4 vs 8 injectors

Just to throw a link across to Ess Three's build thread & give this one a bump at the same time.

Sub discussion over V8 cam covers split to here

Sub discussion about fitting RS4 coil packs split to here

 

Just reading an article on bellmouths and it was explaining 'spitback' and how pointing injectors down the bellmouth can result in unwanted spitback of fuel.

Also something that grabed me...

ie talking about these types of bellmouths.

 

interesting extract smudge, wonder why the LS chevy engine uses mostly rectangular ports?

 

Message received and understood...my bellmouths have been reduced in height accordingly.

 

Just dug out this CCC article. 8-10 bhp at peak gain from eight injectors.

Interesting variation on fitment from what we're seeing on this thread, plus some useful info on phasing.

















^^ Nice to see someone abiding by the MSA Mod Prod sprinting rules and using the standard engine block. RobT

 

wicked stuff great info

 

Just to stick this here - Skoda Felicia Kit Car motor kindly posted by mattday on the p0rn thread here:



There were 2 1600 engines it used IIRC, and this is the later VW engine, as opposed to the pre-VW buy out Skoda unit. Jenvey bodies makes this rather closer to home than we'd normally think, with a bespoke inlet manifold dealing with the inner injectors, hardly uncreatable.

From the other pics (see p0rn thread) to me it looks based on the old 1100/1300 blocks, but anyway, 1600's the capacity reference. The outer row don't look mega far out from the valves, less I think than the 2-litres we've seen, and perhaps the capacity is why?

 

with modern multi-pintle injectors and better atomisation etc, i wonder if the gains for the 8 are what they were when DW did his tests.. (a long time ago on old injectors)

 

indeed, i see only 4 injectors on some high end engines, even if the injectors are as far as 350 mm away from the inlet valves !

 

I think that is to do with the limitations of S2000 regs?

http://www.fia.com/resources/documents/1623371895__AppJ_Art_254A.pdf

 

That Skoda engine is very Rev happy,with good trottle respons and that on 4 injectors far away from the valves...that proves, it can be done !

The reality is that there is very little between 4 or 8 injectors.

Will an engine make 3 hp more because there are 4 more injectors ?
Very unlikely !

Will there be better trottle respons with lower injectors ?
YES, but then you need to control transients on these to get best results ...and it can cool the valves extra...

 

Agreed, but by the same token, Gayton Hayot says the Winderickz engine isn't pulling out of the corners as much as he'd like. Now part of this is being a race engine, not a hillclimbing engine, but it has 4 injectors, not close to the valves.

Clearly modern spray pattern is a (unknown) factor, but the abilty for fuel to mix and needing time to mix is a physic which does not go away, accepting that Skoda/Seat/VW work with the regulations they have.

Damn shame the WTCC/S2000/S1600 has been managed down to a single butterfly, otherwise we'd know all this for fact through demonstration!

What other clever tricks have the works engines got I wonder!

 

There are so many variables between engines,but an engine that runs ``off the cam``
will need time until its back on the cam , lower injectors can help a bit , dont expect miracles....