As the topic suggests I am looking for some more power for my 88 GTU and was hoping someone would know whether I could acquire the s5 VDI and air meter and bolt them directly up to my s4 block?

If the answer is yes, would I need both the upper AND sower intake manifolds off of an s5 or just the upper?

Would my s4 ecu be able to learn the new air/fuel map to run the VDI wired open? Or would I run too lean when I reach 5k+ rpm?

The s5 air flow meter flows more smoothly than the s4 meter and I was hoping that my ecu would accept the signal if plugged or spliced in to the existing line?

I did some searching on the forum but couldn't find any posts about interchangeability. Thanks in advance for the help guys!

-Lee

 

The S5 VDI manifold will bolt up, but you'll need to grind a small bump off one of the irons to get it to mate. You'll know it when you see it. Either the VDI will have to be wired open, since the ECU doesn't have any provision for activating it, or you'll have to come up with a custom activation scheme (air solenoid and RPM switch from the airpump outlet is one option). The 6PI actuators are the same as far as method of activation (positive pressure moves them). Do what you will.

The S5 AFM will wire up. It's pretty straightforward. Jumper the safety connector (and don't get into a wreck), and wire every other one up as you'd be expected to (see the respective wiring diagrams). Stay within your aspiration method between series and you'll be fine.

The ECU will automatically compensate for the additional airflow of the S5 AFM and VDI - that's the beauty of metered airflow. The stock ECU does tend to overcompensate, however, and you can pick up 8-10 hp from leaning out your mixture with an S-AFC or the like.

Brandon

 

go to this link
there is a write up on this
http://homepage.mac.com/carldavis/intake/intro.html

I did this swap and in order for the VDI and 6pi to work you need to have the Airpump or devise a way to have them open at the right time...it requires 6 psi to open the VDI and 6pi --- but they are supposed to open at different times--ie 6pi 3800 and VDI at 5200(i think)!

People are trying to devise other ways of opening the 6pi besides the air pump---this could also be applied to the VDI as well... if u find another way then u'll probably need a RPM switch to control the opening!

 

Thanks for the info guys! This has helped a whole lot. I am going to start searching for s5 intake manifolds and the s5 air flow meter.

-Lee

 

http://cgi.ebay.com/ebaymotors/ws/eB...408239348&rd=1

Here is the complete S5 intake system. Compliments of me.

Jarrett

 

For an updated version of this, go to:
http://wozzoo.tripod.com/Info/89Intake.htm

I've changed a couple of things since I first wrote that page...