16V inlet manifolds

I have a 1990 16v with the smaller bore inlet manifold, why did vw change them from the old larger 52mm manifolds? Is it worth fitting the old style manifold to improve airflow?

 

Yes if you want to gain high end power and lose low down torque, no if you don't.

 

Don't think I'll bother then, I'm missing the low down torque my 8v had as it is.

The car is also fitted with a superchips icon box anyone know how much difference these make?

 

So for top end use the old inlet manifold and for more mid range use the smaller bore inlet?
Is their any other mechanical differences between the earlier and later 16v's?
I prefer top end power that the valvers have as compared to 8v's.

 

I coverted my corrado from the small to the big!Instead of the semi smooth power delivery with the small 1 you just get a kick up at ass between 4-5k onwards.yes it is a bit flatter upto 4k tho doesnt bother me as ive changed my inlet cam and that gives more lowdown torque anyway

THER WILL ALWAYS BE A BIG DEBATE ON THIS,BUT IT REALLY IS A CASE OF TRYING IT

 

50mms work well on 1.8s 42s are better on a 2.0

 

Suppose I'll just have to give it a go then, I have a 50mm manifold anyway so its worth a try.

flusted, what cam did you use?

 

I thought the earlier manifolds were 42mm and the late ones were 50mm.Mine is a 91 and i thought mine was the 50mm one, if you look at the two together the 42mm one is straight whereas the 50mm one has to go narrower where the spark plugs are! also does the colour of the writing on the D.O.H.C tell you whether it is 42mm or 50mm? ie-blue=42mm,red=50mm?

 

the other thing to consider is not just the diameter of the runners, but also the plenum size

 

how much of a difference is there in plenum size?

 

and all the throttle bodies are too small

 

exhaust cam modified to an inlet cam

 

Colours dont tell anything i dont think.

Early mk2s had the 42mm upto d reg i think then they changed to 50mm till the mk3 which all had 42mm/
Also all corrados have 42mm

Correct me if im wrong

 

just to be dull:
Corrado's had the 50mm up to engine no. KR 148313, and all 9A engined (2.0 16v's) had the 42.5mm one
In fact the part no's are the same for golf 2 16v's and have the same change over point, i.e. they had 50mm ones up to KR148313 and 42.5's after that.

BUT ... there is also a 41mm manifold for PL engines... which I don't think we got in the UK anyway!

Don't argue, this all came off ETKA.
David.

 

no, no, no, ignore that rubbish, I'm talking crap, it's far more complex than that, apparently some early KR's had the 41mm lower part manifold, the upper only came in 42.5 and 50 on the KR, but PL's had a 41mm upper part too, VW generally in the UK seemed to start with 42.5's on the early UK golf 16v's then change to 50's then back to 42.5's, the early swap from 42.5 to 50 was on a particular chassis number and the later back to 42.5mm based on engine code,

confused, I know I am

David.

 

flusted, exhaust cam modified to an inlet cam?

How much difference does it make? Is it a lot of work to modify it, or do you just replace the inlet cam with an exhaust cam?

 

Anyone know why vw changed the size of the manifolds?
Was it to improve low down torque, or for some other reason?

 

i got the 50mm fitted,and didn't noticied any drop of power in low-end,but after 4k,man it goes!!
its a good swap.and the mani for free,even better!!!

 

Bigger manifold was an attempt to get more peak power.

 

I've got a 42mm on my 9A - good enough for 170bhp