Viper engine firing order - 2 at once

[Jason Doucette]

I just watched a TV show on the topic of exhausts. It explained that the noise of the Viper is something that owners often complain about. It explained that while someone may expect the V-10 to sound like a McLaren, it doesn't because of the firing order of the engine; two are fired at the same time. I have a few questions:

1. Could the firing order be changed so that all 10 cylinders fire at times evenly spaced apart to improve the sound?

2. I think the answer to #1 is obvious - anything can be done with enough money - and it should certainly improve the sound. So, perhaps a more proper question is: What would be involved in changing the firing order?

3. Would it hurt the engine's performance? I would have assumed an engine that did not fire two cylinders at the same time would perform better (on the hypothesis that it would produce a more consistent force).

Any ideas or thoughts?

[Samurai75007]

Ill ask the viper tech at work today...

[Jason Doucette]

Thanks for making the inquiry, Samurai75007. Let me know what they tell you.

[Jason Doucette]

I just found a good thread on the explanation of the sound of the Viper on ViperClub.org:
The Vipers' Double-Piston Firing Sequence
(I apologize if I am not allowed to link to other forums, but this thread has good information)

[VenomInMyVeins]

A large part of the problem (which was fixed in the srt-10) was that on the cars with side pipes you were hearing just 5 cylinders which made it sound like a goddamned UPS truck when it idled. But on the srt-10 (I thought this was a great idea) after coming out of the headers the pipes go into a cat and silencer, and then cross underneathe the car. the pipes follow each other for the width of the car and cross in the center. This creates resonation between the two pipes and the sound waves mix enough that the sound is all 10 cylinders out both sides. The result is an amazing sound that you can only get out of the snake's 8.3L v10.

[VenomInMyVeins]

Check COchevySS's "Viper Exhaust" post for a more detailed explanation for anyone that's interested in this post.

[Jason Doucette]

I have a copy of Motor Trend, I believe, that shows a cut out of the insides of the SRT-10, including a specific picture of just the exhausts. The H-connector was a very good idea. After listening to the sounds of an old RT/10 with the side exhausts, I realize that they do sound horrible. I would have thought the rear exhausts of the Gen-2 Vipers would solve the problem (it did, but not as well as I imagined), but apparently, people are using H-connectors even in the Gen-2 model to improve the sound.

One thing I do not understand is that the new SRT-10 still has the same firing order as the older models, thus it should sound no different than the Gen-2 models. Apparently they have a good understanding of sound and resonance, and they implemented a better solution, since the SRT-10 sounds great. I still think it'd be even better with evenly spaced firing orders...

[VenomInMyVeins]

Performance, or exhaust sound? ;-) jk.. umm.. I'm not exactly sure, but I believe that's impossible with any v-10 design. We have a v10 7.5 F350, and we looked at true dual exhaust, but after hearing the examples we shyed away immediately. A v-10 just isn't able to be set up with firing times that are in an order condusive to exhaust sound. I believe that you'd be putting stress on the crankshaft in uneven places if you put the firing order with equal spacing... if there's a techie that knows anything about firing sequences please pipe up though.. I'm not for sure on this

[Samurai75007]

yes you are right that the fireing order is the way it is BC of the stress on the crank. when the sound of only five is being herd out of one side its crap compared to the two pipes so close together out the back that makes the sound seem to be better. the SRT-10's sownd so sweet with them beeing dumped into one tube then back out. with them apart and never mixing sound it sownds like crap.

[VenomInMyVeins]

Samurai... I believe you mis understood.. the exhaust gases do not get "dumped into one tube" they pass through their respective tubes, but they follow each other the width of the car. I studied quite a bit of physics... and i see the genious in it that the sound of each 5 on each side is blended together because of the resonance between the two pipes that pass alongside each other. they never go "into one tube" as you said. if they went into one tube there would be a lot of back pressure because the exhaust from each is going in a diff direction

[Samurai75007]

In the viper truck thay do go into one tube.