Gti16 Exh Manifold Into Rhd 405 Mi16

[JeffR 51]

Hello everyone,

 

This is my first post & I'm trying to establish a couple of facts & fitting issues about the 309 GTi16 exh manifold.

 

I've done a search on this forum & it appears that the tuned (equal length) system at 54mm I.D in the 309 compared to the 62mm I.D. & divided (unequal length) header of the 405 suggests there is little difference between the 2 in std tune.

 

1. Can some one supply the hard (factory) figures of the power & torque ratings of both engine configerations-ie: 309 & 405? (we didn't get the 309 in Australia),

 

2.If the XU9J4 engine has been modified to a higher tune (+200hp), does the 309's system prove better than the 405 8 branch job?

 

3. Can anyone confirm (or deny) that these would fit into a RHD 405?

 

I have tried to fit GTi6 (XU10J4RS) exh manifold into the 405, but they foul on the arb & gearchange mechanism, even with an angle plate to accomodate the different port & stud patterns.

 

Jeff

[cybernck 400 1 Cars]

iirc, dutch guys tested it and it gave 0 bhp and like 4 nm over 8-branch manifold, on a standard engine.

[maxi 36 1 Cars]

Or if you are really clever you would run a GTI6 exhaust manifold modded and mated to an XU9J4 head........ just like me!

 

The std manifold becomes restrictive around 190BHP I was told, My made 216BHP with the 306 item.

 

Maxi

[JeffR 51]

Maxi,

 

How did you get around the different stud pattern? I heard it's not possible to drill & tap the XU9J4 head for the top 5 studs.

 

I think it would be possible to weld up the ports & reshape them to fit the GTi6 manifold, but I'm not sure that even then they would clear the arb & gearchange linkage.

 

As it's a big valve/ported/machined for bigger cam lobes head, I would hate to go to this effort & find I still have clearance issues

 

Jeff

[maxi 36 1 Cars]

Maxi,

 

How did you get around the different stud pattern? I heard it's not possible to drill & tap the XU9J4 head for the top 5 studs.

 

I think it would be possible to weld up the ports & reshape them to fit the GTi6 manifold, but I'm not sure that even then they would clear the arb & gearchange linkage.

 

As it's a big valve/ported/machined for bigger cam lobes head, I would hate to go to this effort & find I still have clearance issues

 

Jeff

 

 

I didnt, I drilled the GTi6 manifold for the XU9J4 layout. There was a LOT and I do mean a LOT of fabrication work involved. I should think I spoent a total of 5 hours with the mig and die grinder. I kept building up the port shape inside and out of the manifold and dressed the shape to match the existing Xu9 ports. I then spent a LOT of time reinforcing the fabrication as with the heat im sure it would have easily cracked. Its now done about 7K miles of absolutely flat out driving. Its still perfect.

 

Maxi

[mfield 20]

I didnt, I drilled the GTi6 manifold for the XU9J4 layout. There was a LOT and I do mean a LOT of fabrication work involved. I should think I spoent a total of 5 hours with the mig and die grinder. I kept building up the port shape inside and out of the manifold and dressed the shape to match the existing Xu9 ports. I then spent a LOT of time reinforcing the fabrication as with the heat im sure it would have easily cracked. Its now done about 7K miles of absolutely flat out driving. Its still perfect.

 

Maxi

 

 

Did you have to re-angle the manifold at all, or was all the work to do with the port reshaping ?

[B1ack_Mi16 67]

Did you have to re-angle the manifold at all, or was all the work to do with the port reshaping ?

 

What would be better at all with the GTi6 manifold compared to the GTi 16 ?

 

Afaik the pipe diameters and the tuned lengts are the same on both the manifold, so I can't really see wht the GTi6 should be any better than the GTi16 one.

 

On the 405 the MC sits behind the firewall too, so I guess it would fit a LHD car.

 

I believe it's a big difference between comparing the std. 405 Mi16 manifold with the gti16 manifold when using rather standard camshafts. With my 285deg @0.1mm and 260@1mm...

 

I already know a 205 Gti in Norway producing 230bhp with uprated cams, 48mm TB's and ported head on the GTi16 one, so I tend to believe the GTi16 is as good as the GTi6 one.

Edited August 20, 2006 by B1ack_Mi16

[welshpug 1,627]

Have you got a picture of the GTi 16 manifold? I'd guess that not many have seen one but we'd all be reasonably familiar with the GTi6 stainless steel octopuss

[Mandic 0]

Here u go...

 

 

Cheers

 

Ziga

[jochem 0]

I think the only difference is the length of the collector and port shape.

Shouldnt be any difference in performance. The gti16 ones seem to crack easier.

[JeffR 51]

Thanks for the pic Mandic-makes for an easier visual comparison.

 

I've just measured my spare GTi6 manifold & it's 62mm I.D. with 55cm primaries.

 

The GTi16 manifold certainly looks smaller-both in pipe length & collector diameter & i've read it also has it's own unique engine pipe (maybe complete system).

 

Black_Mi16, I'm encouraged to hear that this manifold can produce 230hp

 

 

Jeff

[Hilgie 16 2 Cars]

I think one of the major reasons for the UK guys to use a GTi6 manifold instead of the GTi16 is that the GTi16 does not fit a RHD car, due to brakeservo issues.

 

Furthermore the GTi16 manifold was never available in the UK and therefore pretty expensive.

[petert 554]

Here's some hot off the press flow figures that might make you think twice about using a GTi6 manifold on a 1.9L Mi16 head. I made a 12 deg. angled wedge plate, 25mm thick, hoping to allow for the mismatch between the Mi16 and GTi6 ports. The wedge allows the GTi6 manifold to fit perfectly in a RHD 205, positioning the flange in the centre of the tunnel. However, the results speak for themselves! You'd need to have a wedge plate 57mm thick to do it properly, or build your own headers with tapered reducers at least 57mm long. 57mm gives a transitition angle of 6 degrees. On the port centreline, the transistion angle is approx. 15 deg. with the 25mm wedge. Trying to turn the gas flow that abruptly just kills the flow.

 

Of course the other side of the coin is to consider the % difference between the GTi6 manifold and the inlet. The flow doesn't drop below 70% until 0.350", when it's 63%. Remember the std. exhaust cam lift is 0.362". So maybe there's more than enough flow there anyway, to allow the 4-1 GTi6 manifold to work more effectively at scavenging than the 4-2-1 Mi16 design.

 

This should make interesting discussion.

Edited August 22, 2006 by petert

[B1ack_Mi16 67]

Don't suppose you have access to a GTi16 manifold to test too?

 

And might it not be that the GTi6 flows a little lesser because of the tubing going all over the place (like on the gti16 also), while the std. Mi16 goes more or less straight out compared.

[petert 554]

I've been chipping away at this and have managed to reduce the angle down to 9 deg. by blending into the GTi6 flange (see section drawing). My advice for anyone attempting this is don't. I'm sure it will now work but it's just not worth the agro!

[gti_al 1]

Jeff, have you had the second dyno session yet? From what you said a couple of weeks ago it should be insane when it is all sorted...

 

When was that trackday you were aiming for? Was it the HSV one coming up at sandown?

[JeffR 51]

That's a mighty effort Peter. I hope the results reflect the work you've put in.

 

Looks like I'll have to continue with the Mi16 manifold at this stage (unless a GTi16 becomes available real soon, or I can find a way to shoehorn the GTi6 one in).

 

Al, the full tune & dyno hasn't happened yet. A few issues came up which will be addressed when my garage is free again (the GTi6 is getting some overdue attention atm).

 

The Mi is my daily driver & 'tho still rev limited to 5000rpm leaves plenty in its wake!

 

I haven't decided when it'll hit the track, but it will definately be Sandown. I'll let you know when.

 

 

Jeff

[gti_al 1]

The Mi is my daily driver & 'tho still rev limited to 5000rpm leaves plenty in its wake!

 

I haven't decided when it'll hit the track, but it will definately be Sandown. I'll let you know when.

Jeff

 

It is good to hear you are getting some use out of the 405... It is always good to see it somewhere other than the garage on axle stands.

 

And i was asking about the HSV day as i'll be out there with a mates car. I will definately be interested to see yours whenever it makes it out though.

[Sam 4]

How does this work for the other way round - i.e. using a T16 exhaust manifold on a GTI6 head?

[Hilgie 16 2 Cars]

no...T16 manifold does not fit a GTi6 head. Twin port vs single port design...bolt holes don't line up.

[maxi 36 1 Cars]

I've been chipping away at this and have managed to reduce the angle down to 9 deg. by blending into the GTi6 flange (see section drawing). My advice for anyone attempting this is don't. I'm sure it will now work but it's just not worth the agro!

 

 

I did this last year so the GTi6 manifold fitted my XU9J4 head, im convinced it helped my engine make 216BHP. Took me around 6 hours to do including chopping the manifold and reangling it to miss the bulkhead.

 

Maxi