16v inlet manifolds

hey guys and gals

so im sitting hear thinking that a 50mm inlet manifold has got to be a good thing. then i stumble across a posting (from dex) on a.n.other forum were pretty positive stuff is being said about the 42mm; that its larger plenum chamber is more suited to larger engines like the 9a/6a

im running a totally stock kr in my '89 (G) valver. what size inlet manifold would it / should it have? can i find out easily without pulling it apart? (ie from engine number?)

what would whacking on the other size do to its performance with no other mods? shift the peak torque up / down? (bearing in mind its a stock 1800)

cheers

ps: i presume the 50mm came first if the 42mm is better for bigger / later heads?

 

42mm came first, 50mm later

are the DOHC bit on the inlet in blue? if so for sure 50mm inlet.

 

nice one,

"is it blue?"

..thats the sort of technicial identification i can cope with

 

also the 42mm has 3 ribbed bits on each inlet where as the 50mm is all smooth

 

you da man!

and if i bung a 42mm manifold on my stock kr...?
Edited by: dohc

 

will make it abit better low down, i have had both and the 50mm is better top end, but mine is playing up and wont go over 100mph

feels great to 60 though lol

 

..i figured the chaps at vag would have gone for the best all-rounder when they put the thing together - i spose with no other mods to take advantage of the manifold, its not worth doing

..your 16v won't do over a ton? commiserations [:^(] there's something badly wrong there. i cant remember the last time i did a motorway run and didnt do 120! naughty but v fun


edit - sheesh my spelling is awful sometimes, now corrected

Edited by: dohc

 

i think you can get an audi one thats a bit bigger and only has one opening

 

Where did you get that bit of info?
Edited by: Golden

 

oh man...
i believe in 89 it was with the 50mm ones.a friend of mine has a 88,and it haves 50mm.
50mm are blue...oh man!they are all blue!!i had a 42mm and it was blue!!
i changed from 42mm to 50mm.i didn't noticied any lost of power in any rev range,and i did notice that from 4000 to max RPM,its a wild thing!!

 

It is actually 41mm not 42mm and the one on my car is blue and that is an 86.

 

I just had to check to remind myself.

The 16V manifold came in 3 sizes.

41mm 42.5mm and 50mm.

The KR engine in the MK2 had 50mm manifold from introduction up until mid '92 when it was replaced with 42.5mm manifold.

Before '92 the smaller manifold was only fitted to PL engines.

I'll go get my anarak ....................

 

So what size is my manifold?

 

Dave yours should be a 41mm manifold.

The order they were manufactured goes

1st 41mm
2nd 50mm
3rd 42.5mm.

 

Doh! - Mine must be a 41mm also then, it was off my D plate 16v
It was a RHD UK car with KR though



Edited by: G_V_K

 

how can you tell which one is ths 41 and which is the 42.5

 

With a 1.5mm difference I don't think there is going to be alot in it performance wise. With the quality of cast parts there are going to be imperfections and size differences within the cast.
If you really wanted to, then use telescopic gaugess or an inside caliper in conjunction with a vernier or o/s mic.

 

50mm

Bigger runners narrow to pass the spark plugs.

42.5mm

Bigger plenum, fairly straight runners

41mm in Dave's post, has a big circle cast on the no1 runner.

 

Then there is the Canadian 38mm runner on my 1.8L 89 Gti 16v. What were they thinking? I'm getting a 50mm sent over.

 

Ive just converted mine back to 42mm 1 about 10mins ago!!! I was a strong believer in the 50mm 1 but i have 17s on my car and it is crap for acceleration especially in first