It has been said, the more bends you have in a pipe, the less it performs (well).

Every time you add a curve, you actually are adding pipe length, whether it be in the intake side or exhaust.
Years ago in testing, we found that adding just one 90 degree bend was equivalent to adding 12’ of pipe (after the bend) regardless of diameter. Same principle applies regardless of intake or exhaust, pipe is pipe....

I see two bends in your ITB stacks. The M6 has one continuous bend— think about it. Hilborn injection systems use no bends, unless they’re seriously worried about Helmholtz. Then, it’s multiple height stacks.

I realize this is your exercise, but you’d been better off with a sheet metal intake an one large front mounted throttle body.... with a blower and stand alone efi. A lot less money, but probably not your style.....

Cheers-

 

The radius of the bend matters a ton. Those M5 stacks have long enough bend radius that they'll run really, really well.

 

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For optimum flow the intake duct shall be a straight shot to the intake valve(s). However, if you want everything under the hood you have to compromise. I think Sterling's design with the long M5 air horns is as good it is possible to do. Relatively long intake ducts is a must for good torque in the mid range. Flow testing has shown me that a flat wall can sit quite close (15-20 mm) in front of the bell mouth before the air flow will be affected. The air always flows from the side around the bell mouth radius into the air horn. Therefore it is important to make the air box sufficiently high/deep.
Åke

 

With this type of intake tuning is more important than flow.

Yes bends affect flow but smooth larger radius minimize this.

With a 2" ID port and tubes you're not going to risk running out of airflow even with a few bends, the flared end will only help.

 

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Looking awesome Sterling!

I had contemplated re-clocking the trumpet section on their bases just you did (I actually separated one of the horns to see if splitting was feasible without destroying them), but then I decided to leave them be. My concern was in the stock configurations, the intake horns have an engineered long side radius and short side radius.

It may not matter, but re-clocking them so they fit in a compact package gives them an "S" type bend. I don't know if that is an issue or not when it comes to air flow into the ports. Its probably so minute that its not an issue.

 

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I like that, that’s a great idea for the engine bay look. Functional too.

 

Quote: "with the longer trumpets /airbox we went from 240NM to 300 NM ".
One more that has found out that long tuned intake ducts is the way to go. It seems hard to convince our american friends how important intake length tuning is.
Åke

 

Sterling , this is a amazing clever design …. chapeau !

 

The runner has a bit of an s curve there and it still works great.