teflontom, you might likr the 1.6 manifold. Google Image Result for http://www.sweb.cz/rene.kramar/images/felicia_13_sada.jpg

very nice..... i've already got one off ebay tho... did i post the pics of that??

it would be a bitch to get that to fit anyway, 4 single pipes passing under the engine, andthen you'd have to find some way of merging those 4 into one.. plus it propably would lead to a slight decline in low rpm performance because those primaries are a bit too long for my liking... far better off with 4-2-1 manifold

, 4 single pipes passing under the engine, and then you'd have to find some way of merging those 4 into one..

hello. welder!

yeah, i know you can buy ready made collectors which are made of stainless steel from the likes of jetex (and a few others). but it's a space thing, not awefull lot of clearance down there

yer your right. both the downpipes i'v got, have massave flat spots were i'v ground them out a bit hard.

Is it just me, or do that lot seem to have a thing about 4 into 1 systems for 4-pot motors? I notice that their 6-cylinder systems are mostly 6-2-1s.

why have 2 holes when you can have 4?????

sorry, being dirrty again.

Serious answer - because a 4-2-1 system tends to give you more torque, and a wider rev band, so it makes for a nicer road-going engine.

further to ken o'neill's comments i will try to explain this a little bit further

this is the way a 4-2-1 manifold will be linked on a 4 cylinder engine with 1342 firing order.

basically when cylinder 1 is on it's exhaust stroke, number 4 cylinder is on it's intake stroke... the exhaust gas flows out down the tube and causes a partial vacuum on the other tube which serves to fill that cylinder more effeciently. this effect depends largely on the camshaft used, without reeling off pages on how cam timing affects this i'll briefly explain it... at bottom dead between the exhaust and intake strokes there will be a short period when both intake and exhaust valves are open at the same time(overlap) this is when the 4-2-1 manifold does it's magic! and obviously the longer both valve are open the more effect this will have... but in reality your average road cam doesn't have enough overlap to fully take advantage of this.

the next thing to take into consideration is the length and diameter of the tubing used. changing the length of these primaries alters the rpm at where you get the most benefit from this effect. likewise the diameter of the tubing also changes this. it's a common misconception that bigger is better.. although technially a bigger diameter tube can flow more gas because it has a larger area, a smaller tube will increase the speed of the gas due to the higher pressure created by having a smaller area, and higher pressure means more vacuum applied to the other pipes:)

moving further down the manifold where the pipes from 1+4 & 2+3 join, it works on the same theory one is flowing whilst the other is empty causing a partial vacumm, but the effect is less prominent here.

the other important design features are having 1. nicely bent tubes which dont deform thier diameter during the bending process 2. having joins which flow well without any sharp changes in angle or direction.

so in summary, a 4-2-1 manifold should give a wider power spread, so long as the tuned lengths of the headers/collectors/etc have been carefully tailored to the engine/cam.

i hope that makes sense:O i'm rally bad at explaining stuff like this:(

It makes sense to me, but then I already knew the theory (if not the maths).

so whats the use of a 4/1 manifold??????

4-1 manifolds are cheaper to produce... normally cast iron! and they are more compact so will fit in a small space.. the majority of production cars below 2.0 will have one fitted.

as i've said above. the camshaft profiles of your regular car aren't enough to make proper use of a 4-2-1 manifold so the manufacturers just simply dont bother. but that isn't to say that a 4-1 is no good, in fact some are pretty well built and they flow very well.

As Tom says, plus, again with the right cam lift and overlap, and primary tuned length, they can increase top end power over what a 4-2-1 would offer. Which is fine for a full race engine, but nor so useful for a road or rally unit, where you'll spend more time further down the rev range, and on part throttle.

the obvious exception to this is turbocharged engines where all the exhaust gases are merged into one before entering the turbocharger... it would still be possible to use a 4-2-1 on a turbocharged engine(like on the old skool F1 engines from the 1980's) but for the road it is more benificial to have the turbo as close to the engine as possible becuase there is less exhaust pressure loss and the more heat is retained