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Its amazing how all of these reasons for the design creep into these automotive forums.. As a GM engineer it gives me much entertainment. Its always fun to see someone offered something they heard from a guy who dated a girl whos father worked at a Texaco gas station back in the 60's and got the information from him.
No disrespect to any especially the guy who was part of a 4 man team of windshield washers, oil level checkers, tire pressure checkers, and gas pumpers, back in the sixties.
If this is regarding the coupler, which is correct? Just for flex, or also to introduce turbulence?
Those of you concerned about rain water intrusion with the vararam, it just isn't a factor. I ran this setup in a torrential Texas thunderstorm with no issues. If this didn't suck up water, nothing will. (granted I did NOT drive through standing water, but that's because I like my car)
When GM was programming the C5 they were using the flex coupler and used and Adaptive Strategy (AS) that based all the calculations between the MAF and the TB. Using anything else will alter the engine performance, however every engine will act differently and some will not notice any change and some will. However going to a smooth (Silicone) coupler will increase you chance of being out of range for your engine to re-calibrate and adjust. Most of my knowledge came from fellow club members. In the early 90's, GM acquired a company that was know for its programming skills and they heavily influenced the different computers in the C5. Several of those members and a few GM engineers belonged to our local club and were heavy autocrossers, HPDE, W2W, etc. I still have a few emails from them about the PCM,BCM,etc systems and how they worked. When John Cafaro (the C5's chief designer) and Henry Iovino's retired for GM they had a few development books on the C5, a club member obtained a copy and I was later able getthe 12 Volume development books on the C5 dating from around 1991 to 2004.
MAF reads airflow. Making the intake tract more efficient means more airflow. MAF will read that and adjust accordingly in open loop. When you go WOT closed loop kicks in. Factory programming is very rich and safe. Changing the airbox and coupler does not create enough new airlfow to create issue with the OEM closed loop tuning.
You might be mistaking the C6/C7 PCM vs the C5. When the C5 was developed they used a 16 bit chip for the PCM and most of the data was that was used was non-programmable Adaptive Strategy. An excerpt from the #2 person on the development staff
"A cylinder can only hold so much volume and that is with a mix of air and fuel which is only in grams, yet the intake manifold holds quarts of air and the intake runners can only allow as much air mass as the runner size increasing MAF, air bridge or TB cannot make the runners of cylinders flow or pack in more volume than their size is." " Larger airflow requires what GM did with the C6/C7 and that is a new faster PCM with A.S software to make use of the airflow to help response times and not to make more HP"
A MAF will read airflow but the AS determines the calibration changes the MAF can make. If the air flow to the MAF is too large a volume it will actually slow down the air passing thru the MAF and cause lean condition. This will affect the trims and the PCM can only correct within a +/-25 value. On the later models the faster chipsets were able to react faster and make the corrections in a shorter time span
You know, I think we all appreciate when all the techno wizards tell us all the science and behind the scenes info. However, in most cases there is no final layman's determination of what all they just said means. I doubt I am alone in trying to figure out what the wizards are saying. A simple "use this" or "don't use this", or, "do this" or "don't do this" would be real helpful.
Add an intake all you want... the OEM tune can handle it just fine and not go remotely lean. Add headers and it's a good idea to get a revised tune just to keep the catalyst efficiency MIL from coming on.
I love my Hurricane CAI. It uses an awesome AFE filter, water doesn't get in and it added to that hungry growl I get on acceleration! : ) I notice a lot of guys don't like it though...not sure why.
Are there any major gains to be had by using a cut down radiator and fixed diameter tubing into the MAF inlet? Aside from being incremental prep work toward a supercharger, that is.
Just don'r expect much more power. I've never seen CAI manufacturers post actual before and after (no other mods), dyno pulls in support of their products. I guess there's a reason for that.....
Just don'r expect much more power. I've never seen CAI manufacturers post actual before and after (no other mods), dyno pulls in support of their products. I guess there's a reason for that.....
Haven't looked at their ads recently, but thought most do say 15hp, or *up to 20HP gain.
Surely some forum members have done dynos before and after. I didn't before, after my Halltech was 325.8 RWHP & 333.7 RWTQ
Just don'r expect much more power. I've never seen CAI manufacturers post actual before and after (no other mods), dyno pulls in support of their products. I guess there's a reason for that.....
We've driven our 04 C5 6speed vert in absolutely pouring, torrential, cow peeing on a flat rock rains, with the Vararam B1 CAI and not had any issues...
I chose to stick with the original bottom-feeder design of the C5 and installed a Callaway Honker CAI. I also added a set of perforated fog light housings to improve the air flow. I'm not sure how much they help, but they were given to me new by a friend who never installed them before trading into a C6.
02-12-2019, 03:01 PM
