Differences of the manifold concepts?

[Oliver_K4M]

Is here somebody who can explain to me the differences regarding torque and power of a 4in1 compared to a 4in2in1 exhaust collector at a 4 cylinder engine?:S

Two cases:

case 1: The single hose lenght of the 4in1 collector is as long as the overal length of the 4in2in1 collector.

case 2: The single hose lenght of the 4in1 collector is as long as the length of the 4in2 part of the other collector.

Thanks.

regards
Oliver

 

[mini-valver]

I've always been led to belive the 4-1 is better for torque but don't quote me on that. I'm looing for a Exhaust manifold for my K4M at the minute but the stock system is a crap design as everything is very compact from the block to the cat.
Ideally i'd like a 182 style manifold to move the de-cat underneath as a straight pipe like the 182 instead of the dowpipe-cat set-up as stock....

Anyone shed some ight on this???

 

[kully]

4-2-1 for more lower down power , 4-1 for more top end power.

 

[mini-valver]

I thought it was the other way round??

 

[kully]

i've had the 182 manifold conversion and was advised to the loss of top end power .

 

[Oliver_K4M]

I've always been led to belive the 4-1 is better for torque but don't quote me on that. I'm looing for a Exhaust manifold for my K4M at the minute but the stock system is a crap design as everything is very compact from the block to the cat.
Ideally i'd like a 182 style manifold to move the de-cat underneath as a straight pipe like the 182 instead of the dowpipe-cat set-up as stock....

Anyone shed some ight on this???

I would also like.....
At the moment I run with the supersprint manifold at my K4M, that´s more ore less a smaller copy of the 172 manifold.

A tuner here in germany (sk-tuning) sells an exhaust manifold for the K4M engine in "4-2-1 style", but in my opinion this thing is also crap, bad finish and differnt length of the second Y-connection....:dapprove:

 

[Oliver_K4M]

i've had the 182 manifold conversion and was advised to the loss of top end power .

But the 182 has a higher revolution level?

 

[mini-valver]

I was looking at the Supersprint one. Do you reccomend it? My engine will be far from standard. Look further down the page at my thread "Finally, A little update" for the spec.

That manifold does look a little shoddy, 1 and 4 are loads longer than 2 and 3!!

 

[Oliver_K4M]

I was looking at the Supersprint one. Do you reccomend it? My engine will be far from standard. Look further down the page at my thread "Finally, A little update" for the spec.

I think there is nothing better availible at the moment, except of other handmade and excklusive stuff. With this thing and other mods (cams, etc.), but with still the stock intakemanifold and no head work or lighter fly-wheel, I have 133hp and 178Nm.

Your intake system looks amazing!

 

[mini-valver]

133bhp is a great figure with just cams! Im hoping for 150+....
I will probably get a rebuilt bottom end with better pistons etc and be able to rv higher and create more power!
I will probably go for the Supersprint manifold then, thanks for the advice!!

 

[Oliver_K4M]

In your case, where you like to touch the 100hp/l, I would think about simply modifying a 172 manifold (or even 182...). The flange to the cylinder head between the F4R and the K4M engine ist completely the same except the 9mm smaller cylinder distance, so I think this is possible by welding on another flange or cutting the flange...

In addition you can also use the 172 down-pipe which has a bigger diameter than the normal K4M one.

 

[mini-valver]

I knew the port spacing was different.. 9mm bigger between each cylinder? So you're suggesting cutting all 4 outlets off and welding them onto a flange of the K4M cylinder head? That's something I'd definately look into using the 182 manifold as i'd be able to shift the cat (de-cat)in this case under the car and make it easier to change come MOT!

 

[Oliver_K4M]

Might be a possibilty, too.

 

[BenR]

Your question is too simple, there is no straight answer.

Exhaust tuning is a complex system and to sum it up is quite possibly impossible to give you a true answer. A few OEM manufacturers have their own proprietary software that is into the millions.

Your main problem is space, there is none. Unless you start from scratch and make the rest of the exhaust system after the manifold is complete, you will not have enough space to create a header with long enough primarys and a merge of a low enough included angle. A 4-2-1 will require even more space.

Your second problem is knowing what your trying to tune for, and without some serious time spent on high end simulation software, you wont even come close to knowing. Anything else is best guess, and thats what most people will work off........trial and error.

And you have to decide if your trying to achieve highest possible negative exhaust pressure circa overlap, or if your simply going to work towards reducing pumping losses, you cant have both.

 

[GordonD]

4-2-1 for more lower down power , 4-1 for more top end power.

Well, that's sort of true.

A 4-1 exhaust allows the manifold pipe length to be tuned to help the power at one point in the rev range. A 4-2-1 exhaust allows them to be tuned for to help the power at two different points in the rev range.

Its like Honda's VTEC valve gear having two different cam profiles so there's a cam profile that's right at both low and high revs.

The general engineering rule is that you can make something simple do one job extremely well, but it usually takes complexity and all the things that come with that (cost, unreliability) to make something do a number of different jobs well.

The 4-2-1 exhaust on the 182 gives it a wider flatter power band than it would have had if it had had to retain the 172's simpler 4-1 exhaust. They could have chosen to build a "182" (except it wouldn't have been a 182) with the same amount of power but without that peaky torque curve (everyone talks about how it takes off when it comes "on the cam"). They chose to give it a slightly better bottom end and slightly more power to make it a little more driveable and more powerful.

 

[fmp_]

taken from a very well respected Cit/Peu tuner....


There has been a bit of controversy recently regarding our manifolds against various others, especially against others stainless steel units and the benefits of 4-2-1 and 4-1. Regarding the merits of 4-2-1 and 4-1, some people seem to have the facts all arse about face. From a technical point of view a well designed 4-2-1 will give more low down power and reduce a bit off the top and the 4-1 will give more top end and bit less at the bottom. The critical words here being WELL DESIGNED. This all goes back to my comments about Sound/Pressure waves. When this was talked about above it was in relation to exhaust systems, but the same rules apply to exhaust manifolds. For things to be correct if you have a 4-2-1 manifold, you have the 4 pipes coming out of the head, 2 pairs (primary pipes) then join up to make 2 more pipes (secondary pipes) and then these 2 pipes join to make 1 pipe. For the pressure waves to be working correctly on 4-2-1 manifold the lengths of the primary pipes must be the same as the secondary pipes, regrettably some manifolds do not follow this pattern and therefore I cannot see them being much benefit. I can understand why they have not done this as it should be, it is a question of space, as 4-2-1 is more complicated, having more joints. So the argument about which is best does not stand up to a proper comparison. All I can say is ours are all 4-1 and they all work very well and give more power

 

[Oliver_K4M]

Thanks for all answers.

 

[kully]

i could defo feel the difference from the 4-2-1 manifold , more responsive at lower revs , especially after the remap .

 

[MarkM]

When you read threads like this you start to realise the amount of knowledge and developement required to make parts that work. And by work I mean increase power where its needed relative to where other components, cams, inlet length, exhaust bore diameter etc. etc. etc. etc. make there peak power.

Its like the throw away comment that 4-2-1 is better for low down torque and 4-1 is better for peak power. They are made by people who have a very small amount of knowledge when it comes to tuning an engine 'properly'.

A company called clockwise motion builds exhaust manifolds for Honda engines. They use an adjustable manifold on a dyno to find the best configuration for a specific car. A sensible well thought out approach with a proven power increase and a true custom manifold designed for performance.

http://www.clockwisemotion.co.uk/index/honda-k20-exhaust-manifolds.html

 

[stan*]

A company called clockwise motion builds exhaust manifolds for Honda engines. They use an adjustable manifold on a dyno to find the best configuration for a specific car. A sensible well thought out approach with a proven power increase and a true custom manifold designed for performance.

Its the only way to do it, as its such a specific area of performance tuning. So many variables which alter pulse effect, which cant be considered fully on a drawing board. Thats why theres no definitive answer alot of the time...it soley depends on the spec of the engine initially and what your trying to achieve/what the application is.