Divided Plenum Manifold HOW-TO

[mouce]

Hey foam, what software package do you use to do all your computer models of the engine?

 

[greenfoam]

The plenum is too big on the VN anyway, I know the major reason divided plenums were invented was to give a better signal strength through the carby and better atomised fuel. All that doesn't count on a efi motor but I figured isolating the runners and the interference they give each other might help something, there is alot of air kicking aroung in there, you can tell when you hear how painfully loud this manifold plate is when the sound waves hit it. But anyway obiviously with this engine and this firing order it just doesn't help : ), With a twin throttle body long runner (12 inch) and each plenum about 70 or 80 cubic inches each. You would see +20 hp through the top half of the rev range but the same peak power and +50 foot pounds of torque at peak torque, that is enough to put a VN V6 straight under 15 seconds on the quarter mile with a CAI and good filter but yeah, it's a big job and 7 or 8 inch runners are probably better because they will increase the top end power but still make alot of extra torque. It's a good engine I mean it's won the indy 500 after all?, a few times maybe?. It's just that the stock manifold setup is really really really crapy

 

[greenfoam]

mouce, engine analyzer. It's hard to get it set just right when you don't know exactly whats in the VN motor, but you can get close. It allways gives more power than the VN is "supposed " to have but the 1/4 times add up spot on so the only way it makes sense is that Holden wern't telling the exact truth on the flywheel power of those engines, you can't run a 15.37 in a car that weighs the same as my VN unless you have 200 hp but they are only supposed to have 168 or so, mine runs 134 hp at the rear wheels on a g-tech flat out in second gear but you are loosing at least 20hp in wind resitance, there's a calculator for that on g-techs site somewhere. My friends 351 falcon pulls 250 hp at the rear wheels but his car weighs 2 tons.

I'll put my old manifold back on tomorrow, I'll remember my experiment for some time though because theres a 30 meter strip of rubber comming out of my driveway and down the road that happened on my second test run, in fact it was the first time my car has made a proper cloud of smoke with these tires but I don't usually give it heaps taking off around a corner, only in straight lines testing stuff

 

[Matt_vp]

oh well 2 bad ehh
i guess i will leave the divider out of mine and just stick 2 the twin tbs
where do u get a copy of engine analyzer?

 

[Frd_thmsn]

Did you try the split manifold with a VN chip.
I read somewhere that the VN's control the fuel injectors both banks at once (group fire), whereas the VR runs the injectors in bank fire , that is the two sides.
Not sure if you modified this in your VR memcal , or even if it matters due to the wiring to the injectors, but was thinking that maybe with a split plenum like you have,then bank firing would be better as before the air/fuel was shared in the common manifold plenum and now with the split it isn't.

I think the signal for the bank firing on the VR came from a cam angle sensor, so how do you bypass that when running your VR modified memcals in a VN ECU?

 

[PaRaDoX]

notice a big diffrence??? much power benefits?

 

[Stewart1000]

well you had a go at it and got some more knowlege out of it, pitty it didnt work tho.

 

[sic_vn_v6]

mate all i can say is that u r an idears man lol if it works i reackon i would give it a crack good luck brother!