I've always looked at the runner for number six and thought it looked like crap, regardless of flow it looks like crap and if you actually cut one out and look at the cross sectional area they are smaller in places than the others. Now I know some will say number five and six get more air than the others anyway due to momentum etc etc - I don't care I can tune for that so figured I'd take all the air I can get Yip number six might work a little harder than the rest - maybe I'll put a shorter spark plug in to reduce compression ratio :rofl: Anyway the basics are done and ready for tidy up and install of some pressure sensor bosses etc:
never really had an issue with number 6 its always been number 5 that gives me the s***ts as for air flow maybe with a NA engine but I think with the turbo issues would be a lot less
yeh - no 5 has been more of a problem for me as well I put the highest flowing injectors of the set in 6 and 5 and its been better since
Dont worry about pressure, flow is what counts, bolt it to some heads and flow it. And a stock one too please.
Naaaaaah most of us know what the results will be, stock number six will flow just a touch less than the others on a bench IMO BUT if you test it in a more 'real world" environment number five and six flow more air. Take a stock plenum and block off the balance pipe holes with some duct tape, flip it on its back and blow compressed air in the throttle, most of that air comes out number five or six depending on what side you are blowing in. The same but to a lesser degree has been proven to be the case on the engine during operation at boost. What we will be doing is running six EGT probes so we can tune the individual cylinders to their maximum potential - but this all starts running in to another subject I will post up in a few weeks But back on topic a flow bench would show the potential advantage for someone with an NA who wanted to do this All they would need to do is test a stock plenum and confirm if number six is crap or not, I changed it because to me it looks wrong - it MIGHT work fine but it's ugly :zlove:
I like the look of the symetrical shape, but it raises a question. Why did the Nissan engineers design the plenum with number six in that shape? I know we delete systems to "improve" the engine perfrmance eg EGR, AIV, and under plenum water pipes. But to change the shape is more costly Vs the advantages. Porting and polishing would be more efficent mods.
I admit EGR is a perfomance (albeit minor) improvement but I thought the underplenum pipes were to stop them living up to their other name ..... b*st**d pipes. AIV in mine is gone due to aftermarket exhaust.
The stock one is shaped the way it is for only one thing as far as I can tell: Ease of assembly at the factory. The heater pipes live just behind and below number six runner and if it were shaped the same as the others it would have been just that little bit harder to get the heater hoses on and clamped at the factory. The taper at the end of the main tube/runner that runs front to back is to clear the clutch master cylinder and pipe etc and the odd shape of number six runner is so they can fit the engine with less ergonomic stress on the workers. Besides, I've replaced the runner with one the same as the others (actually number two is not ideal also) and will now give the whole thing the usual treatment of spending a stupid amount of time on it to squeeze every little bit I can out of it :zlove: If we test it and it turns out there is a good amount more power available then we all learn something, if we test and it does f all (the more likely result) at least it will look better IMO
According this AutoSpeed article Nissan spent a considerable amount of time designing and tuning the intake manifold. http://www.autospeed.com/A_109870/cms/article.html
Yes I appreciate Nissan spent a lot of time and money on the plenum and this is one of the reasons why it wasn't simply ditched and replaced with some ugly lump of crap like a lot of people have done. My goal was to improve on what was already there, I have no doubt the cylinder filling ability of number six is improved over what it had before and with individual cylinder tuning on my ECU it's all good Next step would be to use round tapered tubes with trumpets internal to the two primary runners - that's in the too hard can't be bothered basket for now though.
It's not bad aye I would tuck the radiator in the front so it can't be seen. Also he has a bolt missing on number three coil pack - what!? I HAD to pick on something LOL!!
even with all the work done theres still more that could be done though. polish or paint the cas and bonnet release, throttle linkages, clamps on the throttle body, hpc coat or paint the headers........... no denying its a spectacular looking bay though.....
I just noticed the deleted windscreen wipers THAT'S pretty serious! Always more that can be done no mater how far you take things, imagine the bill if you weren't a hand on man and just paid someone to do that for you ..... Actually might pay to not imagine that :rofl:
Aztec red looking much better than the orange pretending to be red it was before: Before: During: New injectors - 555s were up to 99% last dyno tune LOL!! fair to say we got as much as we could out of them! As it is now: Still a heap of things to be done but for now this will do, no significant change in how it looks but I feel better knowing it has been done and with the larger injectors ....... I smell trouble coming............
yes , yes , yes ....... very nice finished alloy job .... ready for the color that you've since done and re-done again..... where's the pics of the cut open runner ? where did you cut n shut it ? did you just replace the scolloped off section with a full section or cut n shut an entire new tube in there ? what part of another runner did you chop off for the conversion or did you simply use some thick alloy plate with abend to suit ? what porting was done internally? pics of up the inside of the runner since the "re-shape" are ??? hurry up n get the real tech happin I DEMAND PICS
What and show everyone how I did it? so they can say it's wrong? :rofl: Well I tell you what the other red plenum that I took off today is going to get the same treatment although with a couple of lessons learnt from this one it should be a neater job A few of my customers and mates have had a look at what was removed and most laugh at the extraordinary shape of the original - just plain ugly I cut the entire runner from number four and used it to replace the runner for number six, you could also use number three and five but I wouldn't recommend number one due to the odd shape at the inlet end.
