Quiet Screamer Pipe

[**RB2530**]

I had been thinking about doing this for some time and eventually did..I was making a new dump pipe (3.5") and was about to start making the waste gate plumback pipe but thought I might try a screamer pipe just to see how it went...

No dyno runs were done but it felt much stronger above about 4000-5000 rpm....ie when WG starts to open a fair bit...Then I did the maths and 3 1/2" pipe + 2 1/4" WG pipe is equivalent to at least a 4" dia pipe....Btw I have a 60mm external gate so it is very free flowing...So at this stage I confirmed to myself that a screamer pipe does have a performance advantage (as long as WG pipe isn't some small pissy dia)...But the noise is huge...Way too loud and sure to be pinged for it one day...

Now I am not sure who else had tried this and I was told by quite a few that it wouldn't make any difference but I fitted a muffler to my screamer pipe...Now I know some are going to say that you lose the advantage of the screamer due to extra back pressure and I agree partially. You do restrict the screamer pipe a small amount but where you gain is that the WG exhaust never re-enters the exhaust..This is known to cause extra back pressure due to turbulence...This is fact...also the way I look at it, when my WG opens my exhaust system increases in size by the equivalent of 2 1/4" dia...So it is equivalent to 3 1/2" when you are just cruising and jumps up to just over 4" when you need it...

Not rocket science...

Now as far as what it sounds like...It is hard to describe...Definitely a lot quieter than a full on screamer pipe...It still has a rough note to it but you can only just hear it above the main exhaust...Part of the reason would be that it dumps under the drivers seat...But it is heaps quieter than a standard screamer..I would describe the sound as being a touch louder than plumback exhaust but engine sounds more like a V8 or V12....

From a RTA point of it is wrong on 2 counts...A) It still bypasses the CAT and its outlet and B) is not 1m past the last opening window...As far as B) is concerned it is not safety issue because whenever the WG opens, the car will be moving and exhaust fume will be blown away by air travelling under the car... Point A) concerns me and I my plumb it back soon...

Anyway just thought I would put this out there... Any comments good or bad welcome...

[R31Nismoid]

What turbo? Im assuming something up near 350-400rwkw mark?

If thats the case, you really need a 4" exhaust on there (if it was to be plumbed back).

So yeah, your seeing a really good improvement now that you have made some extra flow that was lacking before.

Also the angle the gate plumbs back in on play a factor, where it plumbs in etc etc.

Good work overall (even if its not legal just quite yet )

[NYTSKY]

Wow.Thats a great looking screamer.Would be interesting to hear what it sounds like (hint hint)

Ill be getting two dump pipes made soon, One to go with the screamer and one fully plumbed.

Best of both worlds,the screamer will be only for track use though.

[GeeTR]

Very good work dood!

Fan'tabulous to see ppl being innovative!

Bout the whole legality thing... if a 1L motorbike doesn't need a cat.. why should a ~2.5L turbo car motor.. get done for a screamer without one? Seems silly, when its only venting sometimes... - basstards.

[R31Nismoid]

Bike's run a lot leaner through factory (just something to think about)

[Guilt-Toy]

that is so damn bollocksing coool man!!! i been thinking about doing a mod like this for years now, except i was going to run a cat on it and run it all the way to the rear of the car to try and make it legal.

I was thinking though, during the emissions test my turbo never came onto boost so if the waste gate is not opening then as long as the sound is ok you shouldnt legally be required to have a cat?

how much did that cost you to setup?? your wastegate pipe looks huge compared to mine as mine is only a 38mm.

what kind of muffler is it ?

good work!!

[TTT]

What turbo? Im assuming something up near 350-400rwkw mark?

If thats the case, you really need a 4" exhaust on there (if it was to be plumbed back).

From a previous thread where we were chatting about Bosch bovs..

I have been using Bosch BOVs on my Skyline for 4 years without a drama!! I have been running around 260rwkW (1.1 bar) for the last 12 months and the BOSCH BOV is fine.

would have been good to see before and after dyno results..

If you have a 3.5 inch exhaust, and only using 1.1 bar boost, it doesn't seem that it would cause a restriction (in theory)..

but seat of the pants is all that we have to go by sometimes..

you sure it didn't seel stronger due to sound under your seat?

Edited March 5, 2008 by GTST

[race_snooze]

find a new bike cat and use that. I know the VFR's have them.

[Guilt-Toy]

i maate 363rwkw with a 3" plumbed back.

From a previous thread where we were chatting about Bosch bovs..

would have been good to see before and after dyno results..

If you have a 3.5 inch exhaust, and only using 1.1 bar boost, it doesn't seem that it would cause a restriction (in theory)..

but seat of the pants is all that we have to go by sometimes..

you sure it didn't seel stronger due to sound under your seat?

[l0WRB]

just a quick question, where abouts do you buy them steel straps that u use to hold your heat wrap on?

[GeeTR]

just a quick question, where abouts do you buy them steel straps that u use to hold your heat wrap on?

Repco,

[GeeTR]

find a new bike cat and use that. I know the VFR's have them.

Serious? Hrrm, maybe i should actually look up the law, see from what year onwards they had em lol. Doesnt matter, ill still whinge bout it. I red a statistic that Ozzi cars account for 0.0000001 of the worlds carbon footprint, and they threaten us with $20k fines for no cat - *sniff*

[GeeTR]

Bike's run a lot leaner through factory (just something to think about)

I think it was GT who found that when tweaking his car for emissions, a richer mixture was needed to lower noxious gases?

Seems crazy. I been watching all Club Sports and BA V8's, and gee they do shoot the soot when under load.

A mate mentioned that when getting his car over emissions, the guys there said often the RTA or what ever, will swoop on a OEM shop front... like Holden or Ford and demand tests of all the stock cars - many of them fail. STOCK cars failing set emissions laws? hrrrm.

Somthing more to think about.

[**RB2530**]

that is so damn bollocksing coool man!!! i been thinking about doing a mod like this for years now, except i was going to run a cat on it and run it all the way to the rear of the car to try and make it legal.

I was thinking though, during the emissions test my turbo never came onto boost so if the waste gate is not opening then as long as the sound is ok you shouldnt legally be required to have a cat?

how much did that cost you to setup?? your wastegate pipe looks huge compared to mine as mine is only a 38mm.

what kind of muffler is it ?

good work!!

It cost me about $100 in total..About $50 for the muffler (I will check invoice for type but it is straight through 2 1/4" inner with a 4" outer dia centre chamber glass packed)..I was lucky to find some 2nd hand SS mandrel bends very cheap ($20) and then a 2 bolt flange kit and gasket etc took it up to about a $100...All labour supplied by me...free....I spoke to a couple of 'exhaust Gurus' and they said dont do it..."Its not the sort of noise you can muffle...WTF?? What does the main exhaust system do???

Just on the power, bit yes the car is making about 250-260rwkW and I know I will have my doubters here but 'I use a standard ECU' with standard injectors...I run a rising rate regulator and run heaps more ignition advance than stock. I will be the first to admit that the tune would be shit and fuel is my limiting factor by far. I run a very fast acting thermocouple in my exhaust and measure EGTs regularly and never exceed 850deg C...Engine also has forged internals and I have Nissan Consult software to see what is going on...

Just a note on exhaust...I once spoke to a Guru once who told the for a turbo car the best exhaust is no exhaust...Cam overlap and the fact that the turbine provides heaps of back pressure means that anything after turbo acts to impede gains...So in saying that even if you are only running 200rwkW on 3" exhaust, going for a 3.5" exhaust will still give you a gain...and then if you go for 4" exhaust even more of a gain..but probably not as much....Nothing is linear in the real world....Have you ever heard anybody say "shit I have put on a larger exhaust and lost power" Not on a turbo car...Maybe yes for a NA car...

Also the bigger the exhaust, the less laggy it will be...simple reason is that increase pressure drop across turbine which puts more energy into turbine wheel...So yes the exhaust is big but will be perfect for when bigger injectors and good tuning happens..

[**RB2530**]

And yes it does sound louder because I am sitting right in top of the muffler....I had to put it on the right side of the car due to space limitations...

[GeeTR]

I once spoke to a Guru once who told the for a turbo car the best exhaust is no exhaust

Yup, thats my understand, i dont listen to ne1 who speaks differnt.

60mm WG, Consult, EGT probe, do your own welding - respect. This setup/thread rocks!!

[Guilt-Toy]

How do you get around the air flow cut ? is the ecu remapped at all? like one of those jap ones?

good work... will you do mine for $150 ?

[tacker]

some thing like this one

[GeeTR]

Now thats a low mount

Assuming thats a cat in Porsche?

[tacker]

yer it is good guess