Intake tuning for your quads

[SpotterOne]

Got a package in the post today from Elettra.

The trumpets I got are the 49mm x 230mm long versions. They were $54 each. The donuts were $22.50 each.

I did some measurements, and have some numbers for a 16v.

Valve face to edge of the head - 80mm
Average distance* from valve face to outside edge of silvertop throttle bodies with a smallport T3 adaptor - 220mm.

*Average distances are quoted because of the taper and bend in the port

T3 Trumpets are 75mm high.

By my calculations, the ideal length for trumpets is in the 380 - 400mm range, so another 105mm (max) needs to be found. Plan is to chop up the donuts as required to get the bend angle right, then chop down the trumpets to suit and weld it all together.

I've attached some pics for an idea of what you get from elettra. The material is pretty thin, but its only supporting an air filter pod. They look nicely made, and will have plenty of room for me to cut bits off for straight bits. The short trumpet is a T3 item.

Leo

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[attachment=22940:tn_DSC00388.JPG]

[350hp4agte]

i plan in the near future to build a turbo plenum for my 20v not using quads using a single 90mm throttle body if i were to make the runners to the head as long as possible should this in theory help in lowering lag time
i assume that having long runners once on boost wouldn't make to much difference as air is forced in but should help to build boost quicker

your thoughts

[rthy]

thats exactly what my theory has been for a long time, others have also said that harmonic resonance is a small factor under boost.

Please let us know how it works out if you ever do it

[350hp4agte]

yeh I'm keen to give it a go and I'm definatly getting a plenum made i'll spec it how i want it so keen to give it a go

[Ke70alex]

<div class='quotetop'>QUOTE (350hp4agte @ Mar 10 2008, 05:39 PM) </div>
there was a story AGES ago in zoom i think it was where they were building a killer taxi, basically the guy had too much spare time and wanted to put an rb20 turbs in a vr taxi. Come hell or high water he was going to use a modified rb26 inlet plenum, without the 6 throttles I'm pretty sure. The result was an absolute dog to drive with MASSIVE torque holes. They then put the standard rb20 gobber on and the engine ran a million bucks

they put it down to the short runners on the rb26 being optimised for top end and 2 small turbs and this led to the 2l inline 6 sucking all the air out of the short runners befor the turbo could pump replacement in - if that makes sense. The longer runners provided a much better cusion to draw from.

[rthy]

yeah thats true I remember that now, man that was a while ago. I could be the rb26 intake has much larger diameter runners though.

[350hp4agte]

would the size of the plenum its self make any difference (remember 90mm throttle not quads)

[rthy]

its meant to, they say the minimum 1 to 1.5x the displacement of the engine

[350hp4agte]

so max volume is best?

[rthy]

as a rough rule it seems like it, a bit hard practically for us right hand drivers though. The americans have got it easy in that regard they have no brake booster/clutch gear on that side to hinder them.