Autospeed had a VERY interesting article comparing intake pipe lengths. In short the gains were about 8 percent (in the mid range RPM) just by changing/optimising the length of piping between the filter and throttle body. This is an 8% gain for $10 worth of pipe!!!!!!!!!

Has anybody played around with piping lengths (in anger)?

Also theres a lot to be said for the kits with the filter down by the bumper, or any CAI kit for that matter. Any 'cold air induction' gains may be lost through incorrect pipe tuning.

Got a link to the article? Are there calculations to be made to work out the optimum length (I'm guessing the key is volume) of the intake pipe between filter and TB for a given engine?

http://autospeed.drive.com.au/cms/A_107749/article.html

There was no theory involved/explained. It was trial and error on a dyno with a Charade.

well unless they've factored in air speed from the road, the dyno testing seems to me to be mainly irrelevent.

I mean a main feature of an intake system is it's ability to channel moving air (relative to the car). Intake length definately needs to be tuned though.

Personally as i no longer run a maf sensor i ran some 3" piping over the gearbox and down out the gap between the g/box and crossmember. Lost some low down torque but top end definately improved.

lol dyno in a wind tunnel. Does anyone know what racing teams do ie v8 supercars or f1

i think this is right up ezboys alley!

Ive heard about this too. I was at autobarn a while back looking at doing a cai. The guy told me that in NA cars increasing the distance between the throttle body and the maf sensor increased torque. Havent got around to trying this yet.

Same principle to variable inlet manifold in the 2nd gens where below 3000rpm, air flows
the long way, between 3000 and 3500 rpm, air goes a mixed path and above 3500rpm, air
goes the short way. Long way for torque and short way for power.

Ive heard about this too. I was at autobarn a while back looking at doing a cai. The guy told me that in NA cars increasing the distance between the throttle body and the maf sensor increased torque. Havent got around to trying this yet.

All depends on the SIZE of the pipe. It would be interesting to put a vac gauge on a plenum, inlet tract, air box etc etc to see the vac readings at peak torque. Then it's a matter of selecting (read: lots of trial and error) a pipe size or several pipes that will reproduce that vac reading at the rpm band you want your peak torque (ignoring other limitations/variables such as camming, plenum vol, runner length, port sizing etc.). This is the point were your motor is at it's most efficient. Moving the band lower will make the car a great daily traffic car with improved fuel econ, moving it higher will reduce throttle response and produce low rpm dead spots but it will get lift-off at higher rpm.

Sounds like a job for someone else 'cause I'm pooped :coffee:

Yeh i wouldnt say that in a large motor that there's alot of a power 'gain' to be had, but the ablity to alter the power/torque band ranges is a good advantage!

Generally; longer pipe = greater bottom end torque
Shorter = top end power.

Generally; longer pipe = greater bottom end torque
Shorter = top end power.

Thats right, but as EZ Boy said, the pipe diameter also plays a part in this (i.e. intake velocity) :)

So is anyone going to give this a shot??

is it just a matter of taking off the maf then running a smaller or larger pipe from the throttle body to the MAF???

so say i were to move my maf and air filter to behind the bumper with a longer intake pipe id be expecting more torque gains? i thought youd only see a difference with longer runners

so say i were to move my maf and air filter to behind the bumper with a longer intake pipe id be expecting more torque gains? i thought youd only see a difference with longer runners

Intake pipe is attached to runners so is considered an extension to runners hence differing
lengths have different affects.

ah ok i was thinking everything before the throttle body wouldnt do much but oh well cheap power

More Autospeed stuff on intakes - aftermarket pod/panel filters, MAF, CAI, and airboxes.

"Into the Intake"

Part 1 (http://autospeed.drive.com.au/cms/A_1361/article.html), Part 2 (http://autospeed.drive.com.au/cms/A_1370/article.html), Part 3 (http://autospeed.drive.com.au/cms/A_1379/article.html).

Did someone say charade?