Ok, since it seems as though the Pathy manifold will be a bit of a hassle to make work correctly due to the height I figured it be easier and take less time to just do my own using some mandrel bends and steel pipe. This is basically what I have in my head at the moment. Does this design seem like it'd be worth my time making or do you guys thing it wouldn't perform all that great?

Any comments/suggestions/useful links/flaming/questions/etc will be helpful.

Note: this is using the Pathfinder lower intake since the ports are all circular and in a nice straight line. It will make getting a custom flange made much easier as well as having round pipe to match the round ports.

 

Use aluminum, not steel. you're going to have a TON of weight on there if you use steel.
also use shorter intake runners, IMO. the Z31 manifold should provide good power, but the pathy manifold is a bit more.. since you're going custom, basically see how big you can make it and go from there.

Also keep in mind that you want to keep air velocity up inside the ports, so don't make them too huge. you also want to keep total air volume relatively small so the turbo spools quicker. If you have a ton of airspace you have to pressurize, it's going to slow down turbo response.

 

Hmm... I could probably pick up some aluminum wire for my welder or take it to the local welder for some pretty TIG welds. Do you know what a good source would be for aluminum mandrel bends?

As for the ports/pipe size I'm planning on just matching the port size and for the collector piece I'll probably make it no bigger than the Pathfinder collector (probably around 3 inches ID or so... I'll have to go check again as I haven't studied it all that much).

 

Here's a link to a friends Procharged 69 Chevelle with a Holley stealth ram EFI Lower IM and a custom tuneable runner upper.
http://home.comcast.net/~procharged69/efi.htm

Just to give you a few idea's. The general rule is shorter runners will push your powerband up, so keep that inmind.

 

i think one of my biggest hassles is going to be trying to find mandrel bends that are less than 2 inches... pretty sure those ports are smaller than 2 inches.

 

id just cut the flang off the pathys upper manifold or cut the patthys uper in half and weld a 3in aluminum tube onto that then weld the TB flang onto the end.

id use a Q45 90mm TB or pathys 70mm like what the 4th gen guys use but you could use whatever, remember 3in is 75mm so going any smaller and you have a restiction and the stock maf is 75mm so thats cool

take a look at this guys setup for some more ideas, some people simply amaze me at what the can fab

http://www.toohighpsi.com/SCTC/88intake.htm

http://www.toohighpsi.com/DadTT/dadTT1.htm

 

Comments:

Port side ok.

The other end: Whats the purpose of the huge turbulent 'air reservoir'? I would think that gradual increase (cone -shape) toward TB would cause best laminar flow, and thus I would 'cut off' its 'lower' leftmost sector.
Also question the air reservoir 'endplate' parabolic mirror works: the turbulent air pressure pulses in the reservoir are mirrored towards TB 1*, for what purpose?

The sharp edges will create crimping turbulences as air is sucked into the 'pipes' from the 'air reservoir'. I would round those edges.

Edit: =NoNews: Air sucked to a cylinder with near supersonic speeds is suddendly blocked by the valve. This causes collision, compression, and then 'mirrored negative air flow' =the energy pulses now backwards, towards the TB. This repeated six times, means that the channels are echoing negative&positive air 'pulses', seemigly random. The 'pulses' are mirrored and guided by the intake walls, defined by its shapes. When all these positively match and produce maximum fill to the cylinder on some rpm, that can be seen on the produced power curve. I suppose that any shape enforcing the flow towards TB is not good 1*.

 

basically i'm just trying to design it like the manifolds available for most 4 cylinders. supposedly that "collector" offers the best performance. i'm not 100% sure though.

 

I just read an article of intercooler collectors; basic idea is the same: big idle corner areas are not only bad waste, but turbulent crimps. The collector diameter should relate to the supposed gas flow in any section. Sounds reasonable to me. Dunno, never tested that, but the article writer had tested many intercoolers on the market, and said that most do waste a lot in unnecessary turbulences... What I know from experience is that parabolic mirrors are effective, and the pictured collector RH end forms one such; from gasflow -point of view.

 

here's a problem this this design that i see...the port that's closest to the intake (TB) hole will get the most air and then it'll trickle down to the rest. having to feed 6 holes all lined up is going to be a tough job. the last bank might starve for air.

 

IMO you're barking up the wrong tree. what's wrong w/ the factory intake manifold? have some extrude hone done to it and it should work quite nicely. at the most you can try and modify the stock intake manifold to flow more air (different flanges and etc) but making a one off manifold from scratch will be the never ending project. if you can do it then more power to you.

let me tell u that a good welder is $. in MIG welding, a good welder would charge by the foot. TIG...they charge by the INCH. this manifold will probably cost you more than it's worth and you don't know if the gains will be all that when you're done.

oh and i told u so on that PF intake.

 

if u make the volume of the collector 6x (for 6 cylinders) as big as a port's volume then shouldn't the flow of the collector saturate the 6 ports nicely and maintain a constant flow with little turbulance?

 

Yes it does, but flow is not laminar. Everything that disturbs laminar flow, makes waste in turbulence. What Danny said using other words, is the same issue I stated.

To get ideal flow, the collector should become narrower towards the end.

 

the problem with the factory manifold is that the whole throttle body setup is pointing in the exact opposite way that i need it. on top of that with as low as that aluminum elbow goes i think it is picking up quite a bit of heat from the exhaust manifold.

 

Could it be easier to modify that than build all new?

If you think of the airspeed at full throttle, alu temp has practically no effect on the air temp = oxygen amount in cylinder. Idle is different, then the incoming air has time to warm up.

 

sorry about the repeating what you said...sometimes i have a hard time reading your posts...but i'm trying to pick up on it.

 

well don't reinvent the wheel. you're better off cutting the TB flange and TIG on a elbow piece to point it towards where ever you need it.

 

How about getting the current setup working well first?

 

i have to change this setup to make it all work well.

 

i understand what your saying but seriously once the turbo spools it doesnt matter because the thing will be pressurizzed with air so all cylinders will be getting the same amount.

and ive seen ton of manifolds like this one and most are on high HP cars with great success so its kind of a proven design at least when dealing with FI

this could be done for next to nothing if you welded it yourself but if you dont have a tig i wouldnt even try ive never heard good things about welding aluminum with a mig

 

high HP cars running high boosts right? the log style manifold is great for those race motors...but what if you're not on boost and you're on the hwy...what does that manifold do to your air flow? since now your air flow is not that much on the + side anymore and you might be drawing a vacume. in this situation would you say that the cyls that closest to the opening would get more of the air compared to the last cyl?

 

Yeap, which is why the 5.ohnoes EFI manifolds have uber long runners in the upper intake manifold and the throttle body is placed in the center.

The other thing I dont understand is why he spent so much time on that manifold and didn't use the GT-40/Cobra manifold instead. Those 2 manifolds are the perfect example of what Matt is talking about with keeping the air velocity up (the GT-40/Cobra runners are smaller but flow more).

 

Also being used widely does not mean smtg is the most efficient way to do smtg, always there's compromise between myriad things. In this issue, for laminar airflow, -pressurized or no-, there is no need for such 'idle bulbs' that the excess 'right end portion' represents.

Now mtcookson is seeking something better than off the shelf designs are; that is a goal one should go after, even if without results...

Like Maxima. If no price restrictions, no mass producing restrictions, no policy restrictions etc. - it would be totally different. But given these side limits, I think the car is marvellous...

 

In my mind, the red area is not needed. To have laminar flow (green) to all cylinders, its good to have flow in the collector with parallel capacity to input ports. So the capacity at fifth cylinder, is the A X 5.

On cyl six, I illustrate a situation where almost supersonic air has been rushed in, and valve is slammed shut. This causes a backflow pulse flowing back to the collector.

'My' thinking: These pulses in the collector are reflected all directions, and the 'parabolic mirror' at left is a doing its idle job efficiently = trying to focus air pulses towards TB, hindering laminar flow...

The input port edges form eddies, if not knife shape. All eddies restrict flow.

 

Here is what I suggest, try getting your hands on a VG30DET intake manifold. That manifold has the TB in the same spot as the 3rd gen VG does. Then you'd have to make and adapter plate to bolt it to the lower IM. It should give you more top end powa. Another way to I guess weld up your own IM, but as far as the runner measurements or collector volumn who knows were to start? I say make a custom IM with the same size/volumn runners/collector as the high port SR20DE. This should shift your power peak to 6400rpm and torque to 4500rpm and would allow power up to 7500rpm. So you would need valve springs for sure.

 

The VG30DET manifold?



If that's the one you're talking about that's my friend's engine that is pictured and I'm sure he'd sell the manifold to me as he wants to make a sheet metal style intake for his.

 

that seems like a very interesting setup. maybe i should just try making a bunch of manifolds and dyno all of them to see which one works best.

 

I think this would be quite straightforward if the flow would be continuous. The sudden flow cut and its consequences - who conquers them, is THE millionare. Regardless of computer simulations, theres still space for somebody to get the grand idee...

Your life calling? At least its so big problim that one life is nothin... maybe we speak someday of Cookson -intake at F1?

 

lol... that would be sweet. F1 is coolest, bestest, greatest, neatest, most awesome racing that has ever existed.

 

First u must device a way to simulate the flow (with valves) to test/try/modify the assumptions. The backflow is THE issue causing 'virtual blocks' to the cylinder sucking air in. This must also be the main reason for VGE have its 'power' valve -system.

In the backflow we speak of multi physical issues. 1. Air pressure mirroring from the suddendly closed valve; the pressure 'bolt' can move against actual flow (tsunami?). 2. Sound waves (they use resonators to cut them off on stock engines), and 3. actual air flow and its 'random' eddies.

I am afraid that if all diameters in the pic are as stated, the center cylinders will grab more than their share. Assumption that has to be tested.


Quote: "F1 is coolest, bestest, greatest, neatest, most awesome racing that has ever existed"
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