Power limit of mods with VF1 SSV stock exhaust

[daves8]

thats where i like the DPE system as i dont like any raspy sound and theres keeps it deep and still with bark but it dosnt echo esp on the decel, but still small rear mufflers and im sure u could double the size and still not affect anything just quieter, i made over 700rhp with the stock rear mufflers on so they are no real limitation

I have the DPE cat back with headers and cats, it’s awesome.

I have mine with marriage saver rear mufflers in place of the DPE. Lots louder but still no drone.

It’s the meter long resonators before the mufflers that weave the magic

 

[Banjo79]

Wonder what everyone with OEM cats will do if/when they cease to function. I guess it will be off to the unknown aftermarket. Surely they're not available new anymore? Facebook has a pair of LSA cats almost new for $1800, which is probably about right. I'm glad I kept my pair.

 

[RevNev]

But the drone was like doing 100 k's on the highway with one window down, I couldn't hear the radio and it was tiring to drive it.

Drone is typically with windows up and down you hear the exhaust note more. Did yours only drone with a window down?

thats where i like the DPE system as i dont like any raspy sound and theres keeps it deep and still with bark but it dosnt echo esp on the decel, but still small rear mufflers and im sure u could double the size and still not affect anything just quieter,

Fibreglass packed perforated tube mufflers I think DPE use make the smoothest and deepest note. Straight though mufflers don't make any power differences regardless of length and cannister size and only quietens the exhaust the bigger they are

personally id go for 1-7/8 on the headers to get the exhaust out then u can deal with it how ever after then

I always use the smallest primaries that doesn't rob the engine of top end horsepower to maximise scavenging on an NA engine. Too big in the primaries although it may make 2 or 3 horsepower more on the top end in circuit race cars, can increase the car's lap times with the bigger headers bogging the engine off the corners. It doesn't show on a dyno with torque loss, the car's just off the pace on the track.

 

[RevNev]

I have the DPE cat back with headers and cats, it’s awesome.

I have mine with marriage saver rear mufflers in place of the DPE. Lots louder but still no drone.

It’s the meter long resonators before the mufflers that weave the magic

The meter long resonators DPE used was to compensate for small rear mufflers. Alternatively, they could've maximised the rear muffler size and used smaller resonators in the midpipe that don't interfere with the trans tunnel brace.

 

[Piano player]

After reading some comments on here regarding maximising rear muffler size, I was just wondering what would the result be if I were to re-install my 3" Hurricane mid-pipe (4 resonator type) and install the stock rear SSV mufflers in place of the Zetti sports oval mufflers?
Higher overall flow than the current setup for a better result when tuning but with minimal drone? Or would the 3" Hurricane mid pipe still cause drone?

That way I would pretty much have a 3" Cat back system but with stock rear SSV mufflers.
I guess that would depend on just how restrictive the stock 2.25" mid pipe is compared to the 3" Hurricane.

 

[Ginger Beer]

Wonder what everyone with OEM cats will do if/when they cease to function. I guess it will be off to the unknown aftermarket. Surely they're not available new anymore? Facebook has a pair of LSA cats almost new for $1800, which is probably about right. I'm glad I kept my pair.

Ouch

I've been looking for some low km VF HSV cats, unfortunately you cannot pick them up for cheap anymore, and they once were a throw away item, and the price for high km rubbish is insane, you can get new 4-5 bodied quality 400 cell cats for rhe price that some people want 100k km old standard cats, apparently the newer VW Tiguan's have a large body cats that flow well and will accommodate chop fitting



Quality large bodied mufflers cost a bit more than the cheap small bodied mufflers that 90% of "bolt on" aftermarket brands use

I've found the price difference between a "bolt on" and a custom exhaust built to spec to be very close, and I'm more than happy to pay for quality

You can get a well designed exhaust quite and able to flow big power without drone

I just think alot of people prefer brand name bolt ons and use rose coloured glasses to validate their purchases

 

[RevNev]

After reading some comments on here I was just wondering what would the result be if I were to re-install my 3" Hurricane mid-pipe (4 resonator type) and install the stock rear SSV mufflers in place of the Zetti sports oval mufflers?
Higher overall flow than the current setup for a better result when tuning but with minimal drone? Or would the 3" Hurricane mid pipe still cause drone?

That way I would pretty much have a 3" Cat back system but with stock rear SSV mufflers.
I guess that would depend on just how restrictive the stock 2.25" mid pipe is compared to the 3" Hurricane.

A 2.5" diameter exhaust will flow nearly 550hp (flywheel) so an engine rated at 400kw naturally aspirated. An LS3 is rated at 304kw in a VF Commodore so unless you intend to modify an LS3 engine to make an additional 100kw, a 3" exhaust is a waste of time and harder to control noise level and drone potential and a 2.5" exhaust is plenty big enough.

Having said, we're talking exhaust pipe diameter, not dyno testing bolt on 2.5" systems poorly designed and manufactured with restrictive bends and mufflers and comparing them to a 3" exhaust that makes more power. A stock SS exhaust we can say is 2.25" but in fact, it's 2" between the midpipe resonators and reduces down to 1 7/8" inside the flex joint at the rear muffler flange. It's not really a genuine 2.25" exhaust. Some 2.5" bolt on's are like this and are more realistically 2.25" exhausts flow wise and even a poorly designed and manufactured 3" exhaust will make more power in this instance. HSV 2.5" exhausts are fitted with 2.25" resonators in the midpipe and reduce down to 2.25" tail pipes and they're not genuine 2.5" exhausts either! 2.25" tail pipes or beyond the rear muffler flange where the exhaust gas is cooler with less volume doesn't seem to flow restrict a stock or mildly modified engine.

I believe there's quite a few 2.5" bolt on systems you can choose from to make a bit more power and sound better that'll likely be a better solution.

 

[Piano player]

A 2.5" diameter exhaust will flow nearly 550hp (flywheel) so an engine rated at 400kw naturally aspirated. An LS3 is rated at 304kw in a VF Commodore so unless you intend to modify an LS3 engine to make an additional 100kw, a 3" exhaust is a waste of time and harder to control noise level and drone potential and a 2.5" exhaust is plenty big enough.

Having said, we're talking exhaust pipe diameter, not dyno testing bolt on 2.5" systems poorly designed and manufactured with restrictive bends and mufflers and comparing them to a 3" exhaust that makes more power. A stock SS exhaust we can say is 2.25" but in fact, it's 2" between the midpipe resonators and reduces down to 1 7/8" inside the flex joint at the rear muffler flange. It's not really a genuine 2.25" exhaust. Some 2.5" bolt on's are like this and are more realistically 2.25" exhausts flow wise and even a poorly designed and manufactured 3" exhaust will make more power in this instance. HSV 2.5" exhausts are fitted with 2.25" resonators in the midpipe and reduce down to 2.25" tail pipes and they're not genuine 2.5" exhausts either! 2.25" tail pipes or beyond the rear muffler flange where the exhaust gas is cooler with less volume doesn't seem to flow restrict a stock or mildly modified engine.

I believe there's quite a few 2.5" bolt on systems you can choose from to make a bit more power and sound better that'll likely be a better solution.

Mines just an L77 6.0 series one SSV. I am not chasing big power, so perhaps the stock 2.25 mid-pipe will do. I doubt I will be able to get anymore than 260 rwkws with a tune.

 

[Banjo79]

The physicist (not) in me would say if your pushing through a s1 OEM cat that has around 2.5x the substrate volume of a typically sized small aftermarket 400 cell cat or 10x??? the substrate of a 100cell, then 2.25 v 2.5 wouldn't make any noticeable seat of your pants hp difference, 2.5 would probably give a nicer note though.

 

[RevNev]

Quality large bodied mufflers cost a bit more than the cheap small bodied mufflers that 90% of "bolt on" aftermarket brands use
I've found the price difference between a "bolt on" and a custom exhaust built to spec to be very close, and I'm more than happy to pay for quality
You can get a well designed exhaust quite and able to flow big power without drone
I just think alot of people prefer brand name bolt ons and use rose coloured glasses to validate their purchases

I started doing custom exhausts on the weekend in 1978 as an apprentice mechanic with a hacksaw, vice, car ramps and oxy set using my mum's coat hangers for welding wire. In 44 years, I've never had bolt on exhaust in any of mine or my wife's cars with every exhaust I've chosen to modify I've custom made often using parts of the stock system and muffler cannisters. Getting the right note and drone minimisation was essential in road cars and then eventuated into race car exhausts from the early 90's maximising torque and power potential.

Bolt on's are primarily a compromise based on costs to compete in a market unless you get into Euro stuff like BMW M series bolt on's they're paying 10k+ for name brands like Akrapovic and the like that are loud, raspy, sound lousy often drone like crazy. As I mentioned previously, drone control is best achieved using the biggest rear mufflers that'll fit under the car, exactly what the aftermarket don't do then try and "band aid" it with midpipe resonators like DPE's metre long hot dogs. All you need in a VE/VF midpipe are 12" long 4" diameter resonators with big rear mufflers to control drone. Here's mine, a modified HSV Maloo midpipe with a proper 15 degree X-pipe and resonator change from 2.25" hot dogs to 2.5" of similar cannister size.