 for the pair of AC Delco. cars a 93 OBD1 so they are just the old one wire 02's. here is a better clearer picture.
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Did you install LED lights in the engine bay? I have mine disconnected as I don't want to drain the battery with frequent/long hood up periods, but those look super bright!

I use a small amount of antiseize on the threads of the 02 sensors. They will twist right off in the future without pulling threads out of the headers.

Yes eventually I do want to ad a switch to turn them off for the same reason you mentioned. Corvette Central sells a plug and play switch for $50 but easy enough to just do myself. the lights are very bright.
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Yes I did use never seize on threads when I re installed them. my 02 bungs are in the reducers, not the headers. but they were stuck pretty good in stock pipes. (original)

Did you get the rich running condition resolved?

BTW, that under-hood lights on/off switch is great; I have one installed on each Vette.

Not yet. I just got new 02's that I have to install and take back to tuner

How powerful is your car? The black wheels really make the car look great. I have been looking at aftermarket wheels for my Daytona Yellow Corvette. I want to move up to some 17 or 18" rims at some point so I can actually buy some real performance tires.

I went to Pep boys and bought the LED bulbs for my 1988 C4, it sure does reduce the load on your electrical system using all L.E.D.'s. The LED's use a fraction of power when on that the original bulbs did.

Have you ever seen one of the GTECH Pro's before? I have an old one and am thinking about upgrading my unit. It is an accelerometer that will measure the performance of your car accurately IF the correct weight was entered. I emptied the car and weighed it and that is the number I use when playing with my Gtech. It will show even a slight improvement in power or even a slight loss very accurately. The best part is the smart shift lights that watch your torque and the minute it peaks the light comes on telling you to shift, it is not just an RPM shift light, it is a "smart shift light" as it follows your torque curve not the engine speed.

I am now permanently installing my Snow performance water/Methanol injection system and having this GTECH tool will save me a lot of time getting it dialed in right. Check out GTECH's web site out, you might find it to be useful tool for your beautiful car! I like it as I can compare my 40-60 mph times or whatever, it is very helpful when drag racing. Since I have no roll cage I am not allowed to do my testing at the drag strip, I do have a hard top for my Corvette but I doubt that would help much in a roll over. I can play as long as I stay out of the 12's on the race track. I got pretty good at getting 13.01 to stay out of trouble...at least it was consistent. Thanks for the education regarding the fragility of the O2 sensors, very helpful information! Good Luck with your tune!

Best Regards,
Chris

My car is not too powerful the only engine upgrade is it cam 1.6 roller rockers stockthe car dynoed 268 wheel horsepower, at the track it ran 14.2 I added shorty headers and a stall converter, 3.54 gears and it went 13-2 I added custom ground camshafts how to dyno tune Made 318 rear wheel horsepower and personal best what's a 12.6 at the track I've since added long tube headers and a cold air intake after I installed a new O2 sensors and I'm going to put new injectors in it it will be Dyno tuned again I don't expect much games maybe somewhere around 330 wheel horsepower. I have not heard of the gtech does it work with OBD1

Hopefully after this I can get it back on the dyno and hit the track in a couple weeks.
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Hello again,
The GTECH Pro that I have works on my C3 with no problems. The Gtech does not connect to anything but 12 Vdc power from your car. The whole unit is a tiny bit bigger than a pack of cigarettes and has to mount on the windshield and has to be perfectly level. It has all the parts inside the case and is very small. The beauty is that you can see if the change was positive or negative right away. I used to use it for carburetor adjusting and it was great. Take a look at their web site and you can learn all about this useful gadget. Being able to take the data and download it onto your PC is a really nice feature. It will plot out a graph showing the horsepower and torque curves over time. My unit is about 20 years old and it still uses a Serial port for connecting to my PC. The new ones are all USB and have even more features than mine does. It is the most useful tool for tuning my car without going to a dyno, people have compared the results from the Gtech and the Dyno and they were virtually identical. They cost about $300 and can become a very valuable tool in your "box of tricks". Here is the link to GTECH: https://www.gtechpro.com/

Your car has a different engine than my 1988 C4 does. I thought the LT1 engines made a lot more power than the L98 was able to. You just don't have the torque and power all drop off at 4200 rpm....

I have long tube headers on my C3 and even with them the heat soak after shut down is causing problems for my hood. The amount of heat that is under the hood is actually cooking the paint on top of my hood. The paint starts cracking in little cracks over the areas above the headers, I suspect that they are the source of the heat as the worst damage is right over the headers. It could also be the cast iron heads running the 12.25-1 compression ratio that makes problems for me but the damage looks more like it is over the headers and not the heads. I may have to install a smaller fan to keep the air moving under the hood when the engine is first shut down after running for a while. There is a lot of damage to the ceramic coating near the cylinder exhaust ports on the long tube headers. My headers were originally silver coated with the ceramic exhaust coatings. That ceramic coating is junk if you have any real compression as it is not designed for the higher temperatures that higher compression brings along with it. The company whom I bought them from wants to have the same coatings used on the Race Cars like Nascar so they want to remove them strip them down and spray them with a newer Higher temperature material that won't burn off. Are your headers coated? It really works if it would only hold up for more than a couple years like it does on my car. I keep getting reddish orange spots on the silver ceramic coating that will not come off.

Has this happened with your long tube headers on the C4? Any signs of heat related problems anywhere under the hood?

How much room do you have when installing the long tube headers on a C4? I am so spoiled by the engine compartment of my C3, there is room everywhere it seems. After all the horsepower my 1968 makes it might be time to start modifying the L98. I have thought of removing the entire fuel injection system and installing an aftermarket system that will allow the L98 to breath a bit better and make a bit more power. Those ridiculous long runners are the Achilles heel of the Earlier C4's.

Good Luck and thank you for your time and thoughts!
Chris

I have not had any heat issues, however not driven car a whole lot yet, a friend that recommended these particular headers Hooker super comp. with ceramic coating has had them on his LT1 C4 for a while now with no issues. he did a under hood heat test and temps never rose over 400 deg. as far as fitment there actually is a ton of room to install the long tubes on a C4. stock the car had 2 giant can cats right there. without them there is a lot of room. not sure if relevant in your situation as far as coating issues but this is a disclaimer on Hooker site. " Breaking in an engine with ceramic coated headers WILL result in damage to the coating and will VOID all warranties. Hooker recommends using cast iron exhaust manifolds or old headers during your engine break-in period to avoid damaging your coated damage. Please call Hooker tech service at 270-781-9741 for additional information regarding ceramic coated exhaust products. The use of header wraps can cause the header tubes to crack or rust due to excessive heat and moisture build-up. Hooker does not recommend the use of header wraps as this will void the warranty. Hooker long tube headers do not come with header reducers." I am sure the aluminum heads on the LT1 helps with temps. and the LT1 is 9.5:1 compression.


I went on the Gtech site. it will give you info. but not a replacement for tuning. my guy just happens to do all tuning on a dyno. however the device does look cool.

I have not seem(or heard of) this with the ceramic coating on other headers. Does TPiS, Melrose or Exotic muscle have this warning with their coatings for engine rebuilds?

You are correct about tuning, on a computer controlled car you need to "program" the changes. The Gtech seemed like a gimmick when I first looked at it. Using the shift light function gives you the most accurate times to shift while monitoring the torque curve. Getting the vehicles accurate weight is important or none of the data will be accurate.
Any source of information that helps your car go faster is worth the money to me. When I first bought it I was surprised at how small it was and then when you see the graphs it can make showing the horsepower and torque on the curve. While making changes to my carburetor I was able to see places where the power had changed even just a bit. I tried a 650 cfm carburetor and that was the worst for my engine. I then tried a 750 Double Pumper and it improved considerably. Each time I could see exactly where the changes occurred and whether they were to be beneficial for the car's performance. The last carburetor I bought was a Modified Holley (850 cfm) Built by AED Performance in Richmond, VA. It is an 850 Body with some custom work to make it better for my Corvette. It flows closer to 1100 cfm and makes the most power I have ever seen out of this engine Combination.

Thanks for the information regarding the ceramic coatings! I broke this engine in with the original style BB Exhaust manifolds and switched over to the Long tube Headers made By HedMan Hedders. After a year or so they started developing what looks like measles on the silver coating so Hedman sent me a second set which did the same thing. I have spoken to a couple coatings experts and they both said that my Compression is the cause of the heat. The guy who does the Hedman Hedders coatings said that the standard was a low temperature version of the material that is less expensive. I was told that professional racers use a higher temperature coating that is available for more money of course. One guy I spoke to suggested that "I probably park my car on bare Concrete" and that was the cause as something leaches out of the cement mixture that damages the coatings. My car was parked on a Painted concrete floor and not exposed to Concrete or cement.

Thanks for the update on installing headers on the C4, I did not think that there was enough room for them. I would love to do a before and after with the GTECH to show the improvement. I had planned on getting rid of the two pre-Cat's anyway and this might make it happen sooner. I will certainly measure that to see if there was any change at all getting rid of the pre-cat's. After putting on the Chambered exhaust on with a new Higher flowing catalytic converter I saw a 14 HP increase in my power, I never did analyze the graphs before to see where that power came on. But with a GTECH you can do that and so much more. By the way I am not in any way affiliated with GTECH, I am simply a satisfied customer who likes their product enough to tell others about it.
Thanks for the help! I appreciate both your time and experience!
Chris

I'm not sure. I was bouncing between Melrose and the Hookers when I bought mine. I went with the Hooker because a friend had them so I knew fitment would be good. as far as warning I wasn't installing on a car that needed break in so I wasn't concerned with that either way.

Yeah that Gtech sounds very cool. I may actually get one. when I get the car tuned the changes from previous dyno tune will be:

Old=stock cats, X-Pipe in place of stock resonator, modified airbox, cheap shorty painted headers, muffler deletes

new will be= long tube headers, cat's delete, full 2.5" Borla exhaust with resonator and 2 mufflers, SLP claw cold air intake.

these will be the only changes from last dyno tune which was 318 RWHP

I didn't do the Long Tubes for performance gains, it was more for under hood temps and installing the Borla exhaust that I had, without having a Hodge podge which my previous exhaust was.

I might gain somewhere from 5-15 hp.