what would be the best length of runners for a fuel injection manifold on an a1400 turbo for street use and also straight or curved? for the phlenium 21/2" or 3" round or rectanguler hope someone can give me some advice this is all new to me thanks
moridat

Once you're on boost, the hermholtz efect goes out the window, so runner length mean bugger all.

You probably want to make them as long as practical to fit in the limited space. I've got ~600mm runner on my A15 but haven't gotten around to dyno or anything yet. I was aiming to have my VE peak around 6000rpm.

You can use this http://www.bgsoflex.com/intakeln.html (as I did) to help estimate wave tuning, it's probably within 10-20% and would stay about the same under boost. The only trick is that runner length is from valve face to just outside the port inlet but it's approximate anyway.

Inertial boosting usually means the longer the better until friction starts slowing down air flow. (You wont get anything that long under the bonnet anyway.)

For the Plenum there's no easy way to estimate, but in general a smaller one lowers the torque peak (in rpm and absolute) and spreads it out. The bigger it gets the more it starts to behave like ITB's open to the atmosphere.

How longs a piece of dog poo? You and ya stupid questions. Can't a man enjoy one day of fresh aid without being polluted with your verbal poison?

hi and thanks to the people who put in positive feedback if you dont know and dont ask you never learn.
and to answer your question SANDERSON i would say that a piece of dog poo length would be a mirror image of yourself including your brain which would be more like dried dog poo.......

sanderson where have you gone

Mori don't get involved with this flanders esque person.
Under boost runner length won't be as critical. Off boost is what you want to maximize it for.

thanks unfarmila will take on board your advice. car will be for stret use im thinking runners over the top of the rocker cover so there will be a fair bit of length on them and this will mean it is not so clutterd on the turbo side. like i said earlier this is all new to me so i take on board what people say as they know more about applications and how they work but i am learning thanks

You can look for a guide engine like a late 1400cc TSI polo turbo.
If you can use most of that hardware with aftermarket ecu
you can prob get close to 80% hp/tq figures using same turbo
(A14 77mm x 77mm vs 1.4 TSI motor 76.5mm by 75.6mm)

Has serious torque of 250 Nm from 1,500 to 3,500 rpm
Heres what happens with 1.5bar .... 270hp / 396Nm
https://www.youtube.com/watch?v=B_oxTnUy-o4

The tsi seems to be direct injected but its seems to make very big
numbers using very small capacity inlets and plenum
http://s1.cdn.autoevolution.com/image ... i-engines-explained_7.png

In regards to the TSI engine, I'm sure it's supercharged and turbo charged. Both are small units, but together it has good torque and drivability making it perform like a much bigger engine. I think this is like comparing apples with oranges.