6 x tb's

[gavinvr6 0]

i probably already know the answer to this but what sort of a difference would it make if i popped 6 smaller tb's onto a lower inlet mani and ran the car that way? i was thinking a set of rb26 skyline tb's, will i need to run custom management or would it be possible to fit em on and drive? main problem im guessing is the maf or throttle position sensor, how do i get round that?

[AJmk2 2]

If your talking about running 6 open trumpets then you wouldnt be able to use a MAF sensor , so you would need an airbox on the unit.

Id imagine whichever way you will need a minimun of a remap but best would definatly be use of a standalone ecu.

[FishWick 21]

But even with a standalone running manifold pressure instead of Mass air, you still have the problem of the lack of plenum volume pulsing the MAP sensor too much, it will be tricky to map. In fact I've known people to run ITB engines purely on TPS as load, which isn't ideal.

As you say, the best way to do ITBs (individual throttle bodies) and in my opinion, is to do it BMW M power style. I.e. enclose all 6 ITBs with a flow balanced plenum. That way you will have one air input to all 6 TBs and can use a MAF sensor.

You'll get much better torque aswell if it's done properly.

It won't roar half as much but I think that horrendous racket is an over rated noise anyway!

[gavinvr6 0]

hmmm need to get out then pencil and paper and see if i can come up with a plenum type thing to feed all 6. well 3 banks of 2 if swapped in from a skyline. then fit the maf at one end and a filter on that, that would make it a short runner type set up but 6 instead of 1 tb, wouldnt that make #1 run lean and #6 rich by enclosing them? also ive got a twin roller throttle body from a nissan v6 race engine but the 'trumpets' are staggered and wouldnt line up unless i cut/weld, but that would be ruining billet tb's lol

[FishWick 21]

How about an M5 Plenum? The older one, 3.4 straight six was it?

You would just need to make a base plate to fit around your ITBs and then attach the M5 plenum to it.

I reckon you'll need some pretty hefty slam panel / radiator mods to make room for it all :-)

You're right about one end being lean, that's why you need a plenum that's larger in volume at cyl 1 and less volume at cyl 6. The air will speed up as it's sucked down that end and balance out the flow.

You can't beat OE ITBs for reliabilty and ease of setup, but with the VR6 head ports being so close together, I'm not sure which ones will fit on there, unless you fan them out, if that makes sense?.

[gavinvr6 0]

yeah i get what you mean about faning them out, but then there is even more space being taken up. and as you say having a balanced plenum stuck in there as well could be tricky unless the tb's were very short but then they would be pointless due to being to small. the nissan roller tb's are out of the question by the looks of em, the unit itself is the size of a shoe box plus id have to make some sort of twisted pipe up to get the lower section into line with a straight configuration like the vr since the ports are 3 each side where it bolts between the heads on a proper v engine. never thought about using a bm inlet, even some of the smaller engined bm's were straight 6. and the plenum size is considerably smaller than a stock vr. eventually though wouldnt it just be cheaper to buy a short runner from sp or something instead of trying to fit and faf with other models, coz then the ports might not even line up or the mounting holes could be wrong, blah blah

[gavinvr6 0]

bm mani

is this the m50 mani you was thinking of? looking at it, it would sit quite high, possibly fouling the bonnet. plus the tb port would need fitting a custom induction hose to it, or even a vr tb and custom induction, but i doubt i could squeeze 6 tiddler tbs between that and the vr lower mani,. im thinking i'll just pinch a short runner from somewhere, and use a single tb

out of curiosity how tapered is a short runner mani? are they well balanced? would it be best just using one of them since my aim is to keep it n/a and get the best i can out of it for now, f/i is out of my league at the mo. but obviously the short runner would be nice to have in place once f/i is an option.

[gavinvr6 0]

gto main

hmmmm wonder if an adaptor plate on this would work, thats a nice looking inlet lol