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Stegea Dump Split Or Single?

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andy65b Veteran

andy65b

Posted
Posted
Hey Guys,

First thing is first, yes I am in the Exhaust industry, and Secondly I am not here to cut anyones Grass with the Group Buy thats going on at the moment.

What is the general feel on Dumps, Split or single on the M35's?

E man

I have not been able to read a lot about the preferred choice on dump pipes for the m35 as there are not available. The only ones I have seen ex japan are single bell mouth.

I know Liverpool exhaust have done a split dump for the M35 and the guys who have this are happy with the results.

Beyond that I can not really add much to the discussion if this has added to it at all. :P

I would personally be happy with any improvement at a reasonable cost.

Cheers

Andy

nickcorr Proficient

nickcorr

Posted
Posted

Coming from an R33 GTS-T, I have always been led to believe that split is better than bellmouth.. But on the RB25s you get a combined dump and front pipe replacement, that seperates the wastegate and turbine gases all the way to the single cat. Aparentlty the power benifits are huge...

With the M35s having a much shorter run from the turbo into the next cat, are the split benefits more margional, like those little dump replacement pipes for the RB26s?

Exhaust man Newbie

Exhaust man

Posted
  • Author
Posted
i take it i met you today @ liverpool

what size pipes are you running for the spilt?

I am he, as for the split sizes I am un-sure.

As I said at the start of the conversation I am not hear to cut anyones grass, just to provide advice and receive feed back.

Here is the punch line, I did mention to you about the dump being available on the market soon, well it's available now.

E-man

Exhaust man Newbie

Exhaust man

Posted
  • Author
Posted
post-31456-1244120591_thumb.jpg

dont see the need for a split with the m35's exhaust housing, its not going to do what splitting the housings/gasses is good for, wouldnt a bigger bell mouth exhaust flow more?

p.s. tell em the price son!

Firstly 3" will flow 3", and whether it is split or single 3" if will still flow 3".

The reason for the split is to stop the turbulence caused when the wastegate opens, we can all establish that.

The next thing is to make sure you have a long enough split. If the separated pipe is introduced to early you end up with turbulence again (eg the jap branded version 1 split dumps on sr20's RB25's and even RB26's).

What we have found is that you have to introduce the waste gases after a certain point to start an extraction effect, same way we design Headers(Extractors).

Back to the bigger bell mouth.

Yes Bigger is better than some split designs, to give an example.

In the XR6 Turbo's, people pull off the split 3" designs and go for a single 4" design, gaining more torque and top end power, but the difference here is that the XR6 has heaps of room for a big dump, where the M35 does not.

With this info at hand We tried for a 1 piece design, but required donut bends to be used as the first bend of the dump pipe, hence providing more work for no more power.

You will notice that in the photo of the single dump of the single design thats floating around on the forum that the first bend is a different shade to the second bend, this shows me that the first bend has been casted and welded to the flange and the second bend (a standard mandrel bend) has been welded on to the casted piece.(outlined in my illustration)

post-63520-1244126104_thumb.jpg

Now the M35 has very little room, so the split design is the most efficient for power, torque, and clearances to the body.

Back to the question "wouldn't a bigger bell mouth exhaust flow more?"

the answer is yes, but a 3" single flows the same as a 3" split but the 3" split extracts the gasses out better and more efficiently giving you better torque and power.

Angus, now since you asked I will work out a group price for forum members but would require a show of hands (PM Preferred).

But as I said I am not here to be the Jim's Mowing Man and cut your turf or your dump pipe, but offer M35 Enthusiasts a good quality product.

PS. we also do Ceramic Coating, and yes it is the Made in USA stuff

E-Man

zei20l Grand Master

zei20l

Posted
Posted

just so you know, that top piece is CAST, there is no such word as CASTED.

and im happy to purchase from either person, maybe whoevers is first, looks the best quality (probably THE most important part), the material and price...........

Jetwreck Grand Master

Jetwreck

Posted
Posted (edited)
Back to the question "wouldn't a bigger bell mouth exhaust flow more?"

the answer is yes, but a 3" single flows the same as a 3" split but the 3" split extracts the gasses out better and more efficiently giving you better torque and power.

What do you think if you have a high flow turbo? Would it not be better to still have a single? I had an R32(about 650hp with high flows) years ago and we started with splits and switched back to singles...worked out better for us....is that because we had more room to do it properly.

Also what do you think if you had no Cat(for off street use only)....would a single or split work better?

Edited by Jetwreck
Angus Smart Grand Master

Angus Smart

Posted
Posted

that first piece isnt cast. your kidding right??

and your main exhaust pipe from your split isnt 3 inch. it would be closer to two.

the first bend is a tight 90, not that hard to achieve. it is in no way cast!

its stainless just like Tomei's version below.. these are on my gtr, and without a doubt flow alot more than a split design system like Trust's long split front/dump

RB26-outlet-580.jpg

iamhe77 Grand Master

iamhe77

Posted
Posted (edited)
Also what do you think if you had no Cat(for off street use only)....would a single or split work better?

no Cat for "off street use only"? Take that tongue out of your cheek young man!

hmm, I don't think that this will be a "one size fits all" type of item.

You and I both have highflowed turbo's, but your is much shorter than mine.

You also have a custom dump back I believe, where as I have a Kakimoto front pipe and a Fuji exhaust... probably a different total length (I couldn't fit that flexy bit between the dump and the front pipe from the OE system)

I have seen a couple of other M35 exhausts and they are both different lengths as well (muffler tip to front pipe flange).

How much longer than the OE dump will these units be?

Will they need a specific front pipe/cat?

Could/would a bellmouth design be shorter than a "correctly extracting" split design?

Edited by iamhe77
wolverine Grand Master

wolverine

Posted
Posted
Back to the question "wouldn't a bigger bell mouth exhaust flow more?"

the answer is yes, but a 3" single flows the same as a 3" split but the 3" split extracts the gasses out better and more efficiently giving you better torque and power.

it is an interesting area. we made more power everywhere with a bellmouth over a very high quality name brand long split dump.

there wasn't heaps in it but back to back more power/torque with a bellmouth up around 250rwkw.

having a larger negative pressure area just outside the turbine outlet provided by a bellmouth may allowing room for thermal expansion that a split doesn't allow?

Angus Smart Grand Master

Angus Smart

Posted
Posted
it is an interesting area. we made more power everywhere with a bellmouth over a very high quality name brand long split dump.

there wasn't heaps in it but back to back more power/torque with a bellmouth up around 250rwkw.

having a larger negative pressure area just outside the turbine outlet provided by a bellmouth may allowing room for thermal expansion that a split doesn't allow?

I'd like to note, the flange for the stagea fully open will just fit a 3 inch round pipe belted into shape..

his is a split system.. now that means you've just lost over 50% of the flanges size dew to the split design..

there is no way his exhaust is 3 inch all the way.. its impossible to do this with a split design..

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