1-2-4 Intake System [Archive]

CatiaChris

11-27-2005, 01:54 PM

Guys

This is our first year car and we think about a 1-2-4 intake system with a plenum size of 1.5 liters for two runners. We want to design the runners as straight tubes with a calculated length to get the advantages of the Helmhotlz effect. What do guys think?

Special greetz to all Beavers!

CatiaChris

11-27-2005, 01:54 PM

magicweed

11-27-2005, 04:45 PM

Not a bad idea. I was going to suggest this to our intake guy after finding this article:

http://www.hotrod.com/featuredvehicles/98518/

Basically it's a dual plane intake. Juat wondering if you would set it up as a 180 degree or 360 degree tri-y. If you just want an opinion, I say go for it. Just make it easy to adjust so you can take measurements on a dyno or flow bench with different runner and secondary lengths so you'll have some info for the judges to evaluate it on.

DaveC

11-27-2005, 05:32 PM

A good hint might be that the Honda has the middle two runners a different legnth than the outer ones. I've seen both shorter inners and longer inners on two different intakes.

Maybe this offset runner design will provide most of the benefits two individual plenums will provide? I have yet to test this in Wave, but its on the to-do list.

edit: Honda f4i w/ 1243 firing order...

BeaverGuy

11-28-2005, 12:19 AM

Hey, good to hear from ya Christian.

I think it would definitely be worth considering. I saw one car with that set up in '04. The firing order would be very important in the decision of which two cylinders to pair.

Good Luck.

Analogue

11-28-2005, 11:10 AM

MIT tried that in 2003. There was little to recommend that car, which is, to this day, lovingly referred to as "Deathtrap."

Here's a shot of the 14 pound stainless steel intake. In hindsight, even 7 lbs per plenum seems excessive.

http://web.mit.edu/fsae/107_0781.jpg

Also visible is Acar's, umm, exhaust.

Ben Inkster

11-28-2005, 03:44 PM

Using different length runners will help you balance and distribute you torque peak but I would suggest using induvidual cylinder fuel and spark trim. The difference in airflow and VE to each cylinder could be dramatic.

Cheers
-Ben

(former) UWA Motorsport

John Bucknell

11-30-2005, 07:00 PM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Ben Inkster:
The difference in airflow and VE to each cylinder could be dramatic.
</div></BLOCKQUOTE>

Ditto!!!!

DaveC

11-30-2005, 08:22 PM

Does anyone know if Honda used different spark and fuel maps for the center two cylinders on an f4i?

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