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Old 27 Dec 2005, 09:34 (Ref:1490449)   #1
R59
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Supertrapp's / power loss

Looking at the design of the supertrapp, I can't help but think that they must strangle the system and cause a power loss. Does anyone have an experience of them, and have you done any back-to-back comparisons to see what they do on a dyno?

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Old 27 Dec 2005, 15:36 (Ref:1490580)   #2
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I have used one on a 4 ltr V8 - to get through the noise problems at Castle Combe. Subjectively there did not seem to be a difference - and I got to race as they do knock several db off. I suspect on a rolling road you would see a few bhp but probably not that much.
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Old 27 Dec 2005, 17:11 (Ref:1490623)   #3
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your right they do look very restrictive, i know of one vauxhall engined sprint car that used to have to use one at combe and goodwood and it owner reconed it really hurt the top end power on his full race 1600v ecotec. i suspect the amount of power loss is entirely dependant on how many discs are fitted, the more discs the more the noise and less power loss, i also suspect that the state of tune of an engine will also have a big effect, 250bhp vauxhall Xe lump would probably loose a big chunk of power but a similar power out put 350ci V8 would barely notice it
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Old 27 Dec 2005, 21:14 (Ref:1490736)   #4
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Never done a back to back but have used them at trackdays and did not really notice a lot of difference but a bit hard to tell really in that environment, I can say they definitely knock the db's down though. I feel a conventional silencer would probably do a better job and save these for backup incase of scrutineering failures.
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Old 28 Dec 2005, 03:05 (Ref:1490823)   #5
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Supertrap with plates hurts a bit. I went to a Magnaflow, and still have a sub 100DB reading (103DB is my max)
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Old 28 Dec 2005, 08:37 (Ref:1490859)   #6
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I suppose the logical answer is that any form of silencing is going to hurt performance and open pipes will always be better performers, I doubt this method of silcencing is any worse and at least it is adjustable and a lot of bike racers swear by them, also I believe you have the ability to adjust the torque range by adding or removing discs. I currently have a big single one on my black car which I will take to the track with me and if it fails the sound test will pop it on. I have a pair of smaller ones that you are welcome to try if you want. I actually bought a pair of the biggest available for the Penske IROC project as I will build that with open pipes as it was but I doubt the neighbours and track officials will appreciate it! I still have the smaller ones I was using.
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Old 28 Dec 2005, 08:43 (Ref:1490863)   #7
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I fitted one on my car, and it felt like it was strangling things a bit, it only dropped off a few db as well ( Goodwood testing, I wish the miserable old gits living near the circuit would hurry up and die, the tracks been there longer than they have)
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Old 28 Dec 2005, 08:58 (Ref:1490865)   #8
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I am going to be using the Jetex/Laser decibel killer inserts on my kit car and, probably, race car. Certainly the kit car will be rolling road and noise tested with and without the device(s).

The best thing about this device is you just have is sitting around in the tool box when you need it but can run the 'normal' exhaust system the rest of the time. I looked at the Supertrapp system but was happy about the gas/sound having to somehow do a sharp 90 degree turn right at the end of the exhaust.

I'll let you know the results but don't hold your breath, I've already been waiting 2 1/2 years for the engine.
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Old 28 Dec 2005, 20:57 (Ref:1491125)   #9
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As probabley som of you have seen I use Super Trapps on my car... 2 with 3 inch core. The reason is they fit the car. They are VERY light and does not shake the rest of the system appart. Using 5 discs each the header will become very hot and it hurt power over 4000 rpm. But the engine is 8,7 litre so no wonder. But it gives a fair "city sound level". 20 disc and high rpm (7000) power seem fair, but one dont step the trottle with the men in blue around. But it is way softer than NO discs, althrought NO discs dosen sound like totally open headers, as there IS a absorption damper inside the damper housing.But no discs gives power as an open system.

Normally it takes 10 times the damper to engine size volume to effectively silence an engine. This means a damper volume of 10*8,7=87litre in my case!!! Thats half a barrel of oil size. Or else there will be a power loss from dampening to reach sivileced sound level.

I have a few ideas about sytem design that should get sound down while at the same time not loosing power, it can be done, but a bit tricky.

Goran Malmberg

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Old 28 Dec 2005, 23:31 (Ref:1491179)   #10
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Used my car with and without a Supertrap and although I didn't do a rolling road check, fitted wrongly they'll loose you a lot of power, but fitted and tuned correctly you won't see any difference at all. Some claim you can get a power increase, but I think that's on road stuff where the standard system is too restrictive.

Anyway, back to the real world. There are two basic types of Supertrapp, the simple end units and the full silencer type. I'd suggest the former is fine if you are adding to an existing back box, but personally I would go for the full silencer type instead of any boxes in the system. They are fully repackable silencers in their own right and are designed to work with the plated exit system. I resorted to the latter and effectively cured a nasty noise problem.

The first thing to note is that with both types, just looking at them, appear very restrictive, but that's actually just an illusion. Each plate is formed so that the gap between is the same as the thickness of the plates. At (from memory) 12-13 plates, the open area between the plates is equal to the area of the hole down the centre. So if you have a 2 1/2" supertrap, that many plates gives you the equivalent open area as having no Supertrapp fitted. Obviously because the gas has to turn 90deg there is effective resistance, but by the time you get to around 15 plates, even this is minimal and you have approximately an open pipe. It also means the noise you make is pretty much as if it wasn't fitted, but it does spread in a different way, so may increase or decrease a noise test depending on how its measured.

This gives a very effective way to "tune" your silencing down to just enough resistance to meet any given noise requirement. It's also a really neat way of meeting different requirements at different tracks by changing the number of plates fitted.

On that point, I said they can be badly fitted, because when I bought mine it came with something like 5 plates. I fitted it and the car was flat as a pancake. Then I investigated properly, bought a ten plate extension pack, put 7 of them in, and hey presto noise solved and car back to normal power.

Two last comments. First, I've seen people fit them like I did, then take the end plate off to get their power back.... err... can't see why you'd bother keeping the rest without the end... sort of defeats having one fitted. Second, even more investigations (I've done quite a bit ) suggested that silencer volume is the key, not backpressure. So I modified the bodywork and swapped out my 5" diameter 18" long Supertrapp for a 6" diameter 24" long Merlin straight through box, with no baffles or plates at all, and achieved the same noise level with much lower restriction. I also know a bloke who could get 4.2 litre Jag saloons through a noise test with a straight through 3" bore system... with just the one Leyland Roadrunner Truck silencer box in the middle

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Old 29 Dec 2005, 08:34 (Ref:1491292)   #11
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But it is way softer than NO discs, althrought NO discs dosen sound like totally open headers, as there IS a absorption damper inside the damper housing.But no discs gives power as an open system.
Am I reading this correctly Goran because it appears you are saying NO discs fitted gives more power because that is not the way I read it from the Supertrapp instructions that came with the units. They say the more discs the more noise and more power as you are opening up the restriction.

While we are on this subject can someone ofer some advice on silencing. I have just got the Black 3rd Gen in the workshop and the last job I did a year ago was to siamese the twin exhaust system because of space restrictions following fitment of some Spoone Racing components (modified crossmember etc to stop gearbox breaking.) Anyhow it is a three inch system and revving it at standstill feels really responsive and sharp but am I likely to loose performance and if so if I rebranched about two foot from where they pipes siamese to a twin system again would there be any improvement or gains in either performance or sound dampning.
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Old 29 Dec 2005, 08:51 (Ref:1491298)   #12
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Has anyone read vizards a-series tuning book?
He flow tested a supertrap against another(?) box and the supertrap did,nt perform to well.
Dont know how long ago the test was done or if the design has been improved since.
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Old 29 Dec 2005, 12:03 (Ref:1491375)   #13
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Quote:
Originally Posted by Al Weyman
Am I reading this correctly Goran because it appears you are saying NO discs fitted gives more power because that is not the way I read it from the Supertrapp instructions that came with the units. They say the more discs the more noise and more power as you are opening up the restriction.

While we are on this subject can someone ofer some advice on silencing
If we discuss the exhaust from the starting point at the heads of the engine, we got a primary pipe that has to have a diameter that create the desired gas speed and a lenght that put the return pulses at the desired rpm. We might put this at peak Tq or peak power or at any place we want them, I am just ralking priciples here.

Then we got a collector that also could be constructed in different ways which is a bit more complicated these days. "Merge" collectors is popular and very good but a little tricky to fabricate. They may also be followed by a short timeglass shaped tubing. The "Merge" collector is a well flowing device.
Then we got the opposite collector that is more "pulse" oriented, and can be found in older English books. In fact it could be seen in the film "the Persuaders" with Roger Moore from the 70s "someone waiting".
It is a baffle type collector letting all tubes enter the collector in a flat "wall".

I mention those two types of collector to show the two features that must be taken under concideration when building collectors.

After the collector we got the collector tubing tha should be about the same lenght as a single primary pipes, and a suitable diameter for the number of primarys in question. We can call it System A.

OK, this is about the exhaust system. But the we may use a longer pipe under the car depending on wher to locate the exhaust behinde the car.
We may have a silencer etc, and here we may face a number of problems. We may experience a power gain when changing a silencer for another, but this is due to that the first system was HURTING power.
We NEWER get better than the first basic system mentionend.
Supertrapps on a Pantera is a special situation. The collector pipe is very short and a no disc system is very close to system A.

If the system A is the perfect system what do we do to silence it? The trick is to simulate an open atmosphere at the finisch of the collector pipe, to make the engine think it breath in the "open". So, we need an expansion chamber at the end of the pipe. This chamber should be made as large as possible. The expansion chamber should in turne be "wentilated" to the free atmosphere over some type of silencer.

Without writing a book here, this is the layout of the system.

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Old 29 Dec 2005, 12:33 (Ref:1491382)   #14
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Quote:
Originally Posted by Robyn Slater
Has anyone read vizards a-series tuning book?
He flow tested a supertrap against another(?) box and the supertrap did,nt perform to well.
Dont know how long ago the test was done or if the design has been improved since.
Did Mr Vizard then go on to recommend his custom designed RC40 system that he earned commission on?
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Old 29 Dec 2005, 13:02 (Ref:1491393)   #15
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Ermm steady Dennis I have heard a few tales from people in the know on this subject of recommendations that you would not believe.
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Old 29 Dec 2005, 13:39 (Ref:1491411)   #16
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What was the original question Dennis?


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Originally Posted by racing59
Looking at the design of the supertrapp, I can't help but think that they must strangle the system and cause a power loss. Does anyone have an experience of them, and have you done any back-to-back comparisons to see what they do on a dyno?

Rob.
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Old 29 Dec 2005, 14:50 (Ref:1491440)   #17
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Originally Posted by Robyn Slater
What was the original question Dennis?
My point is that even 'scientific' proof can be rigged, either intentionally or accidentally.
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