Effects of longer intake manifold port lengths?

[SPEEDSTAR]

What difference does a 5" intake port length have over the stock length, say 3", dont know the length exactly. My CAS sheetmetal intakeports are 5" long. Are they longer because it helps midrange power? Do sheetmetal intake fabricators test different lengths to see what works better.This question will need expert comments I think , but any input is welcome.

Jeff

 

[Reggie West]

My Dad is using a Mease sheet metal intake on a Stage 2 block now.

The 74 twin bb turbo makes sure there is no lag with this set up at all.

He was told there would be a small amount due to the longer runners but I have not seen it. The motor idles nicely and there are no flat spots in the rpm range with it.

The datalogs I am seeing indicated more fuel at a lower rpm ( 25% in some spots!!!) but that was about all.

The longer runners make the motor peak at 4800 rpms and it just keeps on pulling from there. Mind you this is with a 400 trans too so that is part of it.

Where one of these intakes really help is when you want to start spinning the motor up 7500 to 8000 rpms.

Hope that helps.

 

[The Radius Kid]

Should be less lag with the longer runners,not more.
You opened up a can of worms here.
Wanna see a properly tuned intake for the Buick 3.8?
Look at the 3800 intake[mid to late 90's,molded plastic,long runner],same bore and stroke.
Those runners are longer than the runners on the 3.8's intake.
Those 3800's also made more power than the 3.8[N/A....unboosted].

 

[GNSCOTT]

You mean runners like this.... http://hometown.aol.com/gn1270/images/mvc-014f.jpg