Novel feature on a new Dodge Challenger!

[XfireZ51]

If you watch this vid, you'll see that a message on the display of the Hellcat
saying "Red Key In Use"
Nasty sounding exhaust too.
http://youtu.be/7r1bOZd7T8Q

[Bob Eyres]

Sounds great. In fact, it may be the nastiest sounding "factory" exhaust I've heard.
I'm not a Mopar guy, but that's a real 21st century muscle car.


I'l take mine in matte, (hot rod), black.

[weldbead]

the key is a way to switch the secondary throttle system on/off..,but the system itself is just there to produce baloney numbers for the epa, right? an expensive failureprone box of parts that impedes airflow ? or have i missed something?isnt the secondary system another trick like the AIR system which the engine would be better off without?

[Hog]

Originally Posted by weldbead

the key is a way to switch the secondary throttle system on/off..,but the system itself is just there to produce baloney numbers for the epa, right? an expensive failureprone box of parts that impedes airflow ? or have i missed something?isnt the secondary system another trick like the AIR system which the engine would be better off without?

The key may be there to play with EPA numbers, but the Port Throttles are there retain low rpm torque as well as to provide excellent high rpm power numbers.
Graham has posted dyno printouts with both the Port Throttles Open and Closed. Marked difference. The LT5 system is akin to the effects that variable cam phasing accomplishes in the GEN 4/5 SBC. Just remember that the LT5 is 80's technology and at the time the Port Throttle and moreso the dual injector/cylinder logic and ECM calibration were technological breakthroughs in engine management.

[weldbead]

thank you hog i didnt know about the low end torque advantage

[efnfast]

Anybody got a link to Graham's dyno sheet's? I also didn't know that yanking the secondaries would impact torque.

[Paul Workman]

Originally Posted by efnfast

Anybody got a link to Graham's dyno sheet's? I also didn't know that yanking the secondaries would impact torque.

I saw those sheets - some time ago, but a couple things struck me:

Most of the difference was at relatively low rpm and load. However, you don't have to be very deep into the throttle or rmp and the secondaries open anyway - mitigating any low-end torque advantage when they do open.

And, for a fully-ported LT5 the WOT low end torque is substantially above stock.

Case in point, my stock LT5 vs. after the "500" package (sans secondaries) was in effect:



Some commented on this during the recent Mountain Run.

[Hog]

Originally Posted by efnfast

Anybody got a link to Graham's dyno sheet's? I also didn't know that yanking the secondaries would impact torque.

Here is the dyno sheet that Graham Behan posted in reference to the action of the Port Throttles being open for a run and closed for another.



From this thread.
http://zr1.net/forum/showthread.php?t=19823
You can see the torque advantage of 30 lb/ft at 2600rpm for the closed Port throttles, but at just 4500rpm, the Closed Port Throttles give up roughly 45hp at 4500rpm to the open Port Throttles. At this same 4500rpm, the CLosed Port Throttles are all done and power falls off abruptly after than as airflow is choked off It should be noted that the low rpm torque difference between the Open vs. Closed Port throttles would increase if the dyno run was started at a lower rpm.

The Open Port throttles continue to build another roughly 125hp from 4500rpm to their peak of 469hp at 6600rpm or so.

All totalled the Open Port Throttles are worth an extra 160hp vs the Closed Port Throttles.(469 vs 309hp) and an extra 428 lb/ft of torque (417 lb/ft vs 389 lb/ft) when the entire vastness of the LT5 rpm range is considered..



The 1992-1995 Vortec 4.3 V6 that was used in the Highride ZR2 and S-10 SS and others that had engine VIN "W", used a variable geometry intake manifold, where there was a plate that blocked off part of the intake to promote low rpm torque without sacrificing upper rpm power. There is a parameter in the ECM calibration that uses engine RPM to activate the mechanics of the intake.