Gibson Headers

Discussion in 'General Discussion' started by Tcorsrt10, Apr 7, 2019.

Car Parts
  1. Tincup

    Tincup Full Access Member

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    Sorry to dredge up an old thread, just wondering if anyone has any performance data on the Gibson headers? I contacted Gibson and asked for a dyno sheet, and they told me that it's "For internal use only". Are they hiding something? Just wondering if the small tubes "Hurt" performance. I know they are just manifold replacements, and I think they are worth it for the weight savings alone. I have a complete drivetrain from a 05QC in my 67 D100, and in my opinion, the performance is un-impressive. I weighed the truck at 4750lbs with me (250lbs) and some junk in the bed, so it's lighter than a QC. I also have a CAi, a 91 tune by Torrie, 3" duals, with x-pipe, no cats, no mufflers...
     
  2. shirleyjp86

    shirleyjp86 Member

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    With your mods, you should be making around 450-ish at the wheels - which should be pretty snappy in a 4750lb rig. I'm not sure what other cars/trucks you've owned and maybe you're used to more? I know I had an '04 GTO with longtubes, tune and a stall - it would easily stomp this truck, but it was also like 3600lbs.
     
  3. rottenronnie

    rottenronnie Well-Known Member Supporting Member

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    Good Morning/Afternoon/Evening:

    This is kind of a re-post but maybe contains a bit more info...

    First and foremost: What year is the engine in your truck??

    Personally, I like small(er) primary tubes as they tend to build torque in the most useful rpm range.
    Longtubes also tend to make more torque than shorties because of when the exhaust pulse phases.

    To the contrary of that, I've read many header shootouts ON THE DYNO that lean towards large primaries reigning supreme BUT that tends to be peak power gains and not useful gains that make a heavier vehicle (particularly with an ancient automatic trans) more enjoyable to drive. It's all about velocity. If you want to crush any gains a header otherwise might produce, put on a pair of headers with really large primaries.

    The exhaust manifolds on the trucks are actually quite good and have a better design than the Viper cars (more room to make them that way).
    Headers can be an expensive addition for the power returned by the investment.

    My header manufacturer (B&B), when asked, claimed a 50 horsepower increase using their headers on an SRT-10 truck.

    Headers were one of the last mods I did and in fact was they were installed after I had swapped out heads, tried another cam grind (my fourth), etc; and my power gains were "considerably" less than 50. Even considerably less than 1/2 of that.

    I try to make ONE change at a time which is a slow process but it lets me know if a change is positive or negative. My first mod on my brand new SRT-10 was a cold air intake which showed a loss of power (i also hated the sound) so off it came. Unfortunately, my headers went on with some other changes.

    The 8.3 can be an extremely stubborn engine when it comes to it's response to exhaust (headers in particular) and I've seen several Viper cars and SRT-10 trucks that have shiny new headers installed. If the engine could talk it might say something like: " Yeah, so, what do you expect me to do with these?".
    I've watched with more than a bit of confusion as these vehicles (some of which are still strapped down to a dyno) don't really change when they do some pulls after Headers were installed. Sometimes a re-tune helps A BIT.

    Years ago when exhaust manifolds were truly dismal, headers made an immediate and very noticeable improvement in torque and top-end horsepower if the rest of the combination was good enough to support them.

    Some guys/gals do report power improvements with headers on these trucks.

    But back to the top: What year is the engine in your truck??
     
    Last edited: Oct 12, 2021
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  4. VIPR PWR

    VIPR PWR Full Access Member

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    Ronny .. you confused me .. in the post is the bottom line headers arent really worth doing as the gains arent there also the bottom header on your profile stating the porting of heads doesnt necessarily make more power on these engines ?? Or am I misinterpreting what is being said ???
     
  5. rottenronnie

    rottenronnie Well-Known Member Supporting Member

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    Hello Jim:

    Headers can help in the power department by getting more exhaust out (as exhaust gasses can't burn twice) that otherwise take up valuable room inside the combustion chamber for the fresh incoming charge of fuel and air.

    In my case (with aftermarket heads and a ported Intake), headers should have really helped as the engine's airflow increased considerably on the Upstream side. If you are increasing airflow/fuel into an engine, it will also require the ability to vacate that increase on the exhaust side to maintain a balance between the two.

    More often than not on the 8.3 Viper engines, headers have provided less of a power increase than I've seen on other engines.

    Headers work and are more than just free-flowing pipes to help exhaust gasses get out of the cylinder.
    They work on "rarefaction" as well.
    When the piston is on the way down during the Power Stroke (nothing to do with Ford Diesels here ;)), the Exhaust valve opens and exhaust gasses begin their journey out of the cylinder and out the exhaust system. The piston (now on it's way UP) pushes most of the rest of the exhaust out.
    As the exhaust is leaving the cylinder (piston still rising), the Intake Valve Begins to open and the fresh air/fuel charge coming into the cylinder gets an assist by the draw of the Exhaust gasses leaving the cylinder.

    You may have heard the term Overlap (when both the Intake and Exhaust valves are open) in camshaft terminology and that is what/when it is.

    Now the theory comes into play: When the exhaust pulse is travelling down the Header tube it hits the collector and a negative pressure pulse goes back towards and into the exhaust port which can partially block the new air/fuel charge from leaving the cylinder (a good thing). These pressure waves (Rarefaction in action) assists exhaust scavenging and increases torque.
    WHEN this occurs is a function of camshaft design, the length of the exhaust header pipes and the diameter of the header pipes. That is why a properly designed long-tube header helps produce torque as there is enough pipe for the good stuff to be able to work their magic.

    Shorties do not have enough pipe to work as above. But they could help IF the exhaust manifolds were restrictive to start with, in which case anything would help. On a race engine, Shorties can be beneficial for other reasons.

    More often than not, headers seem to do little to increase performance (much) on the 8.3 and it could be because of a low overlap camshaft as many manufacturers are going with.

    I hope you didn't glaze over too early as this can be pretty dry stuff but isn't easy to try to explain without creating a baseline then yakking' from there.

    As for ported heads: Flow numbers tend to sell cylinder heads and I don't really know of any other way of trying to promote them if I were a head porter.

    Do ported heads help power production? Yes, absolutely, but only to a certain point when comparing flow numbers. A head that can flow 350 cfm does not automatically make more power than that same head ported to flow say, 310 cfm, for example. All heads have there limits and sweet-spots.

    If you are out shopping for ported heads don't believe the one with the high(er) flow number is the best one to get. With that, there are several ways to "cheat" cfm numbers that don't translate into better performance once they are bolted on.

    Our o.e.m. Gen III heads flow 270 c.f.m. (cubic feet of air per minute).

    Aftermarket Striker heads flow 330 c.f.m. but keep in mind that increase was NOT from porting the oem head but from a replacement aftermarket head.

    That increase in c.f.m. the Strikers brought to the table (coupled with advanced port and combustion chamber design) and a small camshaft, provided an increase of 143 horsepower to the wheels on my engine and the identical power number on another SRT-10 (regular cab) with the same camshaft.

    Would either of these engines produce more power if say the Striker heads were ported to flow 400 c.f.m.? No.

    At a certain point, increased flow (c.f.m.) becomes detrimental to engine performance in the form of air fuel separation (incomplete combustion) and/or port stall where efficient airflow drops dramatically.

    MPH at the end of the 1/4 mile is a great indicator as to whether an engine picked up power or not.

    I've seen ported heads that made a dramatic difference and produced big MPH gains. I've also seen some really high-flowing ported heads that made NO difference or actually lowered MPH.

    Tearing these engines apart will often tell the tale. You can SEE evidence of combustion on the piston tops (and often the area immediately above it on the combustion chamber.) The idea here is to have as much of the cylinder showing evidence of combustion as possible. An engine with lackluster performance likely shows a lack of combustion).

    The worst example (best example?) of a high-cfm porting disaster I saw years ago was on a 440 piston that had a burn spot about the size of a silver dollar. The rest of the piston was silver as was the combustion chamber. This meant this engine (HEAD) was experiencing massive Air/Fuel separation. As fuel is heavier than air, if the path through the heads and valve isn't properly designed, fuel and air (still in a vapour form and ready to be burnt) will part company and combustibility drops substantially.

    Liquid fuel doesn't burn and the silver areas on the piston top indicated that.

    Often when someone is bolting on some shiny new ported heads, a number of other engine changes occurred as well: An increase in compression, a changed cam profile, exhaust changes, intake changes, a tune, weight reduction, gearing, tires, etc; and it's often difficult/impossible to say how much of a performance increase was attributable TO THE HEADS.

    Rather than going off of flow numbers, look at track performance, combustion burn-patterns inside the engine (not often an option) and to a lesser degree, dyno numbers.

    But to close with Headers/Exhaust, I spent almost as much on the exhaust system as I did on cylinder heads. The performance difference wasn't even close to being comparable.

    If this generates more questions, fire away and I may even be able to answer them.
    I hope somebody got something from this LONG post and even if you disagree with it...that's something! :)

    Ronnie
     
    Last edited: Oct 11, 2021
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  6. AMS3

    AMS3 Well-Known Member

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    Great summation, and I just learned something valuable. Sometimes adding shiny objects don't necessarily mean gains. I was going to go with B&B last year before covid, but the cost is astronomical for the long tube ($2200 at 2020 price) and 1K for the high flow mid pipes. After what you've said about the stock manifolds, I'll just stick with those and just change out the mufflers.
     
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  7. Tincup

    Tincup Full Access Member

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    I did consider this, my other vehicle is a Hemi powered Dodge dart, it's light (3400) and has about 400hp and I'm sure it could kick my trucks butt.
     
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  8. Tincup

    Tincup Full Access Member

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    Thanks Ronnie, my engine is a 2005 from a QC SRT10. Like I said in my post, I'm not really looking for gains, (would be nice) I put on the headers for weight savings, and the cool factor. I just don't want to loose HP due to a crappy design.
     
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  9. rottenronnie

    rottenronnie Well-Known Member Supporting Member

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    I hear you loud and clear but I don't want to turn anyone away from purchasing headers OR trying anything else for that matter. I'm simply passing along what my experiences were with my engine (and others I was involved with). I don't think you would ever lose power bolting on headers; but some engines responded better than others. Sometimes a bit of re-tuning will optimize a change like installing headers and/or changes like cat-deletes, for example.

    B&Bs' claim their test truck picked up FIFTY with headers and exhaust was interesting.

    There were cam degreeing issues with some of the 2006s to meet emissions that particular year and they were installed retarded** Nothing to do with possibly offending anyone as this is a valid term and is officially grandfathered. :) (Hopefully this crap has run it's course)

    They were hard(er) on fuel and were considerably down on power (what more could you ask for?) :)

    A stock Gen III engine's vacuum should be 12" with a fully warmed up engine. Some of the 2006s engines were down around 10" or even a bit lower; which was a dead giveaway.
     
    Last edited: Oct 11, 2021
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  10. rottenronnie

    rottenronnie Well-Known Member Supporting Member

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    I owned a 1971 Hemi-Charger RT years ago. That engine was a pain in the ass to keep tuned (dual-point did NOT cut it) and plugs lasted around 1000 miles primarily because of the HEMI "BOWL"-Combustion Chamber. That chamber had no Quench like the modern "Hemis" do and the plugs on those older engines took a real shit-kicking from heat.
    One of the very best things I did was to convert the dual-point into the MUCH better Electronic Ignition systems Mopar was offering.

    But when they were properly tuned with enough advance, they were killer!!

    That low 425 horsepower rating (at 5100 I think), was funny.
     
    Last edited: Oct 11, 2021
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  11. rottenronnie

    rottenronnie Well-Known Member Supporting Member

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    I'm glad you got something out of the info.

    I have a B&B system and it sounds great. I wish it picked up some power with the addition of their headers but it's nice to wish for things. ;)
     
    Last edited: Oct 11, 2021
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  12. rottenronnie

    rottenronnie Well-Known Member Supporting Member

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    Thanks, it's tough to know how much "stuff" to put into responses because there isn't just one individual reading it and everyone comes in at different levels.
     
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  13. Kiwi SRT10

    Kiwi SRT10 Well-Known Member Supporting Member

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    I think the Gibsons should sound real good.....well their guitars do....don't they??:cool::cool::cool:
     
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  14. rottenronnie

    rottenronnie Well-Known Member Supporting Member

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    Ya know, it's tough to find fault with logic like that...
     
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