Down-Pipe Troubles

veecee · Post by **veecee** » Mon Aug 25, 2008 10:26 pm

damn those dogs are funny!!!

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

Pinkfluffybunnys · Post by **Pinkfluffybunnys** » Tue Aug 26, 2008 9:40 pm

Pinkfluffybunnys · Post by **Pinkfluffybunnys** » Thu Aug 28, 2008 6:39 am

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

Daniel · Post by **Daniel** » Thu Aug 28, 2008 8:39 am

Good job, let us know how it turns out

mario_200sx · Post by **mario_200sx** » Thu Aug 28, 2008 9:05 am

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.......

Daniel · Post by **Daniel** » Thu Aug 28, 2008 3:49 pm

I want to hear it too one day...was thinking of the screamer pipe route till i saw youtube vids with the same screamer pipe setup as you, dont think i could live with that noise

Pinkfluffybunnys · Post by **Pinkfluffybunnys** » Mon Sep 01, 2008 10:33 pm

OK After getting the car back today I can confirm the spacers have made the car a little quieter but you cant believe the sound she makes when you come onto boost I had a huge smile from ear to ear but I think I may get sick of it.

But the performance is night and day change and its not the sound shrouding my judgment but it might be the clutch, quick shifts kick out the back-end all the time on boost my wideband is still very lean even after taking a long drive not sure why this has happened

Gary57 · Post by **Gary57** » Tue Sep 02, 2008 8:21 am

Now what difference do you think there would be going from a shitty bellmouth to a diffused DP like this?? I have been looking at doing this for ages but you cant buy a downpipe for my Turbo.

Now tell me, your DP is 63mm and your exhaust is 76mm, Dont you think it would be better to go with a 76mm DP to suit the Turbo?? On my turbo a 63mm pipe would fit perfectly but I am concerned if I will loose the benefit of the 76mm exhaust if I fit a 63mm DP.

Pinkfluffybunnys · Post by **Pinkfluffybunnys** » Tue Sep 02, 2008 10:39 am

As long as the system is increasing in size there will be no back-presure build up but I couldnt fint a 76mm pipe and keep my screamer set-up

Just extra input

Off boost before my waste-gate is closed my exhaust system is a maximum of 63mm because this is the smallest point very big for an N/A low compression motor. But once I start boosting and the waste-gate opens the exhaust system theoretically increases to 101mm as the wasted-gasses will be vented down the 38mm screamer. It is true that more exhaust energy will be needed to drive the compressor wheel as engine RPM increases to keep the car at the desired boost level but this would never reach the full capability of the 63mm Pipe.

Also you need to take into account the velocity of the gasses slamming into one another as the waste-gate opens in a bell mouthed set-up, and then being funned down from a large opening just after the turbo to a 76mm pipe as I said in a previous post in this thread the exhaust gasses will speed up to move through the smaller diameter opening but there will be an increase in pressure just before the diameter change just after your turbo causing back-pressure.

The screamer set-up also allows for better boost control as the exhaust energy will take the path of least resistance and not flow through the turbine ,why because the pressure difference will be more on the waste-gate side because on the Atmo vent. If you do go with a Divorced Down pipe please remember it needs to be at least 30cmin length before it rejoins the exhaust system this allows us to move the pressure point further down the exhaust system and not making the bottle neck right after the turbo

Gary57 · Post by **Gary57** » Tue Sep 02, 2008 11:14 am

Phinx the thing is the 38mm pipe and the 63mm pipe dont make a 101mm pipe, they only make a 73mm pipe, you have to take the area of the pipes not the diameter.

I dont want a screamer pipe setup but I do want the diffused setup, I personally think its better. Do you think I will get any major gains by changing from bell mouth to diffused DP??

Pinkfluffybunnys · Post by **Pinkfluffybunnys** » Tue Sep 02, 2008 11:51 am

Phinx the thing is the 38mm pipe and the 63mm pipe dont make a 101mm pipe, they only make a 73mm pipe, you have to take the area of the pipes not the diameter.

LOL that was an EPIC Math fail on my side

dont want a screamer pipe setup but I do want the diffused setup, I personally think its better. Do you think I will get any major gains by changing from bell mouth to diffused DP??

To be honest Dude, I don’t really know I have seen gains with this change over but I can guarantee any improvement on your set-up

Gary57 · Post by **Gary57** » Tue Sep 02, 2008 12:02 pm

I am just trying to weigh up the cost vs gains, I know there will be a gain, there has to be, i am just not sure how much of a gain there will be. Also I am not sure how much one will cost to build.

Draco · Post by **Draco** » Tue Sep 02, 2008 12:23 pm

Gary u are a machanical ingeneer....I am sure it's not that hard....get that mad scientest of your other half going...do a little test, before and after...see if this thing really works and how much....

Just think.....our own 200sx myth buster

Gary57 · Post by **Gary57** » Tue Sep 02, 2008 12:52 pm

Draco it will work and will give an improvement. But the thing is it will cost me about R400 to make and a good day to build it properly, I was hoping to find out if it is worth this effort cause somehow I dontthink it is

.

Draco · Post by **Draco** » Wed Sep 03, 2008 7:56 am

Mr Turbos T28/T3.....looks promising......