Down-Pipe Troubles

Howzit Guys

After reading allot of info on turbo systems, I am going out and resolving issues with my current set-up, I am still hell bent on attempting to achieve 250Rwhp 186Rwkw on 0,5 bar boost on my set-up so I need to remove all the bottle necks.

One of the biggest trends I have been picking up on allot is the down-pipe outlet is normally never the same diameter as the exhaust system it joins to now an exhaust system in a big generalization in only as good as it smallest point.

Example: if you had a length of pipe and it was all 76mm except for one section being 52mm then there would be a slight pressure build up before the 52mm section as exhaust gasses speed up.

If a Turbo could select its exhaust system it would choose none what so ever but unfortunitly that makes things very noisy for the average guy but by having a correctly set-up system both power and spool-up can be increased a turbo gets its energy primarily from two sources Heat and pressure , Heat can be kept in a tubular system by wrapping the manifold but if you want to make the pressure more effective you have to make the pressure difference more dramatic across the turbo (hot gasses expand and want to fill low-pressure area's a crude example would be 'wind') this would increase spool-up and lowering the pressure between the turbo and manifold allowing an increase in power, lower the DET threshold and is a generally good thing

Anyway now that the science lesson is over 😂 I will explane my problem my down-pipe is set-up completely wrong.

The primary inlet is only 46mm expanding to 52mm

The divorced wastgate pipe is 37mm nice sized

Now this is not that bad if kept separate but they join just before the flange at a 52mm opening plus the wastegate gasses join at a very sharp angle and the wastegate pipe is way to short creating turbulence at the weakest point in the system, Now not to get into to much arguments I still beleave a Divorced set-up in better then a bell mouthed set-up so I will need to make this work

anyway stay tuned because I have a few idea's I need to through past the local exhaust places to solve this issue.

Chances are this might not even make a difference but maybe I will get lucky 🙄

Freddy had a 76mm one made up at a place in Rosslyn...can't remember the name

Draco wrote:

Freddy had a 76mm one made up at a place in Rosslyn...can't remember the name

Cheetah exausts 😉 just down the road from my work

Nice but its a bell mouthed Set-up , That I don't really want but it will work much better then this set-up.

But I have handed the pipes in at an exhaust place and they will try to implement my idea

Hay I work in rosslyn daniel there are two SX's in that area a dark blue one and a white one that I have seen

So what different type of Down pipes do you get on the market? And whats the difference?

In my opinion it's different, the bellmouth setup has 2 seperate pipes where this has only 1 thick pipe, the 2 different ones you loose alot because the hot air has to be pushed in different channels....

Pinkfluffybunnys wrote:

Nice but its a bell mouthed Set-up , That I don't really want but it will work much better then this set-up.

But I have handed the pipes in at an exhaust place and they will try to implement my idea

Hay I work in rosslyn daniel there are two SX's in that area a dark blue one and a white one that I have seen

[off topic]

Cool i didnt know that. Mine is white, could be me.

I work for BMW SA, at the end of Frans du toit street....but run around through rosslyn to all the suppliers of BMW.
Anyway got a promotion and im off site mostly for traing

[/off topic]

Howzit Guys

Its been a buzy ass day for me, I have take leave this week so I need to sort all my issues out this week 😁

Anyway Here is my solution to my down-pipe issues , I wan to allow the waste gate gasses to bypass the restriction on the exhaust system this allows for better waste-gate control and effectively kind of doubling the size of your exhaust.

Here my new set-up it does have issues and I have to say to Hennie he mentioned every one when we spoke.

Con's
-------------------------
Because of integrated wastegate the divider doesn't seal correctly (its not a S15 turbo) so there are exhaust gasses leaking through not allot but enough to make a noise.

The exit of the screamer is close to the body, This could cause issues in the long run but I can still touch the body in that area after spirited driving.

Pros's
-------------------------

POWER - And my butt dyno is not acting up here, The clutch started slipping after switching to second in every run but it is the old one 🙄

AFR - This has seriously changes , I am allot leaner not dangerously lean but the whole graph has changed now it could be because of the leak but I have never seen air flow into a high pressure area.

It could also be because less gasses are getting to the sensor but there is allof of pressure coming from the exhaust

Waste-gate Control - This is now second to none when the EBC opens at 8 psi it stays there

But if things get to noisy for me, I can just join the two pipes together

I love it! This is the same thing I would like to do!

Quickly eplain the leak your getting? Me not catching on? 🙁

There is a divider , Welded or bolted between the main Turbo-out let and the waste-gate, To keep the Gasses separate now this divider does not fit very exactly and has no gasket so the exhaust gasses leak around it into the separate Screamer pipe. It sounds kind of like an exhaust leak. 😢

My current divider

work for BMW SA, at the end of Frans du toit street....but run around through rosslyn to all the suppliers of BMW.
Anyway got a promotion and im off site mostly for traing

Off-Topic
-----------------

I work where they make the Beer.. 😂 😂 😂

We must arrange a hook-up for the PTA guys like at a Dros or something

Pinkfluffybunnys wrote:

There is a divider , Welded or bolted between the main Turbo-out let and the waste-gate, To keep the Gasses separate now this divider does not fit very exactly and has no gasket so the exhaust gasses leak around it into the separate Screamer pipe. It sounds kind of like an exhaust leak. 😢

My current divider

OK! Just as I thought, so how would you fix this problem?

i thought you would do something like this and it looks good. this way there is no turbulence from the wastegate gasses entry into the exhaust!

what about a side exit for the wastegate pipe...

or

what about running the pipe further under the car...

or, at least, maybe pointing the pipe down towards the road??? might not be considerably less noise, but it would be further from the body, with little direct flow onto the chassis???

i thought you would do something like this and it looks good. this way there is no turbulence from the wastegate gasses entry into the exhaust!

what about a side exit for the wastegate pipe...

or

what about running the pipe further under the car...

or, at least, maybe pointing the pipe down towards the road??? might not be considerably less noise, but it would be further from the body, with little direct flow onto the chassis???

I have thought of all the above, But pointing at the road does increase the noise not a fan of this noise increase , Dont like the side pipe Idea plus the costs involved in doing this , I will just use the spare fiber heat tape and possible glue it to the body or get the same shields that they use at the exhaust places

OK! Just as I thought, so how would you fix this problem?

To be honest mario I don't Know how to resolve this issue,adding more material to the divider then trimming it down to size to match perfectly seems to be the solution but then the expansion of both metals need to be taken into account and this will take some serious time and still might not seal correctly.

Welding a Divider onto the back of the turbo then trimming back any splatters seems to be the best solution but this needs to be done with the turbo off the car.

The best solution will be to weld on an external waste-gate and weld the waste-gate on the turbo shut this will offer benefits like more effective usage of your A/R and so but will cost a pretty penny

damn those dogs are funny!!!

check how the great dane gives the stupid labrador a skeef look!!!

After Chatting on the forums to the WRX STI guys in the states that run a similar type of down pipe it was suggested that the divider was possibly not sealing correctly so after we dropped the gearbox for the clutch I set to working checking the divider , The Divider is 4mm to short from sealing so after making a few spacers and a nice port 😂 this is the new divider hopefully this will make her allot quieter

Good job, let us know how it turns out

I actually wanted too talk to you about that, read up that is a major problem eith most screamer pipes for internal wastegate turbos.

Let us know how it is now.......