Dump Pipe Advice.

[GTSBoy]

Here's a tasty looking split dump off a Group A car, follows up on what GTSboy was saying

That is a lovely looking piece of work.

[The Dan]

Now that is what I call a nice sidepipe Zebra, but I don't understand why they would even plumb the wastegate back in...

The rear section of it pulls apart from the front section. I assume they wanted everything coming out in the same place and/or rules/restrictions in the class they are racing in

[hardsteppa]

hey GTSBoy, your postage was highly detailed and it sounds like you know your shizzle on where the dumpipizzle is concerned. What are your thoughts on this slice of exhaust action?

http://www.ebay.com.au/itm/TOG-NISSAN-SKYLINE-RB20-RB25-R32-R33-R34-EXHAUST-TURBO-DUMP-FRONT-PIPE-/130709924344?pt=AU_Car_Parts_Accessories&hash=item1e6eeb29f8

It would appear to match your specific criteria mentioned - spilt pipes, seperator, merged much later in the pipe, at a smooth flowing angle, and flaring out in a cone-type shape as much as possible in the space available. Good price too. Granted I am sure it would be made of incredibly low grade s/steel, but from a design point of view?

[GTSBoy]

That's essentially the same as the cheapy I got. JustJap used to have them for less $$ than that, but don't seem to stock them for RB engines any more. Only seem to keep the short ones.

These cheapies are OK. They're not as well thought out as the CES one, and if I have my choice I'd make the re-entry of the wastegate gas on top of the bend rather than shooting into the back of it (hard to describe without drawing some MSPaint magic). My idea might not fit against the floorpan though.

[discopotato03]

Unless there were specific regs dictating its design I wouldn't view that pipe as you beaut . It looks like 500 short sections welded together and thats not required these days to get good pipeforms - if you have money .

My problem with the second small pipe is exactly that , its small and wouldn't have a lot of volume for expansion . Also note how it rejoins the pipe down the back , same scenerio as the IW type turbine housing debacle .

I also have issues with mobs that start the gates vent pipe out as a holesawed hole through the flange plate when the gates outlet hole is not round .

Where I agree with some carefully made twin dumps is when they are made firstly to be a turbine outlet pipe and second a wastegate outlet .

Its all the same deal with Evos and if you can find some pics of the American Megan Racing firms Evo dumps you can see why they work . What they do is form a slow expanding taper (elongated conical tube if you like) that curves down to run the exhaust back under the engine .

They have a "shell back" section that vents the twin wastegate (twin scroll) and it comes back into the main tube after its diameter has increased in size .

The findings with Evos is that 3" outlets don't seem to work any better than 2.7" ones even though the front pipe is 3" .

I think at the end of the day it depends on the engines state of tune and ultimately its use .

Obviously if you have a GTRS on an RB25 you're not looking for 500 Hp so most reasonable dumps should be adequate . If you are super serious it'd be a GT30 or larger using an external gate .

I have that RS and dump and I wouldn't bother spending good money on a split dump because I don't think the returns are there . An open collector is much simpler and easier to form and if the turbine housing is a good design it won't fire the gates gasses sideways into the turbines outlet .

All the race tech thinking is fine on a race car thats mostly driven flat out , road cars mostly aren't so the full load time is short/small .

A .

[zebra]

Disco, that exhaust is/was good for 500+hp on a ct26 turbo'd 7m and built by TRD

I don't see there being any disadvantage to the lobster back pipe work apart for the poor bugger who had to make it lol

[Nee-san]

Disco, that exhaust is/was good for 500+hp on a ct26 turbo'd 7m and built by TRD

I don't see there being any disadvantage to the lobster back pipe work apart for the poor bugger who had to make it lol

Meh, everything can always be better but the question is one of economics and whether it is actually worth the time and money.

[zebra]

I agree lol

[discopotato03]

Well the issue aside from the time and costs involved , splitting hairs I know , would be grinding the bead off the inside of every weld to maintaain boundary layer flow . A mandrel bend would be easier cheaper and less heat stress into the material . May not look as pretty but when function is everything ...

I wouldn't know at TRD level but 7MGTEs are known for headgasket sealing probs and people who used to race them could tell by the witness marks left by the fire rings how many times they really let them have it .

Again don't know about noise issues but you'd think they would have ovalised the outlet rather than form a collector to three short pipes .

Just my observations , cheers A .

[GTSBoy]

On that dump, the lobsterbacking in the top half is for the purpose of getting the steady conical increase. Arguably the first 4 or 5 inches below the solid conical section are still incraesing diamater also. I agree with the rest of the lobsterbacking from there to the exit is gratuitous, but it serves its purpose in the top.

[The Dan]

I think you're both missing the point that it's made of titanium. The reason for them choosing titanium for an exhaust material is pretty obvious but the reason for lobster-backing the pipe is because of the almost impossible bend-abilitiy of titanium. They can't use mandrel bends.

The weight saving outweighs (no pun intended) the flow capability of the pipe

[Nee-san]

they should make a part of it out of aluminium, sounds stupid but could be probably made to work.

[scotty nm35]

I think you're both missing the point that it's made of titanium. The reason for them choosing titanium for an exhaust material is pretty obvious but the reason for lobster-backing the pipe is because of the almost impossible bend-abilitiy of titanium. They can't use mandrel bends.

The weight saving outweighs (no pun intended) the flow capability of the pipe

I have Ti mandrel bent pipes in my workshop, granted they are Jet engine parts but they are available.

they should make a part of it out of aluminium, sounds stupid but could be probably made to work.

I'm still trying to talk someone into an alloy cat back, no-one has been game as yet. It's more common in the US it seems. We will catch on eventually.

[zebra]

I'll stay away from alloy exhausts after I saw what happened to the Full race S14

[scotty nm35]

Pics?

What happened? I would have thought it would be fine as a cat back, perhaps road cars only...

[zebra]

Pics in the motorsport section somewhere, but basically it melted and set fire to the power steering lines (i think) and burnt a heap of stuff

[zebra]

Here one I found, I dont know exactly where it melted, or if the dump pipe was aluminium too

[Manuel Kasko]

Honestly this topic has been done over and over!

Zebra I'm having deja vu because I swear you said the same thing before to someone about this

Could be possibly I'm drunk as a kunt

[zebra]

hahah I vote both

[Plattsy]

Pissed as a bastard. Check my emails ...... This topic got wayyyyyy outa hand!