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Hi all , Im new here and have a question ,Im hoping to get some help with. I have a 81 vette with factory headers and am thinking of installing aftermarket headers. First off will i gain anything by doing this and if so do I need to pull the engine?
Thanks gary
 

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I don't think you'll need to pull the engine, but putting the front up on blocks is necessary. You can remove the stock pieces from underneath easily and also fit the new headers fairly easily.

You will have to fab new connection pipes to the remaining exhaust. My advice is to fab all new 2 1/2" at a muffler shop that can do it.

Your gain will be more low end torque, but it's expoential to other engine work. A stock engine will see the least difference, but still noticeable. You'll probably also see a small improvement is gas mileage. You'll also experience more engine compartment heat because all the added header tubing now has more sqaure inches of area to radiate it's exhaust heat.

Contact Jet Hot. IMO, they have the best ceramic coatings and will send you the headers of your choice fully coated and with a stupendous warranty.
 

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What kind of headers are you putting on your 81? looked in Ecklers and the only ones for 81 talk about "D ports"? I guess I am trying to see what problems arise connecting to engine, not so much concerned about connecting to exhaust pipes. My brothers 77 has a lot of heat from the headers and we are getting ready to wrap them.
 

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Forget Ecklers. Call Hooker, or Flowtech, or another Header maker and buy from them. Or call JetHot, and they'll get you headers that fit and are coated delivered to your door.

Use an aluminum gasket at the head and you won't have any sealing problems.

I hear wrapping headers rots them because of trapped moisture from condensation.

Summit is a good source and their tech's will give you phone numbers. Most venders also have websites.
 

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Discussion Starter #5
Thanks

I'm just thinking of ways to boost horsepower and help the motor to breath better. Cam , intake and headers . or drop in a crate motor and weighing out the pros and cons vs cost of either.
I have never done the add ons but i had a 68 chevelle with a 307 and dropped in a 396 /375hp and that wasnt to bad other than alot of rewiring. any thoughts on this?
Thanks for all you help on headers
Gary
 

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There's a good selection of crate motors out there. I have one. For around $3000 you can get decent power and a 3 year warranty from GM. Swapping out the engine is a lot faster and cleaner than working over your block on an engine stand.

Ther more power you want, the more it will cost either way.
 

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if you get headers I'd say stay away from the hedman 68300, they do fit but since the primaries make a 90deg. bend the collector is pointing down towards the road surface. It takes a lot of work to hook it up to the stock system (you could cut the Y pipe and swap left & right for the proper clearance), I eneded up bubba building my own true duals (didn't have a mandrel bending machine so it was 2,75"with yucky bends and shoddy welding by me) but it worked. I never was really satisfied with it, it performed quite good, it sounded awesome but it looked like crap. I removed it completely and am starting over with a completely different system (3" duals)
 

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Originally posted by Jlreyna ...<br>
I have been looking into the chambered exhaust. Has anyone heard anything on them?<br>

Flowmasters are the absolute, no question about it, performance muffler leader. A 1 or 2 chamber Flowmaster muffler actually flows BETTER than open exhaust. Flowmasters allow a small amount of atmospheric suckback on each exhaust pulse, which creates a low pressure pocket within the muffler that actually pulls the hot exhaust gas from the cylinder on the next exhaust pulse. That distinctive Flowmaster sound also can't be beat, IMO.

Here is my recipe for a rock solid exhaust system that will improve any stock or street modified C3:

1) Long tube headers. stay away from the shorty's. They don't flow as well. if you can find tuned length primaries (meaning that all the primary tubes are the same length) then that's better than unequal length primaries. If you use ceramic headers or drive your car daily, then wrap the headers in Thermo Wrap. This will decrease underhood heat and help prolong the life of your starter, as well as increase the efficiency of the headers. An aluminum starter heat shield is STRONGLY recommended with any header install on a C3. The shields are $20. If you use uncoated headers, then I recommend the Thermo wrap ONLY if you drive your car several times a week and don't store it over the winter; otherwise the steel could rust away under the wrap.

2) If your car is a single exhaust system with the large Catalytic Converter, scrap it. Replace it with a dual 2 1/2 inch system with dual modern high flow Cats. That stock frying pan converter on C3's is an ENORMOUS barrier to exhaust flow. Catalytic converters were were extremely in-efficient back then.

3) Flowmaster Mufflers. They don't make a Flowmaster install kit for C3's so the muffler shop will have to fab up the system custom. ask them to install an H-Pipe, if possible. (some times there isn't enough room under a C3 for an H-pipe)

4) Use the best quality, most expensive header gaskets you can find. I use the latest re-usable aluminum type. They are great and I haven't had any leaks yet.


This system won't win you points at a restoration show, but it will deliver real performance. I did this exact system on my wife's 76 back in 1995. It was AMAZING how much better that car ran afterward. The mileage went up about 4 MPG, and later, when I installed a new cam, intake manifold and roller rockers, the car actually ran in the high 13's one street tires, while being completey emissions-legal. I also did the same system (minus the Cats) on both my 68 and 69)

Just one Dyed in the Wool Hot rodders opinion...
 

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I'm going to stay away from the flowmasters. Half the cars in this town have flowmasters and the mustangs and camaros and trucks are all starting to sound the same. I have a pair of Heddman headers with straight pipe all the way back and tipped with KBD Targa chrome tip mufflers. It's almost as loud as a Harley.
 

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I ran borla stainless steel mufflers (C4 mufflers, they're now available with C3 hangers too) and they were very loud, just how I like them :)
 

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Muffler flow ratings, source unknown..

OEM................................................................................225
Gibson SuperFlow 788200..............................................311
TTS Bullet Cat Converter.................................................324
Flowmaster 40 series 42540..........................................352
Flowmaster 50 Series.....................................................362
Flowmaster 40 series 43040..........................................392
Dynomax Super Turbo....................................................410
Flowmaster 62631..........................................................435
Carsound Cat Converter.................................................436
FLP Cat Converter...........................................................440
Edelbrock Victor 5535......................................................562
Flowmaster 40 series 435409..........................................576
Edelbrock RPM series 5511..............................................579
Flowmaster Delta Force Racing 54040-10........................634
Edelbrock 304 series 5560...............................................640
Edelbrock Gen App 5505..................................................708
Dynomax Race Magnum Welded 17216...........................711
Borla XR-1 40600.............................................................836
Borla XR-1 40615.............................................................854
Dynomax UltraFlow SS 17263..........................................1000
Dynomax Race Magnum Welded 17218...........................1000
Borla XR-1 40575.............................................................1100
Dynomax UltraFlow..........................................................1133
Edelbrock Victor 5537......................................................1400
Borla XR-1 40450.............................................................1400
Borla XR-1 40741.............................................................1450
Dynomax UltraFlow SS 17296, 17268..............................2200
Dynomax Race Magnum Welded 17220, 17224...............2200
Dynomax Race Magnum Welded 17225...........................2600


The formula for required exhaust flow is: horsepower times 2.2.
So if your car makes 400 hp, you will need a total of 880 cfm muffler capacity for an unrestrictive exhaust system. So for dual exhaust, you would need mufflers that flow 440 cfm.
For reference, a 2.5 inch diameter pipe flows ~500 cfm. Adding non-mandrel bends will lessen that amount.
 

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oh boy, I have a pair of those dynomax stainless race magnums, they're oval in/out 4,5" wide 2,75" high.. hmm, they're gonna be loud YEAH :D
 

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AlwaysWave said:
Forget Ecklers. Call Hooker, or Flowtech, or another Header maker and buy from them. Or call JetHot, and they'll get you headers that fit and are coated delivered to your door.
Hello AlwaysWave (or others with an opinion)

I am curious as to how you like your Flowtech headers? I ordered some through my local muffler shop yesterday, but then started to read of horror stories of welds breaking, think metal construction, awful for GM products, etc. My take on the whole header issue is that I am going with a header within my budget and am being told that unless I want to spend some coin on Hooker Headers or Hedman, this is the best bang for the buck. Just wanted an opinion if your willing. My car is a 73. Thanks in advance.
 

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Couple of quick things.

1. You will have to get creative, or simply expect a few issues getting your a/c and altnernator supports to bolt up to headers since the flange is not set up the same as the factory.

2. I suggest getting your headers (long tube) just plain painted first. Take the time to fit them to the car THEN remove them and send them out to be ceramic coated....or just leave them plain if you are not worried about the look. Many people rush out and buy the pre-coated ones only to end up scratching, denting, and modifying them to clear spark plugs, suspension....etc.... Putting dimples or "bending" headers is nothing unusual, even on the ultra high dollar ones.

3. There are these really cool new aluminum re-usable header gasket and header flange gaskets. They cost about $10 more than standard, but well worth it. Summit sells them. Ask for them...you won't regret it.

4. Your car has two into one and back to two pipes. You will need the help of a muffler shop to connect the header flange. This can get expensive to build, so call around first and make sure you know what you are getting into there. After you have the pipes cut and the car is on the rack...that is the wrong time to ask "how much will this cost?" I would suggest going to 2.5" from the header flange, and have a NEW Y pipe made at 2.5" flowing into 3". See if they can fit a 3" down the car (single) back to a new rear Y pipe going to 2.5" and into the mufflers. The two into one and back to two creates a more mellow balanced tone at the rear vs. pure dual exhaust. You will appreciate the more quality sound to the exhaust note, and it will work with your stock cross member that is only designed for a single pipe to go down the middle.

5. I have been running imco mufflers of late. I love them. They make clean sound that does not re-verb into the cabin and drive you crazy. I ran a pair of stainless body muffs on my 69 Camaro that not only look great, but are compact (the size of a flow master 2 chamber) and have very reasonable (your neighbors will appreciate them) sound.

http://www.grabthepower.com/


Power wise...I seriously doubt seat of the pants will tell any difference. That is why I would suggest keeping costs down as much as possible instead of getting caught up in the hype and blowing $1,200 and having nothing you can feel...and possibly something so loud that your neighbors send you nasty letters.
 
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