Jag v12 inlet manifolds and throttle bodies

[nicktruman]

Hi Guys
I raised this question in my build thread but somehow it got overlooked.

My twin turbo 5.3l Jag V12 has its throttle bodies in the middle of the manifold. This works well when he engine is in a front engine jag, but not so well when in a midengines car. I want to move the throttle bodies to the end of the manifolds more like the OEM Zonda, or Ferrari config.

I realise that this will mean a lot of cutting and welding the aluminium casting but in theory its very doable. My question though is will this affect performance?

I can open the plenum, which on the Jag is very small and make it larger with a bigger air capacity, but would this make the car run badly?

I appreciate your help on this please

Cheers Nick

[AdrianBurton]

Nick you could actually replace the entire plenum with a "rectangle box" and put the TB's at the end like they are on the BMW, Merc, and Viper engines Since you are still planning to turbo you can get away with a bit more and it might be a bit less work.

Performance wouldnt suffer and the extra volume would be nice too

[nicktruman]

Nick you could actually replace the entire plenum with a "rectangle box" and put the TB's at the end like they are on the BMW, Merc, and Viper engines Since you are still planning to turbo you can get away with a bit more and it might be a bit less work.

Performance wouldnt suffer and the extra volume would be nice too

Thanks Adrian
I did read somewhere that if you increase the length of the inlet tracks you can improve torque. But maybe that is on a NA setup. I don't have enough room above the engine for a proper plenum, So I will have to improvise

[AdrianBurton]

The longer intake runners will improve TQ but you are turbo'd so that isnt much of an issue for you, the shorter runners will give you more upper RPM power, that will soften the TQ down low and give the trans a fighting chance behind the 12

[nicktruman]

The longer intake runners will improve TQ but you are turbo'd so that isnt much of an issue for you, the shorter runners will give you more upper RPM power, that will soften the TQ down low and give the trans a fighting chance behind the 12

Thanks Adrian

[AdrianBurton]

NP, I have to live thru your build since mine is about 1000 miles from me :'( :'( :'(

[nicktruman]

NP, I have to live thru your build since mine is about 1000 miles from me :'( :'( :'(

Hi Adrian
What would you think if I cut off the plenums and in their place bolted 3 1/2" steel or aluminium tube sealed at one end and with the throttle body at the other. I could then flow/open out the intake runners. So using tube, the inner surface will be dead smooth and being 3 1/2" have a much larger inner area.

Each intake runner is about 1 1/4" iirc

This is a very crude mock up and the oem

Then I can clear the V of all the throttle linkages, the only complication would be the TPS (throttle position sensor).

[AdrianBurton]

That is how the BMW intake is, so I see no problem at all with that. The TPS shoul not be a problem either since most throttle bodies have TPS provisions on them