dual plenum intake,yes or no

[grundey]

I have been doing CFD studies for while on dual plenum intakes. My data shows that it doesn't actually flow that well as many think. On a flow bench it wouldn't compete any better...But the magic is there and has nothing to do with flow... When flow is needed go for a single plenum, it can flow a lot.
Some shots of my flow simulations


P.S. Lehmann WRC 1.8T engine had 300hp and well over 700Nm....

[Thuppu]

Repo what sorta cost is your intake manifold. At 550 bhp on the modified aan intake do you feel your manifold would bolt on and make much more power? Approx how much? 5 bhp or 50 bhp? Assuming the turbo can flow some extra air obviously.

I also have a modified aan intake similar to the one pictures here on my urq build hence the interest.

Just trying to answer the important "is it worth it" question.

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I don't know nothing about repos setup, but many restricted rally-cross cars make huge torque figures compared to the power level. For example some 4-cyl engine makes 350hp/750Nm or 600hp/900Hm figures depending if there is a 38mm or 45mm restrictor. Without the restrictor the engines make a lot more power but not much more torque.

[quattro-nick]

conclusion,maybe you gain some torque but no or little hp with a dual plenum intake
so if you need to save some money until you can buy a dual plenum you better can keep your own single plenum intake on the engine
and what happens when you make a 80mm throttlebody with a 80mm inlet hole on the intake? probably an other throttle respons i guess..........
what is the power restriction from a 70mm throttlebody?
i'm just want to learn some things here guy's

[gnutz2]

conclusion,maybe you gain some torque but no or little hp with a dual plenum intake
so if you need to save some money until you can buy a dual plenum you better can keep your own single plenum intake on the engine
and what happens when you make a 80mm throttlebody with a 80mm inlet hole on the intake? probably an other throttle respons i guess..........
what is the power restriction from a 70mm throttlebody?
i'm just want to learn some things here guy's

I don't think there is a limit for certain diameters tb and piping but I've heard that above 0.5 mach your efficiency starts dropping off, this info below is what I've found on the web.

Now to convert that to CFM, you take 50lb/min x 14.27 = 713.5 CFM. When you refer to the table above, you can see that we're starting to max 2.25" piping, but we're still in the "good" range for 2.5"

The velocities are in miles per hour and mach, and the flow rates are in cfm. Measurements for the piping are in inches.

0.4 mach = 304 MPH

2" piping

1.57 x 2 = 3.14 sq in

300 cfm = 156 mph = 0.20 mach

400 cfm = 208 mph = 0.27 mach

500 cfm = 261 mph = 0.34 mach

585 cfm max = 304 mph = 0.40 mach

2.25" piping

3.9740625 sq in = 1.98703125 x 2

300 cfm = 123 mph = 0.16 mach

400 cfm = 164 mph = 0.21 mach

500 cfm = 205 mph = 0.26 mach

600 cfm = 247 mph = 0.32 mach

700 cfm = 288 mph = 0.37 mach

740 cfm max = 304 mph = 0.40 mach

2.5" piping

4.90625 sq in = 2.453125 x 2

300 cfm = 100 mph = 0.13 mach

400 cfm = 133 mph = 0.17 mach

500 cfm = 166 mph = 0.21 mach

600 cfm = 200 mph = 0.26 mach

700 cfm = 233 mph = 0.30 mach

800 cfm = 266 mph = 0.34 mach

900 cfm = 300 mph = 0.39 mach

913 cfm max = 304 mph = 0.40 mach

2.75" piping

5.9365625 sq in = 2.96828125 x 2

300 cfm = 82 mph = 0.10 mach

400 cfm = 110 mph = 0.14 mach

500 cfm = 137 mph = 0.17 mach

600 cfm = 165 mph = 0.21 mach

700 cfm = 192 mph = 0.25 mach

800 cfm = 220 mph = 0.28 mach

900 cfm = 248 mph = 0.32 mach

1000 cfm = 275 mph = 0.36 mach

1100 cfm max = 303 mph = 0.40 mach

3.0" piping

7.065 sq in = 3.5325 x 2

300 cfm = 69 mph = 0.09 mach

400 cfm = 92 mph = 0.12 mach

500 cfm = 115 mph = 0.15 mach

600 cfm = 138 mph = 0.18 mach

700 cfm = 162 mph = 0.21 mach

800 cfm = 185 mph = 0.24 mach

900 cfm = 208 mph = 0.27 mach

1000 cfm = 231 mph = 0.30 mach

1100 cfm = 254 cfm = 0.33 mach

1200 cfm = 277 mph = 0.36 mach

1300 cfm max= 301 mph = 0.39 mach

This should allow what size piping you need for the flow rate of your turbo....

[repo]

Speed of sound changes depending on temperature.

I was simply posting my numbers not to brag, but to give perspective of what I have achieved.

This particular 45mm restricted engine makes same torque, and tiny bit more power without the restrictor, because the max flow of compressor and the restrictor is very close the same.

Boost was high, but if You want more torque and run 1,5bar peak, instead of spending a small fortune on intake manifold, yank Your boost up until there is no gain. Then swap intake and see if it did anything.

[quattro-nick]

that's the plan repo
in a month i go on a dyno so i can see what hp and torque i have
afterwords i gonna try to make my own dual plenum intake(or buy one) and put it on the engine
afterwords back on the same dyno to see the results

[vti2]

It is alot more complicated has the most people thing, a dual plenung manifold will reduce velocity from the air being pushed to the engine and will also be able to distribute the same air better to the cilinderhead, throtle response will be better, another efect is that by reducing velocity the air get´s cooler, you can run more timing, this will produce more torque and HP and a better driveble powerband.
Most of the guys foget about how power should be delievered by the engine, they only matter about peakpower, for me doesn´t make sence to have 800+hp for only 500rpm and the rest of the rpms only 400, it doesn´t drive good.
Dualplenung is all about drivebility, throtle responce and torque.
On the track or street you will outrun a bigger HP lazy bitch :-D

[A80Avant]

Therefore contradicts what Thuppu mentioned before as well then, that dual plenum is not for cars making up to 550hp. They way your mention it now it's makes More sense to use a dual plenum on a mid range hp car that has a smaller turbo and mid range of boost rather than high hp cars.

[Thuppu]

I was only thinking of the aspect that air goes as equal as possible to all cylinders. The more power you make the more important thing that is, so you don't melt a cyl or two.

[Ficksy Heart]

For 550HP AAN intake manifold works well, very good twin plenum you can buy such jenvey one:

thats the enginebay of Peter Kowatsch's S2 Coupe (Owner of PKM)

2.7L 790hp/990nm 2,2bar!!!

[varia]

friend of mine who designed this manifold told me:

"Honestly I wouldn't go this route at all. These intakes were designed for a very narrow torque band as the engine spends it's life in a very narrow rpm range. There are many other great designs that would do a much better job. This manifold I designed here is a concept by a friend of mine who wants the car to perform a certain way and also be somewhat like the factory cars, but in my opinion does not make for a really drivable car."

I really like Wolfgang's car with the dual plenum manifold, because it is forward facing, (less plumbing) works with stock radiator and location
cons: need electric power steering, cost

But i still think mtm or wagner forward facing manifold is the best for a for chassis car around 500-600 hp.

[repo]

I agree with Thuppu, best benefit of a dual plenum comes when Your flow speed gets really high. That's where the air tends to rush against the back wall.

Also, that's when even small change in air charge per intake stroke can melt parts.

However, I have witnessed gains at midrange with my intake manifold over others.

[diesel des]

Repo can you post some more pictures of yours and costs please?

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[Vorsprung durch Technik]

Most of the guys foget about how power should be delievered by the engine, they only matter about peakpower, for me doesn´t make sence to have 800+hp for only 500rpm and the rest of the rpms only 400, it doesn´t drive good.
Dualplenung is all about drivebility, throtle responce and torque.
On the track or street you will outrun a bigger HP lazy bitch :-D

I can't agree more!

[Thuppu]

It is alot more complicated has the most people thing, a dual plenung manifold will reduce velocity from the air being pushed to the engine and will also be able to distribute the same air better to the cilinderhead, throtle response will be better, another efect is that by reducing velocity the air get´s cooler, you can run more timing, this will produce more torque and HP and a better driveble powerband.
Most of the guys foget about how power should be delievered by the engine, they only matter about peakpower, for me doesn´t make sence to have 800+hp for only 500rpm and the rest of the rpms only 400, it doesn´t drive good.
Dualplenung is all about drivebility, throtle responce and torque.
On the track or street you will outrun a bigger HP lazy bitch :-D

Well, all depends on what you wan't and need. If you build a mile racer for 330+km/h or for 1/4 drag race you may need 1000+hp. And 1000hp from a 2.2l engine cant be delivered with a large power band. I'm sure OEM guys are pleased with their mapped stock setup or RS2'd setup. 500+hp with HX35S on street is a very nice and responsive setup and also great for trackdays, but quite booring in the end.