Budget K10 4-1 Manifold

ollyc98

ollyc98

Ex. Club Member
As some of you may have seen in another thread I am building a manifold for the K10.

I have the collector, that cost about £20 inc postage from demon tweeks.

I got my 10mm plate from ebay for £20 but that will make about 4 sets of flanges.

I went to nissan for a gasket so I knew where to cut the holes, they told me they needed my chassis number, I didn't have the car with me so went to a local motor shop and picked one up for £7. It looks to have a bit missing for EGR but I dunno if I need a blanking plug or something....

Next I need to buy some pipe and a few 90 degree elbows.

Although 90 degrees is a little steep I don't have a pipe bender and it'll still be less restrictive than standard, plus the space between the block and the rad is kinda tight for the sort of bends I could do.

So that's it so far, til I get paid then I can start putting it together.
 
I'll do that, I may even write a guide as this can be built by anyone that welds.

I'd also like a dyno run when I have got the whole system done, the collector has a 2 inch output so I'm gunna go for a full 2 inch system exiting in front of the d/s rear wheel.
 
Because firstly I don't have the knowledge to do it properly and if it was done properly it wouldn't be budget. This is just to allow the engine to breath a little easier.

I may get lucky and it'll work out perfectly.
 
Just go for it! as all the complaining lately has been about people not doing stuff practically and trying it out after the theroy has been discussed!!
 
I'm going all practical no theory, I'm not listening to any compaints on this thread cos, when it comes down to it, if you don't like the way I do it, don't make one.

Plus for less than £100 even an extra 5hp gained will be worth it.
 
This might make you lose a little faith, not all pipes will be the same length, from what I can gather the pipes can be within a 9 inch tolerance of each other, this is so I can get round the sump.
There will only be about 3 inches difference between pipes 1 and 4.

At least you will get a nice sound though lol. A different note from every pipe.

Here's a high quality sketch to show you what it's gunna look like, it's not to scale and I'm not an artist.
DSC00212.jpg
 
There is an easier way to get the pipes alot closer to being the same size, just have the ports furthest away from the flange connected to the closest ports.
Just in case your not sure what i mean.
4-1manifold.jpg


Also being very good friends with "Arch chassis" (people who make chassis for Caterham, areo etc...) There gonna be tig welding and powder coating an inlet manifold for me, part mini for the SU and part micra just like the ones bob does, will hopefull be able to get a few made up but expecting a price of about 170 inc the carburettor.
 
Since this is a manifold / exhaust thread, I'd thought I'd plan out a little exhaust project that'd have the end result use the scavenge effect noted here:-
http://www.superchevy.com/technical/engines_drivetrain/exhaust/0505phr_exh/index.html

I'd like to point out that this is speculation and I do not have any proof regarding this. Although I do hope I'll be able to build it at some point in the future.

Primary Header Internal Diameter
Using this chart you can work out an almost perfect primary header internal diameter for the engine. (Bottom = Port Flow Capacity @ Full Valve Lift. Side = Internal Primary Header diameter in Inches)

Primary Header Lengths
According to the article, V8's are far less sensitive to prim header lengths than flat 4's. So assuming this is the case, It'd be a smart idea to have equally long primary headers.

Secondry Lengths / Diameters
This apparently the most key section. Getting it right can be a "large chunk of performance". Acorrding to the article, you'd take the port flow based diameter (of the primary header) then multiply it by 1.75 to get the secondry pipe diameters. In terms of lengths, the shorter the length of the secondry (measured from the middle of the collector!) the higher the RPM the "boost" will be. 10" would be good for a 8500rpm peaking engine, where as 24" would be good for a 4800 - 5000rpm peaking engine. Considering the micras power band, I'd imagine somewhere between 26" -> 30" would be around right.

Muffler / What ever after secondry!
The article goes on a rant about poor muffler design in the market place, then goes on to show different types of muffler which are more efficient for performace. (Apparently glass packed mufflers destroy performance!) How ever, after a bum load of muffler stuff, it goes on about a resonator box (pressure wave terminator!) which allows your "tuned length" of the secondry headers, to be preserved regardless of what muffler or length of exhaust you tacked on the end.
http://images.superchevy.com/technical/engines_drivetrain/exhaust/0505phr_exh_14_z.jpg
One of thems.

So basically, this is my full mock up of what it should look like the attached.
A to B: As long as needed, try and keep equally lengthed but not as important as achieving the correct diameter using a Port flow bench test then above chart/calculations. Avoid sharp corners and try and keep smooth.
B to C: B -> C pipes should be primary header diameter times 1.75. From when A -> B pipes end in the collector, there should be a distance of around 26" -> 30"s to the middle of the resonator box. Pipe lengths should be matched as closely as possible. Shorter distance between these two points means that the RPM the effect kicks in gets higher. 24" = 4800 -> 5000 rpm. The resonator box will kill off the effect of the pressure wave making anything beyond there null on the "tuned exhaust" effect.
C to D: C -> D matters less in terms of the pressure wave, but flow is still important. The article doesn't specify if you should have a specific width compared to your second stage, but increasing diameter slightly can't hurt performance much anymore. In terms of muffler, not much matters to the pressure wave as the resonator box killed it, but you need to make sure it doesn't increase the pressures in the exhaust. Glass packed are "worse" than "flowmaster" style.

I'd like to repeat that this is speculation and that the majority of it could be wrong for all I know, but untill it's been tested we'll never know. Writing up the theory can help anyone with the urge to give it a shot, eh?

If anyone has any corrections or spots any mistakes, chime in. Sorry if this seems like a high jack, I really don't mean it as one. (mods if you think this belongs in its own thread, shift it or delete it.)
 

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Your manifold design is too long to fit in the engine bay I think, there is only 15 inches from the top to the bottom any more than that and your scraping the floor.
 
ollyc98 said:
Your manifold design is too long to fit in the engine bay I think, there is only 15 inches from the top to the bottom any more than that and your scraping the floor.
Click to expand...
Well, I believe the article was written around this sort of exhaust system:-
0505phr_exh_01_z.jpg

Although surely it's possible to drop down 15" then turn to go along the bottom of the car?
 
justin

imo, (PURELY AN OPINION ONLY :grinning: ), the stock manifold design is compromised where the 4 ports join (ie some of the gasses coming out of one port try to go up the other ones) and the main objective is to get the end of the primaries facing the same way
once you,ve achieved that, the pressure vave, equal length etc stuff has minimal effects, and only at certain rpm
 
Its not minimal at all. With a properly designed system the effects can be so different that you can get a vacuum in the cyl at the top of the exhaust stroke!
 
Agreed ^^

Have alook at some NASCAR and F1headers if you can, they are absolut works of art...


You can also calculate a good starting point for primary lengths using the following formula (off the top of my head):

P = [(850 x {180 + deg. BBDC ex. valve opens} )/TARGET RPM] - 3
 
Doing it properly would involve buying some mandrel bent pipes - unless you have thousands to spend on a bender, then you're gonna have to buy bits and do some cutting...
 
I'll just buy the mandrel bends off demon tweeks then, gunna cost a bit though cos I need 6 15 degree bends per pipe and thats just to get it to point directly down, then I need to get them into the collector and pointing towards the back of the car.b
 
If thats the case, you might as well design one and get someone else to make it for you!

On another note, this is Mclarens 2005 F1 cars manifold:

148586520_cc2232db89.jpg


Work of art :)
 
Ideally I want it to be easy to build so other people can do it. I'll just stick with my original plan of 2 90 degree angles. It isn't perfect but it's better than standard.
 
you,ve gotta bear in mind tho, a manifold designed for a powerband of 10 to 19000rpm and 320deg+ duration is a different animal to a micra one
 
why are people putting up pictures of manifolds that have no comparison to something that you would use on a micra..

this is were you get this miss information from

i throught this was a budget manifold thread

dont bother making you own up they never work unless you no what your doing..its much better and easyer make one fit that was made for another car...
the easyest one's to use are off some peugeot/ford fwd engines because the deep part of the sump is the same side as a ma10/12 engine

you need to look for something like this which is off an peugeot 106 1.4/citreon ax gt tu engine
1734482730edf1b54.jpg
[/IMG]

or even this one off a ford zetec
173448273298ad585.jpg
[/IMG]
 
Retepetsir said:
If thats the case, you might as well design one and get someone else to make it for you!

On another note, this is Mclarens 2005 F1 cars manifold:

148586520_cc2232db89.jpg


Work of art :)
Click to expand...

Note those stepped headers ;)


Thing is, it's not going to be budget if you buy an aftermarket one for a different car and then fiddle it to fit is it?
We were using pictures of fancy headers to show that it is a job that should be done properly, not just bung something together witout thinking about it.
 
Yeah if I buy a pug one it's gunna set me back 200 odd quid.
This is budget which means 'won't give such a boost but will be better than standard and is still good bhp per £'
 
ollyc98 said:
Yeah if I buy a pug one it's gunna set me back 200 odd quid.
This is budget which means 'won't give such a boost but will be better than standard and is still good bhp per £'
Click to expand...
Might as well try and get the lengths right though. If you're running a 4-1, read the article I posted and have a go at something like that rather than just banging something together that fits. Potentially a custom made exhaust, even a cheaply made one, can out perform the after market ones because as far as I know, they're not designed to be fully exhaust tuned. Don't just slap together a load of large diameter pipes and be done with it, atleast take some time to look up what you can do whilst staying in budget. :)
 
I'm using 38mm pipe, the size of the ports, it doesn't get much better than that.

Plus you pretty much can't go wrong with this, it'll work well at some rev range, the fun is finding out which.
 
I'd be interested to see how a 'free flow' manifold works, i always thought the idea wasn't just large bore pipes, it was also to use the exhaust from one cylinder to help suck out the exhaust from the next firing cylinder?
Or is that just me talking out my other end?
 
I'd be interested to see how a 'free flow' manifold works, i always thought the idea wasn't just large bore pipes, it was also to use the exhaust from one cylinder to help suck out the exhaust from the next firing cylinder?
Or is that just me talking out my other end?
 
Ceirwan said:
I'd be interested to see how a 'free flow' manifold works, i always thought the idea wasn't just large bore pipes, it was also to use the exhaust from one cylinder to help suck out the exhaust from the next firing cylinder?
Or is that just me talking out my other end?
Click to expand...
That's sort of how it works. See, say you've got a 4 - 2 - 1 manifold. For now we'll focus on Cylinder 1 and 3 (C1 and C3). C1 fires, the exhaust travels down the primary header and it's backed up by a "pressure wave". As primary header of C1 meets primary header of C3 and forms the secondry header, the "pressure wave" from the primary header of C1 causes a vacuum effect in the primary header of C3.

This is where it gets interesting! By making sure your primary and secondry headers are the correct length and diameter, the moment this vacuum effect hits the exhaust valve AND intake valve of cylinder 3 will be open! This means that the exhaust gas gets sucked out AND more mixture is drawn in. It will do this effect regardless of lengths, but lengths control at which RPM it does this at, which means you can slap it in a nice power band (3200rpmish for a micra?) It's been shown that this effect, if done right, can cause 6-7psi of pressure on the intake valve, where as the pressure from the piston moving down is around 1psi. (This is taken from an article on large V8 engines mind)

Works better on 4-2-1's but works on 4-1's as well.

Another note, the article says that V8s don't require accurate primary header lengths, flat 4s are FAR more sensitive.

Edit: In ideal design you'd have perfect length primaries, secondaries and a resonator box on the end. The resonator box would kill the pressure wave, meaning that your tuned primaries / secondaries wouldn't be affected by anything past it...Which means you can slap on a decent flow muffler and have a quiet race tuned exhaust!
 
So basically how long the pipes are (simply speaking) controls the rpm at which you will get the scavenging effect?
How does that work because i would have thought that although at different rpms the exhaust gasses are flowing at different speeds, because the engine turns over at a different speed as well, it is relative and the exhaust should have time to reach the correct point no matter what the rpm.
 
ceirwan

you get much the same size slug of exhaust gas coming out, at any revs (at wide open throttle) but i can,t see how you can get much of a vacuum in a manifold thats largely under a lot of positive pressure (it takes a lot of pressure to spin a turbo up for instance)
a vacuum close to the valve maybe, but further down, i dunno ?
 
It works on the principle that the exhaust gasses have a mass, when this is sent down the header it leaves a spacce behind it when the valve shuts due to the monentum - a bit like a train going throuh a tunnel, this low pressure wave will 'travel' down the manifold until it finds some thing to suck in to fill the pipes again, which will exualise the pressure in the connected pipe, thus drawing more ofthe spent mixture out of the cyinder (as you can't empty out all the spent gasses) and if done correctly, as mentioned above, can suck more mixture in during overlap - getting to (or maybe even exceeding if the inlet manifold is similarly designed) 100%VE.

Sorry if you know all this already, but (if it makes sense) it might help others who know less :)

Craig
 
craig

but at highish revs, there,s probably about 15psi of pressure at the collectors, i can,t see how you can have a vacuum in those conditions ?
 
If you look at the exhaust as a complete system from the combustion chamber to the collector, great pressure builds up in the cylinder during the power stroke, when the valve opens, this pressure forces a mass of hot gas out and then the piston helps some more on its way, at this point the pressure in the header is greater than that at the collector, otherwise the cylinder would not 'breathe out'.
This pressurised gas comtinued down the header in a continuous stream until the exhaust valve closes, thereby cutting off the stream of high pressure gas.
As the gas has a mass, momentum keeps the stream moving, but where the valve has cut the stream off the pressure will be much lower, when the back of the exhaust gasses reach the collector, the pressurised gas from the other cylinder will flood back up the first header pipe to the back of the (now closed) exhaust valve.

Thoughts?


(Did I manage to make a coherent argument, or did I wander again lol?)
 
craig

all very logical, i agree about the vacuum at the valve (scavenging effect) , but can,t see how there,s any scavenging at the collectors, with all that positive pressure
 
JStone said:
That's sort of how it works. See, say you've got a 4 - 2 - 1 manifold. For now we'll focus on Cylinder 1 and 3 (C1 and C3). C1 fires, the exhaust travels down the primary header and it's backed up by a "pressure wave". As primary header of C1 meets primary header of C3 and forms the secondry header, the "pressure wave" from the primary header of C1 causes a vacuum effect in the primary header of C3.

This is where it gets interesting! By making sure your primary and secondry headers are the correct length and diameter, the moment this vacuum effect hits the exhaust valve AND intake valve of cylinder 3 will be open! This means that the exhaust gas gets sucked out AND more mixture is drawn in. It will do this effect regardless of lengths, but lengths control at which RPM it does this at, which means you can slap it in a nice power band (3200rpmish for a micra?) It's been shown that this effect, if done right, can cause 6-7psi of pressure on the intake valve, where as the pressure from the piston moving down is around 1psi. (This is taken from an article on large V8 engines mind)

Works better on 4-2-1's but works on 4-1's as well.

Another note, the article says that V8s don't require accurate primary header lengths, flat 4s are FAR more sensitive.

Edit: In ideal design you'd have perfect length primaries, secondaries and a resonator box on the end. The resonator box would kill the pressure wave, meaning that your tuned primaries / secondaries wouldn't be affected by anything past it...Which means you can slap on a decent flow muffler and have a quiet race tuned exhaust!
Click to expand...

how will this work, seeing as the inlet valve is closed when the exhaust one is open?
 
Not with high duration, long overlap cams, even std cams have an element of overlap in their timings during the intake phase.

Frank, the pressure at the collector is what helps with the scavenging effect (if I remember my theory right) as this pressure will lower in order to fill the vacuum left from header pipe 1, thus helping the exhaust gas from header pipe 2 to flow quicker as the pressure slope will have increased.

Also, the angle, volume and shap of the collector can have a huge impact on this effect as it also acts like a resonator box.

Keep the discussion coming :)

Craig
 
Maybe someone could start an inlet thread and explain why you need to tune the length of the inlet manifold. The exhaust makes sence to me, but the inlet I am struggeling to understand.
 
craig

i agree you would get that effect at low revs, when the exhaust pulses were creating high/low/high/low pressure waves in the manifold, but at highish revs, it would be producing high/very high/high/very high pressure pulses,
so the adjoining pipe would have to force its way out, into that high pressure enviroment
which is why i said on the other thread, that 4 separate pipes might produce more power (the gas from 4 individual pipes only has to fight atmospheric pressure to get out)
 

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