who has done this??

[goonie]

has any one build their own intake mannifold?
if you have let me know what the sizes are off the mannifold
may be some pics?
tia

 

[thegreatms]

yes, people have done it. I remember see in one pic of a white 1g with a custom IM that was also the water/air IC, pretty sick.

But if your looking to do something more mild take a look at:

http://www.jmfabrications.com/dsm.html

you can buy a intake flange and throttle body flange from them for like 85$ then all you have to do is weld up the pipes.

 

[2.4 turbo Hyped]

I dont see the gains. Tests have proven for overall power the 1g manifold outperforms all.

 

[peregrine]

I dont see the gains. Tests have proven for overall power the 1g manifold outperforms all.

your high. i certainly hope your not using the stocker on your 2.4

 

[2.4 turbo Hyped]

your high. i certainly hope your not using the stocker on your 2.4

:laugh: Do some research. Dont believe the "money making" hype.

KISS= keep it simple stupid Own a dsm for over 7 years and you will see what I mean.

 

[peregrine]

:laugh: Do some research. Dont believe the "money making" hype.

KISS= keep it simple stupid Own a dsm for over 7 years and you will see what I mean.

ive had mine for over 8 years now. ive done nothing but research for about 3 years now since sheetmetal intakes became the rage. i do agree with you that they are lacking in several aspects but for yours and my 2.4 motors the stocker will choke the shit out of them over 5000 rpm with a big turbo. your turn.....

 

[2.4 turbo Hyped]

I can pull 11s all day with the stocker. Thats stock head and intake manifold. Plenty good enough for me. Pretty good for a 20 dollar intake if I do say so myself.

 

[coltboostin]

The test you speak of were skewed because the were done on a lightly modded car, on a small turbo, with weak boost. Sheatmetal, Aluminum, or any other aftermarket manifold you would buy is geared for high flow, hogh power, top end performance. If the tests in question were done with a, say 2.4, with a to4e (your choice of wheel) or bigger at decent boost levels, the stock intake manifold would begin to show its weaknesses. Fir big flow and big power, a Short runner, big plentum will own the stocker. For a lighty modded car, the low end torque provided by the stocker will be optimal.

This being said, I am running a stocker on my project, budget limited only. And I WILL trap 130mph or better

 

[DSMJim]

My magnus manifold took 5/10ths off my time (half second) and added 4mph to my overall 1/4 with no other modifications.

Honestly I'm a skeptic on many things but not when it comes to an intake manifold on a turbocharged car. They make big power. When the JG Edelbrock one come out at first for the Honda's we put one on a Turbo GSR making 330whp and it picked up 37whp with no other changes over the GSR intake manifold which is a pretty good design to start with. I couldn't believe it honestly it was huge and we all thought something else changed for the longest time. AFter seeing the results again on my own car I believe how much difference it makes now.

 

[anconover]

I dont see the gains. Tests have proven for overall power the 1g manifold outperforms all.

The stock manifold outperforms in the mid range, but sheetmetal manifolds offer quicker spool and much more top end. Stock manifold tends to be best choice on smaller turbo's, as well as cars not reving to redline and beyond.

 

[2-0turbo]

You guys are arguing peak numbers versus area under the curve. I have no doubt big manifolds will make big power. But, with few exceptions in life, you have to rob Peter to pay Paul; Higher peak numbers (be it with manifolds, cams or a combinatation of the two) will sacrifice some power in the lower RPM bands.

 

[anconover]

Obviously. Hence why its not the best idea for a small turbo that starts to die off earlier. On a larger turbo that really doesnt make much low end power, yet will pull strong to 8k+, theyre ideal.

 

[goonie]

thanks for your replies guys
i am aming for more top end thats why i want to make my own intake mannifold
all the sheetmetal mannifold i saw are square what if the mannifold was made in a round shape ,lets say for example a 4"pipe with the outlets welded in
would there be more flow with the round shape compared to the square ones ?
i dunno just some ideas i am working on
let me know what ya all think
thanks.

 

[goonie]

no ideas??
i made a little picture of the design tell me if this will flow better than a square sheet metal one??
and about the painting? its just a rough sketch so lets leave the comments for what they are and trow in some usefull tips
thanks

 

[phatTSi]

I'm not 100% positive but i think the buschur smim is cylindrical in shape.

 

[goonie]

I'm not 100% positive but i think the buschur smim is cylindrical in shape.

i dont know they dont have a pic on their w-site of the mannifold all i know it costs an arm and a leg
the venom intake is also round but flat on the runners side

 

[DSMatMSU]

'NOTE! im in no way an engineering expert on air flow'....
now that thats out of the way, dont most manifolds become progressive smaller the further they are from the throttle body?? doesnt that have something do to with keeping pressure equal in the runners that are further away from the throttle body... just a little curious...

 

[goonie]

good point
thats why i started this post in the first place to learn more about the are flow
if it will increase if the mannifold was totaly cylindrical
i dont know about the pressure inside tough but i think that wont be a problem a total cylindrical one will be a bit larger than the stock ones or the sheetmetal ones
correct me if i am wrong but when you switch from a side mount to a front mount intercooler(for example) wich is much larger you still get the pressure you need
i dont know (just thinking out loud now)
thanks any way

 

[coltboostin]

has any one build their own intake mannifold?
if you have let me know what the sizes are off the mannifold
may be some pics?
tia

The "aftermarket" manifolds liek the buschur, Magnus, BJ's....did not just fall out of the sky you know. :0

 

[pboglio]

'NOTE! im in no way an engineering expert on air flow'....
now that thats out of the way, dont most manifolds become progressive smaller the further they are from the throttle body?? doesnt that have something do to with keeping pressure equal in the runners that are further away from the throttle body... just a little curious...

The plenum gets smaller to simulate a rough 90* bend. There may be a wave tuning affect but that I know nothing about. I've seen an intake manifold on the 1995-1996 FORD/Cosworth RS200 rally car that had the throttle body in the middle, then a diffuser shaped plenum of average volume (like a good intercooler end tank) which encapsulated the 4 short manifold runners. The plenum was bolt on too. By no means did Buschur or Magnus invent the short manifold runner, they are just the first to adapt it to a DSM.

I give them a lot of respect though, no doubt about it. The only problem with the FORD manifold layout is the throttle body gets put high or low dead center in the engine compartment, not an easy install but this thing has a straight shot into whichever cylinder is aspirating at that moment. My Desktop Dyno text book suggests a 2*-5* runner taper for best results, I'll track down the exact number if anybodies interested.

I'm right now looking at a chart plotting volumetric efficiency vs 4 different manifold runner lengths on a 2.3L spark ignition engine. Assume a 6000 rpm rev limit, so torque values are going to be at lower rpms than our 2.0 liters. Lets see, a 26" long runner gives a strong hit at 3000 rpm (95% efficiency) but dies off to 59% at 5800 rpm. A 13.3" runner gives a double peak, one at 3000 rpm and another at 5000 rpm (90% efficiency in both cases). This one dies off to 75% volumetric efficiency @ 5800 rpm. This is most likely our stock manifold runner length. The 6.69" runner length peaks once at 3800 rpm @ 91% efficiency and holds 82% efficiency to 6000 rpm. The 3.3" runner length is a tiny bit worse than the 6.69" runner but very close in shape. Everybody thinks they invented this stuff first but I'm looking at charts that were published back in 1988 at the very latest.

I've got all the data I need to build my own, don't think I'll spend $600-$700 for a thin piece of aluminum sheetmetal. Using a round plenum is good because you don't need to get access to a sheetmetal pressbrake to form it up. I would slice it in half to mount the radiused inlet horns and runners. Then weld it back together. Cheers.

 

[gixrman]

The best intake manifold design would center the TB between the 4 inlet horns. Inlet horns should be free flowing. The lenght of the runner has a strong effect on the amount of air that actually get in the cylinder. Longer runner are better for turbo's (street that is) to keep the vilocity high off boost. The plenum volume should be 50-70% of engine displacment.

 

[pboglio]

Its surprising, the area under the curve (efficiency wise) for a 13.3" (stock manifold) and 6.69" short runner is very very close. The stock manifold peaking 500 rpm earlier but the shapes are close, one with a single peak, the stocker with a double peak. If you had a fast spooling turbo I don't think you'd notice a difference, really. After seeing this I'm not afraid of running a short runner manifold now. I think this jives with DSMJIM's impressions of MAGNUS's manifold, very good driveability.

 

[mntalon_05]

'NOTE! im in no way an engineering expert on air flow'....
now that thats out of the way, dont most manifolds become progressive smaller the further they are from the throttle body?? doesnt that have something do to with keeping pressure equal in the runners that are further away from the throttle body... just a little curious...

that's correct. I'm not sure that most manifolds do that, at least not stock ones, but aftermarket manifolds taper at the end to have equal air going into each cylinder. that's the reason we tap our egt guage at the end opposite the throttle body because the last cylinder runs with a little less air causing it to run a little hotter making it the hottest cylinder and the best to guage whether your motor is ready for a complete melt down when running it hard.

 

[thegreatms]

I'm right now looking at a chart plotting volumetric efficiency vs 4 different manifold runner lengths

can you post this pic?
does anybody know any good resources with this kind of in depth info?(like informational websites or textbooks)
thanks

 

[pboglio]

can you post this pic?
does anybody know any good resources with this kind of in depth info?(like informational websites or textbooks)
thanks

O.K. time to share the wealth. The best book of any textbook I've picked up on I.C. engines and the one that is the most comprehensive is "Internal Combustion Engine Fundamentals" by John B. Heywood. Got the book because I took the class in Mechanical Engineering Graduate School. This book is HEAVY in experimental testing, on vehicle testing. So all you doubters would love this book. Its deep in theory too but its very balanced. This book has so many vehicle tests from flow of intake exhaust valves at different lifts, to intake manifold tests, turbocharger efficiency plots, cylinder head designs (high port low port etc) you name it. When somebody asks me to prove some stupid point about cars I just shut my mouth and point to this book. Everything else is reference material. Websites are junk, one good textbook is worth 1000 websites.

I'll take my digital camera and post a picture of the plot tonight. I'll take a pic of the theoretical equation for determineing the correct runner length too, but the experimental chart is by far more useful. Cheers.