Extrude Hone Exhaust Manifolds

[WyoSRT]

I am considering the Stage 2 Heads/Cam upgrade on my 2015 Viper which is presently stock with the exception of the Arrows Venom PCM. I am not a fan of installing headers to complement the upgrade. Does anyone have experience with having Viper exhaust manifolds extrude honed? I realize that extrude honing will not provide the same exhaust flow increase as a set of headers but it may be an acceptable alternative in conjunction with high flow cats. The Viper is used street only. Thanks in advance for your expertise.

[99RT10]

That would be the definition of a waste of money. Extrude honing will do very little to nothing in regards to performance.

[Vegaskid]

Agree with 99RT10..why not change the headers?

[J TNT]

I recall someone saying that you are only giving up 20 hp at the wheel with stock manifolds.....
And pick up 12 hp by removing the secondary cat...

[SRT_BluByU]

Stock viper manifolds I believe are fabricated/welded and are not cast units. If that’s true it doesn’t seem like you’d pick up much if any horsepower..

[WyoSRT]

Stock viper manifolds I believe are fabricated/welded and are not cast units. If that’s true it doesn’t seem like you’d pick up much if any horsepower..

That seems to be correct, SRT_BluByU; according to Allpar the manifolds are a stainless steel tube-in-shell design. Extrude honing is not an option. Thanks!

[SRT_BluByU]

they flow quite well.. unless your going all in looking for every hp (9L stroker h/c twin turbo) imho the tradeoffs for the headers arent worth it.. its not like the 70s-90s where headers were an easy 50hp for $99 bucks...

[simon455]

Stock manifolds do a much better job controlling underhood temperatures. Gotta ask yourself what are the intentions of the car, is it going to spend most of the time on the track or on the street, live out in the country or busy city? What rpm will the car see most of the time? Headers do help with more power definetly, most beneficial at certain rpm range, usually closer to the top end, is the car going to spend much time there?

[Jack B]

Stock viper manifolds I believe are fabricated/welded and are not cast units. If that’s true it doesn’t seem like you’d pick up much if any horsepower..

Exactly

[WyoSRT]

Underhood temps and having to insulate all the ancillaries around the headers is my reason to keep the manifolds. But would I be severely compromising benefits of the H/C upgrade without headers?

[99RT10]

Underhood temps and having to insulate all the ancillaries around the headers is my reason to keep the manifolds. But would I be severely compromising benefits of the H/C upgrade without headers?

I would bet the difference of Stock manifolds vs. headers on a heads/cam car is going to be about 30-35RWHP.

[ViperGeorge]

Duplicate post deleted.

[ViperGeorge]

Personally I'm with WyoSRT on this. My experience with headers on the Gen 5 was not positive. Melted wire harnesses, melted fuse box, pulled timing because of engine heat, etc. If I could use stock manifolds on a H/C or a 9L and still significant gain RWHP over the stock 8.4 that could entice me to pull the switch. We need Prefix to chime in and tell us if they ever tested those packages with OEM exhaust and what the gains/losses were.

[Jack B]

There is a lot of push and pull in this thread, let me try and do a logical summary:

1. For those that do not believe that headers are needed, merely call Scott or Dick at Prefix and you will have your answer.

2. As far as underhood heat, it is fairly easy to add radiant barrier/insulation to safeguard those areas where the headers are close to wiring and plastic parts. As a side note, I personally found that the coated ARH headers run much cooler on my car than the previous Belanger headers i had on the car.

To further the issue with heat, Arizona Viper recently posted about his experience with wrapping his headers and the huge reduction in underhood heat. the point here is, if you decide you need headers, there are ways to mitigate the heat issue.

[SilveRT8]

The Tech who installed my headers, added some Gen3 manifold heat shields and fitted them over the Belanger. Gen4 and 5 did not have those.
He used to work as a mechanic for the Comp coupe series and they used those to manage heat succesfully. So far, after one season with the car, all is good and nothing melted.

[RedTanRT/10]

Tire kicker what if thread!

Gonna spend 5 figures and leave out a bunch of hp?

As for the headers and heat, Jack and Silver make excellent points. Shops like SPT, Dan Cragin, know what is needed to shield header heat from years of Viper experience

[ViperGeorge]

Tire kicker what if thread!

Gonna spend 5 figures and leave out a bunch of hp?

As for the headers and heat, Jack and Silver make excellent points. Shops like SPT, Dan Cragin, know what is needed to shield header heat from years of Viper experience

Thing is no one has shown, at least to my knowledge, how much HP you in fact lose by not having headers. The Viper's exhaust from the manifold back is actually pretty efficient, are the OEM manifolds that much less so? The mufflers are straight through and while the Cats aren't you could lose them if you don't mind the smell. Only way to know is a before and after dyno run. I seem to recall some back to back runs on stock engines with and without headers that actually didn't show much improvement (could be wrong or I could be mis-remembering this). This debate is starting to sound like the debate on K&N filters vs. the stock Viper filter.

On my 15 TA I had to insulate the crap out of everything under the hood. It looked like some kind of science experiment. If I lost 20 HP without headers (which I doubt) but still gained a bunch over the stock engine with the H/C or 9L it would be a worthwhile trade-off. Remember too that unless you reduced heat to the same level that the OEM manifolds you run the risk of losing more power as the PCM pulls timing from the heat.

Wrapping the headers while a good solution can only be done with the headers off the car. That is a bit of a problem for those that already have them installed. I do like the option of using a Gen 3 exhaust shield, that seems smart and looks like it could be added on cars with headers already. However, I think someone like Doug Shelby could come up with specific shields for the ARH and Belanger headers that would be a good way to go. He could prove their effectiveness with the thermal camera he used for his airbox shield. Mind you, the O2 wires would still need to be insulated as they run close to the bottom near the collector.

[ViperTony]

I am considering the Stage 2 Heads/Cam upgrade on my 2015 Viper which is presently stock with the exception of the Arrows Venom PCM. I am not a fan of installing headers to complement the upgrade. Does anyone have experience with having Viper exhaust manifolds extrude honed? I realize that extrude honing will not provide the same exhaust flow increase as a set of headers but it may be an acceptable alternative in conjunction with high flow cats. The Viper is used street only. Thanks in advance for your expertise.

On an otherwise stock engine its a waste of money for headers IMO. In your case, since you're considering the Stage 2 package it will be worth it. I don't know of any Gen V Viper owner that went with a Stage 2 package and didn't also go with headers to maximize HP/TQ. But your best option is to call Prefix and ask for the details stock headers vs. aftermarket with their package because its just conjecture here. Have fun with that package! Many who have it....have a permanent shit eating grin on their faces.

[Arizona Vipers]

Just wrap the headers, problem solved. Push the heat out your sidepips, not your engine compartment

[WyoSRT]

The Tech who installed my headers, added some Gen3 manifold heat shields and fitted them over the Belanger. Gen4 and 5 did not have those.
He used to work as a mechanic for the Comp coupe series and they used those to manage heat succesfully. So far, after one season with the car, all is good and nothing melted.

I like this SilvRT8. It sounds like it's effective and appears to be a 'factory' install rather than a 'science project'...Thanks for the info.

[ViperGeorge]

Just wrap the headers, problem solved. Push the heat out your sidepips, not your engine compartment

Did wrapping the headers make it any more difficult to install? Bolt clearance is pretty tight as it is if memory serves. How long does wrapping take? I ask because if I were to get headers I would not install them myself (I'm getting too old for that sh!t) and hence would end up paying somebody to wrap and install. I've PM'd Scot at Prefix to see if they have any info re OEM manifolds vs. headers. No response yet.

[J TNT]

I do recall a few Team Viper Engineers who have Gen 4's and they opted for a tune on stock manifolds with stock set up . Was surprised they didn't opt for headers , I guess on a stock engine they felt it was minimal gain and the tune was more effective ...

[Steve M]

I do recall a few Team Viper Engineers who have Gen 4's and they opted for a tune on stock manifolds with stock set up . Was surprised they didn't opt for headers , I guess on a stock engine they felt it was minimal gain and the tune was more effective ...

There is a lot to be gained on the Gen 4 with a tune. Still on the stock manifolds here.