Im not sure if this has been done before, although i have found few threads toying with the idea, and have done some reaserch on this. It seems to me thats the 8v manifold is very poorly designed, and supplys less air at any given air velocity speed other than idle to pistons 3 and mostly four. This is due to the tb being at one end of the manifold. My thinking is that centralising the tb and making it face the front of the engine bay would be for benificail for air distribution and velocity. Im going to be making a manifold in the next few days out of an 8v mani and a ford early zetec mani. Looking at it, its not going to be too difficult, once iv checked out physical space. What do we reakon guys, am i wasting my time or does it sound ok? The sceience behind it says i should see a very mild increase in bhp, but more on the torque side id see a bit more. Any input...............?
seems like a good idea, just need to make sure your welding is spot on so no leaks occur. thought the early zetec manifolds were plastic??
no thats the later ones, the later ones are a better design too. Early ones are metal. Oh yeah i realise that, i plan to take my time, then il take it to my local garage to get it pressure/crack tested, and get it thouroghly pollished inside and out.
Looking at both the manifolds now, shouldnt be to dificult, the spacing is pretty much the same. Will need to check for bonnet clearance tomorow.
Hi mate, just a couple of points, if you think about it vw have invested millions of pounds into developing the car if their testing resulted in the design of the throttle being detramental to the performance I dont think they would have made it that way. Oh sorry I forgot the other one. Bob.
I reckon there will be room for improvement, as with any engine. As much as I would like to think they made everything to be as free flowing as possible I don't reckon they did.
that is very true, they have invested millions, but like was just said, there is always room for improvment, engine designers build based on compromises like cost, econemy etc etc. I beleive based on what iv read that having a foward facing tb as in the pic will make a noticable difference, especaily on a BVH head.
im glad my development manifold is stil in peoples minds!!! has any1 else out there built 1 yet???? this was my first build ..... produced around about the 18 - 28 bhp if i remember.
ah ha! i knew it would make a difference, i stand corrected, someone has attempted it on here! Well rather than claim im re-inventing the wheel, im just going to get on with it myself. I never thought to use the standard manifold, very clever!!
use the manifold from an AGG 2.0 8v engine with a 2E throttle body. these are the rolling road figures from just the manifold being fitted ..... oh these are 'at the wheels' figures as well. And this is where you mount stuff around it : Let me know how u get on. Steve
cheers fella, il have a crack at that when im next in the workshop, im going to do it on a pb 1.8 8v manifold as im swapping the bottom end to a 2e 2.0. il c if it will fit ok
ah mk2 stuff ... im lost already i know nothing about PB manifolds etc so i cant tell u how that may or may not work!!!! If u manage it tho ... get it rolling roaded before and after ... so we can compare what it does (same rollers of course
yeah il wip it down to janspeed for a before and after. It makes sense to do it because it gives more even air distrubution at high revs, im going to look into using a zetec metal manifold. Credit to you steve for starting it off tho! Everyone should do it, conclusive proof my theory and reaserch is right, take that non beleivers!
i only built the 1 manifold, got a bit slated for my rolling road statements and never developed that engine any further!!! good luck with it.
well if i get it to produce similar results then its conclusive. Even 2bhp gain is proof it works. il get busy with the welder and see what happens
i got a 2.8bhp increase just by upgrading the earths to thicker o2 free cable on my old mk3 gti 8v, so anythings possible!
