Jason Moyle Racing

This is an interesting one. The 'works' 16v VW engines seem to run 8 injectors as do JRE top spec engines amongst others. They are a pig to set up as I understand.

As I also understand the closer to the head the injectors the better for bottom end power. The further away the better for top end power. So ideally (you would imagine) you would have one set in the std position and one set mounted out in the centre of the trumpets at the far end.

I know one of the guys who runs a 16v who had to go to an 8 injector set up to find any torque in an ABF/KR type set up after coming form an 8v Spiess set up.  As this engine struggles for good torque anyway seems like a good way to go.

As to type of injectors I don't know, but you want the type that your ECU supports as a very minimum. You would imagine with 8 injectors you could get away with some fairly standard set up as the flow is split across 8 injectors.

I'm sure Jason has some info on 8 injector set ups 

Tim, your still alive!

Normally I'd agree that they need to be in the centre of the trumpets but if you look at the geometry they are pointing straight down the centre of the inlet port which is what you want, the curve on the end will mean you can fit them under the bonnet and pointing forward so looks good to me.

I'm sure I've seen this set up on a European racer or a very similar  setup because I remember thinking that the injectors were wrong and then realising where they pointed.

digging up an old thread , I recall Dave Walker testing 8 injector set ups , and found that you didn't just switch from one set to another , they had to phase in and out? And that on a 2.0 Pug IIRC , the gains weren't that large.

Pretty sure it was in CCC as well.

As I understand one of the reasons for 8 injectors was that older injectors lost their spray pattern and control at bigger flows so twin injectors allowed you to run smaller injectors well within their designed range.

In addition you could inject fuel in at different positions in the inlet tract [times] to suit the cam etc.

There is probably far more to it than that but as I recall it meant more power could be made by better control over the injectors as more fuel could accurately be injected and a better spread and torque by better positioning/phasing.

With modern injectors I guess flow control is not such an issue so I would imagine a more 'fussy' engine might still benefit from the different injector positioning.

The KR and ABF 16v's seem to benefit from 8 injectors as both VW and Audi top spec rally and race engines generally seemed to have 8 injectors.

Just a few thoughts.

I'm going to experiment with them further out on evo2 of the WallyKa , going to leave both OE inner sets and the bike injectors on the bodies which are a lot farther out, and dyno each if them.
Any  opinions on why injectors are always on top , not underneath?

Purely the angle they spray at? Seems they allways point down towards the valve because of the head/runner shape. Maybe others reasons too.