High guys. Early last year i picked up this fantastic looking manifold as mine was cracked (looks like medussa's head). Anyway ive been putting off fitting but the other day i thought id give it a go. Its nearly done now. I have two questions really. 1st is im not sure im going to be able to get a torque wrench on all the bolts as something is allways in the way. Any advice would be great? 2nd What sort of power increase will i get considering the car has just been serviced and is tuned to about 260 - 270bhp.

The manifold probably won't give you any more power.

If its a top-quality item, it may help you achieve greater power from extra supporting mods, but if it's what I suspect, it'll soon fail at the welds and you'll be back to square one.

The standard manifold can support over 500bhp, so there's really no need for a tubular until you're somewhere north of 600bhp

The simple test will be how much you paid....

I paid 250.00 for it nige. It was made by our truck workshop fitter, I know he copied the design from somewhere. Well its nearly on so i might as well give it a go for now. If it cracks ill get the one i have taken off welded. What advice do have about the torqing of the bolts issue? Nige your always helpfull so cheers in advance

Ah - OK, so its not one of the cheap Chinese jobbies that are currently swamping the Coupe community - you should be OK then

Having been built by someone you know, you should be safe.

I stand by my performance statement - in fact knowing that it's not made by a tuning company, I now think you may even lose a bit of performance. One of the main issues with turbo manifolds is keeping the gas speed up (by making the primaries narrow) whilst reducing backpressure by allowing good flow (by making the primaries bigger) - its a fine balance and one that few manifold builders are capable of getting right.

Check the Tigart manifold for how to do it properly

Tigart manifold for 20vt

I like that manifold, the engineering involved looks good.

Shame there arnt more conpanies making them

Remember, with tubular manifolds it's absolutely essential to brace the downpipe so the manifold isn't taking the weight of the turbo and exhaust. Without these any manifold will crack eventually.

I see reference to the standard manifold being good to 500 bhp and can understand the use by many if only due the trouble had with after market versions but I do wonder if the standard manifold flows decent. I know the 16v one flows terrible, not just in numbers but turbulance in the extreme and even a pretty tightly bent tubular version does much better on a flow bench test. Anyone got a broken manifold they can send me to test on a 20v head I have? I can return it if needs be.

Also, knowing only a tiny bit about 20vt exhaust manifolds such as I do can anyone offer a reasoning for Fiat's use of the longer individual runner for no 1 cylinder whereas the other four are grouped together. I've wondered about it and haven't come up with much.

The nature of keeping exhaust gas speed up in the runner isn't necessarily linked just to using a smaller pipe size. I believe that very good air speed can be had with a so called bigger pipe and that the biggest influence is tightness (centre line bend) and number of degrees of bend used to make the manifold. Gases/air don't like to turn corners.

It has to be for packaging Nik surely, aka ease of casting could you imagine the size and mass of one to equalise the pipe length or even up the shortest length. Obviously the 4 cylinder could run a log manifold that the 5 cannot as the ex valve events are too close together in the 5.

I did think ease of manufacture or even some effort at controling the movement of expansion when hot.

I can see the valve event being closer too but honestly don't think the 4 cyl is doing much of a job of seperating that, at least judging by the stinky dirty inlet manifolds I've cleaned out it doesn't seem to be.

now i know where the design has come from. mine looks almost identical to that tigart one. I hope it doesnt fail as ivee had a day of cursing the spanners and scraping my knuckles. just have to wrap it now. thanks for all your input guys

Hi,

enclosed you will find my new manifold.
It has been done on the basis of certain dicussions with 1NRO.
Thank you for these good discussions, Nik.
In next future we will see, if this manifold can support better power range than my old manifold.
Difference between old - new:
diameter old: 38mm OD, 34mm ID
Diameter new: 42mm OD, 38mm ID
Almost equal lenghts - but I am quite sure that you Nik would have chosen another route with less bends etc. :-)

Link:

https://mc.gmx.net/guest?path=10-07%20von%20Stichl%40gmx.de&token=D00CAE3709E7B828&mandant=01&locale=de&viewType=1

Please press GMX Mediacenter Gastzugang, green button

Juergen

Hi Juergen,

I'll look more closely tonight as I'm just on my phone right now but from what I can see you've been busy making a fine piece, masterpiece of routing those pipes to get onto the turbo in that position. Top job
we did have some discussion didn't we

Really???

The link doesn't work for me?

Me neither.

Please try the link once more:


https://mc.gmx.net/guest?path=10-07%20vo...&viewType=1

And please do NOT forget to press the green button
"GMX Mediacenter Gastzugang"

Juergen

Either it doesn't support iPads or that's a pretty poor image hosting site, clicking on the thumbnails doesn't enlarge them......it just does nothing?

The manifold looks very nice though

Works on my laptop.
Looks like a lot of hours went into that

I hope it works

Well that prob other reasons for that dirt Nik, lets say something beyond fiats control. Incidentally its the reason the 4cyl has much longer runners then the 5 as it has to damp the stronger inlet pulsation while the 5 inlet events are close enough to cause very little pulsation in the inlet - which depending on what you want to do is a good or a bad thing, on the exhaust side it dictate the need for seperate runners (on the 5).

Juergen, good stuff as always.

Nice work juergen!

I've had a better look Juergen and it is true, a fine manifold indeed, especially since the turbo has remained in the standard (ish) position. The runners nest as well as could be done I'd venture to say, bet it took some time!

Thinking back, maybe discussion was biased a little towards persuasion

Right-click then "ofnen". To enlarge just drag the window bigger.

Any pics?