Bypass exhaust screamer valves

[tzortzViper]

1. You cant cut that cat there. Try and and you will see why, lol

2. You wont gain a thing.

3. How are you planning on opening that wastegate? Wastegates require HIGH exhaust back pressures to open them, something you don't have. You also have zero manifold vacuum at WOT to use to pull it open.

1. Why shouldnt I cut it there? It is 5mm above the cell.

2.I will not gain anything? How can a free flow cat can gain? Please justify.

3. The spring within the wastegate will be removed, and will be working like a double pressure/vacuum actuator (it will be accompanied with an electro-pneumatic 2 way valve). Also, as I said at the beginning, I will steal vacuum off the brake booster ( it always have vacuum because of the check valve)


I will post a scheme with the electric and pneumatic connection .





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[plumcrazy]

sounds juts like this....

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

 

[tucker]

I love it when people ask for advice, and then when facts are thrown at them, they themselves become experts.

 

[shine]

I have electric cutouts on my supercharged Challenger, and on the dyno it actually loses about 3-5 HP with the cutouts open.

I'd be very surprised if you gained any HP at all without specifically tuning the engine for the loss of backpressure.

As for driving with cutouts open, all I can say is, I hope you have earplugs! Yes, it sounds awesome at low RPMs or if you're showing off for short periods of time, but actually driving at highway speeds with them open will give you a headache in a few minutes. I broke one of mine in the open position about 40 miles from my house and I had to take 4 Excedrin by the time I got home.

 

[treesnake]

Like the other have asked,...why?

Are you having some issues with scavanging the cylinders or backpressure?

I could possibly see this helping if you were FI. Being a Gen 4, I know that's not the case.

Oh well, good luck with your project....


Hey Plum. You are on a roll....

 

[shine]

Those electric cutouts I have read that they do not last working for a long time, because the heat easily melts the insulation within the motor that makes the movement of the butterfly.


Secondly, they are quite slow to open and close instantly.


And last, the butterfly cutout compared to the wastegate valves, does not close completely, and especially after extended use.

Electric cutouts last quite a while, they are made for the temps. My problems with mine are from the Y-pipe being welded too dangly, and they hang 2" off the ground. Clearance issues break my cutouts regularly.

As for the amount of time to open and close, you're right, they're not instant, but they are reliable. Mine are less than 5 seconds open to close, which isn't a problem because even while they're in transition, you can hear the exhaust note change. It's nice being able to have them fractionally open too, so that you can just crack them a bit and get really nice sound, or go wide open for the full dragster effect. Don't be so quick to dismiss electric cutouts; they do their job well if you take care of them.

I don't have any dog in the fight over what you're trying to do, but I can vouch for cutouts as an effective way to do the same thing you're trying to achieve, which appears to be the "open header" sound.

Good luck with your project!

 

[tzortzViper]

I have electric cutouts on my supercharged Challenger, and on the dyno it actually loses about 3-5 HP with the cutouts open.

I'd be very surprised if you gained any HP at all without specifically tuning the engine for the loss of backpressure.

As for driving with cutouts open, all I can say is, I hope you have earplugs! Yes, it sounds awesome at low RPMs or if you're showing off for short periods of time, but actually driving at highway speeds with them open will give you a headache in a few minutes. I broke one of mine in the open position about 40 miles from my house and I had to take 4 Excedrin by the time I got home.

Good points, thank you.

I have been reading all over here, that the headers and any other combination with the catbacks upgrades would give improvement only with the Mopar PCM.

Do you believe that the Mopar PCM TEC learning will not help make the necessary adjustments to such a mod?



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[shine]

Do you believe that the Mopar PCM TEC learning will not help make the necessary adjustments to such a mod?

That, I have no idea on, I'm still learning the V-10 ins and outs myself. I know the 6.1 L V-8 PCM will not, even with an aftermarket one.

 

[tzortzViper]

Like the other have asked,...why?

Are you having some issues with scavanging the cylinders or backpressure?

I could possibly see this helping if you were FI. Being a Gen 4, I know that's not the case.

Oh well, good luck with your project....


Hey Plum. You are on a roll....

Thank you for your comments.

As of my initial thinking, I would release all the flow after the headers.
This will propably result to loss of backpressure.

What if I release everything after the cats, or even the resonators?
Would it give any better result?




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[tzortzViper]

That, I have no idea on, I'm still learning the V-10 ins and outs myself. I know the 6.1 L V-8 PCM will not, even with an aftermarket one.

As soon as I have it ready I will retune the PCM with my Starmobile.

I am really too curious to see if it will be any positive or negative difference on the dyno.

Thanks again for the advices.





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[Mopar Steve]

Don't worry about stealing vacuum from the brake booster. Even if you have no brakes everyone will hear you coming.

 

[treesnake]

As soon as I have it ready I will retune the PCM with my Starmobile.

I am really too curious to see if it will be any positive or negative difference on the dyno.

Thanks again for the advices.





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Please post your dyno results before and after.
The results would be interesting. The info would help with the longstanding discussion of the good/bad effects of exhaust mods....

 

[tzortzViper]

Don't worry about stealing vacuum from the brake booster. Even if you have no brakes everyone will hear you coming.

Definetely will hear!
But this time it won't be a bicycle with playing cards in the spokes!





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[tzortzViper]

Please post your dyno results before and after.
The results would be interesting. The info would help with the longstanding discussion of the good/bad effects of exhaust mods....

Sure will.

My only concern is if placing it before the cats, will lose power.

The loss of backpressure will need to be considered.


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[Black Moon]

 

[Catwood]

nope...........

Hey plum, how do you keep a retard in suspense?

 

[Catwood]

Sure will.

My only concern is if placing it before the cats, will lose power.

The loss of backpressure will need to be considered.


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Back pressure does not create power.

Washing out the O2s with fresh air is a problem.

 

[tzortzViper]

Back pressure does not create power.

Washing out the O2s with fresh air is a problem.

You mean the pre-cat Lamda sensors?





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[Simms]

????????????????????????

 

[MTGTS]

I wish thread was over on the alley.

 

[tzortzViper]

Looks like that I did not get any feedback from anyone here with proven results of a benefit of the open headers setup.


As of my research the backpressure "could" be beneficial only at the low rpm's where the valve overlapping could help synchronise with the harmonics of the backpressure.


Since I am using that exhaust valve, I could open the headers only at around +4,500rpm when in WOT.


In similar applications with cutouts, the results were positive ONLY with a properly tuned engine. Otherwise, a lower performance would occur because of the leaner mixture.


Now my question is, would the MOPAR pcm adjust to that open headers setup?


I would appreciate to get serious comments and not the kind of a bicycle with playing cards in the spokes.






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[plumcrazy]

thats a lot of effort for something to sound stupid and give maybe 4 hp if youre lucky

there has to be better ways for you to spend your money on this car.

 

[tzortzViper]

thats a lot of effort for something to sound stupid and give maybe 4 hp if youre lucky

there has to be better ways for you to spend your money on this car.

So, you mean that any combination of exhaust/cat upgrade would not benefit also?






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[plumcrazy]

no, im just talking about your ******** screamer valve. other exhaust mods are worth it to a point on a NA viper. headers being the best with a 3" cat back

for sound alone the other mods are certainly worth it though

 

[tzortzViper]

no, im just talking about your ******** screamer valve. other exhaust mods are worth it to a point on a NA viper. headers being the best with a 3" cat back

for sound alone the other mods are certainly worth it though

Looks like you dont understand what I am asking...

Ferrari and Porsche use similar bypass system at the high RPM range to gain those extra hp.

Please Plum$$, dont intervene since you dont have anything to answer to the question of the scavenging or open headers gain.

Anyone that has any experience please comment...




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[plumcrazy]

ferrari and porsche run at a HIGH RPM, vipers dont

and now im gonna post more often in this thread

 

[RichieSRT10]

tzortsViper I was reading last month how several members on ViperAlley did this mod with some incredible results. Good Luck in your quest for more power.

 

[Mopar Steve]

tzortsViper I was reading last month how several members on ViperAlley did this mod with some incredible results. Good Luck in your quest for more power.

Yes, I agree, post this on ViperAlley. I'm sure they can give you some more "feedback".

PS, I have built several race cars (most recently building a 8 second Daytona) I know just a little about making HP. This is an exercise in futility. Will you make any more power? Maybe a couple, will it need to be tuned to make the power? Yep!, Is it worth the effort? Nope.

A high flow cat, and good cat back system, engineered to be correct for your vehicle will out perform seat of the pants design. Have fun, it's your car do anything you want.

 

[MarcRoth]

One coment " assinine" Why;

 

[Dom426h]

Which one of these best describes your goal:

1. Have the cutouts always open at a specific RPM and tune according to this. (i assume this is what ZO6/ferrari/porsche do...)(only downside i see to this on your Gen4 is that it could get annoying having those things always popping open making an obnoxious sound as where the ZO6/ferrari/porsche systems are "tuned" to sound good.)

2. Have the cutouts open on demand of the operator while leaving the "cutout tune" running on the car. (this could cause the car to run poorly with a non-optimal A/F ratio when the cutouts are Not open)

3. Have the cutouts open on demand of the operator without a tune. (this could cause the car to run poorly with a non-optimal A/F ratio when the cutouts Are open)

4. Have the cutouts open on demand of the operator while simutaniusly being able to switch the tune on-demand to compensate for the cutout.
This would be the best case senereo IMO, However i do not think it is possible to change the Viper's tune on the fly.

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I personally think that a better approach to making power and getting a better sound from your viper would be to do headers, full exhaust system, &Tune. These mods are proven to make over 50hp&tq. so use that as a reference when you get to test out your cutout mod on the dyno.