OK, well just about everyone out there has done some basic intake mods, like removing the snorkel, upgrading to a high flow filter, but has anyone out there tackled the real bottleneck issue with the intake tube from turbo to manifold? This in my opinion is undoubtedly the king of design flaws, taking a nice 2" outlet from the turbo, flattening it out to about a ½" and for those unlucky 'S' engine owners like myself, putting a plate that covers about 3/4 of the underside. I've done some slight mods to mine, drilled holes in the underside, and swapped in a HD manifold underneath, but its just not the way it should be. So I've decided to try and redesign and replace this piece altogether, just wondering if anyone else has already done a custom intake tube. Surely we can all agree that a decrease in drag here will result in lower IAT's, and snappier throttle response, the way I see it, it can't hurt. Edited by: Texas Diesel Guy

Actually after yesterdays tow in 100+ heat I'm looking to do something there myself, I'll have to dig it up but a buddy of mine modded a Cummins Snorkel to supply his engine. I have to run with the filter top off as I always set the DP indicator with the lid on then I'm pulling in the high temp underhood air, which really makes my IC work overtime.

how did you plumb that IC in there anyway? do you have any pics?

I made a steel plate that corrosponds to the bottom of the snorkel.
It has the bolt pattern for the six bolts and i was going to weld the rest of it to the base.
This approach worked when I wanted to mount the stock throttle bodie to the performre intake I already had on the motor .
I never went forward with it because I really got cought up in the choice of intercoolers, twin turbos and the need for a new/ better intake/ ehxaust manifold.
Edited by: quantum mechanic

Hm, shorten the tube and put something like http://cgi.ebay.de/ws/eBayISAPI.dll?ViewItem&category=33597&item=7912033081&rd=1&tc=photo or like this http://cgi.ebay.de/ws/eBayISAPI.dll?ViewItem&category=33597&item=7911579487&rd=1&tc=photo in between the charger and the intake under a ramscoop?

I wish I were not so much impeded by the legal regulations here!

not exactly what I had in mind lee....

A few pics here


http://myweb.cableone.net/tbogemirep/Edited by: Turbine Doc

As a basic reference, the plenum internal rectangular opening is 0.75" x 5.25", giving an opening area of 3.9375 sq in.


Inlet tube diameter is 2", figuring pi x r squared gives area of 3.1414 sq in.


While GM had other considerations, that area was considered more than adequate for an engine of ~400cfm at 3500rpm max.


Excellent way to increase flow rate is to increase pressure of flowing gas...........Voila!!!!! Turbocharging gets the job done.


And, remember - when flow rate of compressor exceeds flow rate of engine, it stacks up in the intake as Boost pressure.


Three ways to increase power -


1. Increase rpm - more flow rate, more combustion events per unit of time - 6000rpm vs 3500rpm


2. Increase displacement - more flow rate - 600ci vs 400ci


3. Increase input pressure - more O2 per cubic foot - 20psi vs 7.5psi


Increase engine flow rate, for more oxygen thru-put, add more fuel = more power.


If flow rate cannot be increased - 400ci and 3500rpm -, increasing input pressure increases oygen per unit volume, allowing more fuel for more power.


Also, decreasing compression ratio allows more Boost pressure, for more oxygen, for more fuel, for more power, while maintaining cylinder pressures equal to the higher cr.Edited by: gmctd

alright, all I'm saying is the stock piece, could be plumbed better, sure the underside might have more opening than the inlet, but I'm talking about where they pancaked the 2" tube in between and ran a braced bolt hole right in the middle of it.

I did not factor that bolt casting in, as it is more into the open plenum area, allowing for smooth flow transition.


If you have not, check Quantum Mech's earlier posting for show-and-tell on opening up the plenum webbing and inlet tube for better flow characteristic.