Hi all

As I'm sure most of you 16VT owners know, the standard exhaust manifold a downpipe is a very poor design. The exhaust manifold ports are about as uneven as you can get; ranging from about 12 inches long on cylinder 1, to a just a few centimetres on cylinder 4. The 2 inch bore of the downpipe and exhaust elbow is restrictive on standard horsepower, let alone after the power has been raised.

I am looking into developing a totally new tubular manifold and downpipe combination to fit standard T3's, hybrids and T34. The idea would be to re-locate the turbo more centrally to enable a better flowing header.

My current idea for the spec is as follows:

Manifold
304 stainless steel
42mm o/d
Turbo relocated to allow good flow from all cylinders
equal length headers
42mm internal diameter tubes.
T3 flange
flow-tested to at least 350bhp+

downpipe
304 stainless
either 2.75 inch, or 3 inch diameter
One single turbo flange designed to fit both standard turbo and Cosworth style turbine housings (maybe V-bands as well, if possible)
exhaust flange to fit standard cat' or decat pipe.

Price for downpipe and matching manifold together: around the £600-£650 mark.

Currently there are several different designs of 16VT manifold on the market, most of them of pretty poor design - the one I currently own included! And, AFIAK, there are no uprated downpipes currently in production for the 16VT. So the idea is to finally have a well-made manifold/downpipe combo for the 16VT. Designed the way it should have been made in the first place!


Please note, this is NOT a group-buy ad; I'm not asking for money! I'm merely polling for interest to see if it's worthwhile proceeding. Providing there is enough interest, these wouldn't go into production until next year.

Developing and manufacturing a run of manifolds is expensive, so I must please ask with the greatest respect to put your name down only if you would be genuinely interested in purchasing.

Thanks

Couple of points :

• You mention that the O/D is going to be 42mm, but the I/D is 42mm, so which is it going to be?
• If you move the turbo more central, are you going to provide a new oil feed and return line, as you will not be able to use the standard items anymore.
• Are you going to keep the turbo at the same height, as if you drop the height slightly, you won't be able to use the oil return in the block
• On the downpipe, if the turbo is central, you will need to make sure it bends under the car quite quickly, else there will be issues with the wiring / alternator

I use different lenght pipes on my manifold..

but I have twinscroll and they are about same lenght on pairs.

I use standard oil return ( design for that )

evo turbine housing is good, because its already going down like 45 degrees for the exhaust pipe connection.

anyway sorry for my bla blaa blaa.

here is one picture of the design you might be after.. and this is NOT my car.

http://www.alfabbs.fi/album_pic.php?pic_id=10578

The bore of the primary pipes is obviously the critical dimension - the OD depends on the wall thickness. For the standard exhaust valves, 40.3 mm ID primaries is what I calculate you need as both a minimum and maximum. Any larger and exhaust velocity will be too low and have a negative impact on spool time and turbine efficiency in general, any smaller and it will become restrictive at higher revs (though give a better turbo response below 7000 rpm).

The pipe after the turbo (down pipe) should be a minimum of 54mm ID - any bigger will be fine, but will not bring any measurable power advantage.

The std manifold isn't as poor as you'd make out Kj.

Well, your right on the 40 mm ID but the rest of what you wrote is rubbish.

I agree but you put it such a nice way

lol, you're right, I meant to say 42mm o/d! Nothing like proof-reading, is there!


That's right, if the turbo is moved more centrally then new oil fittings would have to be provided with the kit. Not a difficult thing to do, but it's another thing I'll have to into consideration.
On one hand it would probably be more simple to keep the turbo in the oe position. But on the other hand, if you have a big turbo it would be nice to be able to remove gearbox without also having to remove the exhaust manifold and turbo!

It's very early days yet and like I say, this post is mainly about polling to see if there is enough interest in finally getting a decent design manifold and DP. Most of the aftermarket manifolds that have come and gone have suffered from poor manufacturing. So I think it would be good to finally get one that was made properly. If there isn't enough interest then no worries, I'll just make one for myself!

BTW, Group5lancia 1NR0 might have said that a bit harshly (!) but I promise you, there's definitely a performance advantage to going larger than 54mm on the DP!

I know it's early days yet, but i'm just highlighting the problems that will happen as i have already been through all of them

I have to disagree with you on that.
I just finished another batch of Ø70mm SS downpipes for 16VT, bolt on. I've been producing these downpipes for the last 5 years.


For the manifold, i would not use stainless steel as it tends to crack verry easy.

Thanks and much appreciated



I remember seeing your downpipe a few years back. Didn't know you were still making them.

Like I said: if there's a call for them I'll make them. If not, I won't.

Just a few points, I am certainly no expert, I'd like to see something decent on the market too, but before you undertake this seriously read up a bit more.

The standard manifold is not restrictive, your exhaust valves will like it better than most tubular headers. The length of the ports in it- uneven or not have little or no effect on flow per-sa.

Why 304 grade ? Would 321 not be a better choice ?

Exhaust manifolds are not really about flow, you can't flow test one to any level of BHP you care to mention.

I'm not going to beat on, just carfully look at things again.

"Why 304 grade ? Would 321 not be a better choice ?"

The problem for manifolds to please the masses is the cost of 321, your looking at £500 ish just for the mandrel bends, not including collector, flange or labour. People will always flock to the cheap manifolds, they are blind to what is good or bad I'm afraid Richard, just as long as it's shiney eh!

Yep 1NRO, like you said in your usual polite way, 321 is the better choice, but most people wouldn't pay for it.

Anyway doesn't look like there would enough call for this so it so it wouldn't be worth looking into it any further.

It's not about being polite KJ, more a case of not mincing words. I'm not here to kiss ass or tell lies but hopefully to cut through some of the bull at the same time as pointing out the reasoning as I see it. I've had/seen more than my fill of "nice" bullshxt over the years and don't/won't subscribe to it.

You dont like shiny?

Yes, dear

Nik, I know the 321 it's a bit dearer yes but there MUST be a market for something good ? Maybe I'm dreaming, trouble is I find lots of conflicting information even between very well informed soruces.

Two things I am pretty sure of is when a wave see's a turbine it returns and is not damped. The second is the speed they travel could be anywhere between 1700 and 2250 fp/s making it very dificult to calculate a distance. How do you know without knowing the exact EGT ?

This brings another question, are we trying to use it to the advantage for scavenging or is it more a case of fighting backpressure just before evc ?

Thats as far as Iv'e got so far anyway. Maybe I'll just buy something off the shelf and quit now ! Cause I'm getting stuck

Shiny is good, you have to polish the inside to reflect heat inwards. Better than ceramic coating you know !

I don't like shiny shxt, just so happens shxt usually comes polished up.

Shiny = Contribution to engine failure


Not so shiny = hopefully lots of power

Richard,

The wave is reflected off a change in cross section (where the gases meet the collector usually but not always) not off the turbine.
The wave action changes as it travels through the runner, slowing as it travels towards the turbo but at the same time speeding up as it returns towards the valve. Nothing is ever exact in the calculations used as it's application dependant, the best that can be hoped for is a ball park figure to make the first manifold to which if that way inclined is then used as a base to make further manifolds from in order to evaluate the traits seen. The strength of the pulse can be manipulated by different cross sectional areas amongst other techniques.
You'd be trying to get the returning pulse to coincide with valve overlap to assist in pulling the fresh charge.
There's a big difference between the cost of 321 and 304, 321 is about four times the price. A proper turbo collector is also very expensive unless you are very skilled and can make your own, it would require so serious machines and practical skill with a healthy dose of knowledge. I think some people would buy a good manifold but they are few and far between, the market is too tight/poor.
I read lots of threads like this with someone wanting to supply the best but it's very rare that they know even a little about what is involved, some of them struggle with a BOV's purpose eh, dear?!

Your just hacked off because I can cut through your waffling with ease.

Don't waste time effort and money, buy one of my manifolds on this group buy for £200 and use the spare cash towards a decent turbo. I use this manifold to run 340bhp from a 16v with the same torque from a GT2871R turbo. With the new GTX turbo's on the market I'd be looking at those rather than manifolds.
£200 for a proven, does not crack, produced decent performance and fits manifold. http://forums.delphiforums.com/evoforum/messages/?msg=25419.1
Paul

I did'nt mean the wheel it's self I was thinking of the CSA of the housing, where it cones down, much like an expansion exhaust from a 2 stroke, but yes the collector too if not at a very shallow angle is a big difference on CSA.

Makes sense actually, speeding up and slowing as the gas cools.

The calculation is vastly complicated, I doubt all but some of the best software could manage it and we haven't even inculded the engine rpm !

So at the very worst case, it will be timed wrong so it ends up that the + (pos) pulse coincides at overlap, which is not good !

I'm going to have a go at making one anyway, some time off but still learning

No thanks paul, not for me any way.

tigart do one for 16vt

there is actually some good space for coupes, when you replace the radiator fan for a smaller one
( ebay slimline ) and for 16vt you get 2,5kg weight saving for the same
flow bench is a good friend, when doing these jobs, with the manifolds..
I actually gonna buy / build one, so in the future I can test my buildings and buyed stuff, before use, and make them a little better, or maybe worse

for the material, I would use standard black metal, or then this :

http://www.sandmeyersteel.com/309-309S.html

light, and cabable of 1100 degrees of all day long.

here is one picture of manifold for evo..
http://www.amwdynoservice.com/page25.php?view=productPage&product=151&category=2#

The thing is though Paul you could save the £200 and use the oe manifold, it doesn't crack and it fits and it can do the power you have and more, they used it on a restricted works car afterall. The point is for some people who would like to build a full engine package a tubular manifold can be made to serve a function that isn't provided by others.