6 branch exhaust manifold..good modification or not?

[matth76 0]

Hi

I'm having a 6 to 2 to 1 stainless steel branch exhaust manifold fitted to my Golf VR6 (ODB2). Is this a good modification and what kind of power gains are expected if any - are we talking approximately 5bhp / 5ft/lbs? Will the drivability / throttle response be improved? I currently have a high flow cat and free flowing stainless exhaust system.

 

I'm having my head gasket and timing chains done at the same time and I was told by Storm Developments (the company doing the work) that it would be an opportunity, with the head off, to fit one. It's one of their own make and used on their racing golfs.

 

I also need to know what kind of heat wrap is required (something good quality that will last) or whether some kind of heat shield is better than heat wrap but if so where would it be situated in the engine bay? I'm assuming the standard heat sheild can be still be used?

 

And do the engine mounts underneath where the manifold will be, need to be replaced or is this not really necessary - or do ALL the engine mounts in the engine bay need replacing? Is this something that can be done at a later date or is it far easier to get done while the manifold is being fitted? Is fitting of new engine mounts a quick inexpensive job? Should uprated mounts be used?

 

How long will an aftermarket stainless steel 6 branch last for? Will it last longer than the stock exhaust manifold?

 

Thanks for any help.

 

Matt

[Kevin Bacon 5]

2 things with tubular manifolds - Keep them hot and keep engine movement to a minimum. Uprated front and rear mounts takes care of issue no 2 (use Vibratechnics if you value refinement) and a good quality thermal wrap properly fitted takes care of the heat issue.

 

The reason iron manifolds are so good is because iron stores heat a lot better than thin walled steel tubing and the heat of the manifold helps pull spent gases out of the cylinders. This is why you need to wrap the tubular manifold. They cool down too quickly if not wrapped in a blanket.

 

No body really knows what you'll gain as there is very little info around on 6 branchers on VR6s. So the only way to tell is by pre and post dyno runs. Normally you'd seen improved torque in the midrange but not huge amounts of extra power.

[matth76 0]

Thanks for your reply. Is a tubular manifold still more effective due to it being a "6 branch" as opposed to 2?

 

Will a stainless steel tubular manifold tend to last longer on average then the stock one made of iron?

[Kevin Bacon 5]

It can be, it's entirely down to how good the tuning design is. The amount of branches is irrelevant, you need one per cyl regardless, but the length of the branches and how they converge together in the collectors is more important.

 

The standard VR setup is 6-2-1. But the 6-2 bit is very short (iron). The 2 - 1 bit is long, using front pipes (stainless). Your 6 brancher is the same but it's all in the length of the headers and collectors, rather than seperate components. The other bonus of tubular manifolds is they are a constant bore from head to first collector. Some iron manifolds can be quite restrictive in places.

 

Designing a 6 branch requires a lot of knowledge about exhaust tuning and also in the case of the VR6, assymetric head characteristics. If they get it wrong, it will be more of a hinderence than a help.

 

The iron manifold will last longer as it's not subject to any metal fatigue caused by engine rock. The flexi joints in the front pipes ensure that. Iron manifolds can crack, but it's rare on the VR.

 

Providing the tubular manifold is kept as still as possible and the flexi joint at the Cat junction is a good one, then it should last for years and years.

[matth76 0]

Thanks for your reply. I've just been told by Storm Developments that the 6 branch I'm getting is one of the best on the market today. It's their own design and made in China. It has flexible bolts/brackets/joints that are stronger than the standard ones that use springs to keep it totally independant to engine lump movement because I did ask about stress fractures. It's apparently the highest grade stainless steel you can get (not quite as good at retaining heat as iron but constant bore throughout so will transfer the exhaust gasses quicker.. )

 

It uses the original heat shield they say so shouldn't need extra heat wrap. Although should I insist on heat wrap? Is it only the top part that connects to the engine lump that needs the heat wrap?

 

They seem a helpful company and told me recently I didn't really need a 'metal' head gasket as the standard one is good enough. Unless I was going down the supercharged route there's no point getting a metal gasket which actually raises compression as it's thinner - costs an extra £100 so I know they aren't trying to sell me everything they can. They deal with Stealth so must be trustworthy (hopefully!). Does anyone else on here dealt with Storm and have worked on your car?

 

By the way what difference to drivability would fitting a Corrado vr6 2.9 fuel pressure valve make to my Golf VR6? Would it improve response to low down revs? I know it won't actually increase power though.

 

Cheers

Matt

[Kevin Bacon 5]

Interesting, you'll have to send me a pic if/when you get it as it's a mod I've been considering for ages. I especially like the SuperSprint one....and that is definitely the best on the market imo. All SuperSprint headers are thoroughly tested, dyno proven to work and have all the necessary clearance where Anti roll bars and steering racks are concerned. I'm sure the Storm D one is good but ask them if it's in the same league as the £600 SuperSprint!

 

The ideal setup is a schrick inlet manifold and a tuned length tubular manifold. The runners will all be tuned lengths in and out for maximum torque. Ask them if the exhaust runners on their manifold are properly tuned for the assymetric VR head.

 

I would definitely recommend wrapping the runners mate. You want it to retain as much heat as possible, especially this time of year.

 

I've had no dealings with Storm Developments but a few guys on here have, with mixed feelings. They sound OK from what I know of them though.

 

On the pressure regulator, depends what pressure your fuel pump is. Some Golfs had 3 bar pumps, so fitting the 4 bar Corrado FPR wouldn't help as there would be too much pressure at low rpms.

[matth76 0]

Thanks for your reply. Do you think I have to "run my car in" for a certain period as I'm having my head gasket and chains done as well? I'm assuming when I run it in I shouldn't go over a certain number of revs?

 

I'll ask them about the exhaust runners on their manifold. They did say it was specifically designed for the Golf VR6 engine.

 

I do know the FPR on the Golf is 3bar so I'm assuming the fuel pump will also be this pressure. Is there any advantage to fitting an uprated 4bar fuel pump from a Corrado 2.9 and the 4bar FPR ?

 

Cheers for your help.

[Kevin Bacon 5]

I recognise you from the VROC forum? Welcome aboard ;-)

 

As per the other thread on this matter, nope, no running in required. Also note my other comments about turning it over before putting all the inlet parts back on. It's more for peace of mind than anything else as I've seen a VR skip a tooth as it fired up because VW don't always supply the tensioning bolts prepressurised, but if you use the later MK4 stuff, the tensioner is spring and hydraulic, so not quite so critical.

 

Yeah, your FPR will have 3.0 bar stamped on it by way of confirmation.

 

There will be no gain in fitting the 4 bar pump and FPR on a standard engine. If you supercharge it, then yes you will need them both.

[matth76 0]

Yeah, I'm from the other forum :)

 

I'll have to hope that Storm do test turning it over before putting all the inlet parts back on. They seem to know their stuff though.

[Kevin Bacon 5]

It's a standard procedure for the likes of Stealth, so hopefully SD will follow suit ;-)

[NormanCoal 0]

The metal HD used by many instead of the original fitment type is not £100....

 

How much are they charging you for the 6 branch? Be good to see pics of it once you have the car back (or before if you can)

[matth76 0]

The metal HD used by many instead of the original fitment type is not £100....

 

How much are they charging you for the 6 branch? Be good to see pics of it once you have the car back (or before if you can)

 

Hi there, I'm paying £350 for their 6 branch. They aren't charging me to fit it which is good. It's a bit more expensive than other makes as it's supposedly higher quality and more advanced which won't shear like cheaper makes they told me. It's their own design which they have made abroad in China apparently and uses similar flexi joints to the standard manifold but they told me the joints and bolts are actually stronger which use springs to keep it independent to engine movement. My current standard engine mounts are in good condition which they have told me don't need to be uprated. This is something I could get done in the future. How much on average would a garage charge to supply and fit uprated engine mounts (such as Vibratechnics)? Is it an engine out job to fit them and how many mounts are there altogether?

 

It uses the original heat shield. Does the heat shield help to retain heat in the runners similar to 'heat wrap' or is the shield used for something else?

 

Re the metal head gasket - I'm not going for that any more as it would lower my compression very slightly which I've heard reduces total power output (unless I go down the route of forced induction which I may in the distant future) so for now I'm having a new standard head gasket kit fitted and new but standard bolts.

 

I don't have any pics of my engine beforehand but I'll take some of it afterwards definitely.

 

Cheers

Matt

[matth76 0]

What difference will a new flywheel (standard flywheel) make to the driveability of the car? I assume there is no torque or power increase though. At what point can a new flywheel be added? Is it when the gearbox is out?

 

If a standard flywheel (exchange) is £75 - how much would a 'lightened' flywheel be and what are the pros and cons? Is it worth it?