Manifold trickery

[franchise 1]

Ok guys, I know a bit about this and that and can see when someone is making a point but I can't make my mind up about this:

http://www.vwhookup.com/sales_hyper_flow_VR6_intake_manifolds.html

A bit of feedback from engine genius' would be nice here. I can see what they're saying but would this not cause problems on starting up and maintaining smooth running? Obvioulsy a re-map would help.

I'm working on a mani at the moment and thinking whether or not to do this.

[mk3anni 0]

Its the same as a 2.9 manifold is it not???

[Eat this 2]

looks very similer to me it will probably give you a little bit of bhp up top but it will also rob you of low down torque

[clarkie 1]

yep exactly the same as a 2.9 and exactly the same as what im in the process of doin my self.

[franchise 1]

Could someone post up a pic of the underside of a standard 2.9 mani?

So, the burning question is, should I do this to the one I'm polishing up at the moment for mine or would the downsides outweigh the benefits?

i really don't want any more lag at low end.

[Petesvw 0]

2.8, OBD2

2.9, OBD1

[franchise 1]

Ahhhh, now we're talking!! So with the obd2 having the same tb as the 2.9 ( I think I'm right there) it kinda makes sense to do this mod. There shouldn't really be any downsides...in theory. F'k it lets have a go!!!!

[Petesvw 0]

The 2.9 is OBD1 al!

Your p plate should be OBD2 ; )

[franchise 1]

I know chief, just thinking out loud, the standard obd2 has the 2.9 larger tb doesn't it or similar? I'm thinking I'm gonna do this to mine and see how we go, can always swap back if needs be.

[gav_113 0]

doing mine now!

just need to tidy up machining and weld it up!!

Phatttt!!!

[Petesvw 0]

Na mate. OBD1 was the earlie injection, pre 95!

if you wanna put an OBD1 TB on a OBD2, You got to change a fair few bits! The plumbing is differant for a start!

Call me, ya got me no:

[franchise 1]

Its all good Pete, I know they have different tbs, I was just coming at it from the angle that if I was obd1 and had the regular tb and was looking to do this manifold mod then there may be issues with airflow and all that jazz as the 2.9 tb is slightly bigger (I think this is right), but me having obd2 my tb is already bigger so doing this mod should be fine. does any of that make sense?

Gav, get on it son!! Don't forget you need to cut out that bloody big bit in the middle too else it won't make any difference. Post another pic when its all cut out before you weld, i wanna see it naked and hurt.

[gav_113 0]

al75 ,,why wont it work? theres nothing under it. the walls have been removed..think they just used one piece to keep it neat?

[franchise 1]

Sorry chief, just had a proper look at your pic, you've cut the side walls rather than the whole top section haven't you? Sweet!!

Let me know if there is any difference in driving when its on, I need to know for sure before I carve mine up.

[clarkie 1]

heres mine

just needs tidying up then a plate welded on. will get pics up once finished

[franchise 1]

How tricky will welding one of these bad boys up be?

Also, will any kind of ecu setting need doing or will the airflow change be minimal?

[franchise 1]

Hey guys, thought I'd revive this one. Anyone managed to finish one of these manis off yet?

Be cool to know the reults, good or bad, if any.

[gav_113 0]

ummmmm no not yet, keep meaning to! but u know!

will really try this weekend! last time i spoke to clarkie he hadnt neither!!

[VR6_Absy 0]

Top work lads ;_).... well impressed with the initiative and bottle ........ glad i never noticed this link before or i would have ended up doing mine ....... too late now booked in with Stealth ;-)

[dstyrrell 0]

I was discussing this topic with a friend of mine who is a motorsport engineer, he basically one of those guys that can design formula one cars from scratch. When i asked him about this manifold idea, he just said that to design that manifold for VW probably took someone as qualified as him 6 months with extensive testing and calculation taking every aspect of airflow into consideration and if it was as easy as chopping the insides out and welding a plate on top do i really think that they would have bothered with the hassle and the massive cost associated with the design.

I thought about what he said and decided to leave mine alone and shut up. lol.

If you look at performance manifolds and the prices associated with them you can imagine the research and development that has gone into them to get the desired result. I don't think its just about the amount of air that is delivered its also the way it flows and is delivered that counts.

Its all well out of my league to be honest.

Good luck.

[gav_113 0]

if u look at a 2.9 manifold underneath, they are designed like this from factory, combined with a larger TB.. its just u cant ever find a 2.9 manifold for sell? this is just the same as that, vw did this only on 2.9s i believe?? my car is going 2.9 soon and has enlarged 2.9 TB already fitted, of course i will have to get a remap when all the mods are done..

[dstyrrell 0]

Hopefully it will work, what sort of gains do you think that the manifold and larger TB will make ???

[dstyrrell 0]

http://auto.howstuffworks.com/question517.htm

I think that you should take a look at this.

Basically it would seem that for bottom end you want smaller diameter air intake, and a larger diameter air intake for top end.

I think this is why the vw motorsport intake manifold works so effectively basically because it has a butterfly valve that uses smaller intake diameter at bottomend to compress the airflow and almost create a forced induction effect and then the butterfly opens at topend for more free flow air supply when the pulses are more rapid. That the other thing the manifold will be designed so that the length of the intake pipe is correct for the pulse speed (this is where the tuning science comes in)whether its lowend or topend. The butterfly valve is a ingeneous inovation and i can see why performance air intakes are so expensive.

Basically i think that what i'm trying to say is that having a mega free flow air intake with larger TB ect will only benefit you top end, you will more than likely lose bottom end torque.

I probably haven't done a brilliant job of explaining so check out the article, as i said before its not just getting lots of air to the engine its how the air is delivered thats important.

Dave

[franchise 1]

Hmmmm, I like it!! So the cut and weld mod might make the beast a bit more sluggish and hesitant and very low revs but run well on chat. no good for quarters then eh. I gather this is kinda why the schrick works well then as that has two channels feeding 3 runners each, more concentrated air flow...ish.

[PEDROX 0]

bump for a cool thread

any up date??