Bambam7

Ok, I've got the engine.. it's in the hatch. I'm converting it to a mid-engine setup.
Uhh, ya right.
Anyways, The last of the pre-assembly modifications are complete. This involved converting an S5 VDI 6 port intake manifold to be able to bolt on to the (now) 4 port block.
The VDI is operational though it'll open very early (whenever 2.5 lbs of boot is reached!) But it'll at least give me a little bit of torque boost below about 2200 rpms.
I suppose I could put an orifice, then a bleed in the vacuum line to the vdi to let it open later- I might mess around with that... I'm not sure how the reversion wave frequency changes once air is compressed.... it'll be trial and error finding the best switchover RPM.

Any- the manifold... I had to cut the bridge off (jigsaw) and grind away to get the ports the right size and proper flow. Then I filled the top part with 2 part putty epoxy (Steely) and shaped it accordingly for flow. The port shape looks a bit wonky- and it is- There are some very thin casting walls, that inhibit exact shaping, but it's pretty damn good. I shaped the gasket accordingly, there will be no problems with flow! I like the profile better than the TII manifold anyways, it has a longer radius to curve around and meet the engine...

Well... Basically the only difference between this engine and my last one will be slightly lower compression rotors, (86na compared to 90na)and the 4 port housings instead of 6 port ones.
The builder of my engine swears that 4 ports flow better, but we'll see. I'll be able to find out first hand which flow better by simple applied comparison!

projekt

from the picture it doesn't seem that much different, but i was wondering if anyone's ever though to make a manifold for the 6 port so that you don't need the rotating valves, but you could just butterfly off a runner like most every other variable geometry system.
[/thread hijack]

Bambam7

Not that different?
Here's a pic of a 6 port gasket.
It's much different- the ports are totally offset from each other.

NZConvertible

For some bizzare reason, this is exactly what the European-spec FC 6-port engines have; butterfly valves in the LIM instead of rotating sleeves in the block! I didn't believe it until I saw the pics posted here a while ago. I don't know which system would work better, since the port sizes looked the same and there was still an open butterfly in the airstream.

Sorry to continue the hijack Bambam, that's intersting looking work you're doing.

Makenzie71

I've got a bizzare idea...why not use the LIM from an S4?

hIGGI

iTrader: (7)

I don`t know reason too, but our Euro spec manifolds with valves works fine off vac. plenum even u convert to headers and midpipe (no cats)

Bambam7

I don't understand.... the LIM's for all N/A's (86-91) are all 6 port, and all the TII (86-91) are 4 port... regardless of being S4 or S5.

Anyone have any thoughts on the VDI system and actuating point???

NZConvertible

You should use a solenoid valve and rpm switch for the VDI, because it probably is opening to early to give you maximum benefit. Use a dyno to get the VDI actuation point. Do one run with it closed and another where it opens. Where the two lines cross is where you should set it.

TonyTurboII

You N/A guys are crazy.

2Lucky2tha7

iTrader: (3)

Here I am 6 years later and I was wondering about this exact idea today and luckily I found this thread, although it's a bit vague. My reasoning is because I originally had an aggressively ported 6-port setup over a year ago with both the VDI and sleeves wired open. It had tremendous top end power for an N/A, but the low and mid-range were pretty much non-existent. That eventually ended abruptly when after 25k miles or so, one of the pineapple sleeves came loose and shot to the back of the aux. sleeve and knocked the pin out and then the sleeve went back into it's place and the steel pin got sucked in and destroyed the rotor, end housing and rotor housing as well as a few seals. Out of frustration, I decided to go with a streetported 4-port setup using my N/A rotating assembly and TII irons. Now, after 10k miles or so on the 4-port setup, I was just thinking about mating up the n/a s5 intake assembly I still have to take advantage of the vdi setup and see if I can get some gains from doing this. Has anyone else specifically done this and have any feedback on it? I'm wondering if I should waste my time epoxying and shaping the LIM and re-tuning my maps or just building it up again as is --(yes, it's apart again).