[Subscribe to Daily Digest] |
 | [Main Performance Bulletin Board | BBFAQ |
Prev by Date | Next by Date | Post Followup ]
Member Login / Signup - Members see fewer ads. - Latest Member Gallery Photos
Re: air filter in body project Posted by Justin VanAbrahams [Email]  (#32) [Profile/Gallery]
(more from Justin VanAbrahams) on Sat, 23 Feb 2002 14:58:44
In Reply to: air filter in body project, nate_t_g, Thu, 21 Feb 2002 17:07:43 Members do not see ads below this line. - Help Keep This Site Online - Signup |
I think you have that backwards... a shorter intake tract benefits an engine at high rpm, a longer one at low rpm. And, a longer one doesn't inherently provide any benefit - it has to be properly tuned to do anything. Take a look at the early V6 SHOs with their two stage length intake geometry, or the new BMW 745i with its variable length intake geometry. Heck, I think V6 Saabs have dual-length runners as well. In all of these cars, the longer path is used until ~3500rpm and then they switch over to the shorter runners...
But all this changes with the presence of a turbo... Usually the longer runners are designed to work in tandem with the intake charge resonance to maximize the breathing of an engine and even achieve positive intake manifold pressure. But with a turbo, resonance is less important since the turbo should start boosting quickly, blowing (literally) the natural intake air patterns to shreds. Not only that, but geometry that would normally be designed into an intake system can actually inhibit good flow from a turbo... witness all the sheetmetal intakes for boosted Hondas and such... in these cases, you generally want a very short intake tract with short runners and a properly sized plenum.
Ultimately, though, on a turbocharged car I think you'd be hard-pressed to truly quantify direct results of adding an inch or two (or even more) to intake length... maybe a little more lag or a little less throttle response, but certainly not so you'd notice. On my '80 900T I installed an intercooler, adding well over a foot to the length of the tract *and* sticking a big heat exchanger in the middle and I could tell no difference in the car's performance. Did the same thing on a friend's early Thunderbird TC (adding the IC from a later car) and no change there either.
-Justin
posted by 66.123.95...
, Sat, 23 Feb 2002 14:58:44 <-- Viewing This Message
No Site Registration is Required to Post - Site Membership is optional (Member Features List), but helps to keep the site online
for all Saabers. If the site helps you, please consider helping the site by becoming a member.
 |
 |
 |
 |
 |
