Ported Ba/bf Inlet Manifold

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what if the cops have eaten all their chips...

Just go back to donuts I guess?

[Impellor]

How did u go with old mate and the deal u two sorted with that bbm change over and a few back to back runs ?

What happened ?

I spoke to our tuner, he then asked BigAl to get in touch with him, as he said he was happy to do it, but it wasn't a 5 minute job. And it would be up to BigAl to cover costs. Never heard back from BigAl.

Cheers

[Impellor]

So why do companies offer different sized inlet manifolds for the same motor? From your findings impellor, everyone should just make the biggest runners and/or plenum for every engine combo.

Surely you don't believe that?

To answer your question this is directly related to breathing efficiency. Variables such as power your chasing, boost levels you are running, and mods that you have to support your power expectations. Look at the end of the day, the BA/BF plenum is not a great design for the turbo application. Good for the N/A with the butterfies, and low down torque production (which is Fords bread and butter, to combat V6 Commodores). I suspect this is why a change to the FG plenum was made.

If you look at the opening of the plenum in the OP's pics you can clearly see how the bottom of it is quite restrictive (to be honest the opening is smaller than the T/B port also). Now I believe that this is the case to help push more air into the outer perimeter of the plenum. So I removed a substancial amount from that area. But to compensate I also removed a large amount from the sidewalls of the opening to allow good flow to the outer perimeters. You will also see that the internal plenum runners have a substancial lip on them. Again I took some material off them and smoothed. I also smoothed the interal runners with sandpaper and opened them up to match the ports on the inlet runners. The only real testing I did was with water. This was done with the internal plenum runners. I used a watering can and poured into the runners. I tried to keep the test as controlled as possible. I sat the plenum on a table before I started and the water travelled 90cm were it hit the ground. After I finished porting and polishing the water travelled 107cm. So from that result one can suggest that I have been able to increase veloscity.

Why do it to the factory plenum? I believe that the BA/BF plenum has a slight avantage over the FG in relation to low down torque production. Obviously the FG was able to overcome this by using a smaller turbo along with a 40% boost increase.

I have added this video just to highlight how well the car runs. In this particular event ther were many cars making 200-300 more horsepower and I never beat any of them of cause but I was never far behind them. If you look at the 42 second mark this was me racing a VE SS that was making 306rwkw's I was told. My car ran well in all 3, 15 minute events and the temp gauge never moved. Although the poor old Monza cooler started to get heat soak towards the end of the second run, as we ran 2 in a row.

But in conclusion, if you do this mod to your plenum I guarantee it is not a step backwards.

Cheers

Edited 02/05/13 11:16 PM by Impellor

[Bellato]

^^ too many words and not enough pics

[tab]

And there we have it. The 1.5 seconds of video conclusively and unequivocally proves that a backyard plenum works beterrer.

[Paulie2256]

I agree, at the 42 second mark you can clearly see that the car is NOT on fire.

[JETURBO]

And no black paint ..........

[Mr_4.0]

You first paragraph contradicts what you've been saying impellor. First you say bigger is better (earlier in thread) and that its proven, by you, so therefor everyone should port the hell out of their manifolds. Then you say in this post that companies offer different manifolds for different power levels, mods, etc. You getting close to a correct answer now. Wonder what's requiring people to buy manifolds based on power levels and mods? Couldn't be that BIGGER is NOT BETTER in every case? Couldn't be that could it? Could it?

Your idea of fluid dynamics in a plenum are flawed. I promise you, if you tested your theory in a computer simulation regarding your porting and plenum ideas, you would find some very odd and uneven distribution of air. Sometimes you may need to slow OR increase speed to one or two cylinders to achieve even/better air distribution. Not to mention, your better homes and gardens style flow testing is not what I'd call ideal....

Every time you mention the word "restrictive", you relate it to something being small. How do u know its restrictive? Without back to back testing you DON'T know.

For example, why is it beneficial on certain setups to have a 3 inch exhaust that tapers down to 2.5 inch towards the end? It only applies to certain setups and certain power levels. But why is it beneficial? It's directly related to your argument here and shows why bigger is NOT always better. Air speed is key! Remember that. Although the exhaust behaves a little different, the same principal applies to intake. You want to keep airspeed up. Large throttle bodies for example don't always gain you power. On your theory, they must ALWAYS gain you power. In reality they can send you backwards.

In regards to rough surfaces in manifolds, mick touched on it a little before I believe. Having a rough surface CAN aid in air/fuel mixing. However it also has been shown to act as a barrier in some cases. A cushion of air can build up against the manifold wall and aid airspeed further! So polishing, in many cases, does not increase air speed more than a slightly rough surface.

Finally, Fg falcons use a staggered valve timing. One intake valves opens before the other. Why is that? wouldn't opening both valves together produce a larger path to the cylinder and therefor make more power? NO! Opening in a staggered fashion increases swirl and AIRSPEED. In turn producing a better MIXTURE and more power.

Next time you look at runners, plenums, heads anything, and make an assumption on restrictive points, just take a step back and look a little deeper. BIGGER IS NOT ALWAYS BETTER!

[JETURBO]

Spot on

[Paulie2256]