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Thread: Exhaust Header Options

  1. #1
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    Exhaust Header Options

    Hi all. As my forthcoming MKIV build will be my first experience with V8 engines, can anyone help me understand the pros/cons and decision making around headers? Specifically with regard to whether to have a 4-1-4 collector or not. What difference does it make other than aesthetically and giving somewhere for an O2 sensor to be mounted?

    I’ve also heard of double collectors - does this mean that it goes 4-1-4-1? Because I had assumed that as soon as you have single collector (4-1-4) you’ll have a second collector anyway in the muffler itself, unless you’re going for the full-on 8-exhaust pipe extravaganza like a P-51 Mustang (yes, they had the V-12 RR Merlin/Packard engine, I know ).

    Thanks for the education!

  2. #2
    Senior Member edwardb's Avatar
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    Decision really isn't complicated. Is your engine of choice going to have O2 sensor(s)? If so, sampling all four cylinders is better than only one. So the collector provides that. You need the second collector (hence double collectors) since the usual side pipes, including the standard Factory Five ones, have a 4-pipe flange connection. If you don't need O2 sensors, just use straight through headers. Not aware of any particular performance difference either way.

    Assume you probably know this, but O2 sensors are associated with EFI. So if you're planning EFI, whether a crate motor like the Coyote, or a build with an aftermarket EFI installation, do the headers that will take the sensors. Even if you're on the bubble, and might want to add EFI in the future, wouldn't hurt to have the right headers from the start. You can run them with plugs in the sensor bungs.
    Build 1: Mk3 Roadster #5125. Sold 11/08/2014. Build 2: Mk4 Roadster #7750. Sold 04/10/2017. Build Thread
    Build 3: Mk4 Roadster 20th Anniversary #8674. Sold 09/07/2020. Build Thread and Video. Build 4: Gen 3 Type 65 Coupe #59. Gen 3 Coyote. Legal 03/04/2020. Build Thread and Video
    Build 5: 35 Hot Rod Truck #138. LS3 and 4L65E auto. Rcvd 01/05/2021. Legal 04/20/2023. Build Thread. Sold 11/9/2023.

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    Thanks for the reply. Like a lot of folks on here I have read your build threads from beginning to end and have been fortunate enough to have learned a lot from the experiences you shared, so thank you for being so generous with your time and expertise. For my build, I am not certain yet whether I’ll go for a Coyote Gen 3 or a classic pushrod engine. I’m certain though that, whatever engine I end up using, it’ll have EFI for consistency and reliability, so I’d already considered that I’ll need an O2 sensor. I know that some people put them in a single header and some people buy headers with a collector to locate the sensor. I will price up a few options now that I know that it really comes down to “dealer’s choice”. I quite like the look of the collector approach but we’ll see. Thank you for clarifying that, aside from the sensor aspect, there’s not many other deciding factors.

    Andy
    Last edited by mad_dr; 11-14-2019 at 04:58 AM.

  4. #4
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    mad dr,

    You will need to research what your State/Province requirements are for emissions to determine what direction to go with your engine choice. For example, where I live, "year of the block" is key. Speak to other local builders.

    Olli

  5. #5
    Senior Member GTBradley's Avatar
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    This is probably not the direction you were expecting, but don’t discount catalytic converters right off. I have the 4x1x4 stainless headers and GasN side pipes. I love the looks, but they are quite loud and there is an odor of exhaust you have to put up with. In fact, I push the car out of the garage to start it just to avoid long lasting odors my wife doesn’t like. The smell stays in the garage for hours. For these reasons I’m considering high-flow cats to reduce the sound just a tad and cut down on the fumes. I avoided the cats initially because so many people indicated they rob horsepower, but the fact is these new high-flow cats don’t. Depending on your state you may need them, but either way they’ll make the car 49 state compliant.
    Bradley

    Build thread - Mk4, Coyote, IRS, Wilwood brakes, old-style soft top and accessories.

    The distance between "finished" and finished is literally infinite.

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    A place for an oxygen sensor (preferably hidden) is handy even if you're going with a carbed engine.

    Gives you an excellent place to collect quality (wide band) AFR data - very handy info - actually, if you don't have data you're really just guessing...

  7. #7

    Steve >> aka: GoDadGo
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    I'm running a stepped a 4-1-4 set up because I wanted a flatter torque curve than running the traditional 4-into-4 four set up which is essentially a long tube header. While this hampers the top end power, it improves drive-ability which makes me happy.

    > My primary's are 1 5/8" then step into a 1 3/4" before hitting a 3.0" collector.
    > After the collector I run a 3/8" clover leaf (4 X 2" holes) before entering the side pipes.
    > The clover leaf is there to let the gasses expand and not be choked where the 3.0" collector hits the side-pipes.

    The new headers with the adjustable ball flange really are a Great Solution for many problems associated with getting the spent gasses to the side-pipes. I just wish they made them for my application, but I'm totally off the reservation and am running alternate (Not Supported) power!
    Last edited by GoDadGo; 11-14-2019 at 10:36 AM.

  8. #8
    Senior Member Avalanche325's Avatar
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    Pretty much all the info you need is already here. O2 sensors are a must for EFI, of course. But you also need one for carb tuning (unless you have bee tuning them for about 20 years). For a carb, 1 is often put in the sidepipe collector for this. Yes the 4 into 1 and 4-1-4 are loud. Load is fun, but not for long. I have already changed to Flowmaster Slimline mufflers (no longer made) and am thinking about doing another step to quiet it down more. It all depends on your specific engine on how loud it will end up. More power = more noise.

    I have one little niggle. Here I go stepping on toes.....Going to EFI for reliability. Do your research. The top two things that put these cars on a flatbed are MSD boxes and EFI. Mileage, and you don't want to smell like fuel, I'll agree with. Choose your EFI system wisely if you are going to an aftermarket one. There is a lot of experience to lean on around here. There are some guys that swear by their systems, and some that are on a completely different system than what they started with because it just didn't work out. Seek out what has been successful for an engine that is close to what you chose.

  9. #9
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    Hi all - thanks for the replies - there is so much knowledge and useful information on this forum - it’s fantastic. My first “enthusiasts car” was a Japanese import into the UK (where I lived until recently before moving to Canada with my wife). That car was a rarity outside of Japan but despite that, even back in 1997 we had a solid online owners club and a forum where, collectively, you could find out just about anything you needed to know about every aspect of the car: the engine (including internals and tuning), the 4WD system, suspension, body, interior, electrics - you name it. Clearly this FFR forum is similar in terms of being populated by a group of people who know a vast amount and who are keen to share their knowledge and love for the machine. Us newcomers are very lucky.

    Anyway - I’m going to carry on with my research into pipes and headers - the replies above have reminded me of a few things from my previous sports car days:
    1. Loud pipes are fun at first but can be irritating much of the time - especially when cruising on the highway. Ideally pipes that have a nice low idle and cruise volume and that sing at wide open throttle and high rpm would be ideal - perhaps those exist for the FFR, perhaps not.
    2. High-flow cats DO work. I’m prepared to sacrifice a small amount of power in exchange for a quieter ride and to be as emissions-compliant as possible. I’m also in Canada which is (outwardly) striving to be green, so I’d suspect that cats are necessary anyway.
    3. Once I have spent a couple more weeks reading through threads here, I will start a post looking to identify all the requirements that Canada (and, perhaps, BC specifically) mandates. This will include a front license plate and, I am assuming might also include things like wipers, rear fog light, always-on dipped headlights, over riders, etc. Hopefully it’s nothing too crazy like side marker indicators, high-level brake light, airbags, etc...
    4. I will be going for EFI for sure. I know that Papa (Dave) and others had some issues with their initial EFI systems and ended up switching to the Holley Sniper so I’m initially leaning in that direction. Having said that, I haven’t even decided between Pushrod and Coyote yet...

    Having read through a number of build threads, I was initially leaning towards the Gas-N quiet pipes and headers. I know that there were some issues back in 2017 when folks like Boyd were finding that the headers conflicted with the DS engine mounts and chassis - does anyone know if those issues were resolved and are no longer a problem? As I say, I’m still wading through threads so sorry if this has been asked before. Thanks!

  10. #10
    Senior Member edwardb's Avatar
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    Couple responses:

    Agree that side pipes are part of your build plan. Also agree that Gas-N are more mellow sounding than the stock pipes. I've used them on all of my builds and like the sound and the appearance/quality is top notch. I haven't used them, but this is another choice that are supposed to be quieter yet: https://thefactoryfiveforum.com/show...Side-Pipe-Kits!. If you're sensitive about side pipe noise, you don't want the stock pipes. They start loud and get louder.

    Not familiar with the interference problem(s) you're asking about with headers, motor mounts, etc. As long as you're talking about straight tube headers, as opposed to J-Pipes, don't think you'll have any issues. A Coyote is a tight fit, and comes close to the DS footbox. But it's all proven and works. Don't feel like you have to invent the wheel on any of this. There are a number of choices for headers. Factory Five sells them. Gas-N has them. GP Headers is another source. If you go Boig side pipes pretty sure you have to use their actual headers. I've not done cats, but know there are options for some to have cats included.

    One major point, from my side, though is it's not just about the pipes. Your engine choice, and how it's configured, plays a big part in the sound discussion. One of the advantages of the Coyote, in my experience, beyond the factory developed and proven EFI setup, is that it's relatively quiet. I've had two pushrod SBF's (306 and 347) and been around lots of other engines. The Coyote idles and cruises much more quietly. Stick your foot in it and it gets angry. But very civil to live with. Shameless plug, but our local club and the Autoblog organization put this video together last year of my current Roadster with a Coyote and Gas-N side pipes. There are enough throttle hits and drive-by's to get an idea of what that combination sounds like. https://youtu.be/gCBLH-mr7ME.

    You mention airbags. I haven't seen a single Roadster build with those and also haven't heard of a single regulatory requirement. They are designed, installed, and extensively tested for specific vehicles. Nothing you want to be messing with IMO.
    Last edited by edwardb; 11-16-2019 at 04:25 PM.
    Build 1: Mk3 Roadster #5125. Sold 11/08/2014. Build 2: Mk4 Roadster #7750. Sold 04/10/2017. Build Thread
    Build 3: Mk4 Roadster 20th Anniversary #8674. Sold 09/07/2020. Build Thread and Video. Build 4: Gen 3 Type 65 Coupe #59. Gen 3 Coyote. Legal 03/04/2020. Build Thread and Video
    Build 5: 35 Hot Rod Truck #138. LS3 and 4L65E auto. Rcvd 01/05/2021. Legal 04/20/2023. Build Thread. Sold 11/9/2023.

  11. #11
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    Thanks Paul. I’ve actually seen your video a handful of times already (beautiful, of course) and it was your Coyote install that first swayed me in that direction. Since then, having read several other build threads, I’ve flip-flopped back and forth several times between the more refined and reliable Coyote and the more raw but perhaps less complicated pushrod. I suspect that, for my needs, the Coyote will end up being the most appropriate solution.

    I certainly have no interest in tackling airbags unless legally required to and it sounds like, from your response, they’re not normally required, even up here in the safety-fest of Canada. I will try to track down some recent Canadian builds to get an idea of how their build and journey differed from the US path.

  12. #12
    Senior Member canuck1's Avatar
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    Hi mad_dr,

    Whereabouts in BC are you? The province isn't concerned about a lot of the items you've mentioned but the actual mechanic doing the certification can be a big variable. Try to speak to someone in your area who's found a common sense inspector when you're ready.

    I have a set of Quietpipes on the shelf in my garage if you end up wanting to look at going that route. I found them a little too restrictive for my combination and so ended up building my own pipes. I also lived with the 4 into 4 Hooker headers FFR originally supplied, but the ceramic coating is bare minimum. It didn't last very long. My newest cylinder heads weren't a good port match, so I recently had a new set made. I did correspond with Georgie at Gas'n Performance about headers as well. He was excellent to deal with as usual. I had some very particular issues (including delivery timeline) that meant he couldn't do it for me and so I ended up getting them elsewhere:

    IMG_3403.JPG
    IMG_3402.JPG

    That being said, I've bought stuff from Gas'n Performance before and have always been pleased with the level of service before and after sale. If I could have used him for this set, I would have.

    Sean
    MK 3.5 roadster (MK IV body retrofit to MK III chassis) 396W stroker, 4 bbl mass air EFI, QH (self-tuned), AFR 195CC Renegade, XE274HR, GP 4-1-4 SS headers, 3link, 3.73, 15" Halibrand replicas, SAI mod, bumpers, 2 X roll bars, I² electronics, PS, hydroboosted brakes: 95 GT front, custom MK VIII calipers/Cobra discs rear, FFR front, Levy rear LCA's, Forte front, VPM rear bars, CF dash, mod comp layout w/Auto Meter Ultra-Lites, Lucas tri-bar headlights, coupe taillights, painted by SRP (again!)

  13. #13
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    Hi Sean,

    I’m in Vancouver so not a million miles away from you on the Island. I’ve reached out to the only other person I can find on the roadster register who is in Vancouver (there aren’t many in BC/Canada, period) but haven’t heard back yet - he only has two posts so clearly not too involved with the forum I guess so I may never hear back.

    It’s interesting to hear that the inspector themselves can be a factor - I’d feel more comfortable working to a clearly defined list of guvmint regulations/requirements rather than hoping to find a sensible/friendly inspector but perhaps that’s out of my hands.

    I’m guessing you run a front plate but I’d be interested to hear what (if any) of the other things on my list you had to have on your car for it to be legal: cats, daytime running lights, etc. Thanks for your reply!

  14. #14
    Senior Member canuck1's Avatar
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    Some answers below:


    Quote Originally Posted by mad_dr View Post
    Hi Sean,


    I’m in Vancouver so not a million miles away from you on the Island. I’ve reached out to the only other person I can find on the roadster register who is in Vancouver (there aren’t many in BC/Canada, period) but haven’t heard back yet - he only has two posts so clearly not too involved with the forum I guess so I may never hear back.


    Don't forget to try the other forum too (it starts with ffcars) there are some members that may still pop in there as well. There are actually quite a few Vancouver cars that I know of. I can send you a couple links to them, but its probably better if you try reaching out first. I'm happy to offer what useful advice I can about local regs.






    It’s interesting to hear that the inspector themselves can be a factor - I’d feel more comfortable working to a clearly defined list of guvmint regulations/requirements rather than hoping to find a sensible/friendly inspector but perhaps that’s out of my hands.


    You aren't looking for someone who will fudge the truth, just a guy who's been around long enough for you to not be the first replikit certification he/she has done!


    I’m guessing you run a front plate but I’d be interested to hear what (if any) of the other things on my list you had to have on your car for it to be legal: cats, daytime running lights, etc. Thanks for your reply!


    Mike Everson sells a front plate bracket. I ran it for a while, but never really liked the look of the car with a front plate, so I carry it in my trunk, sans the attaching bolts and scratched enough to look convincingly like I just pulled it off on a high curb . Cats not required for my car, not applicable according to my certifying mechanic. Daytime running lights definitely required. You can harvest the DTRL module from a donor Mustang or just buy a new aftermarket one like I did. Simple to wire in.


    Let me know if you have other questions. I know ACBill in Parksville is also a regular contributor on this and the other forum too. He knows his share of lower mainland area builder/owners as well.


    Sean
    MK 3.5 roadster (MK IV body retrofit to MK III chassis) 396W stroker, 4 bbl mass air EFI, QH (self-tuned), AFR 195CC Renegade, XE274HR, GP 4-1-4 SS headers, 3link, 3.73, 15" Halibrand replicas, SAI mod, bumpers, 2 X roll bars, I² electronics, PS, hydroboosted brakes: 95 GT front, custom MK VIII calipers/Cobra discs rear, FFR front, Levy rear LCA's, Forte front, VPM rear bars, CF dash, mod comp layout w/Auto Meter Ultra-Lites, Lucas tri-bar headlights, coupe taillights, painted by SRP (again!)

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