1.6 and 1.8 inlet port sizes

[irwin83r]

hey all

bought a set of quads the other day and the fella i bought them off said he found they gave good low to mid range improvements but not alot up top which was the main reason he was selling..

once i got them home i had a good look at them and noticed the ports are actually smaller than the standard 1.8l manifold.. not good but would explain the better low end and shitty top end.

was wondering if anyone has the dimensions of the 1.6l inlet ports or a photo or two as i think this might be the problem.. would explain why top end was dyin anyway.

also anyone know what dia the butterflys are on a set of quads made for the 1.8? if they are close enough to these ill just match port it to the 1.8 gasket and open out the inside of the quads manifold a little.. if it turns out the butterflys are going to be too small or the wall thikness of the cast is too thin ill either sell em or ask for a money back as they arnt the 1.8 quads i was told they are..

cheers.

irwin

[Okibi]

Don't forget the inlets on the NB 1.8 is also different to those on the NA 1.8, sorry don't know sizes.

[irwin83r]

pics

holding the nb8a manifold gasket over the corresponding bolt holes you can see what i mean by the port sizes being smaller or are the na8 ports this small??



the other thing i was wondering about is whether the size of the actually throttles pictured below would be too small on this set of quads for my nb 1.8 IF it is indeed from a 1.6

[Rotary]

hard to tell from the picture, what size are they exactly?
If theyre 35mm then that should give an increase over stock flow

[ampz]

It also looks from that flange, that it may suit both 1.6 and 1.8 as the bolt holes on the lower half of the flange (the ones your gasket doesn't cover) look like the 1.6 ones.

Maybe it's a dual purpose manidold?

[Okibi]

Well if it's an NA6 one then it's not much use to you, i'll take it off your hands

[zoomzoom]

I would say the two sets of holes correspond to the na8 and the nb8a highport head. The port spacing on the 1.6 is slighlty closer as the engine is a tad shorter, and they would also have to have injector bosses in them for a 1.6.

Tim

[ampz]

Good eyes Tim, forgot about the injector bosses (i call them divots )

[Boyracer]

Last set of Quads I fitted to 1.8 were 48mm......the set I had on 1.6 were 45mm...the smaller port size is to improve torque and low down pick up...as was the case with the ones you bought....probably better to keep the torque and give away some of the top end....especially with your car which will end up being quite heavy.

Not the best to just have the missmatched ports...I have seen some set ups where they have sleaves that slide in to the head that make for a smoother entry.

[irwin83r]

Last set of Quads I fitted to 1.8 were 48mm......the set I had on 1.6 were 45mm...the smaller port size is to improve torque and low down pick up...as was the case with the ones you bought....probably better to keep the torque and give away some of the top end....especially with your car which will end up being quite heavy.

lol
ill see how big the inlets are and how much material i have to play with and then ill decide whether or not to sell them or match port them

[manga_blue]

Some of the aftermarket inlet gaskets I've seen are really badly sized and aligned. I wouldn't trust the gasket alone as a guide.
I'd do a proper scribing job of the head inlet ports onto the manifold ports first to see how good or bad the match really is.

[irwin83r]

Some of the aftermarket inlet gaskets I've seen are really badly sized and aligned. I wouldn't trust the gasket alone as a guide.
I'd do a proper scribing job of the head inlet ports onto the manifold ports first to see how good or bad the match really is.

yeah have checked the gasket to the head it will be used on and it looks to be pretty good.