Well, I have always had doubts about the 16vt inlet manifold, unlike the 20vt it does a hard "gooseneck" turn into the head and looks very restrictivee but looks can be....

Anyway, a few have swapped to the grale inlet manifold for a gain of circa 15bhp (dyno Vas) which is a more direct design.

Anyway guy croft is building a grale at the moment and even the grale manifold is proving to be too poor flowing to match a standard un-ported 16vt head

http://www.guy-croft.com/viewtopic.php?f=10&t=2089

So the question is how much of the good porting work would be un-done by the standard 16v manifold? and who is going to build the first custom intake?

Whats Begbie done on his car - isn't that a coupe engine bay in the photos?

yeah - it is a coupe, it is Honza's NA 16v but that manifold is no longer available.

Not sure what Begbie has done, maybe he will answer, but this is the 16vt standard manifold (all credit to paddy 147 for the pic which google found)



and my Grale one I brought to replace it





so has anyone done any work around a different design and is it weakness link with this vs head work etc

So what is better then? The grale manifold or the 16vt stock?

the grale one is better than the coupe one based on my research but what the GC thread says is even the standard grale one isn't up to much. Vas runs the grale one and picked up BHP as the grale one doesn't have the narrow neck just past the throttle body.

From the GC thread

Standard 16v head flows 133cfm at 10"
Standard grale manifold 125cfm at 10"

and the coupe inlet is worse than the grale inlet but untested apart from dyno results (vas)

so it raises the question is head work a waste of time if you use the standard manifold

There must be some benefits to headwork as the port is not free to flow its maximum all the time as there is a big valve in the way. The manifold has no such restriction. At low lift I would assume the manifold could easily outflow the port and hence work to the port/seats/valves etc could still increase cylinder filling.

But it's obvious from the GC thread than there is no point developing the ports to flow 160cfm if you intend on using the stock manifold.

The integrale manifold isn't the best as you'll see but it can be made to flow better. Some serious removal of meat in the area near the gasket surface and a forming of at least a continual taper is possible. A suitable cross sectional area at least. You'd be amazed how much meat has to come out to do this.

http://i3.photobucket.com/albums/y85/1NRO/various005.jpg
http://i3.photobucket.com/albums/y85/1NRO/various010.jpg
http://i3.photobucket.com/albums/y85/1NRO/various002.jpg
http://i3.photobucket.com/albums/y85/1NRO/various018.jpg
http://i3.photobucket.com/albums/y85/1NRO/various031.jpg

I've built a custom manifold too, a whole heap of graft but fun enough to be making a small batch at the minute to a similar design but better still imo. I'm using the coupe runners for this next one as i like some features it has but no pictures of that for now. This is the one I made already.
http://i3.photobucket.com/albums/y85/1NRO/finalwelding001.jpg
http://i3.photobucket.com/albums/y85/1NRO/finalwelding016.jpg
http://i3.photobucket.com/albums/y85/1NRO/CIMG6529.jpg
http://i3.photobucket.com/albums/y85/1NRO/CIMG6526.jpg

If overal flow is your thing thats covered to excess but there is a fair bit more to it than that.

Nik

Saint already PM'd me last week about this. The manifold i'm using is the one from the Tipo, the swan neck bend isn't as sharp as the coupe one due to using 2 fuel rails (1 is in, the other is a return). GC did work his magic on the part that attaches to head and managed to raise the CFM up on it by quite a bit.

So best bet is to get a Grale inlet manifold and have it ported?

If you read Guy Croft's post, you will read he can't port it, as it needs to be split to be able to do this.

Surely if its that much trouble (and your not bound by race regs on use of OE engines) then it'd be easier to get in inlet manifold and runner purpose built?

Of course, but how much money do you want to throw at a one of a kind inlet manifold?

So best bet for a "bolt on" job having read the post would be to put a straight Grale inlet on and generate circa 15bhp?

No, it would probably be better to get the kappa 16vt inlet manifold

Not a cheap item due to bespoke hand made nature but not mental.

The Kappa manifold flows good enough for a ambitious engine build BUT it tunes at the wrong rpm for that kind of engine. You are afterall asking a lot of the 2 litre engine so rpm comes into play. It also has a less than satisfactory plenum volume and without modification won't accept a suitable throttle.

Sidedraft manifolds are available.

Fitting a sidedraft manifold and twin carbs was always the starting point when modifying older Fiat twin cam engines.

What sort of cost are we talking Nick?

Until they are finished and the costs are known I can't be sure, they'll be in the region of a custom exhaust manifold such as you know about.

Didn't know you were developing a batch of them. Could quite well be interested then.

you want to keep your hands in your pockets beggars and leave them there.

Steve has a point, you could use a GC DCOE manifold but have a plenum and TB made up instead of an airbox - the inlets would need bell mouths/radius entry (unlike this cr*p http://i208.photobucket.com/albums/bb91/.../Picture013.jpg)
, generally I liken it to the seirra cosworth intlet,
http://ferriday.co.uk/Cos_manif.jpg
The injector bosses would need to be added, and not have the TB's,

Alloy air box instead of this set up


oh and Paul, the tipo manifold I had was ported by GC, the same as Begbie's - its now melted down and used for coke cans I suspect.

I´ve found, that it moves peak torque of my engine from 4500 (standart coupe man.) to around 5500-6000. But engine could rev. happili to 8000 - wich was almost imposible with standart manifold. Because of lack of the air engine died before 7500rmp...

Now I am also playing with idea to create larger plenum - i didn´t measured the volume, but it seems that it is quite small (according to my rough calc .. 1,2l..) - in comparsion with similar manifold of S2000/1600 group or peugeot/renault sport manifolds... and general rules , that plenum should be at least 1-2times larger than swept volume..
some pictures of peugeot sport, S2000/1600man.

I'll send you some info when I'm getting closer to them being done.

"Steve has a point, you could use a GC DCOE manifold but have a plenum and TB made up instead of an airbox - the inlets would need bell mouths, generally I liken it to the seirra cosworth intlet,
http://ferriday.co.uk/Cos_manif.jpg"

bell mouths being needed is potentially something to expand on Rich, nice for sure but not the end of the road. I say they have origins in a search for the desired length of runner which inturn required them to protrude into the plenum so as to enable the unit to fit in the space available. A worthy compromise in this situation. That being said thats what i'm doing now as I know people want this feature, need it they don't in my opinion."

"The injector bosses would need to be added, and not have the TB's, suppose its similar to what Nik did."

Not far different to what I did, the biggest hassle was trying to balance the compromised location of the extra injectors. The Kappa manifold has it injectors pointing very nicely at the back of the valve so the secondary injectors could never be as perfect. An enthusiast machinist had the patience to set them up as close as we could fathom but still I'd look for improvement. I'd like to see how injecting the secondary fuel from a further distance might work, the 16v coupe runners lend themselves to this at the same time as having the longest SSR possible.

Nik

I have used the Kappa oneand got it modf to 8 injectors, and 88 mm throttle..
I know it can't match a custom made one.. but er see how far it can go.
i take a better pic in the morning

I can believe your results, right where I would expect the move in peak power to be for the length it is.
Plenum volume for a turbo engine is more about supplying demand, the 2 x capacity is a NA theory.
I like your link, I like collecting pics like that too. Here's a full on blinger for the collection http://i3.photobucket.com/albums/y85/1NRO/throttlebody-1.jpg

Nik

Nik PM sent

re. the last point, my target was to fit it in the space I had and thats the length of the manifold supplied by GC the AT bodies were as short as possible to clear the injector rail, and the trumpets were for a Px 600 airbox which is rubbish to be honest, the reverie one could take longer trumpets, even so they are still too short. It wasnt a road car and I wanted to get out on track hence drawing a line and not worrying about it. Any way GC said I can add length the other end e.g. the exhaust manifold side to assist with the tune.

here you go boys ...

http://www.amwdynoservice.com/page25.php?view=productListPage&category=14


and here is what you do to your intake :

http://kuvablogi.com/nayta/789163/

http://s224.photobucket.com/albums/dd72/jq4tm/?action=view&current=img789164.jpg&newest=1


this is the older version of that AMWORKS design plenum :

http://kuvablogi.com/nayta/789166/

http://kuvablogi.com/nayta/789165/

not going cost you too much, and will flow enough.. I think

here is an example what that kind of manifold does evo engine :

http://amwdynoservice.com/page17.php?view=preview&category=5&image=20

radiused belmouth entry, very similar to the inside of Nik's manifold which has radiused entry, thanks JTM