Outer Limits 4x4 Board

what is the difference in the internal diameter of the throttle inlet between a 3.5 and a 3.9 ltr engine ... if there is a difference and you ues a 3.5 on a 3.9 will it reduce the total power and effiecncy of the engine and if known by how much
cheers
RANGEE

Hi Rangee !

Throttle diameter are the same on 3.5 and 3.9 plenums.
It is 65mm !!!
Doesn´t do any differences if you put on a 3.5, 3.9, or 4.6 plenum !
The standart plenum supplies already quite enough breathing up to 300 horse power engines!

( I am building a medium tuned 3.9 l engine at the moment which I am going to set up with a twin plenum ( 2 x65mm )
Because the two times 65mm are way to much for that engine I´m going to create two aluminium reduction cones with custom made throttle discs.
2 x 40-45mm !!!
Results from this experiment I will be able to tell you by february. )

I've got a 3.5, 3.9 and 4.6 plenum and they're all about 65mm by my reckoning. Will re-measure if I remember next time I'm in the garage,