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Discussion Starter · #1 ·
Hi, everyone....

I have a 99 VR4 intake plenum and manifold, and there are a couple of differences between it and my 94 plenum...I'm thinking it may be too much of a problem getting the work done (portmatching/polishing) just to find that the differences would impede an easy replacement.

So, I was wondering if anyone has a 94 plenum/manifold they'd like to get rid of? If so, I'd be willing to trade...Or, if somebody has ideas about what I could do with the two extra ports on the 99 VR4 plenum, I'd appreciate it! I beieve the extra ports are for a MAP sensor and maybe a pressure diff sensor....


Dan Jett
94 Stealth TT
 

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Yes these are those two additional sensors but I must say that I'd be happy to be able to install an aditional MAP directly to the manifold !

Anyways, the intake manifold is already as alrage as possible and the gasket just fits right. The openings to the heads can be ported but the heads must be too ! The intake plenum is not worth to do anything internally.
 

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Discussion Starter · #4 ·
Roger,

I see your point about the intake manifold...Not much room to "open" things up per se, however, portmatching the plenum and intake manifold is effective...Even opening the ports a little, with a better flow characteristic will enhance swirl effect into the heads...

I do think you are wrong about the plenum though. There seems to be plenty of room to hone with our plenums, and I'd be interested in hearing your argument on that...Do you have data or experience with said modification? Boring the throttle body housing and perhaps boring the throttle body itself out slightly would seem to me to be effective. It's been effective in other motors I've helped with (small blocks, mostly).

I look forward to your reply...As far as having the extra MAP sensor, I'm not sure if it would make a tuning difference...Maybe for gauging, but I'm not sure about the ECU compatabilty in regard to engine control/feedback. Any further ideas on that?

Dan J
 

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Yes, I only meant for gauging or as a feed for my Water Injection system. I use the same boost sensor but again ttached to the plenum somewhere. (you know : WI-Sensor,boost gauge, turbo timer,DSBC,BOV)

The porting stuff was what we decided upon the discussion I had with the mechanic who does the job (he usually works on BMW and V12 from Lambo, gulp). I fully agree with the TB and matching the intake plenum, no question. But then the plenum itselfs should be getting a redesign as the internals are not the best in the world. Any work could easily cause more turbulence and maybe a less good flow in only one runner.

The plenum to manifold connection is not improveable as the size is given by the gasket. Of course we can do it and make my own gasket with the "cream" I have. But I want to use the original ones.

The only part that can be improved is the ports as you said. Here the gaskets have a little more room and we will gasket match them on the heads and the manifold. The tuner also will open the injector path a little more direct to the chamber. This is well shown in the pics from Bob Fontanas Green Beast.

For the needed swirls, it is necessary that this is done in the heads. The path for the mixture down to the chamber is important and the swirling effect happens only in the head. Otherwise it would decrease the velocity of the air in the runners and we want an increase at it's best.

I hope to get some data on the porting but for sure I'm gonna take some pics !

Roger
93'3000GT TT
 
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