Hello guys. This is just me thinking outloud, and todate i havent come across something similar to what i am proposing so i will just spit it out.

People whinge about there SOHC 6G when changing spark plugs (rear bank) well thats nothing compared to the DOHC 6G. Entire inlet manifold has to be removed no if ands or buts.

Anyways to overcome this gripe, and since im handy with my TIG i was wondering what to expect if i tried to fashion up a independant/ multitple TB setup that is part of lower manifold that would have to be short in height that would stand upright out of the valley. I was thinking of finding some smallish, say three 48-54mm TBs from the wrecker, the reason i would use these as once the tubes are made tuning the TB linkages would be easy as i could use each TBs position sensor to set them correctly/ dial them in.

THings i see as the issue

-likelyhood of using this technique and it working how it sounds in my head
-fitting them under the bonnet with some form of air filtration
-anything you can think of?

Just note i have a haltec interceptor with map sensor (not installed sincei havent done any real Km on the dohc yet)

I fail to see why this is a problem? These engines are ment to have the rear plugs changed only every 100,000km (using platnum plugs) and being a magna engine, you are more likely to develop a rocker cover leak before having to change the plugs anyway which is going to force you to take it off either way.

well in my head im seeing it that if i make it the rear rocker cover will be as easy to remove as the front. I dont run cars on platinum plugs anyways, never have which is the reason im thinking about more access. Im putting the haltec in after ive got a few km under the hood and id hate for the tuner to spend a plug while tuning, or for the car to foul before tuning and require 2hours work to change the rear banks plugs.

i figure it comes down to finding the right equipement. Research on the net last night sugests 44mm pugeot 106 TB might do the trick, im heading down to the wreckers this morning to find something or at least look, plus pick up a 3rd gen steering wheel. I guess ill be able to report this arvo.

Takes me <10 minutes to remove entire intake manifold dude, surely cant be much longer for you, just leave the TB in the engine bay, not attached to the intake manifold....

:stoopid:
its not a hard job to do,

So we're a little bit out on the attack! :P

Yes, I agree, many people complain about the task of the inlet manifold.. but me being super junior mechanic (just ask 86_Elite) can confirm that it is definitely not quite as hard as some people think, although its a bit harder on some of the newer models (My 3.5L TL has quite a few more hoses and shit than 86_Elite's 3.0L TE for example, has some EGR and cruise control and other bits his didn't that was easier)

However we're getting a little attack side-tracked from the more interesting idea of making a new inlet manifold.. you can imagine this is a bit of a science, I once found a page about literally 500 pages long describing all the ins and outs of suspension for cars the guy did a total super engineers brain dump.. but I've never seen one for inlet manifolds :P

All I can say is, without any experience, why not try it! Maybe EZBOY can give you some insight? You may end up with a worse air flow pattern or some such at the cost of convenient, however.

to get airflow to the TBs i think you should run ducting along the inside of your bonnet. if you can get them circular you could even use ITB filters on the ends.

i had the idea of making a DUAL TB setup on the Streetfigher manifold, its possible but tricky, getting both TB to open simultaniously i thought the trouble outweighed the benifits

In no way am I an expert on this but I am going to just throw a few ideas around with this. First issue I can see with it is room under the hood. It would not be hard to make a dual TB setup with more of an over head intake if you are handy with a TIG. Have a look at the Holden LS1 setup, intake wise, they are great, the TB comes to the front of the engine allowing a very short intake to the front of the car allowing for more of a Ram-Flo style setup. A new TB setup for the 6G could be similar only side on, but once again, the main issue I could see stopping this would be bonnet room.

I also though can verify, its not hard at all to take the manifold off to do the rear bank (re: lathiat).

But hey! You could be onto something great as we are always looking at ways to improve our cars!

I guess the other thing you'll be changing is the tuned intake length; I have no idea how much effect this has, but it's something to think about...

Correct, but if its designed in an OHC style as opposed to off the side design that we currently run the flow rates will maybe improve.

Similar like this: http://precisionracecomponents.com/data/images/fastnw.jpg

I am a little confused, so you want to go to all the trouble of removing an intake manifold, making up some sort of design to flow 2 throttle bodies into 6 ports all so you can get to your rear bank of plugs easier

You also state that the sohc are easy where as the dohc are not, well this just in, the manifold and the way the plug goes through the rocker cover on both the sohc and the doch is pretty much the same

Now Street Torque as well as those other tools in WA have both played with dual TB set ups. Others have also tested the volumetric efficiency with both larger single TB design vs standard and it has been found that even for a high comp NA engine that the factory set up is actually very good and quite enough flow

Now I dont want to dampen people trying new things but what is being suggested here will remove all of the length of the upper manifold and I would think make the car next to un drivable. If it even worked at all

It is a massive amount of work to go to just so you can get to a set of spark plugs.

Then again, if you have the time, the equipment why not try it on an old manifold, get it set up on an engine stand and then fit to the car once working, stick it on a dyno, drop it down the quater and drive it a bit, we may all be shocked with the result and if this is the case would be awsome

Just my 2c.... unplug the dual runner motor and you notice a big difference in lower rpm sluggishness. and you want to make them shorter?

unless you do alot of high rpm work, this will be a waste of time IMO...

there is a turbo magna on here that has a similar style of manifold to what you describe, but fed from a single TB @ the front of the motor.

Trotty, can you please explain a little more in reg's to dual runner motor and a link to who the member is with the manifold setup?

The best motor ive EVER been behind is the BMW V10 5L. 10x itbs all electronically controlled. For cost's sake, you could cut up a 2nd gen manifold or falcon manifold and adapt/weld the 6x inline butterflies onto a manifold of sorts. You'll need to square away the turbulence from the air filter pipework to the tbs to and ensure equal drinking for the little fellas. Be mindful that BMW know what they're doing and will sting you quarter of a big one to enjoy it. In all likelihood you will change way too many variables and will never be able to track down the cause of all your ills. That said, give it a f*****g go! Life's short, play hard or something like that. Whatever you do don't lose a single kw at wot or that'll be the end of you....

I am a little confused, so you want to go to all the trouble of removing an intake manifold, making up some sort of design to flow 2 throttle bodies into 6 ports all so you can get to your rear bank of plugs easier

You also state that the sohc are easy where as the dohc are not, well this just in, the manifold and the way the plug goes through the rocker cover on both the sohc and the doch is pretty much the same

Now Street Torque as well as those other tools in WA have both played with dual TB set ups. Others have also tested the volumetric efficiency with both larger single TB design vs standard and it has been found that even for a high comp NA engine that the factory set up is actually very good and quite enough flow

Now I dont want to dampen people trying new things but what is being suggested here will remove all of the length of the upper manifold and I would think make the car next to un drivable. If it even worked at all

It is a massive amount of work to go to just so you can get to a set of spark plugs.

Then again, if you have the time, the equipment why not try it on an old manifold, get it set up on an engine stand and then fit to the car once working, stick it on a dyno, drop it down the quater and drive it a bit, we may all be shocked with the result and if this is the case would be awsome

On the bolded statement. The SOHC heads have the spark plug coming in from just above the exhaust manifolds where as the DOHC have them perpendicular to the piston, completely different angle. I knwo this because i do have a DOHC and converted it from the SOHC and even thought the inlet mani's are the same, this offset in angle makes all the difference.

I do agree/understand and know about inlet length and design for certain torque/drivability characteristics but im sure i said in the first post i had all the equipement, say bar a dyno, to do the work myself at relatively minimal cost (for a prototype anywyas) I also have a haltec, so tuning adjustments can be made to lessen the impact of the manifold modification.

Besides finding the manifolds i would and TB's i would butcher i havent started this since ive had to stop working on the car for the foresseable future until work lets up and the weather improves. IF i cant make one for less then 300 i wont be making it.

I can just imagine 6 TBs and short runners on a 3.5L. No power to 5,000 rpm. then BANG, mega power, then all over at 5,200 rpm. Just what a street car needs!

Trotty, can you please explain a little more in reg's to dual runner motor and a link to who the member is with the manifold setup?

All seccond gen V6's run a dual length inlet manifold design. the electric motor only turns the butterflys inside the runners to change length.

the design i have in me head, which after measure will require about a 1.5"-2"inch rise in the bonnet (maybe a tuffyesque bonnet bulge) to fit confortably with room to move and have unifilter filters attached.

Anyways i was thinking (as per the 1st post) 3 TB,s with independant runners to eash inlet port. 3 because to keep costs down i want to use oe TB's of the same type and i wouldnt have room for 6. Todate i have found some 48mm cruise and non cruise TBs from a citron forget which model off the top of my head. they are short in stature, have a 4bolt flange, use the same voltage range as the magna and have a vacuum based cruise option, which might mean i can retain cruise.

Again this wont now be started to maybe november

Lynel, The intake manifold splits into 3.
The first "bit" which bolts to the lower intake manifold is a DOHC only design. From the butterflys back is the same as a SOHC manifold.

BUT, If you want another DOHC manifold to chop up, use a standard 3rd gen 3/3.5L Intake manifold as it's the same bolt pattern and will bolt up to the DOHC motor.

Can you use The 6 butterflys in the manifold as the TB Butterfly's?

I know the WRX's have 4 TB type....butterflys somewhere in the intake (My uncle is using them on a V8 for ITB's) but I cannot remember the name for the LIFE of me.

All seccond gen V6's run a dual length inlet manifold design. the electric motor only turns the butterflys inside the runners to change length.

I know. But how the h*ll do you check if its working properly? lol

i would assume removing it (the electric motor) from the side of the plenumn, start the car, whilst under the bonnet rev the engine using the TB cable and see if it spins. i think it activates around the 3-4000 RPM range.

or get an auto elect to test it.

The electric motor is attached to the whole unit. So you cant do that. I know on the diamante you can see it working on the opposite side, there is like a screw at the end of it and you can see it turn slowly when the revs rise. Not sure if the SOHC manifolds have this on the end.

There is a testing procedure in the workshop manual (or haynes etc) Check the plugs and make sure the metal clip is in, they can sometimes not be put back in and the plugs work themselves loose (had this happen)

Thanks for those hints. Will look into it.

Checked: Nope, my 3.0L SOHC has a blanking plug at the opposite end. Will look at manual.

Weird - Manual says I should have a screw there that moves when the butterflies open, but I have a blanking plug.

Fig 7, "Induction control valve shaft" on p 15-3-5 of the second gen manual.

Guess I will just have to assume it is working properly . . . .

i guess in reality i either have to get it working how i plan/hope for it to or to just forget it because the way i hope it will work (and im not looking for gains, maybe the prestige of having something different and access advantage) but i need to retain a stockish TB for the TPS sensor, because intergrating one into a completely custom item would blow the cost out. Ofcourse with enough money i could get one done but im not spending 1000bucks on an inlet manifold just to look good (as making something better than stock for a road car would be nigh on impossible)

Something cheap i can do myself. As long as there arent noticable losses after a tune ive succeeded in my goal really

Hardest bit would be idle personally.

you can buy aftrmarket throttle bodys that have mounts for TPS.

I also have a haltec, so tuning adjustments can be made to lessen the impact of the manifold modification.

You can't tune parameters that don't exist. Modifications to an inlet system have real, physical affects, if there is little air movement into the engine at a specific rpm, than no addition of spark of change of fuel ratio will change that fact. I'm just trying to highlight very real considerations that need to be made and assessed so that you understand what the results may be and that there may be nothing or very little you can do to mitigate those negative characteristics without a major redesign.

this is waht cthulhu did a few years ago
http://www.wermspowke.net/images/engine-bay-tn.jpg

post http://www.aussiemagna.com/forums/showthread.php?t=23596

EZ Boy I know what your saying. In no way shape or form and i saying i can improve on the factory design about the only thing i know is is that my inlet runners should be roughly 2/3 the length of standard which although i cant test until tried, i hope that isnt too big a drawback to cause untenable tuning situations. IT will be made using spares so i can also go back if need be

It is very possible to improve on the factory manifold - if you are chasing a specific goal from your development. To explain; the oem manifold does a good job of delivering useful torque at most rpm, it is however a carryover from the 3L to the 3.5L so there are no changes in upper manifold at all (bar egr on TH+). Runner diameter, lenght, plenum dimensions, TB bore etc are all identical between motors. There has got to be scope for feeding the 3.5L better. I do believe you are on the right track for top end power by shortening the runner lengths. You can always increase base idle to reduce the effects if any of lumpy low rpm running. If you're making the manifold from scratch using a laser cut flange, see if you can get the runner diameters upto 2" - you probably wont squeeze them in, but aim high. You will need to shape the lower inlet manifold too where they both join. If you're cutting a std manifold and want to weld on the guts from a falcon or 2nd gen manifold (the falcon probably has larger butterflies) onto the runners I think you'll have a good chance of some success.

Further considerations:

Can the Haltech run the motor without the maf sensor? I think you're best served putting a pseudo plenum over the TBs and feeding via oem intake or similar. That way your list of changed variables is a little less ( ! ). I have a few old dead TBs if you want one (cover the freight and it's yours) so you could remove the boss for the TPS and weld it on? That was my plan, or mill another section into the manifold to suit.

Do it. I sincerely wish you the best of success with it.

It is very possible to improve on the factory manifold - if you are chasing a specific goal from your development. To explain; the oem manifold does a good job of delivering useful torque at most rpm, it is however a carryover from the 3L to the 3.5L so there are no changes in upper manifold at all (bar egr on TH+). Runner diameter, lenght, plenum dimensions, TB bore etc are all identical between motors. There has got to be scope for feeding the 3.5L better. I do believe you are on the right track for top end power by shortening the runner lengths. You can always increase base idle to reduce the effects if any of lumpy low rpm running. If you're making the manifold from scratch using a laser cut flange, see if you can get the runner diameters upto 2" - you probably wont squeeze them in, but aim high. You will need to shape the lower inlet manifold too where they both join. If you're cutting a std manifold and want to weld on the guts from a falcon or 2nd gen manifold (the falcon probably has larger butterflies) onto the runners I think you'll have a good chance of some success.

Further considerations:

Can the Haltech run the motor without the maf sensor? I think you're best served putting a pseudo plenum over the TBs and feeding via oem intake or similar. That way your list of changed variables is a little less ( ! ). I have a few old dead TBs if you want one (cover the freight and it's yours) so you could remove the boss for the TPS and weld it on? That was my plan, or mill another section into the manifold to suit.

Do it. I sincerely wish you the best of success with it.

He's talking about the 2nd gen here.
In saying that, I've got both DOHC 3L and DOHC 3.5L Intake manifolds and the 3.5L has a longer lower piece by about 3mm, so there is not alot of difference in them both.
Also, The dual runner design gives the low down torque below 3000 and the short runners kick in above that...

well im unsure on the haltec running a map sensor, but the guy i got it off said he was running it on his xr6t with map sensor harness included. i also got the cables and software with it for SFA so im hoping its legit.

while im not specifically trying to acheive moving the torqueband around on the car, when the haltec goes in the car will be manual, which at least will help slightly on the drivability front if down low rpm is cactus. I dont want power increases, i just dont want power loses haha ultimately its probably going to happen i just hope its not to unbearable