Thread: Its this too big to build an IM for a big bore VE

A 50mm bellmouth stack without any taper? I doesnt make sense to have a 50mm bellmoth since the port on the IM its about 50mm wide unless that you dindnt want any taper at all.
I think one with this dimention will suit better...
Velocity Stack dimensions are : Overall Length of 75mm and Base to Tapered Length 15mm. Top outside diameter of 88mm and inside diameter of 57mm. Base inside diameter of 50mm. Spun from 1.6mm aluminum.
And use small pieces of 50mm ID tube will make it better
The bellmouth have to go further into the plenum to make room for the plenum to clear the firewall..
The 7in runner its fron the inside of the port of the head or from the flange of the IM??

Thats a better option, still not the best in my opinion.
But you have to remember that the port is oval so its 50mm at its widest but only 34mm high. IIRC the area of it is about the same as a 42-46mm round hole. So even though you aren't "tapering" physically in one plane there is still a reduction in area so you will still get that venturi effect.
Also from a fabrication view point when you crush the 50ID stack down to 34 high oval it will now be wider than 50mm. Sommething around the 45 ID range maybe a little smaller would suit better as when you crush it it will widen out closer too 50mm.

I wouldn't go too large on the taper personally, To much taper will hurt you power more than a straight runner because it will slow down the velocity too much.

Also I would think 1.6mm would be a little thin for a aluminium manifold with a plenum etc hanging off it? Maybe someone else can chime in on that.

Thats just how I'd go about it but I haven't built a 2.4 ve so I'm happy for more more knowledgable people to prove me wrong!

Oh also, if your buying cams talk to Kelford.
Kevin is awesome and has a huge amount of knowledge that he doesn't mind sharing so he'll be able to give you some pointers on IM specs

Thank for the comments good points..
Will straigth oval runners with same diameter oval velocity stack on the end will create better flow and velocity than the stock IM with the reverse taper???
Just getting facts in order to get the best results possible...
Since its easier to get those oval tube and velocity from ross machinery to build the IM..

Definitely better then the stock reverse taper.