Custom Throttle Manifold Discussion

[Newbienissan]

Hi all,

Like to start a discussion on custom intake manifold for n/a and turbo engines. Anyone like to start ? I have tested 3 diff cars with custom intake manifold and they responds differently. Some better pickup respond, some slower pickup but huge improvement on the mid n top end especially for turbo cars.

example of a custom intake manifold

pic is borrowed, owned by nchun1 (monster sr20ve)

 

[SkYwAlKeR]

ur tuning is towards NA or turbo??..

 

[Newbienissan]

both na and turbo also uses custom intake manifold for improve engine respond. u like to share you're using one too ? :)

 

[one1002]

where did u get this custom intake done?and what is the price including installation? =)

 

[Kyraemy]

wow this is interesting , anyone care to share their experiences ? might apply to my next project list . N/A is all good .

 

[yeehau86]

nice monster there indeed :top:

by the way, who is nchun1? a ZTH member also?

pic is borrowed, owned by nchun1 (monster sr20ve)

 

[Mrnazmi]

Great jobs bro!

 

[Newbienissan]

nonono, is not mine, is my friend nchun1. i think he is a zth member here too. i was asking is there also anyone using this kind of setup. normally this custom manifold gives about 10% extra engine respond n some extra horses.....

---------- Post added at 09:07 AM ---------- 6 hour anti-bump limit - Previous post was at 09:02 AM ----------

where did u get this custom intake done?and what is the price including installation? =)

bro, my friend told me he done it for rm800, you need to remove your ori manifold, and the workshop cut the tapak n combine welding custom manifold to it + the throttle body (stock or supersize also can).

 

[arturo]

how do they calculate the internal volume of the intake? if myunderstanding of airflow is useable, if the volume in the intake is not rite, it might hurt power instead of increasing it? even the shape of the internal airflow should be important rite? i think to know how to custom make an intake manifold, we'd need to know whats the volume of air needed by the engine at any given rev, then maybe from there can make a variable intake manifold which auto adjusts based on rev?

its this nagging logic that keeps me from just plonking in an open pod into my auto...

**do correct me if my logic is wrong...just thinking out loud.**

 

[Newbienissan]

aturo,
dun worry, your concern is already be taken care by the custom manifold makers, they only need to know your apllication is for TURBO or NA. they're experts

for auto, i think open pod or no filter at all would not effect you auto gbox, what affects is the exhaust setup, normally autogbox MUST use S-flow for back pressure so you autogbox can auto downshift according to volumetric exhaust pressure

 

[TitanRev]

arturo, you will need other supporting mods to compliment the CIM. Things like high cam, bigger TB. Like NB said, the makers need to know your application (RPM range that you will be utilizing most, your supporting mods..etc)

Stock manifold is good for street use on a stock engine as it was design to give you good low-Mid range power. You can see this from the small plenum before the runner (to keep the air velocity high) and the small runner cross section to keep air moving at maximum speed into the intake ports but the small cross section of the runners and small plenum limits how much air can flow into the plenum and runners. When at high speed the engine will try to pull in more air but the air flow is limited by the size of the IM, runners, and TB.

arturo, if the engine is going to operate at high RPM, you will need a CIM with its plenum volume = to the engine displacement or higher + a matching shorter and runner with bigger cross section...etc...You also need the CIM plenum surface and runners to be as smooth as possible. I tried once to custom an intake but I made a wrong calculation at the air volume in the plenum and didn't notice it until I actually give the drawing to the guys that are going to make it...bad result....


correct me if'm I'm wrong....

 

[Newbienissan]

yeap, you're right. to have this mod, you MUST use a piggyback at least, to correct the air volumetric going in. otherwise, idling is impossible n engine wont run normal.

 

[oinkoink]

let me share my exp on custom manifold... i am currently a over size manifold and throttle body.. instead of getting improve my car was very lag... at least 20 to 30 whp lost after fitting in the manifold.... on my stock intake i can go above 200km/hr after fitting it i can't even hit 170km/hr.. this different will tell you how much power i had lost after install it.

for my research from the web and read up.. the runner lenght is to shift your power band in other word shifting your peak troq. the lower rpm you wan your troq to come in the less power you will have on high rpm. the diameter of your runner will decide you have more power in high or low RPM. as for the plenum it shuold be about 80% to 150% of your engine displacement, depend on your application. anything more then that you suffer a lost in power thru out the RPM.

try read up the link http://www.custom-car.us/intake/intake-manifold.aspx

FYI my intake manifold was build by some so call intake manifold expert in sunway.... is my own mistake that i did not do a proper research before doing it..... an expensive lesson learn...

 

[Newbienissan]

im sorry to hear what you been thru, but perhaps the custom intake manifold specs did not suit your engine ? anyway mind to share your car is NA setup or turbo ?

 

[TitanRev]

oink, i think is the wrongly made CIM that causes your power lost if you have the supporting mods thrown into the engine. You are not running back the stock IM or a new remake CIM?

1 thing still not clear with my own trial and error is....I use longer intake runner and my engine was not performing well at high RPM (after 6700RPM) and with a shorter one the engine shows no sign of breathing difficulties at higher RPM even after 8000RPM. I maintain the runner diameter just change the length and the plenum remains the same. Maybe other things I didn't take into account on this....

 

[oinkoink]

im sorry to hear what you been thru, but perhaps the custom intake manifold specs did not suit your engine ? anyway mind to share your car is NA setup or turbo ?

my setup is NA... anyway it doesn't matter is NA or Turbo... the manifold is way too big for even turbo... my engine is only 1.6 and i did a measure and caculate the manifold is more then 3.5L of volume.... so in order for the manifold to work well the engine has to be at least 2.5L turbo engine....

---------- Post added at 06:17 PM ---------- 6 hour anti-bump limit - Previous post was at 06:11 PM ----------

oink, i think is the wrongly made CIM that causes your power lost if you have the supporting mods thrown into the engine. You are not running back the stock IM or a new remake CIM?

1 thing still not clear with my own trial and error is....I use longer intake runner and my engine was not performing well at high RPM (after 6700RPM) and with a shorter one the engine shows no sign of breathing difficulties at higher RPM even after 8000RPM. I maintain the runner diameter just change the length and the plenum remains the same. Maybe other things I didn't take into account on this....

is for sure the mainfold was design and built wrongly.... with stock intake manifold and throttle body i was having 129 whp.... with the manifold i am doing only 120whp even with high cams... my tuner had told me is the darm manifold problem.... my setup should get at least 20 to 30 more whp if i use back the stock manifold..... the engine show breathing difficulites after 6k rpm and drop at 7k rpm...

what engine and cams are you running on may i know? if your cams is not agreesive enough your runner too long will cause power lose also. i have some formulas to caculate it which is at home. i can share later on if you are keen. the forumal is quite complex.

 

[Newbienissan]

if i am not mistaken, custom intake manifold should be not more than 15% volumetric larger than the stock, and the throttle size should not be 10mm larger if you want to maintain full range power band on the engine. and the ram pipe too should not be too short as it will suffocate during idling n low rpm (something like proton's AIFM theory)

imho, what custom intake manifold suppose to do, is giving extra engine respond (torque) rather than horsepower.

---------- Post added at 06:38 PM ---------- 6 hour anti-bump limit - Previous post was at 06:36 PM ----------

my setup is NA... anyway it doesn't matter is NA or Turbo... the manifold is way too big for even turbo... my engine is only 1.6 and i did a measure and caculate the manifold is more then 3.5L of volume.... so in order for the manifold to work well the engine has to be at least 2.5L turbo engine....

then this is the custom manifold maker's problem, did they aware of your engin displacement n mods ? @.@

 

[TitanRev]

oink, PM me the formula....TQ ^_^

Kent Cams
I/E: 258/262
V.Lift 9.34/8.66
Engine: EW10-206

 

[oinkoink]

if i am not mistaken, custom intake manifold should be not more than 15% volumetric larger than the stock, and the throttle size should not be 10mm larger if you want to maintain full range power band on the engine. and the ram pipe too should not be too short as it will suffocate during idling n low rpm (something like proton's AIFM theory)

imho, what custom intake manifold suppose to do, is giving extra engine respond (torque) rather than horsepower.

---------- Post added at 06:38 PM ---------- 6 hour anti-bump limit - Previous post was at 06:36 PM ----------

my setup is NA... anyway it doesn't matter is NA or Turbo... the manifold is way too big for even turbo... my engine is only 1.6 and i did a measure and caculate the manifold is more then 3.5L of volume.... so in order for the manifold to work well the engine has to be at least 2.5L turbo engine....

then this is the custom manifold maker's problem, did they aware of your engin displacement n mods ? @.@

yes... they do know.... haizzz... now i need to sort out my manifold problem.... if a well design and matching manifold is use it can give about 10-20% more power.... is not easy to design a manifold.... :(

---------- Post added at 06:50 PM ---------- 6 hour anti-bump limit - Previous post was at 06:48 PM ----------

oink, PM me the formula....TQ ^_^

Kent Cams
I/E: 258/262
V.Lift 9.34/8.66
Engine: EW10-206

rare car you have there =) GTi version??

okie i go back then share it here.... i have a book on tuning engine.. there is a chapter that explain on design the inatke manifold.... i still haven't fully understand what the book is talking..... i will share more when i understand more..

 

[TitanRev]

oink, yes...I also still not very pro at the formulas and some parts also still can't fully grasp it. after a while, forgot some already if too long didn't read it or do the math....