handmade manifolds

[rikrose]

Dude. You just paid 100 quid for a set of exhaust manifolds. Bear in mind te cost of failure of them - can these take out your turbos? If so, what's your comeback on them - can you afford new manifolds, turbos, and the cost of removing all those little pieces of turbo from inside your block? You're PAYING for a product that is ultimately going to fail by cracking or leaking, and do so in 6 months or less.

What are you thinking, man? Get back on ebay, tell them you'll leave positive feedback for quick postage in exchange for them refunding you in full and not sending the stuff out!

[fletchie55]

I think the idea of buying the manifolds was to examine them for potential weaknesses and then strengthen them where necessary prior to fitting or testing. the main problem with the manifolds on S4 is the cost involved to remove engine to change them, as stated, the manifolds will be going on the 2.7 V6 engine, but not in an S4 so access to them shouldnt require engine out.

if the welds are all re-done if necessary to ensure they wont crack then I dont see much risk with testing out the new product

[rikrose]

there was a message earlier in the thread that I'm too lazy to look for now, stating that they could well be using different metals for various sections of it. This would lead to cracking very easily, and if it doesn't crack it'll bend awkwardly. The expansion of metals with heat is linear with the temperature. We're talking about a 900 degree difference. That's non-trivial. What sort of tolerances are we talking about in the mating of parts here?

If it's just for playing with, for investigation, then I suppose all is cool. I'd just feel bad if someone here was actually going to try to use it for real on their car.

[DavidT]

Yes, it will be nice to see some facts relating to this product.

[confusionhunter]

thanks for the warning, but Im not stupid I did think about that.

These manifolds are for an engine that wont live in an A4 platform so if they crack they will be a peice of piss to fix. Also I have made my own manifolds in the past and 100 quid is cheaper than it would cost to have the flanges made in mild steel and at worst I can cut them up and use the flanges for custome manifolds.

I dont have high expectations, but provided they arent total crap ( and if Im honest they dont LOOK that bad) they wont crack provided I can support the turbos properly.

The std manifolds take the weight of the turbos and the downpipe, clearly these manifold havent been designed with that in mind. As far as the different metals go. Ive previously made manifolds in mild steel flanges and stainless tubing and thats not cracked so Im not concerned to much about the materials. Yes its an experiment, performance wise they've got to be better than std, Ive just got to modify them to take the weight etc.

as for the mating of parts, the fit is all over the place.... in fact the s4 heads have much larger ports than the exhaust manifolds.
So the std s4 fit is terrible... nothing I cant fix as I will port match these if they need it.

[MCB]

thanks for the warning, but Im not stupid I did think about that.

Well I thought you were.

As I'm only joking is your project Top Secret or can you share as it sounds really interesting?

[confusionhunter]

well.... A "special" level of mental disposition is required to do these daft things..... Not secret but it might not happen so I wont get too excited. However I will divulge my parts list consists of K04s, NA heads, RS4 cams, multiple throttle bodies and a DTA P8Pro....

[Dippy]

The std manifolds take the weight of the turbos and the downpipe, clearly these manifold havent been designed with that in mind.

So considering that these manifolds are sold as aftermarket replacements for the stock S4 ones, you are clearly stating that in your opinion they are not fit for purpose?

[rikrose]

Ah good. You're not stupid. Excellent. I wanna hear about the project now!

[confusionhunter]

well I like to think Im not! Thanks for the vote of confidence

So considering that these manifolds are sold as aftermarket replacements for the stock S4 ones, you are clearly stating that in your opinion they are not fit for purpose?

Bang on. my theory is this:

If you think about what the manifold is doing: Imagine the weight of the turbo and the downpipe. Imagine the flex of the engine movement, If you've ever seen the Snub mount demo post on audi world or ever fitted a DTS and felt the difference, imagine the amount of movement there is. Lots.

Now stock manifolds are built incredibly solidly and dont flex much so any flex between the engine and exhuast is at the flexipipes.... exactly the way it should be....

now if you expose those same forces and consitions to a thin walled stainless pipe(which is the weakest point of the manifold eiter by the turbo flangd or at the collector box)..... To me its fairly obvious its going to crack fairly quickly as the manifold is bound to flex. If you eliminate the flex and have the manifold only being a manifold rather than a turbo/exhust support bracket then I beleive it will last as it should.

It doesnt matter how well its made or not if its not designed to take the weight its not going to last, and I know this from personal experience. If you look at this manifold you'll see there is a large lug for a turbo support bracket to the left, thats its only purpose:
http://www.rs246.com/index.php?name=PNp ... hlight=g40

It seems a shame, its obvious someones gone to the trouble of designing a decent 3-1 manifold (from the pics) and manufacturing them and fell over at the last hurdle. Im sure if thick walled had been used or some sort of bracket had been made then it would work, but by that point these manifold may have been made already, theyve realised their mistake and cant really sell them at full price because they aren't fit for pupose out of the box.

I just want to make it clear that there is nothing wrong with thin walled stainless exhuasts.... if there job is only to direct gases.... this is where i think they've messed up.

At the end of the day I'm pretty sure thats the case and I'm willing to put my money where my mouth is..... If I can supprt the turbo properly Im willing to bet these manifold will work well and for 100 quid? I'm laughing.
We shall see!!! whether Id put them on an S4 is dubious, may be difficult to make a turbo support bracket for back there! But after testing I might just do that..... you never know.

[MCB]

My money is with you, metaphorically speaking!

Forgive me if I have missed the obvious , you are building a new engine for your car?

[rikrose]

Ahhhh. Now that sounds like a plan, and an interesting one at that. I'll look up results when I get back from holiday.

[Doug_S2]

the problem I think is that they are made with smelted scrap metals so it is not up to the job of 1000 deg c temps.
I have a 1.8t one sitting in the shop - they even have been hand finished and smoothed inside then polished on the outside. Cpmmon - decent stainless material is not even that cheap!

All the 1.8t cars I know of (5 of them now) have had the runners crack, the flanges warp or the flanges break away from the runners.

I recommend people not to buy them becasue if you supply them and we fit them - if/when they crack - you have a big bill to swap them - so the long run it is no cheaper to go for proven manifolds that work.

confusionhunter has the right test bed of a car to try this - I am looking forward to his results.

[dummi]

as for the mating of parts, the fit is all over the place.... in fact the s4 heads have much larger ports than the exhaust manifolds.
So the std s4 fit is terrible... nothing I cant fix as I will port match these if they need it.

that is the way it should be its so that back pressure has a step down at the heads to the engine

[confusionhunter]

errr... I think you getting confused mate. If you have a step then the manifold should be larger than the Head, not the other way round like on a std S4. And that really an NA trick too. RS4s have smaller exhuast ports so that they are port matched to the exhaust manifolds.....so it seems cosworth disagree with you too .

I personally think the stock manifolds are guff as performance manifolds. Its a log type! lol. But you have to remember its a stonking engine they are attached to so for most people the manifolds arent an issue...