Fins on back of Valve & Fins pre TB

[The1]

Ive always wondered if fins on the valve would help air/fuel mix, this provides some insite.

http://www.ijrdet.com/files/Volume2Issu ... 614_18.pdf

I also have thought about using fins on intake tube into the throttlebody to help with airflow and speed past the throttle blade, it's on my list to design a test tube on the 3d printer.

[immortality]

There are plenty of so called vortex generators to fit into intake tubes on the market.

[vlad01]

There are plenty of so called vortex generators to fit into intake tubes on the market.

yeah and they dont work. There was a good article where a mob tested a whole bunch of different ones and used a dyno to confirm results, most did nothing, the others often made it perform worse by restricting air.

[HQ355]

I think GM would have done if it worked by now, they've been using plastic intakes for a while so it would be quite easy to do

[VL400]

Tried the 'snake oil' hiclone years ago on a mates VS V6, back to back testing using the recommended twin hiclones resulted in a loss of 5hp. Made 140hp, swapped over the plastic intake pipe work to the hiclone equipped one (standard plastic pipe with the hiclones inside), made 135hp. Put the stock plastic pipe back in and made 140hp.

It went back for a refund. The throttle plate did a good job of straightening out the air on the way through, there might be a benefit on a diesel with no throttle plate.

[immortality]

I've always been sceptical but that's definitive.

A lot happens to the air once it passes the TB, what happens in the intake tract, from the plenum to the valve (and past it) would be much more important.

Port induced swirl for good mixture distribution is important. This can be achieved with grinding a bias in the port around the valve guide. Saw a recent wet flow diagram of an intake port and the flow direction over the valve was fairly interesting. Fuel (and even air) is fairly heavy so tends to travel in a straight line. All of this was from an article written about a seminar one David Vizard was giving in NZ about engine design, heads and cams etc. Very interesting stuff. Hope to one day attend one of his seminars.

[The1]

yeh ive been and done the hiclone thing to, but wasn't thinking to that extent, was more if you can guide the air better below and above the throttle plate for example, so air entering isn't as abruptly stopped by the throttle blade. Though gains maybe nill as there would already be enough air on throttle crack anyway in the plenum and at WOT the throttle blade is horizontal.

I also had thought about testing inserts into the runners to change the size or raise them up a bit with proper tapered edges or something even to help distribute airflow better across the cylinders. I will have to look into alot more and do some late night reading.

Anyway this is why i posted it to get some advice, Pretty much any idea if it can be drawn in cad then i can print it out.

[vlad01]

I'd be interested in playing with plenum volumes. I know the general rule of thumb is the plenum must be at least engine capacity.

What normally happens is a smaller plenum than engine will result if best response and good low end torque at the cost of mid to high range torque and power.

equal plenum volume to engine works well. But I came across an SAE paper on a study of plenum vs engine volume and they found the best minimum volume was 1.6x the engine. So in that case ecotec will benefit from 3.8L and be best at 6.1L. Stock is 3.4L


Larger plenum increases torque throughout the rev range and allows greater torque to be made at higher rpm vs a smaller one, the cost is throttle response, but usually its only ms worth of lag.

MACE make a plenum lid spacer in 12mm and 25mm.

these guys, sicsix make a custom 9.6L proto type which would work great, going bigger just plateaus the potential gain available, so its a bit unnecessary really.

you could do some real interesting things inside like increase runners by having velocity stacks inside.

[delcowizzid]

we did a slightly over 4L plenum on a turbo car real soggy down low mad up top had 90mm throttlebody too you could run it N/A and rev it full throttle and look in through the TB at the ends of the runners and see fuel domed at the end of the runners like half tennis balls was pretty cool LOL youde really have to mod the runners to suit the plenum to tune it as a package.

1vrmanifold.jpg

2IMGP5501.jpg

[Holden202T]

I honestly think hi-clones and the like only show weather you have a reasonable inlet or not, if its already reasonably you wont see a difference or will loose power from them.

especially with modern cars these days, injector angle and spray patterns probably make more benefit than the air flow before the butterfly!