Manifolds

10th April 2013, 23:24

What's the difference or what's better between a 4-2-1 manifold or a 4-1 manifold? Both for a 02 vtr, I hear ones better top end, and ones better acceleration? How true this is I don't no?

10th April 2013, 23:28

A 4-2-1 returns more back pressure, so you retain some torque in the midrange. So it's more suitable for driving on roads and the occasional track day and spirited driving.

a 4-1 is purely for achieving high HP figures as it allows for faster flow. Ideal for racing, not so good on road. you'll notice the car will accelerate more slowly until you get the revs right up.

so the 4-2-1 will be for acceleration and 4-1 for top end.

10th April 2013, 23:32

Cheers mate thanks

11th April 2013, 10:49

makes no real world difference on a saxo. 02 VTR is already fitted with a 4-1 manifold mainly due to space issues.

11th April 2013, 10:58

Quote:

Originally Posted by KamRacing

makes no real world difference on a saxo. 02 VTR is already fitted with a 4-1 manifold mainly due to space issues.

I have to say, I don't really feel a difference between standard and the aftermarket* 421 on my GTI. Just looks cool

If your car looks good,it goes faster?

+10Kw if you paint the calipers red.

12th April 2013, 08:41

gti has a 4-2 -1 as std ,
thwe agrument about 4-2-1 and 4-1 is not as clear as it would seem .
it all depends on primary sizes and lengths and of course quality of build .
which is why i have only ever made 4-1 manifolds --once you start to move engine spec awayfrom std with higher lift cams making max bhp at higher revs then the 4-1 will always be the right choice
people who fit ex systems with no centre box will loose far more torque than the dif between the manifold types .

those of you who have such systems will notice at a certain rpm it makes a nasty resonance noise,usually around 65-70mph --above and below that speed it goes --that is showing mismatch of tuned lengths and boxs in wrong place . the cat acts as a silencer box ,on mk1 it is in the best place for maximum torque ,so that where your first box should be
on mk2 they want emmissions low so its up on the manifold so it heats up quick andf stays hot,which has no tuned lengths at all ,
If you want the best then go do some reading on tuned lengths ,which to get correct data you need inlet lengths as well and you will find that the common 4-2-1 lengths are wrong anyway

12th April 2013, 09:37

i can remember trying to get my head around header lengths and an old boy telling me to just make them the same size as the exhaust valve (in the case of an 8v) and 24inch long with emphasis on them being equal length. His theory is basic but pretty effective!

With a supersprint i get a drone at around 3200rpm when on the motorway.

Exhausts are always a compromise at some point in the rpm range, the standard system will make more power at 2000rpm than any other really and as you said, 4/1 being the least restrictive theoretical design will be the one that allows the highest power overall.

I noticed a gain in midrange and throttle response with a 4/2/1, a friends identical car with a 4/1 feel slower midrange, but quicker top end, driven back to back you can notice the difference, its only slight, but its there.

12th April 2013, 09:45

Save all this bother and whack a Turbo in the way

barely matters then!

12th April 2013, 10:54

No, but something else will matter if he doesnt do anything else. lol