mattbenselin 0 Posted October 25, 2008 Hi firstly I'd like to appologise if this is an old topic and people are bored of being asked...but What's better 4-2-1 or 4-1? I know 4-2-1 gives better mid and 4-1 gives better top end power but which is the best for a daily driver? And do you really notice any difference? See my signature for engine spec. Thanks Share this post Link to post Share on other sites
Baz 421 Posted October 25, 2008 All the aftermarket manifolds i know of or had have been 4-1 for an 8v. Not that you'll see a major difference even with your mods. Share this post Link to post Share on other sites
mattbenselin 0 Posted October 25, 2008 Really? I understood that on a standard to lightly mod'd engine a manifold does little to nothing, but with carbs and a 285 cam it still makes no improvement? Share this post Link to post Share on other sites
projectpug 0 Posted October 25, 2008 Probably see a couple of hp increase at the top end of the rev range , Most 8vs have 4-1 manifolds and most 16v use a 4-2-1. Share this post Link to post Share on other sites
mattbenselin 0 Posted October 25, 2008 So is it a worthwhile investment, or just a luxury? (found one for circa £80) I feel I want to get the most out of my engine but that money could be spent else where. Thanks Share this post Link to post Share on other sites
projectpug 0 Posted October 25, 2008 I think its worth it as every little helps IMO. I also think the sound of the 4-1 is awesome Share this post Link to post Share on other sites
hengti 2 Posted October 25, 2008 i thought mine helped torque (a little) rather than power. they're worth a go as they're not a deal of hassle to fit - although they can be unreliable Share this post Link to post Share on other sites
mattbenselin 0 Posted October 25, 2008 Unreliable in what way? Corrosion, cracking? I was planning on painting it with VHT, covering with exhaust wrap, then using a 200mm section of steel exhaust flexi connector to join to system. Share this post Link to post Share on other sites
hengti 2 Posted October 25, 2008 cutting the knuckle joint off and replacing it with a stainless flexi would be a good idea (the knuckle joint is the main problem - there should be more info available on search). otherwise, they're just not all that well made - i had the pipe to head flange welds crack on mine, and the blanking piece that seals in between the four pipes fell out into the collector - had to be cut open and all welded up again. mine didn't corrode too badly at all, but wrapping an exhaust can apparently promote corrosion as you're trapping moisture in - i guess painting it first would help Share this post Link to post Share on other sites
mattbenselin 0 Posted October 25, 2008 Thats what I heard so painting it should help. I'm hoping using a flexi connector will reduce the risk of cracking, I want to keep a rubber bottom mount so engine movement will be an issue. Share this post Link to post Share on other sites
Baz 421 Posted October 25, 2008 It'll still crack, they're crap for that. Use a solid lower mount, and space the top mount out to reduce movement & the likelihood of it cracking if it isn't already. But tbh, i'd save the money and buy some proper carbs... Share this post Link to post Share on other sites
projectpug 0 Posted October 26, 2008 I agree with Baz on engine mounts i uprated mine to grp N items just after fitting the magnex 4-1 stopped it from banging against the subframe! Share this post Link to post Share on other sites
mattbenselin 0 Posted October 26, 2008 Trouble is I want to use my car everyday for the commute and stuff, I've been in a 205 with solid mounts and the vibrations were a lot harsher than I expected. Is the consensus that fitting a 4 branch with rubber mounts, even if I have a flexi connection to the system will eventually crack? Thats s**t! Anything else I can do? My top mount is already spaced for reduced movement. Share this post Link to post Share on other sites
Baz 421 Posted October 26, 2008 It will crack anyway... I meant solid rubber 'GpN' mounts, rather than actually solid metal ones. Everyday commute, with carbs? Share this post Link to post Share on other sites
mattbenselin 0 Posted October 26, 2008 Yeah when I say commute it more of a bash through country lanes! Lucky me i guess! And I want to do something new to the 205, I always wanted carbs! So you think the 4 branch is not worth it cause it'll break? how come so many people have them and they made so many, if they are prone to breaking? Share this post Link to post Share on other sites
Simsy 0 Posted October 26, 2008 Yeah when I say commute it more of a bash through country lanes! Lucky me i guess! And I want to do something new to the 205, I always wanted carbs! So you think the 4 branch is not worth it cause it'll break? how come so many people have them and they made so many, if they are prone to breaking? I had a similar dilemma with an old car, i bought a system from the US that was renowned for cracking, mainly due to poor support of the system. I had this and used a flexi like this as you say you are going to. I know it was a totally different car but the theory is the same, i'd imagine the 4-1 magnex is unsupported so it might just benefit from extra bracketry or perhaps removing the vibration it sees (flexi). Surely its a stainless system too so corrosion isn't an issue? Share this post Link to post Share on other sites
projectpug 0 Posted October 26, 2008 (edited) Its the welds arn't corrosion free. I would fit a 4-1 firstly VHT painted in black/silver then heat wrap it and seal that. And Gp N mounts like i mentioned in my last post i wouln't crack any more than the original one cracks tbh. And you can always have the crack repaired/rewelded if one ever appears. Edited October 26, 2008 by projectpug Share this post Link to post Share on other sites
hengti 2 Posted October 26, 2008 i think Magnex required that the mani was fitted together with an uprated lower mount anyway, and they don't add as much vibration as an uprated top engine mount (ime) you might find a s/h mani will have weld cracks already, so to give it the best chance, you could run over the problem welds with quality TIG welds before installing it Share this post Link to post Share on other sites
Simsy 0 Posted October 26, 2008 (edited) Its the welds arn't corrosion free. I would fit a 4-1 firstly VHT painted in black/silver then heat wrap it and seal that. And Gp N mounts like i mentioned in my last post i wouln't crack any more than the original one cracks tbh. And you can always have the crack repaired/rewelded if one ever appears. Oh right, i assumed Magnex used stainless MIG wire. I've had one of their systems and the welds didn't appear to have any corrosion issues. That said, the manifold sees more thermal shock that a backbox does Anyone got a pic of the manifold anyway, just out of interest, mine is staying standard...honest Edited October 26, 2008 by Simsy Share this post Link to post Share on other sites
mattbenselin 0 Posted October 26, 2008 Magnex 8 valve 4-1. Not the exact one but identical to this. Share this post Link to post Share on other sites
Simsy 0 Posted October 26, 2008 Magnex 8 valve 4-1.Not the exact one but identical to this. Well, unsurprising it breaks then. There is going to be a lot of stress where the primaries are welded to the plate that bolts to the head. I had a piper system on my old fiesta years ago which looked like this..... Might be worth bracing your magnex similar to the way the piper one i had was done? Share this post Link to post Share on other sites
Baz 421 Posted October 26, 2008 That's what i did on one of mine a few years ago, didn't see how long it lasted as i sold it and was better off with the money than the hassle! Share this post Link to post Share on other sites
MarkK 2 Posted November 1, 2008 Ive just fitted a Magnex 4-1 manifold and my car seems quieter....anyone else noticed this or am i losing my mind??? Share this post Link to post Share on other sites
Cameron 16 Posted November 1, 2008 If they're welded properly I don't see any reason why they would crack. None of the manifolds we make (BTB) are braced to the flange like that and I don't think we've ever had problems with welds cracking. I guess we just have a better method of attaching the primary to the flange so the stress isn't all in the weld. To be honest though, a mild steel manifold is regarded as a disposable item so isn't designed to last more than a few years. You're best off buying new. As for the manifold being quieter, have you lagged it? Mine was massively quieter after wrapping the (GTi6) manifold and system. Share this post Link to post Share on other sites
