custom intake manifold?!?! - Boost Forum

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custom intake manifold?!?!
Thursday, November 23, 2006 5:58 AM
ok i want to build my own custom intake manifold but i have no idea of what are the mesurement for each part, i mean what are the best mesurement for the perfect intake manifold for my engine!! here a picture of what i wanna do!



if someone can help with all the mesurement for A,B,C and D please tell me






http://cavalierdomination.monchar.com

Re: custom intake manifold?!?!
Thursday, November 23, 2006 6:32 AM
different length intake runners will change HP and torque numbers, and where the power comes on. NA or boost will make a huge difference too. Diameter (velocity) changes HP curve drastically as well. You will get an array of most likely uneducated answers and they will be said as gospel.

Other mods such as P+P, cams, valves, etc, will all come into play aswell.

I personally have no idea what length or size you should go with, but I wish you luck


HP Tuners | Garrett T3/T04B | 2.5" Charge Pipes | 2.5" Downpipe | 650 Injectors | HO Manifold | Addco front/rear | Motor Mounts | HKS SSQV | Spec stage 3 | AEM UEGO Wideband | Team Green LSD | FMIC | 2.3 cams | 2.3 oil pump swap | 280WHP | Now ECOTECED

Re: custom intake manifold?!?!
Thursday, November 23, 2006 10:24 AM
For something this detailed, I would talk to an experienced speed shop and see what they would do. A lot of times, you can pay somebody to design something for you. That way at least you have somewhere to complain if it doesnt work at all.



Re: custom intake manifold?!?!
Thursday, November 23, 2006 1:07 PM
http://www.gm.com/company/gmtunersource/html/race_shop_build_book.htm

look at that, one of the builds shows and provides the part numbers for the GM intake manis....all you gotta do is find measurments and copy them as long as it isnt illegal.



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Re: custom intake manifold?!?!
Thursday, November 23, 2006 11:24 PM
found on the web some time ago....... I've also read many things that agree with this......

Intake Sizing: The size of the runners should be the same as the intake port, and the volume of the runner should be about 100% of what that cylinder displaces. The length of the runners "Tunes" the resonance at which point this effect will boost the intake. The longer the runner, the lower the RPM for the effect. The plenum size is usually 100% of the total engine displacement.

Volume = 3.14 * (radius) * (radius) * length

The intakes usually end up being about 12 inch long runners, 2.75 inches in diameter, connecting into a 5 inch diameter plenum that is about 7 1/2 inches long. This is about 100% volume for the runners and total engine displacement for a 2.2. The runners usually come off the plenum at a 90 degree angle with the throttle body mounted on the end. The runner diameter may not be correct - I am guesstimating here.

If the throttle body is too big, you don't control the air flow. For example, a smaller displacement engine will only flow X amount of air. If the engine is flowing all the air it can by the time the throttle is 1/2 open, then as you increase the throttle, there is no air flow change into the engine. The electronics needs to have a linear air flow to do the calculations correctly. Again, bigger is not always better.

Another basic is to make 100 horsepower, you need 140 CFM of air. The rule of thumb for naturally aspirated fuel injection, at a standard 1.5 inches of water column, is that for every square inch of butterfly, you will flow 140 CFM. To calculate the air flow for a 2" butterfly, you need to calculate the area first. Area = pi X radius squared. So, 1/2 of 2" is 1 inch, squared is still 1, times pi (3.14) = 3.14 square inches of butterfly area. This means that it will flow enough air for approximately 440 CFM, or 314 horsepower. Now remember this is approximate, and there are losses since the volumetric efficiency is not 100%.

This is a simplified way to design a manifold that works well for most apps. However there are many improvements that can be made to this design. Goodies such as velocity stack runners help control boundary layer and turbulence problems. You can also tune the runners/plenum for different RPM ranges.



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Re: custom intake manifold?!?!
Friday, November 24, 2006 5:32 AM
ge_forcez22 wrote:different length intake runners will change HP and torque numbers, and where the power comes on. NA or boost will make a huge difference too. Diameter (velocity) changes HP curve drastically as well. You will get an array of most likely uneducated answers and they will be said as gospel.

Other mods such as P+P, cams, valves, etc, will all come into play aswell.

I personally have no idea what length or size you should go with, but I wish you luck


ok excuse me i havent givin you all the information !

the intake manifold is gonna be used in a 2005 ecotec 2.2 engine
i'm using it for my turbocharge project! i'm actually running 8.5psi but i plan running more boost
stock cams
head is custom ported on the intake
stock vavles

need other information?? a friend of mine want to sell me is 2.3ho intake manifold welded to a 2.2 ecotec flange?? is it a good idea?






http://cavalierdomination.monchar.com
Re: custom intake manifold?!?!
Friday, November 24, 2006 6:16 AM
defensive much??? I was just stating that if you are going to build a manifold make sure you build it right, and get some good gains out of it. I am sure that the one GM made has some good design characteristics... try to measure one of those up and make that.


HP Tuners | Garrett T3/T04B | 2.5" Charge Pipes | 2.5" Downpipe | 650 Injectors | HO Manifold | Addco front/rear | Motor Mounts | HKS SSQV | Spec stage 3 | AEM UEGO Wideband | Team Green LSD | FMIC | 2.3 cams | 2.3 oil pump swap | 280WHP | Now ECOTECED

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