Let's talk intake manifold design

[E30godz]

designing an intake manifold isn't really something you come decide on with a drawing. there are certainly trends to follow, but nothing is going to be more important than a little flow analysis (or a lot of it)

[der affe]

what about the Dr Schrick VNT variable intake for the VR-6 VW?

i know when i put one on a stock Vr-6 for a customer when i was at Karl's, it made a world of difference, then a month later i did cams and a cat back. holy shit what a difference!

here is some info on it. i will see if i can find more

http://www.autotech.com/instructions/i129020K.pdf

[der affe]

do you mean like a Ford T-bird MAF?
that is what the splitsecond/BMP kit uses they are everywhere at the pic a parts. if anyone is interested, i'll give you the Ford part number for it.

[moatilliatta]

why not a maf of something you can find in the junk yard? MAF to measure the volume at which the second set of runners would open?

I was think you could do that more to engine rpm.

[DCColegrove]

it would be interesting on a straight slant six, you could use the slant of the motor of the motor for the est lengths of the runners and possible have to plenums with something connection them and throttle body. got the idea in my head, just not with words.

I get it...

I was thinking more on the lines of a manifold within a manifold...

You would need an HFM type MAF setup to make it work right... The transition would play hell on a AFM...

I was looking for a Miller MAF a little while back just to play with this idea and even contacted Miller... But no dice... Don't even really have the time for it anyway.

[moatilliatta]

it would be interesting on a straight slant six, you could use the slant of the motor of the motor for the est lengths of the runners and possible have to plenums with something connection them and throttle body. got the idea in my head, just not with words.

[DCColegrove]

Variable intake

http://www.autozine.org/technical_sc...h_engine_2.htm

The truly hot setup... Not simple though... I've been toying with the idea of a staged manifold using a progressive throttle body (similar to the m42s or 4bbl vacuum secondary carb set-up) for a while now... Somebody should try it.

[moatilliatta]

stupid/don't waste the effort/you're an idiot/You should just do a 24v swap :-D

and seriously, I wouldn't touch it as the intake runner length is very finely tuned for a motor/application.. there is a ferrari video out there somewhere where they have variable intake length manifolds to provide a flat torque/hp curve

Variable intake

http://www.autozine.org/technical_school/engine/tech_engine_2.htm

[Tree18is]

just pack it full of boost, all those sheetmetal intakes seem to work fine. Im a big fan of the s38 manifolds you usually see on a turbo motor.. Some how it works just fine and makes a shit ton of HP

[z31maniac]

^Fair enough, but I'm still going to give it a shot.

[Julien]

Julien, I see your point, but the intake manifold was designed for a stock M20 as it came from BMW, not a bored, stroked, and cammed M20.



I want to build a high-comp 3.1L M20, so headwork/cam and everything geared for 4k-7k operation means I would want the intake designed with that in mind as well.

Street, auto-x, HPDE car. I'm willing to give up low RPM power for high RPM power and throttle response.

Yeah but what I was trying to say with my post is that I don't see you building a better suited one in a shed.

[DCColegrove]

PM me...

No matter what you think...

This is something I know something about.

[z31maniac]

Julien, I see your point, but the intake manifold was designed for a stock M20 as it came from BMW, not a bored, stroked, and cammed M20.

Anyway, I think the biggest thing to deal with would be the resonant frequencies and how to spread them out so you can have decent flow characteristics across the board, RPM wise. If you design and build for 8K RPM and the thing does not flow well below that (AKA too high of a resonant frequency) you will loose all bottom end.

Is this thing gonna be a driver or WOT race car or what?

I want to build a high-comp 3.1L M20, so headwork/cam and everything geared for 4k-7k operation means I would want the intake designed with that in mind as well.

Street, auto-x, HPDE car. I'm willing to give up low RPM power for high RPM power and throttle response.

[Julien]

stupid/don't waste the effort/you're an idiot/You should just do a 24v swap :-D

and seriously, I wouldn't touch it as the intake runner length is very finely tuned for a motor/application.. there is a ferrari video out there somewhere where they have variable intake length manifolds to provide a flat torque/hp curve

[StereoInstaller1]

stupid
don't waste the effort
you're an idiot
"You should just do a 24v swap,"


hahahaaahahahaaa

OK, If I were to make my own intake manifold, it seems to me all of the race guys use individual trumpets. www.kinsler.com used to sell trumpets, but good god, look at the fucking fuel pump on their start page!

I wonder how hard it would be to use 6 trumpets inside of a plenum made of acrylic? The mouth of the trumpet can't be against the wall of the plenum or there will be too many reflective waves affecting the airflow.

Anyway, I think the biggest thing to deal with would be the resonant frequencies and how to spread them out so you can have decent flow characteristics across the board, RPM wise. If you design and build for 8K RPM and the thing does not flow well below that (AKA too high of a resonant frequency) you will loose all bottom end.

Is this thing gonna be a driver or WOT race car or what?