I found a 50mm on sale in the US from Autotech but its right at $600. Is it just me or does this seem a bit expensive?
The best size of manifold seems to be largely dependent on the individual engine spec. To say that a 42mm manifold is better on a 2 litre is not 100% true. Maybe thats the case with a fairly standard engine. TSR have tried everything on Ians car and he's running 50mm as i am. It would be good to have some back to back power and torque figures on paper for us all to see.
We all know that unless the runs are done on the same car at the same rollers on the same day - the results won't mean sh1t Edited by: G_V_K
Well i was told by vw motorsport engineer that air intake system on 16v engines be it 42 or 50mm are badly designed and robb the engine of allot power and torque, and the only reason they settled for it was to beet competitores to it and release 16v engined hot hatch! apparently the whole air intake config is pooe design and specially lower part of manifold looses allot of air mass and for experiment they 'v chopped an inch out of lower part of mani to reduce length of pipes, welded it back together and run the car on rollers and saw 16bhp gain, and 14ft torque!!! The only problem was they couldnt close the bonnet as the mani sat to high cose of the angle.
To sum up guys, as a few of you have said, you can't say either size has a diffinitive application as there are so many factors effecting choice. If you want to stick with the standard intake system the only way to tell is to get both manifolds and go to a RR. Then choose the best one for your application. Even a change of the petrol you use could see a change in the results so don't let it keep you up at night .
My corrado is a 1.8 and the 50mm killed it, i agree the 50mm is good on golfs as i had a golf 16v before.
powerdubs on vortex has welded the 42mm plenam onto cut down 50mm runners, but I don't think it's dynoed yet
i believe its all about the tune up after the mani instalation,and also,some "mind" thing...if you think a exaust will give you 10hp,it maybe will,but in your mind!the extra sound and all,can make you believe! the intake mani to!i think(and i'm no mechanic,so i might be wrong) if you get a 50mm intake mani,it will be better!i have one,and i think i didn't lost any in low,and gained(and this i'm SHURE) in high RPM.after 4000RPM it really kicks in!
Prof, I never had the 9A set up at Stealth when I had the 50mm, but it didn't go any worse with the 42mm in the same state of tune
