Which Air Horn Shape would be better

[MONZTER]

Hey,

I am working on my plenum for my turbo individual throttle body set up. Do any of you have opinions which shape would be more effective? The first one is round 88mm big end, 90mm long, 46 at the body. The second one id 88mm square big end, 90mm long, 46 at the body. Both are tangent on the big end and flat to the floor (not protruding into the plenum)

Thanks for the input. Jeff

[JustinOlson]

I'm stumped on this one. I like the rectangular piece, but I'm not sure if its more efficient then the round piece...

 

Justin

[brokebolt]

On forced induciton, I would gather that their would be no difference. After all you are building pressure in front of the throttle blade, that is at less than WOT. You should have less pressure behind the throttle blade than infront of it for most driving applications. I would also assume that the round shape would flow more evenly from any direction into the throte of the TB as aposed to the square one. I'm not Turbo guy for sure but it would seen logical to me.

[johnc]

Ideally your velocity stack design should provide a constant radius entrance that lets air perpendicular to the flow smoothly transition into the stack. A sharp edge at the open end of the velocity stack causes turbulence as air from the sides flows into the opening. Once the air flows past that transition, that actual inner curvature of the stack can be fairly tight (more like a short/fat bell then a long tapered cone) without experiencing flow separation.

 

The TWM carb intakes work very well and I've seen the results in dyno tests on NA L6s.

 

http://www.twminduction.com/AirHorn/AirHorn.html

[johnc]

On forced induciton, I would gather that their would be no difference.

 

That's not true. Pressurized air is still a fliud and the physics are still the same regarding fluid flow.

[brokebolt]

OK, I think we both agree that the conical shape would be best for any application but in forced induciton when you are producing more pressure than needed (a large pressure differential accross the throttle blade) would it make a difference in efficiency? How different is the pressure differential across the throttle blades in a turbo induction vs. a naturally asperated set up?

[johnc]

OK, I think we both agree that the conical shape would be best for any application but in forced induciton when you are producing more pressure than needed (a large pressure differential accross the throttle blade) would it make a difference in efficiency?

 

Absolutely. Turbulent flow is less efficient then laminar flow. Anything you can do to reduce turbulence in the intake tract will increase flow, regardless of pressure. Taken to extremes, a good flowing intake will make more horsepower with less boost then a poor flowing intake at higher boost numbers.

[MONZTER]

Absolutely. a good flowing intake will make more horsepower with less boost then a poor flowing intake at higher boost numbers.

 

Yes, Very simply put this is what I am trying to do. I have seen intakes with Square and Oval shapes on the big end but can’t determine if it is for packaging or for improved flow. I will try to find the pictures. I believe one was on a Corvette LeMans Engine. Another picture I saw was on some V-12 exotic.

[Tony D]

Packaging. CART engines used the squarish inlets because the cylinder stack is so close, and they use BARREL THROTTLES in the heads, so 'differential across the butterfly' is not an issue at WOT.

 

If at all possible, the full recurved stacks like JohnC linked will produce the best flow characteristics.

 

Everything that applies to N/A flow will apply to a plenum with forced induction. No Luminetion Barrel Throttles in the works Jeff?

 

Muahahahahaha! 45 mm hole with tip in characteristics like a 40mm, and WOT flow comparable to a 48.....

[MONZTER]

Packaging. No Luminetion Barrel Throttles in the works Jeff?

 

Muahahahahaha! 45 mm hole with tip in characteristics like a 40mm, and WOT flow comparable to a 48.....

 

Thanks Guys,

Trust me Tony, Barrels mm,mm good, looked into it, but I have to finish this thing up one of these years, oh ya, and not spend all of my kids college money..

[Tony D]

Ahhh, you are immune to the Devil! JeffP is not so strong.

I guess you must be like Wato; Jedi mind tricks don't work on me!" He's more like one of the Stormtroopers... "Those aren't the ITB's you're looking for, move along!"

 

LOL

[brokebolt]

I agree with what you have stated JohnC but do you think the two presented air horns you would have any real world difference between the two? In theory yes, and I agree that more turbulance=less perfromance. As far as I can tell this ideology hasn't filtered into other areas of turbo design, the stock turbo set up has some fairly sharpe twist and turns. I would gather that a air to air cooler would also be an area where you develop a lot of turbulance. Again not a turbo guy so I haven't followed up on any improvements sence like the 80's.

 

My origianl comment I was speaking in general that if you not running at WOT you really should not see a "seat of the pants" difference in normal daily driving. I haven't followed MONZTER's build up or intended use for the engine so I was speaking more generally, not all out performance.

 

Personally I wouldn't send the time to develop an air horn for the prospect of potential gain...unless you needed it for space limitations or something like that. Simply remove the spare tire and I think that would produce more performance gains over any air horn design. I could be wrong here but...

[Tony D]

"I would gather that a air to air cooler would also be an area where you develop a lot of turbulance...Again not a turbo guy so I haven't followed up on any improvements sence like the 80's."

 

That would be why 'bar and plate' I/C's (used in industrial applications for years) have made it into Automotive I/C applications. The problem with using the I/C argument is that it's very far from the point of engine entry in most cases. What may be turbulent there is well relaminated and flowing down the pipe to the T/B again. Once it's flowing smoothly, the idea is to minimize losses at each opportunity.

 

In industrial applications I can show instances where people saves over 600 horsepower of compressor (meaning a whole compressor system shut down) after going through their system and simply having them repipe using the same undersized piping while at the same time eliminating elbows. In some cases, simply adding a second feeder to point of use cuts piping losses in half (intuitively this is obvious) but instead of paying $1500 for piping on the front end, the design engineer saved that money on the capital outlay, and then ran for 10 years pumping air through an undersized pipe system and costing hundreds of thousands of dollars in electrical bills for YEARS before someone comes in and shows them spending $1500 in pipes will save them $30K in Electrical Costs PER MONTH! (Actual Example from Fairfield CA!!!)

 

What the key is designing the most efficient system on the front end, and not worrying about it on the back end. If you utilize the best and most efficient parts in each portion of your design, sweating the details is what it comes down to. Air Horn Shape. A 0.001" on this bearing journal compared to that one. Dial Indicating? Depth micing the pistons in the bore when assembled for deck height. It's the difference between an L24 tha makes 120 hp, and one that makes 180 hp, using identical componentry. And that's on an N/A.

 

On a turbo, even the smallest restriction can compound and cause a pressure rise that costs you unimaginable ammounts of horsepower.

 

It's not merely cramming in air through boost. That is the 60's paradigm. If you make the engine FLOW same as you would for an N/A, the horsepower you make will be achieved at a lower boost level. I have seen 380 Ft-Lbs of torque at 8psi (4500rpms). It's on a stock manifold. Normally that level of torque is had at 2X that boost level. Sweating the details on a Turbo Engine will reqard you will much more power than it ever will on an N/A setup, simply because you are dealing with flow FACTOR under pressure (2X or 3X loss for the same restriction).

 

60's Paradigm was 'no porting is required for Turbo Motors, just use boost'

Repeat for almost 20 years.

Then, in the early 80's these little Renault's and Hondas were making 1500-1700HP from engines of 1.5L displacement. It wasn't simply 3 bar boost that did that!

[brokebolt]

Long rants aside, and going back to the origianl quesiton; I guess what your really saying is that neither design is best. A radiused inlet like the example given from TWM would be the best or better than the two in question.

 

So what plant in Fairfield, Jelly Belly or Bud? And what is a 'bar and plate' I/C's you mention?

[MONZTER]

Hi Guys,

Thanks again for the input. I can see your point that is probably such a small difference it probably won’t make a difference. The truth is, I am just a freak about this sort of stuff. I am really trying to look at every part of the system, and push it for a "textbook" approach. Bottom line is I like the challenge of figuring it all out. Here are some pics of my build. You can see how I am looking at everything from headers being equal length, to minimizing bends in the plumbing to simply how the air flows in and out of the intercooler. The horn in the question above will be built into a carbon plenum for my ITB set up. Sounds like I will stay with the round inlets.

 

 

 

 

 

[hughdogz]

Damn! That buildup is looking insane Monzter!!

 

I'm kind of curious why you went with the V-clamps instead of silicone hump hose...there's not going to be a strain / fatigue problem when the engine is torquing? Nonetheless, AWESOME looking job!!

[Tony D]

Ohhh, Adel Wiggins Clamps...

 

Someone knows proper tubing procedures! LOL

 

"Long Rants"? WTF... I thought this place was about exchanging the maximum amount of information. What, this is now ZC.C all of a sudden?

 

Call me sensitive, but "Rant" is a particularly offensive word when dealing with someone taking the time to elocute a position that is a bit more complex than simply a knuckle-dragging 'it ain't makin' no differunse then pullin yer spar tire out and runnin it'

 

For some, the process of the decision is as much a part as the results. Forgive those of us who revel in the process...

[MONZTER]

Yes Wiggins clamps. You will never see hump hoses used on the upper echelon of motorsports. (Not that my car is that, I just want to pretend)

The Wiggins clamps offer 3 degrees of float per end and the bore inside remains smooth and free of any turbulence causing "humps" in the plumbing. They also are 1 hand quick release, no tools needed. They are so good, except the color purple, but it is a Mil Spec specification for this type of fitting, just like the red and blue on AN fittings.

Tony, FWIW I fully appreciate your insight and ability to apply your real world experiences to so many different areas. Really nothing much from an engineering standpoint is new anymore, much of it is simply reapplying ideas and techniques from one industry to another. This can be as obvious such as military to automotive, but it takes a real creative person to see the brilliance in the simplest most unappreciated things we take for granted.

 

 

Jeff

[Tony D]

Elliott was aerospace related, and used those Adel Wiggins Clamps on their old PAP vertical split compressors. It was 'old home week' for me, as it looked like an overbuilt Bleed-Air Driven Air Cycle Machine from a C10 or other Avionics Cooling Array. I 'appropriate' them whenever I can...what I will use them for is beyond me! I keep them around because they look so cool! LOL

 

You can see the dilution of various industries as 'other' disciplines start to influence machine designs. IHI (new kid in the marketplace) used a DC Drive Variable Speed setup on their Turbocompressor, with Titanium Impellers and cranking along at 120K...floor footprint was comparable to the old Elliotts. Definately Turbocharger Influenced with those speeds in an industrial application! While Elliot marched straight and steady to look like Cooper Machines (blatant ripoff of the design IMHO) with thick castings and massive iron instead of aluminum tubing, Adel Clamps, etc...

 

But again...I digress!

[brokebolt]

Hey Monzter that intake looks real good, almost like you cut up a stock intake...He, he.

 

Their must be a lot of time spend on that project. Thanks for the pics. I noticed that the second injector ports 1 and 2 have the sleeves removed. Are they a weld in design?

 

Again not a turbo guy but is their any gain to be had with a header style intake (like that posted) vs. a design like the stocker turbo Z had?

 

Tony D.,

The "long rant" comment wasn't directed at you freind. I was simply trying to clarify on the original issue and not turn this into "if you want maximum output" discussion. Like it has been stated over and over, you can get more performance but at a cost (both $ and trade offs) and that was where I was headed here...or not trying to head.

 

And yes being that turbo's use exhaust output on forced induction it is really a debate of cost, time, etc. vs. output. That system shown here looks farily costly and time consuming. For someone wanting max. output I would recommend to be prepaired to pay or spend time developing. I'm sure Monzter has done both. Personally I am not that concerned with max. output on a daily driver or hobby car...I would re'con most feel the same. I would gather they want the most perfromance to be had for least cost.

 

If I were more sensitive I guess I would take offence to the "knuckle-dragging" comment. The spare tire comment was really a comparison that your gains would be about the same as removing the spare tire...or I would assume. Compairing weight to lost performance.

 

I don't understand the ZC.C comment you might need to clarify that in a PM or something.

 

Ya know, I thought this was a site of shared ideas...I even read the information posted by Superdan concerning the site rule and mission statement to make sure we were on the same page...

 

So back to business, what is a 'bar and plate' I/C's you mention? I see the pics here posted by Monzter of the air to air cooler that I have seen in the past on other turbo systems and what not.