bling intake runners for webers - more torque?

[haycait911]

another experiment in my quest to improve low/mid range torque. first was 4 inch air horns, some help.

3.0L - how I did 4" stacks on Webers

then I figured more must be better. see version 1.1 below. wasn't hard to do. used silcone elbows with braiding, used in turbo apps I think. and a couple of sets of air horns. runner length now 22 inches fron head to end of the air horn. there does seem to be an improvement in mid-range torque. albeit at the sacrifice of 6k plus power. not a big deal, this engine is all in by 6k anyway. I don't think the one 90 degree sweep elbow will restrict flow noticeably. also, I can stick a piece of breathable foam between the bell ends to keep out leaves and small animals on long drives. now I'm thinking of some kind of air box that would enclose the bell ends, maybe with some kind of ram effect, a winter project I think. I'm going drag racing again on sunday so we'll see how it works there. FWIW, and I know it doesn't really matter, but it sounds AMAZING. and it fits under the stock grill.

no matter what, it's worth it just to see the muscle car guy's faces at the drags, when they see this.

[azasadny]

Looks cool!

[Trackrash]

Dino results?

[James Brown]

does the cool collar help?

[Wil Ferch]

I've been involved in gaseous ( air) flow as well as liquid flow thru pipe and such from an engineering perspective....and can offer these points of opinion.

1.) A 90 degree elbow has more resistance than you think....by forcing a "bend" in the airflow that wants to go straight.

2.) Silicone tubing, even if double walled with a wire in-between the 2 layers, to offer the smoothest airflow on its internal surface, has considerable resistance compared to (say) a smooth solid internal surface....like the inside of a PVC pipe or polished stainless pipe or tubing. Not saying to use either PVC or stainless...simply identifying other surfaces may greatly improve what you have. Like your intake trumpets themselves.

Unless you have some sort of lab equipment to test your system.... or unless you can determine that what you did was basically correct , like checking against technical papers or academic textbooks on fluid flow in piping systems....I think you are only feeling a placebo effect on your changes.....

That all said.. I admire your inventiveness and packaging prowess.....

[haycait911]

Originally Posted by James Brown

does the cool collar help?

the cool collar is there for chuckles. it always gets some kind of comment from those who know what it is/isn't.

Originally Posted by Trackrash

Dino results?

I'm hoping to hit the dyno before the end of driving saeson. should be interesting. my drag times this weekend will give me a decent comparison too.

[haycait911]

Originally Posted by Wil Ferch

I've been involved in gaseous ( air) flow as well as liquid flow thru pipe and such from an engineering perspective....and can offer these points of opinion.

1.) A 90 degree elbow has more resistance than you think....by forcing a "bend" in the airflow that wants to go straight.

2.) Silicone tubing, even if double walled with a wire in-between the 2 layers, to offer the smoothest airflow on its internal surface, has considerable resistance compared to (say) a smooth solid internal surface....like the inside of a PVC pipe or polished stainless pipe or tubing. Not saying to use either PVC or stainless...simply identifying other surfaces may greatly improve what you have. Like your intake trumpets themselves.

Unless you have some sort of lab equipment to test your system.... or unless you can determine that what you did was basically correct , like checking against technical papers or academic textbooks on fluid flow in piping systems....I think you are only feeling a placebo effect on your changes.....

That all said.. I admire your inventiveness and packaging prowess.....

Wil, maybe you can help me. I came up with a number 150 litres/second that the engine is flowing at 6K rpm. if this is going thru 6 runners with a choke point ( intake port ) of 35mm, at what speed is the air traveling in each runner? in MPH. I poked around online but can't find a formula to use. any thoughts?

[911st]

It depends on the cross section area of the runners where you want to know the air flow.

If the area cross section is twice as much I suspect the velocity will be half as much. If it is for times as much air flow will probably be about 1/4 the the velocity.

But I am not a math guy so I could be wrong.

All those little intersections also create turbulence and thus back pressure. It is interesting how an elbow creates turbulence and back pressure as the air has to take longer and shorter paths around the turn. Most the new cars now use flat tubes as runners to make turns more efficiently.

I think longer runners are for low end and short runners for higher rpm power.

[haycait911]

well, flat spot gone now. I drilled out some main jets to 1.7mm and stuck them in. now it pulls like a SOB right to 6k+. as tomorrow is my last day of insurance and I'm going racing, I figured to give myself the best chance possible. pulled off the engine lid and turned the intakes so each has a clean ( non turbulent ) air supply. wish me luck!

[cgarr]

You should mill off the intakes about 7 degrees to angle the carbs outward to help straighten out the intake flow and report back!

[kach22i]

Look to nature for the right sized bellmouth intake.

There's a Giant Hole in this Dam Water! [Bell-Mouth Spillways]

[T77911S]

what about an air filter?

i would take off the 90's and put just the cones on, if they fit.

[Wil Ferch]

That's why race tuners have flow benches to do heads.....a lot of it is theoretically based, but much of it is art and science combined. I was simply telling you you'd be surprised at the effects of a 90 degree "ell"....and you'd also be surprised at the effects of internal flow path surface roughness. I am not going to go thru Bernoulis's equations and such and pretend we can get all the answers on paper....you wont.

[haycait911]

Originally Posted by cgarr

You should mill off the intakes about 7 degrees to angle the carbs outward to help straighten out the intake flow and report back!

I had figured 8.2 degrees, but if you think 7 will do the trick, I'll give it a try.

well, all in all, my experiment didn't work. I think I mistook cool sounds for more power. went drag racing and it definitely wasn't pulling like it was.

well...at least it didn't go BOOM..BANG...BANG...BANG...

new plan:

go back to 4 inch stacks. I can fit 6 inch K&N filters if I bump up the package shelf a little on the right hand side. best of all worlds I think. thanks for all the input. Don.

[T77911S]

if you want to drag race it, try something that will pick up forced air. or use tall auxillary venturies with the 4 inch heels, i mean stacks.

[911st]

Originally Posted by cgarr

You should mill off the intakes about 7 degrees to angle the carbs outward to help straighten out the intake flow and report back!

I heard of something like this some years ago. I think from the old Competition Engineering owner or such but forget.

Anyone have any real world info on this?

[cgarr]

Originally Posted by 911st

I heard of something like this some years ago. I think from the old Competition Engineering owner or such but forget.

Anyone have any real world info on this?

Its done more on 912 engines because of the tight bend in the intake,, I milled a set of 911 heads for a 2.7, will see if it works?

[carslutt]

looks like something off the batmobile in the pic w/ em all trying to face the back of the car. i bet the sound is quiet awesome at WOT.