Thunder

No idea what the noise is - probably just the video mic or the dyno whinging!!! The driver complained that when he pulled 4th gear doing 160 - 180km/h at the track, if he put his foot down, it smoked the 300mm wide slicks!!! Since then we freshened up the engine, softened the suspension, and did some brake work, so it will be pretty quick at the track. There are lots of LSX powered street registered cars with far more power than the Z

My LS1 bakes 4th - doesn't everyones??? https://youtu.be/yjBYU5mbkqo

The pipe measurement is always the OD size, and the stock ports are only about 1.5" The 5.7 engine lacks power and torque down low. The 6.0 litre engine has plenty of power and torque down low. The stock engine is doggy down low, which is nothing to do with the exhaust, however, going too big on the extractors and exhaust makes the problem worse, not better. On a manual, you can rev the engine and dump the clutch, and if it has a cam it has a lot more power and torque right through the rev range. A cam would add 40rwkw - 60rwkw. (60rwkw is more power than some 4 cylinder cars) An auto needs a stallie to give a similar effect. Diff gears will also increase the torque and acceleration. A cam makes it go a lot better, and sound aggro. My point was this, and I am only guessing at prices here, but the extractors & cats $1800, Stallie $2500, Diff Gears $1700, Cam/Lifters/Injectors/Tune $5000 = around $11,000 yet you could buy a VZ or a VE with a 6.0 litre engine cheaper. The 6.0 has far more power and torque than a 5.7 litre and a lot of these second hand cars already have a string of mods done to them. The same as the droning issue. $680 gets a system that sounds great and is designed to be drone free. If the old system was ebayed you may get $400 which means changeover = $280. The valve option was $1200 for the kit, plus fitting. Let us know what they are like in a month or so, and compare your fuel usage as well.

The other video clip on 4>1 doesn't work. On the auto's we usually fitted tri-y's unless the customer specifically wanted 4>1. That video clip was a while ago, but I am pretty sure it would have been tri-y's. The 3.5" system, combined with Ballistic 100cpsi Racing cats sounds great no matter what extractors are fitted. Adding a cam makes it even better. 4>1 will give a higher dyno number - probably 20rwkw extra. 4>1 will give a quicker 1/4 mile time but you probably need a stallie as well. However, 4>1 are doggie down low on the 5.7 litre, but the addition of diff gears will help the low - mid range acceleration. What a dyno sheet doesn't tell you is how much extra fuel you will use on a street car, or how low the extractors sit when you go into shopping centre carparks or steep driveways. Most cars are driven on the street 99% of time and only go to the track, or a dyno day every now and again. Cheers Greg

Yes, the valves have their uses, and in some vehicles (Bridgeported rotaries, etc) it is the only way to keep them quiet. How much would a dual 2.5" cat back system be with your setup? I'm guessing it is pretty expensive by the time everything is fitted, wired and plumbed up. These cars aren't too hard to stop the drone.

We don't do any for the 5.0 litre. I would use a set of Pacemaker. Cheers Greg

The dual 2.5" systems sound disappointing, so DF removed their "Kiss Pipe" (merge) and it basically just has a small hole between the pipes. This makes the sound beefier and why they do it that way. Other people chop out mufflers to make them sound better and this increases the drone. Yes, fitting a proper full flow merge will help with the drone. Yes, fitting bigger mufflers will make it drone less, but it also kills the sound. Bi Modal systems, ie vacuum operated valves, block the flow in order to stop the droning. They work, but they also restrict the power. These are all costly. There is no substitute for R&D as there is a balance between power, sound & no drone, and most systems fail on one or more of these. It is no use having a no drone system that sounds like a vacuum cleaner, or one that blocks a pipe to stop the drone as it robs power. It is no benefit spending 3 times the amount you need to spend using a system with valves when it robs power and sound as well. With lots of experimenting and R&D you can have a 3.5" system that is completely straight through, sounds great and doesn't drone. The difference being, it was specifically designed for this car, for auto and manual, and so it makes power, sounds great and doesn't drone. Cheers Greg Cheers Greg

The only model HSV headers that were good from the factory are the VY2, and these are nearly as good as a set of aftermarket tri-y's. They are still a bit restricted in the collector, but far better than any other model. VT-VY1 are rubbish so don't bother with them. From the extractors you have one cat on each side. The 3.5" system is twin 2.5" which merges into a single 3.5" system, so it still uses both cats. The video clips you posted that sound good have cams fitted, which makes them sound aggro, and they sound even better with a 3.5" system. The size of the cam and the way it is tuned also have an effect on the sound. Search on Youtube for "Sureflo 3.5" and you will probably find some cammed cars up there as well. Ballistic 100cpsi Racing cats also make the sound a lot louder and deeper and add around 10rwkw to your power. The price of 2nd hand cars now, if you want to modify a car, I would seriously think of selling yours and upgrading to a VZ - VE which have the 6.0 litre, that way you can look for a manual. On the VE they spread the wheels by 100mm so it also handles better. It may not cost much in the changeover, so I would look around. The 5.7 is very doggy down low, but the 6.0 has far more power and torque right through the rev range. The modifications you are talking about are probably $10k and will have it going as good or a bit better than a stock 6.0 litre. I would start with the 6.0 litre and then bang for buck you will get much more enjoyment. On a 5.7 if you want to fit 4>1 you really need to upgrade the diff to 3.73 for auto or 3.9 for manual which will fix the lack of power and torque down low. This is probably another $1500 on top of the manual conversion. The cam/valve spring upgrade will probably cost $5k by the time it is tuned, and then you may need to upgrade the fuel as well. You are talking big money if you are going this far, but if you traded for a manual VZ or manual VE the changeover won't be too much if you look around. They were also selling the VF GTS supercharged crate engines for around $13k-15k brand new - that would be a weapon straight out of the box!!! It's only money!!! Cheers Greg

I'm also late to this conversation, and owning an Exhaust Shop that specialises in custom, we have our own dyno, and our niche is GenX Commodores and non droning systems. The worst model for drone is an auto wagon, and our early test mule was a VX auto wagon. The newer (VE-VF) worst model is the auto wagon with AFM and that is my new test mule. Most advice out there is based around dyno numbers and 1/4 mile times, but 99% of these cars are just daily drivers with the occasional track visit. The people that say a DF system is the best is because the Performance Workshop told them it is the best. Most haven't had more than one system, so how would they really know? What suits a manual sedan and doesn't drone, will drone badly on an auto. What doesn't drone with diff gears will drone with stock diff gears. A 20 year olds view of no drone is completely different to a 40 - 60 year olds view. There is lots of conflicting info out there, which is because everyone has a different need, different taste, and different mods. Performance Shops, and a lot of Exhaust Shops that don't like doing custom worl will sell and recommend the brand that they make the most profit on. If they don't have the Exhaust Capability, they will recommend the brands that come as kits from front to back, and that is why DF and X Force are so popular. The exhaust is a compromise. 4>1 hang low on stock FE2 suspension (around 90mm or less on some brands). The legal limit is 100mm so it is a defect without even lowering your car. There are many brands out there, but for quality, we recommend Pacemaker in most instances. For an auto, tri-y's are a good compromise as they are speed hump friendly. They are good in the low to mid range, but at the top of the rev range they will run out of puff. 0-100km/h they are fine and that's where most of your street driving will be. Someone above mentioned excessive fuel consumption. The 5.7 litre is very doggy down low, so when you go too big it makes the problem worse. This means you have to push the pedal further, and this means excessive fuel consumption. On the VX wagon I had a single 3.5" system and the only change we made was changing from twin 2.5" into 3.5" to twin 3" into 3.5". The wagon is heavy and with stop start driving the fuel consumption rose from 14 to 17 litres/100. For sound, dyno numbers and 1/4 mile times it would have been a positive move, but being a shopping trolley for the wife meant a huge increase in fuel costs over the life of the car, so we changed it back. Using big 4>1 extractors or a twin 3" will have the same result. All of the different brands of twin 2.5" system are basically the same design. Most are made in Asia, compete against each other, and can't add an extra dollar to the quality. They are OK on a manual, but drone badly on an auto. The idle is disappointing, they don't sound too bad when revved, but cruising they drone. On my website there are pictures of the DF Kiss Pipe, but since then they changed to a "Clayton's" merge as the Kiss Pipe takes about 25 - 30% off each pipe, so it is much more restrictive. Now they keep the pipes separate and just have a small hole, which makes the note meatier, but does little for drone or to improve the power and torque. DF make the pipework here, but I believe they buy the muffler bodies off Redback or HM, etc. The Chev has a different firing order, so the sound just doesn't sound as good as the early Chev, Holden V8, or even the Ford engine with a twin 2.5" system. We found the 3.5" single system sounds much better and we make them in several loudnesses so that they are drone free on manuals and auto's. This is a customer enjoying his Loud 3.5" system http://www.surefloexhaust.com.au/media/video/vysv8.mpg I had a customer who had race cars with twin 3" and he said it sounded fluffy, and he changed to 3.5" single and loved it. Chev's in Carrum Downs fitted superchargers to a couple of VY- VZ and they were running twin 3" and the customers hated them because of the drone. He put our 3.5" system on and they loved driving their cars again. They were pushing 400rwkw on the dyno. Do a search on "Sureflo 3.5" and you will find plenty of video clips and lots of info. If is was me, I would ebay the DF system - they have a good name so you might get a good price for it. The 3.5" system is the go and they are $680 in mild steel + tip & freight, which is much cheaper than extractors, Ballistic 100cpsi Racing cats, diff gears, dynamat sound deadening, hooker mufflers, etc and you get a much deeper idle, race car growl when nailed, and it goes quiet when cruising. Cheers Greg

If you look at these video clips, the Commodore is one of our customers. The Mazda took him out, and the Torana also became involved, and I believe it was under yellow flag conditions. Back at the pits the Mazda driver told the Commodore driver that he moved across and hit the Mazda, until he showed him the video footage, and then he said sorry and that was it. Each had to pay for their own repairs, and the Mazda had a bit of black paint on his bumper and finished the race. The Commodore has around $15000 damage and the Torana is completely written off, and they were just innocent bystanders. This is all part of racing, and whether it is an accident, or whether someone runs out of talent, the rules and waivers are there for these reasons. Cheers Greg

+1 There is no changing what happened to Eric. It was disastrous, but it was an accident, and unintentional. My Company and I had nothing to do with this. Waivers were signed so each person accepts the responsibility for whatever happens on the track to themselves, or their vehicle, and there are reasons for this. If I had accepted liability, this may have then led to personal injury claims, etc - and I wasn't even at the track, or entered in the event. I also cannot help what happened between the drivers, as I was not there, nor had I met either of them. A lot of what happened on the day, I am only finding out by what I read in this thread, so if I hadn't thanked people, etc - it is because I did not know what happened. A lot of the derogatory comments were from people other than Eric, and some were not at the track, and they have dragged my company into this event unfairly. Some of my comments were probably poorly written, and misunderstood, which also did not help things. The fact is, Eric's car was hit by the car owned by me, and after the fact, nothing can change this. I offered in this thread, and also behind the scenes, to hold a Charity Dyno Day and BBQ at my workshop for Eric. The accident saddens me, and the news of Eric losing his wifes car altogether, is even sadder news. If the dyno day goes ahead, I hope that the Skyline Forum members will support the cause and help Eric. I am willing to help out, but I can't accept liability - there is a big difference. Whether Eric's car is written off and parted out, or repaired, he is still out of pocket and needs help. Cheers Greg B.S. What goes on in the forum, laps the world for eternity. It can destroy the good name of a business or person, whether fairly, or unfairly, and can leave Forum Owners open to be sued for defamation and damages. What happens at the track should stay at the track! This tragedy was between Eric & Richard and should have been left that way. Everyone wanting to help, could have posted or pledged their help, without dragging other parties into this, and pointing the finger. The outcome would have been a lot better for all parties concerned, and this thread would have been a lot better for it. If this had remained a "Help Eric" thread, I believe it would have achieved far more than it has done to date. I am posting this to help get it moving again, and in the right direction - helping Eric !!! Cheers Greg

According to Jason they are both fine. There was a video camera on the passenger at the time of the accident. Jamie said he looked quite cool through the experience - considering. If it was me in the passenger seat there would have been a few choice words said, and I can only imagine the facial expressions. Cheers Greg

Duncan & Gregor If you can get your fire extinguishers to me I can get them refilled, or I can get you new ones. Let me know either way and I will replace them for you. [email protected] Regards Greg