Intake Manifold Idea

[Rob K]

I have been playing around with the idea of turning my intake manifold around on my turbo '94 90, to help reduce the length of my intercooler piping. Currently the intercooler to TB piping is very long going from the drivers side front along the top of the radiation and then along the passenger side of the intake mainfold to the throttle body. If I flip the manifold around I should remove almost half of this piping, clean up the engine bay, and create room for a proper intake. The intake manifold should flip 180* easily as it lines up with the head, but the major problem is the Power steering pump is in the way. The two options I see are to relocate the PS using custom brackets (where it would go I don't know) or use an electric power steering pump from a toyota MR2 which I conveniently have lying around. Other than this the rest should be easy, I will have to find a new serpentine belt, and lengthen the wires for the TPS sensor and the ISV. Maybe I will have to flip the throttle body upside down or use a different one because the TPS sensor may hang too low. I probably am the only one that even has to think about this but any ideas would be appreciated.

[SiV6Qcoupe]

I gather one of the reasons besides the engine cosmetics of reducing the intake piping is to reduce intake temps entering the TB and lessen the effects of slow turbulent air.

Would there be a significant reduction in heat being absorbed from the length of piping being removed? how many tight (90° bends) would be lost?
What material/coating is the intake piping made from - aluminium is great absorber of heat!!

I would try and take some temp readings after intercooler and before TB to see if there is a significant differential, how about some cfm readings too?

Just some initial thoughts!

Would be good idea if it wasn't for the damn PS pump! Does the Toyota 'leccy unit run close to the Audi's volumetric flow rates?

[®ob]

I'm not sure but you may be able to change your pump style to the new one and then use those brackets if you just need to lower the pump a little bit.

[Audiboy]

off your local wrecking yard and welding a 45 degree tube with flanges on both ends so that you can move the TB farther away. May not have to worry about the PS after all. Who needs cruise control

I've been toying with the idea of fabricating my own intake manifold, but didn't want to spend more money on a Tig. Good Luck.

[Rob K]

The PS pump is really in the way, it looks like no matter what I will have to remove/relocate it. The TPS sensor hangs down fairly far. How much does the PES brackets move the pump? Yes, I have access to a few places that do TIG welding, so aluminum is not a problem. Moving the TB farther away from the IM will increase throttled volume, and I worry this will hurt throttle response. Maybe I will look at a few different throttle bodies and see what works best. I really want to keep it as simple as possible. I don't think there will be much of a reduction in intake temps, but I am hoping that reducing the volume of piping will improve lag slightly. My IC piping is not aluminum, it is cheap crush bent 2.5" steel pipe ( I eventualy plan on replacing it with proper piping). I don't know the specs on the MR2 pump, but I do know people have used it on porsches with good success. I will look at it more closely this weekend and take measurements. You can see from the picture that I will really lose a lot of piping, plus it will make running the wiring for the TEC-II easier if it is by the firewall.

[®ob]

[SiV6Qcoupe]

It's for a Honda as usual but it's interesting anyway!

• Intake pipework

[hurricanesteve]

It is my understanding that a boosted engine is best served by the shortest runners possible, since long runners are 'tuned' to give more power in n/a applications (and I believe move to shorter length at high RPM anyway in engines with variable runner length technology).

!

[Audiboy]

see Hurricane's post above for why

[Rob K]

Eventually I would love to but for the time being I am going to have to make the stock manifold do. I have experimented with the change over function from long to short runners, and I have found that running on just the short runners provides a nice midrange bump without a noticeable loss down low. Just for fun I did a few runs to redline on the long runners and the drop in power above 3500rpm was very noticeable.