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Custom exhaust 1988 Vette

 
Old 01-17-2019, 09:51 AM
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Korsou
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Default Custom exhaust 1988 Vette

Hello Guys,

Once again I need ou experienced help.

I just took down my exhaust to be able to access the 4+3 tranny and have realized it has patches all over. A friend of mine, which is a welder, offered to make me a new one !!!

On the pic you can see my exhaust. Is this, except the patches, the original exhaust? From pics I have seen there should only be 1 converter on the center straight pipe. In the future I want to get to 350 - 400Hp and I was recommended that 2.5" pipe would be enough. I am also thinking of getting headers but donīt know if I can get away with removing the AIR Pump etc due to emisión tests each year. Are there long tube headers with the emissions setup and somewhat affordable?

Thanks again

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Old 01-17-2019, 11:27 AM
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vader86
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I'm not seeing any pictures, but the factory exhaust would be a front Y pipe with two precats, into one big converter, then split again into the two mufflers. The original would be rusting through by now unless it had been kept garaged, so would probably be patched in a few spots.

2.5" would be enough for your power goals.

AIR is not needed to pass a sniffer test but if they do visual inspections there, they'll flag you. I don't see your location.

Hooker 2149s have all the emissions hookups as do TPiS headers. The Hookers will need a 16720 front Y unless you are going with dual exhaust.
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Old 01-17-2019, 11:46 AM
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84 4+3
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Dual 2.5 is more than adequate. Melrose also has headers with all the connections for egr and air etc.
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Old 01-17-2019, 04:19 PM
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Sorry Gents, now the pic.
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Old 01-17-2019, 04:26 PM
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Well part of it looks stock, but the rest looks like it was cobbled together out of scraps.

Rear Y is right, but front Y is wrong on drivers side, thats a cat from something else that was welded in place. Was there a main cat between the two Ys? Looks like the front Y has been elongated with another piece of pipe.
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Old 01-17-2019, 04:42 PM
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Hello Vader86,

I agree, the rear Y is stock and all pipes are "original".
The front piece is, as you say, cobbled up with odd pieces. From what I can see the "cat" on the drivers side is different but cannot see any brand/marks/reference and also much bigger than the one on the passenger side. Is the "cat" on the passenger side stock?
The straight pipe in the center is not original either. I have seen pictures of original exhaust systems online and there is where the cat was.
Can anyone share their stock exhaust setup?

I am thinking of building the exhaust (as I am not sure I am changing the headers now) from the original elbow all the way back. If needed I would install a small cat on each side and than go back into an X-Pipe and separate again into separate pipes to the mufflers in the back.

Thanks again
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Old 01-17-2019, 06:36 PM
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SuperL98
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This is a stock 1988 front on the right and I believe a Magnaflow on the left.
It's been about 20 years since I took the picture.

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Old 01-17-2019, 07:05 PM
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If you're emissions exempt, like I am in TX, build whatever you want. No harm in going bigger IF you plan on making more power later.

here's mine. 3" true dual from long tube headers. Mufflers stop just past the rear differential. It's too damn loud for a street car IN the cab, but not too crazy outside unless you are WOT.



Last edited by TravisSchoech; 01-17-2019 at 07:06 PM.
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Old 01-18-2019, 03:35 AM
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That dual exhaust looks great !!!!! Impossibly illegal in Spain though
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Old 01-21-2019, 05:19 AM
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One more question Gents,

As I mentioned I am contemplating getting headers. Given there are yearly emission checks in Spain I have to install cats etc and the AIR pump set-up.

Is there a real benefit to installing shorty headers with a stock engine for now or should I save the money and invest in an intake, heads & cam and long tube headers in the future?

Thanks again
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Old 01-21-2019, 12:27 PM
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If you can find shorty headers that will fit, and have a shop do the customization, then yes. Pretty much anything is better than the stock L98 exhaust manifold.

But you will get more power from the cam and intake changes. Your 88 heads are actually fine, unported, up to about 350HP.
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Old 01-21-2019, 12:38 PM
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Originally Posted by vader86 View Post
If you can find shorty headers that will fit, and have a shop do the customization, then yes. Pretty much anything is better than the stock L98 exhaust manifold.

But you will get more power from the cam and intake changes. Your 88 heads are actually fine, unported, up to about 350HP.
Hello again vader86,

You have just made my day !!!! What intake and cam would you recommend? I thought I had to change heads for sure to be able to get to those numbers. I will look into headers I can get in Spain and ask for your knowledge if you donīt mind.

Today I was reading the RPO codes for my car and it seems to have the Z51, FE7, V01 and KC4 options. I really liked to find that out, had no idea.

Also today I installed my new braided brake lines and replaced the brake fluid.

Thanks again
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Old 01-21-2019, 01:02 PM
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Intake and cam choices are limited now that things are not being made like they once were, and you'd have to make a choice on how you want the car to behave and its powerband characteristics. SuperRam is not in production but can be found used, and is better for a midrange torque monster that is similar to the L98 but with much better midrange power. This is what I have, and I found mine used.

Miniram or a converted LT1 intake is more geared to make the car a high RPM engine that makes its power up high.

Other choices are to just modify the TPI as it is with larger runners and plenum, so thar behaves similar to now but you can still reach 300-350hp along that route.

Each choice warrants a different cam choice, so the intake is the one area where you must make a choice and run with it to conclusion.
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Old 01-24-2019, 07:46 AM
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Originally Posted by vader86 View Post
Intake and cam choices are limited now that things are not being made like they once were, and you'd have to make a choice on how you want the car to behave and its powerband characteristics. SuperRam is not in production but can be found used, and is better for a midrange torque monster that is similar to the L98 but with much better midrange power. This is what I have, and I found mine used.

Miniram or a converted LT1 intake is more geared to make the car a high RPM engine that makes its power up high.

Other choices are to just modify the TPI as it is with larger runners and plenum, so thar behaves similar to now but you can still reach 300-350hp along that route.

Each choice warrants a different cam choice, so the intake is the one area where you must make a choice and run with it to conclusion.
Hello vader86,

Hope you are great.

I have been looking for a superram but canīt seem to find one. Do you know of a reliable seller that might have one.

I have found some used intake manifolds:

85-92 Camaro Trans Am TPI ACCEL HIGH FLOW INTAKE MANIFOLD 91 CORVETTE C4 90

85-92 Camaro Trans Am TPI EDELBROCK HIGH FLOW INTAKE MANIFOLD 91 Corvette

Are these something interesting that will benefit me in getting to my horsepower goal?

Thanks a lot !!!!
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Old 01-24-2019, 02:09 PM
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Just another thought regarding your exhaust system. You can put the front y pipes on with their pre-Cats and then attach a high flow catalytic converter and go with a decent exhaust system. I have a 1988 C4 and I don't have headers but I did replace the catalytic converter with a high flow unit from Summit Racing and then I installed a "Chambered Exhaust System" which is a better flowing system than the original mufflers and all. A Chambered Exhaust system uses no mufflers as it has baffles inside the pipes. The sound that comes out behind the car sounds like side-pipes but all the noise is out behind the car and not in it with you.

Allen's Stainless Exhaust is located in Indiana and has a web site. They offer the parts in Stainless Steel or Alumanized Steel, I have two of their Chambered systems on my 2 Corvettes. One is over 25 years old and the other close behind and I have had no problems of any kind using these chambered system. As long as you have a good catalytic converter that is still working the emissions people should leave you alone. I have both cars inspected every year and here they are getting tough but have had no trouble with the chambered systems as it is a complete leak-free exhaust system. If they have noise restrictions like lots of European countries do you might be stuck with the old bulky mufflers just to satisfy the authorities.

After adding the Chambered Exhaust with the new catalytic converter I gained a whole 14 hp on my 1988 C4. If you decide you want to go with headers be sure to use the long tube kind as they make more power, unfortunately the space on a C4 is tight and your choices limited.

Good Luck with your Corvette in Spain!
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