diy inlet mani

[gavinvr6 0]

right guys this is probably a dumb question but i'll ask anyway.

is it possible to build a short runner style inlet mani but have it draw air from left and right, ie so an air filter sits belt end and chain end. im thinking something similar in appearence to a short runner but not tapered. woyuld this cause the centre 2 cylinders on the intake to run lean like if a short runner wasnt tapered making the last 2 run lean?

im sure witha bit of bodgery pokery myself and my welder could fab either a tube or some decent box section into the correct length and create a lower inlet mani adaptor. but would it work with a tb either end if i just linked the tps's together so the ecu received a signal from just one or both but as a single signal or no tps on the second.

ive got a coil pack obd1 using a rado tb and was thinking twice the tb twice the potential airflow, and in future 2 small turbos or superchargers.

if im being stupid then please say so. it was just a thought.

[trix2702 23]

I don't think so mate as where would your maf go??? I

[AJmk2 2]

Problem is with your MAF you would need a connecting pipe so you can run just one. Also lots of good power levels with single inlet manifold.

I looked at making a box one myself , the main problem to overcome is the lack of space in the engine bay.

Heres a quick picture of the old one i drew up not finished, now doing another completely different one.

[FishWick 21]

I like that /\. Decent runner lengths for good torque.

Would work even better with internal trumpets and the rear 3 being longer than the front 3.....

[sharky_70 0]

Kev you hear any good stuff about the flipside customs SRI? its the plenum welded onto the upper inlet runners so the tracts are longer. obv some compensation going on inside too

[AJmk2 2]

I have to say im a tad confused about this different runner length. Did VW not themselves make it so that due to port sizing and flowing that although they are different lengths when it actually comes out of the head it all flows the same.

Also if you look at the first part of the cast intake the ports are about 2mm larger on cylinders 1/3/5. Maybe thats how they balanced them from factory.

I was thinking of making a set of butteryflys for after the first cast bit so can retain stock fuel rail and use what im presuming is the factorys way of balancing the cylinders.

[gavinvr6 0]

ok so twin tb on a custom mani is tricky, puttin g the maf somewhere with a y peice tb side to feed to each tb, but then it would probably mean the maf sitting over the rocker cover with the filter where the original tb now sit's just to keep things balanced and evenly fed, not very good for cold air flow though. could it not be run maf-less like some of the s/c or turbo set up's?

i like ajmk2's design, thats kinda what i had in mind but with a tb either end. a box section/tube to fit onto the original lower inlet

[FishWick 21]

Kev you hear any good stuff about the flipside customs SRI? its the plenum welded onto the upper inlet runners so the tracts are longer. obv some compensation going on inside too

Most short runners available are 'too short'' date=' LOL! That is to say the runner length is tuned to an rpm the engine isn't capable of. Schimmel's runner length, apparently is tuned to 20,000rpm!! Not deliberately, but due to the space restrictions etc etc, that's what he ended up with.

I've been talking to a guy in America making his own intake which features some VERY nice runner tuning and a good plenum shape. He will be doing a back to back dyno test of his intake versus Schimmel's soon and we're expecting to see some fairly tasty gains in midrange torque. Watch this space. If successfull, I will be hekping him to sell them over here :-)

I have to say im a tad confused about this different runner length. Did VW not themselves make it so that due to port sizing and flowing that although they are different lengths when it actually comes out of the head it all flows the same.

The front and rear head ports themselves do indeed flow the same amount.

The runner lengths though, are unequal length. They are all 420mm long (port inlet to intake valve), but the runner length tuning is done inside the inlet manifold, which you can't see unless you break it open with a hammer.

[AJmk2 2]

Thanks for the information , let us know how the dyno results get on, im hoping to have a new intake set up on mine in the next month or so also.