Gen IV Header Gains

[Stealth]

After reviewing the various VCA and other threads and other information on Gen IV Headers and High-Flow Cats, I am just a bit curious about the claimed gains.

The new ACR-X provides a good example. Dodge states that the ACR-X has 640 crank hp/585 crank trq. on 91 octane and 640 crank hp/605 crank trq. on 93 octane. This SAE Net with the Venom Controller and NO CATS and measured at the crank which of course is less than rear wheel measurements.

What I can't understand is how a Gen IV Viper with high-flow Cats or stock Cats and either stock mufflers, belanger mufflers or Corsa mufflers can produce the 40-50 SAE rwhp and rwtrq. gains reported? Those numbers seem a bit optimistic to me unless the "before" dyno figures are unnaturally depressed.

Any ideas?

Thanks!

 

[RTTTTed]

I believe the gains were for Venom controller, headers and exhaust ...

Something else taht could make a difference is that a Mustang Dyno shows numbers that are equivalent to bhp numbers. Washington had a dyno day and the numbers were really close to bhp Gen 2s were about 450 and Gen 3 were about 497. You have to look up the thread if you want more info - it's in the Washington Regional forum.

Ted

 

[TrackAire]

Hi Stealth,

I just put on the ACR-X headers, high flow cat and the stock muffler two weeks ago. Other than this performance upgrade, my car is stock for the time being. Next up will be the Mopar computer and 3.55 gears with a Giken.

Regarding hp on the dyno's....I really think it all has to be taken with a grain of salt. Dyno's can be made to tell all sorts of numbers (even on the same day, same dyno, same dyno operator) if someone wants to screw with the numbers. I think a dyno is more useful for tuning than proving what the absolute hp is (just my opinion).

Here is about the only "dyno" I would trust....something like trap speed at the quarter mile, 60 mph to 160 mph pulls, etc (and even these will change due to weather, temps, etc). I'm going to ask for some advice on getting high trap speeds with little regard for ET's. I really don't care if my car runs 10's or 12's, it's the trap speed that tells the hp story. ET's are way too dependent on launch, tires, suspension setup, driver skill, track prep, etc. I'd feel like a king if I could run 12 second ET's at 135 mph. My biggest problem now is not being able to run at NHRA type bracket events because stock I've run an 11.6 not knowing what I'm doing. Anything below 11.5 and I've got to have a six point cage, etc. I already have too much trouble getting my old body in and out of the car. If I can add another 2 or 3 mph to my trap speed at Infineon, then I'll know I'm making more usable power.

Regarding choosing a header design, we're pretty fortunate to have at least 3 high quality manufacturers to choose from. I really think you're splitting hairs if your worried about squeaking out 10 more hp with either of the systems available.

My decision came down to the following:

-Had to be stainless steel construction. Every new car out now has stainless steel manifolds and exhausts from the factory. I really think it is a better system for longevity.

-Higher temp version of the Jet Hot coating option if you want them coated. I went with black and it looks fantastic. Once I saw how great the headers looked, I sent in my stock muffler to my local coater and he coated the stock mufflers with a product called "Black Velvet". He does a lot of Harley Davidson exhausts with this setup. It came out fantastic but I can't vouch for the longevity since this is my first exposure to it. Jet Hot has a great reputation, we'll see how the Black Velvet holds up. I think Bad Boyzz Garage took some pics of the setup all black, I'm sure he'll post them up soon.

-I chose the 5 into 1 design with internal spike. There is more to the header design that preceived flow....pulsation and scavaging have a lot to do with how well the car performs across the entire usable range. Our Gen IV's really breath well at the higher rpms, I feel that 5 into 1 design really works with the new VVT and head design we now have.

-SRT chose this header for the ACR-X...I also got to watch a video of the dyno run at Arrow Racing with the SRT guys around. As they say, a picture is worth a thousand words. Our ACR-X distributor is in our NorCal VCA club, so we got to look and handle the headers and cats before anybody else. Quality and design looked great.

Now that they are installed, they sound great....also, I do feel more power, but I haven't gotten on the track as of yet. Second gear pulls above 60 mph do provide more wheelspin than stock

There is a video of my car in the NorCal section of the VCA showing the cars heading to Infineon for last weeks Historics. I'm in the red Viper flashing my lights at the camera, you can hear what my exhaust sounds like as I rev the engine while going by.

So far I'm very happy with the ACR-X headers, very smooth engine feel and a very refined sound. I watched the install and have to admit, everything bolted together great. I did go with Bad Boyzz Garage ARP installation kit..I highly recommend it. The ARP bolt quality and tolerances is top shelf. I wanted the highest quality bolts available in case I have to remove the headers 4 years from now for smog, etc.

Now I'm like a South American dictator..I've tasted the power and I want more!! The controller and new gears should make the car even faster

Cheers,
George

 

[Stealth]

TrackAire:

Thanks for the interesting feedback. I have followed your other posts as well and they are always informative.

My point is quite simply that the gains claimed on the various dynos appear to be overstated based on the smaller SAE-certified gains of the ACR-X which has no CATS and other advantages over a stock Gen IV. I am guessing actual gains with Headers, high-flow Cats and aftermarket exhaust on a stock Gen IV is closer to 25rwhp and 20rwtrq. If this can be achieved without drone and Check Engine Lights while passing the smog sniffer test, then it may still make sense.

Ultimately, time will tell as more people mod their Gen IVs.

 

[Camfab]

Your not comparing apples to apples here. The ACR-X engine is NOT the same as a stock engine. The ACR-X engine uses forged pistons. Ther stock viper with it's eutectic pistons may actually produce more power in a similar configuration. Remember that the ACR-X is built for racing durabillity and not emissions compliance.

 

[TrackAire]

Stealth,

I would say that a complete Gen IV header and exhaust system would be worth at least 40 to 50 rear wheel horsepower. But remember, you're already dealing with 600 crank hp, so as the numbers get higher, you need a pretty big jump in added power over stock to say "wow, this thing is way faster".

I've read reviews of the Mopar controller helping some dyno numbers and not helping others. For me the controller is worth it just to get rid of the stupid skip shift issue. When stuck in stop and go driving it can be a real PIA..not to mention unsafe if you really do need a fast burst of acceleration buy you're now stuck in 4th gear when your mind was thinking second gear. So far with the ACR-X headers, no check engine light, but I've only got about 250 miles on the system. I don't know how many on off cycles I'd have to run before I might get one. The controller should take care of a check engine light in case I get one (IMO). The controller does help make the car sound smoother, plus lets the engine rev up faster and more importantly let the engine rev down faster. This should help drivability, especially with compression braking.

After the controller and 3.55 gears, I'm going to try the modified intake manifold for good measure. If someone could also modify the pcm I honestly feel that the Gen IV could put out an easy 700 hp at the crank without ever opening up the motor. Pretty crazy if you really thing about it.

I don't know if you saw my first impression thread of the header in the suppliers section, but my coupe droned pretty bad at 65 mph stock. It drones much less with the ACR-X headers at 70 mph. I'm hoping that the 3.55 gear change will raise the rpms into the "quiet" range while cruising in 5th gear. I usually drive between 65 mph and 70 mph when cruising on the hiway. Less drone makes for less fatigue on long trips.

As far as dyno numbers, I think the best bang for your testing buck is to pick up an onboard unit like a G-Tech Pro. With this unit, you can consistently check your hp progress and download your results on a lap top for real world results.

Cheers,
George

 

[Stealth]

Thanks again for the information!

Good point about the different pistons, etc. camfab, but I doubt that this explains the different power gains with headers between the actual ACR-X SAE numbers and the informal claims on various dynojet dynoes relating to modification of stock Gen IV car.

With respect to header drone, I do not want to "drive around" the drone rpms, but instead I would like to eliminate or minimize the drone. Header drone usually is noticeable in low rpm crusing on gentle throttle roll-ons and when you lug the engine at highway crusing speeds. Currently I have only the Arrow ported intake, stock cats and corsa catback exhaust and the sound is great and there is no drone.

I do not plan to add the venom or mopar controller. I believe this computer offers very little, if any, power gains on a stock car with headers and 91 octane (it does raise the rev limiter a bit I believe).

Thanks again for the information!

 

[KenricGTS]

When I get my ACR I am getting the ACRX headers coated stock side exhaust, Mopar ECU, Arrow ported lower intake. And lowering the car. Hopefully I will get 600 at the tires. What about ported heads? Anyone do this?

 

[plumcrazy]

get a call into lou bellanger and see what he says. id trust lou!

 

[SNKEBIT]

[media]http://www.youtube.com/watch?v=6K1jt143ddw[/media]
April 09, 2009 — '09 Dodge Viper pulls 585 rwhp and 565 rwtq. Only modifications are M&M headers and a home built exhaust system.

[media]http://www.youtube.com/watch?v=1ppH5C9d4Bc[/media]


Awesome headers!!!! M&M Performance Home--Viper performance exhaust headers

 

[Coloviper]

3.55 rear gears and Fidanza lightweight flywheel got rid of the vast majority of drone on my 06' Viper with full Bellanger exhaust. Low RPM and highway cruising speeds are almost non-noticeable now for drone.

Like you, I am skeptical of some of the gains. I have not put mine on the dyno to see where it might be now. I really don't care as my ass if the only dyno that counts. In my situation, my ass is telling me I really woke the car up and have seen a pretty good improvement.

On these newer cars, cold air intakes and full exhaust system upgrades are going to make a pretty big difference on almost any new vehicle out there, so if you are on the fence, I would say go for it. My only comment is that the Bellanger set-up is made to comply with a 50 state EPA compliance where as the ACRX is designed for off-road racing. That is not to say the ACRX is not going to pass emissions or not throw CELs, but I am just saying that the two were designed for different applications. Not sure the cost differences but my full Bellanger set-up was pretty expensive but worth every dollar I paid. Over 2500 miles now, no CELs and passed strict rolling dyno CO emissions with flying colors.

Wish you the best with what you decide to do. Mine, I also had the side tips dipped in Black Jet-Hot coating so it looks factory. No one even knows it is on, until I start the car up. You can definitely hear it.

 

[CCBrian]

One thing to watch for is doing a baseline vs improvement-the numbers don't lie. See the link below for my car. George has ridden in my car on the track and can tell you how the car pulls.There was a very noticeable difference before and after. Any of the headers out will work wonders-while I have the Belanger- I really do like the sound coming from the BadBoyzz headers that George has-much rawer sound-and would seriously consider them as an option. In fact on a gen 3 they sound much like my Comp Coupe does. I used the stock mufflers/hi-flow cats on our ACR, and have NO droaning sound at any speed. Whatever gain you might get from different muffles is nominal but you loose your sanity on a long drive. I have a great setup here. Thanks DC Performance and Dan.

http://forums.viperclub.org/performance-modifications/623294-acr-performance-testing.html

 

[Boxer12]

The engine designer (Dick Winkler) told me personally that there is closer to 20% drivetrain loss in a Viper, than the 10-15% that lots of guys assume for HP numbers. My car with Belanger racing headers and hi-flow cats, Mopar controller and K&N filter pulled 568 rwhp on a Dynojet at 500 mi on the odometer. Dick said that my motor is probably very close to 680 hp at the crank. (Maybe he is biased like the father of a child, idk. Take it for what it's worth.) Dynojet will show lower numbers than a Mustang.

I can say this without a doubt, the Belanger setup that I have is definately LOUDER than the ACR-X setup. (I have spent 5 track days around both cars.) The Belanger is said to be designed to have more grunt in the lower end than the ACR-X header, which is said to have a bit more ultimate HP. Since the ACR-X is a spec series, it wouldn't matter to SRT which performance dynamic the cars had, although higher HP numbers tend to sell cars, don't they! I would have to drive both cars to tell you which I would prefer on any given track. Most tracks would probably benefit from the lower grunt. Just my 2c. as a road course guy.

 

[redtanrt10]

Stealth,

Below are the results from the July 09 Dyno Day @ DC Performance.

2 stock Gen IV's made around 508-509 HP.

3 Gen IV's w/belangers, ECU, hi-flow cats and belanger/corsa or stock mufflers made between
545hp to 565HP. A 4th made 540 hp and this viper had stock exhaust including stock cats, and 3:55 gears which lower the numbers compared to 3:07's. The 545hp viper is Dan's (Viper X) and 3 months later when he pulled the intake off there was alot of oil which probably impacted his hp by 5 or more.

The belangers and exhaust make a real 40 rwhp and the ECU helps it pick up another 5-10hp (along with a number of other benefits).

At that event I made 554hp. I went to Dan's a couple of months ago and had the octane at 94 plus (vs. 93 last time). My viper made 563 then after Dan did the ported intake it made 580hp.

We were at Spring Mountain last weekend. I can tell you that in the long straights my car pulls noticibly against stock gen IV's (including ACR's)

Mike

--------------------------------------------------------------------------------------------------------
DC Dyno Day Post

http://forums.viperclub.org/srt10-s...5-4th-annual-viper-club-dyno-day-wrap-up.html


Great people, good weather, and better-than-average BBQing by DC's own Tony Parr made for a very successful 4th Annual Viper Club Dyno Day @ DC Performance and we'd like to thank everyone who helped make it such a special day.

Name: HP / TQ
Anhtuan Pham: 580.70 / 543.70 (Gen 3) - Headers, cam, intake manifold, 355 gears, heads (Stage 3 by DC Performance)
Sean Casey: 550.14 / 532.62 (Gen 4) - Headers, ECU upgrade, 333 gears
Eddie Arguelles: 509.23 / 473.69 (Gen 4) - Stock
Randy Tribolet: 409.43 / 445.01 (Gen 2) - Roller, rockers, headers
Dan Everts: 545.29 / 519.09 (Gen 4) 0 Headers, ECU upgrade
Angel Calderon: 432.08 / 452.32 (Gen 3) - Stock
Mike Buckingham: 553.45 / 531.20 (Gen 4) - Headers, ECU upgrade
Mike Sinkinson: 431.68 / 446.96 (Gen 3) - Corsa exhaust
Lawrence Kraus: 507.73 / 482.69 (Gen 4) - Stock
Eric Dedominc: 629.77 / 656.13 (Gen 2) - Supercharged
Siam Kobi: 564.58 / 538.41 (Gen 4) - Headers, ECU upgrade
Bruce Li: 540.08 / 516.55 (Gen 4) - Headers, ECU upgrade, 355 gears
Dave Sweeney: 570.05 / 544.88 (Gen 2) - Supercharged
Hugh Hoard: 519.01 / 498.61 (ZR1 Corvette) - Stock
Rick Hollis: 850.38 / 809.82 (Gen 2) - Supercharged
Ken Alker: 422.28 / 464.38 (Gen 2) - Headers, catback, 355 gears
Jose Avila: 379.42 / 433.69 (Gen 2) - Stock
Bill OConnell: 397.82 / 433.79 (Gen 2) - Stock
Gary Gawlas: 567.17 / 517.96 (Mustang GT500 KR)
Mark Rhodes: 341.67 / 409.05 (Gen 1) - Stock

Best Stock: Eddie Arguelles
Best Modified: Anhtuan Pham
Top Eliminator: Rick Hollis

We are in the process of editing a video and some pictures and will have them posted soon...
__________________
DC Performance, Marketing
Blog: brandonatdc.blogspot.com
www.DCPerformance.com

 

[TrackAire]

Coloviper,

If you live in a State that has sniffer only tests, then I'd bet most systems will pass if running the stock controller and cats with O2 sensors. In the more smog **** States, unless the header system has a CARB type number on it, it will not pass the visual part of the smog test, regardless of how clean the car runs. As far as I know, nobody has a CARB approved header for the GEN IV.

Cheers,
George

 

[Stealth]

Thanks for the excellentI information!

Hopefully I will be able to attend the next DC Performance Dyno Day!

 

[Coloviper]

TrackAire;

Colorado Emissions Testing is right up there, right behind Cali which is the worst. Not sure about your visual aspect but they verified that I have cats in place, etc. then ran it on the start-up test, rolling dyno, fuel tank pressurization tests, and hooked up the state computer to it, etc. I posted in a thread a while back, my full emissions results. The car with full Bellanger set-up was cleaner than a brand new Shelby GT-500. You are right that there is no CARB number on the headers, but mayeb that is just a Cali visual requirement.

Now I coated the tips of my Bellangers Jet Hot Black so they look factory. Regardless, it passed just fine. Considering what you go through here in Colorado as I just explained, I am not sure it can get much more demanding or obtrusive.

 

[KenricGTS]

Anyone have Dyno numbers for the ACRX header? All I see is the Balanger.

 

[Boxer12]

The first ACR-X's were just delivered last weekend.

 

[mbccenter]

Anyone have Dyno numbers for the ACRX header? All I see is the Balanger.

If you don't have them on the same dyno at the same day the data is not comparable at all. There is alot more to gain then just top hp numbers. We have done many installs on the gen 4 and there is a huge difference in the feeling of the car. It revs a lot faster in the lower rpm range while pulling harder all the way to the top. I have driven gen 4's with other header systems one them that also do well but just seem to fall short in the lower RPM range. They all do very well on the Gen 4's and are a must if you own one.

 

[BAD BOYZZ GARAGE]

Here's the first dyno run of the ACRX-Track Headers on the Chrysler's Brass ( Mr. Winkles & Staff ) daily driver, test Viper.

Track Headers:
1 3/4" long tube
5 to 1 merge collector
2.5" finished pipe
stock muffler
delete cats

The gen 4 engine with it's VVT camshaft & high flow heads responds better to the long tube, Burns type merge collector header, than the prior systems. You know Chrysler has the Track Snake dialed in.

Very respectable gains throughout the entire rpm range & this was a conservative run, not all the way to redline gentleman.

=DISTRIBUTORS OF POWER=

Thanks,
Toddy

 

[Bill Pemberton Woodhouse]

California Air Resources Board ( CARB ) numbers , I believe, are only required in California , and they should not affect your vehicle in Colorado. It is basically just a number stamped on the aftermarket product saying it complies.

 

[RTTTTed]

Stealth,

Below are the results from the July 09 Dyno Day @ DC Performance.

2 stock Gen IV's made around 508-509 HP.

3 Gen IV's w/belangers, ECU, hi-flow cats and belanger/corsa or stock mufflers made between
545hp to 565HP. A 4th made 540 hp and this viper had stock exhaust including stock cats, and 3:55 gears which lower the numbers compared to 3:07's. The 545hp viper is Dan's (Viper X) and 3 months later when he pulled the intake off there was alot of oil which probably impacted his hp by 5 or more.
exhaust


Eric Dedominc: 629.77 / 656.13 (Gen 2) - Supercharged
Dave Sweeney: 570.05 / 544.88 (Gen 2) - Supercharged
Hugh Hoard: 519.01 / 498.61 (ZR1 Corvette) - Stock
Rick Hollis: 850.38 / 809.82 (Gen 2) - Supercharged
Gary Gawlas: 567.17 / 517.96 (Mustang GT500 KR)


We are in the process of editing a video and some pictures and will have them posted soon...
__________________
DC Performance, Marketing
Blog: brandonatdc.blogspot.com
www.DCPerformance.com

I just have to say, "What's with the 498rwhp out of the ZR1? Would that be a normal representative number for a 640bhp vette?

Great post.

Ted

 

[Simms]

A little off topic, but does the ACRX still have the cam-in-cam design? When the press first came out about the ACRX someone reported it had a solid cam and a non-venom controller.

What's the true story?

 

[redtanrt10]

I just have to say, "What's with the 498rwhp out of the ZR1? Would that be a normal representative number for a 640bhp vette?

Great post.

Ted

Ted,

The 498 is the trq, 519rwhp for the ZR-1.

2 stock gen IV's were 508-509 rwhp and 474-483 trq.

Vette was a 2K mi car. Everyone was a little surprised

The extra 40 hp at the flywheel made only 10 rwhp over the 600 hp Gen IV's.

Mike