Jump to content
SAU Community

Dump Pipe Or Front Pipe

mrsr32

By mrsr32,
in Engines & Forced Induction

 Share

Recommended Posts

mrsr32 Rising Star

mrsr32

Posted
Posted

I've got a 3" exhaust off the factory dump pipe and would like to replace the stock dump pipe with one that seperates the w/g gases.

Should I go for something like this that looks like it would bolt in and replace just the stock dump pipe

http://www.drivenperformance.co.nz/scripts/prodView.asp?idproduct=329

or go with a whole front pipe which seperates the wastegate for much longer (this just means I need to get my existing exhaust modified to suit)

mgp-rb20.jpg

Link to comment
https://www.sau.com.au/forums/topic/410435-dump-pipe-or-front-pipe/
Share on other sites
Moodles2 Grand Master

Moodles2

Posted
Posted

All a split does is create more problems, cheap ones almost always have the internal wastegate flap getting jammed against the splittter you can see in the photo that seperates the 2 streams of gases

jjman Mentor

jjman

Posted
Posted

Except for when you install them carefully and properly (like mine) and then you get no such problems.

and so when it is done properly like this what does it truly do?

create a more stable flow/boost pressure?

iv got this setup too that works perfectly but iv always wondered what it truly does over a big bellmouth...

gtsttrk Mentor

gtsttrk

Posted
Posted (edited)

If you were looking at a split dump I'd say look into the CES split dumps. Apparently these utilise a a longer split pipe, unlike the JJ ones etc and are supposed to effectively reduce back pressure on the waste gate flap (iirc).

So therefore I'd say the full split front, and not the just replace the stock dump.

Edited by gtsttrk
GTSBoy Grand Master

GTSBoy

Posted
Posted

and so when it is done properly like this what does it truly do?

create a more stable flow/boost pressure?

iv got this setup too that works perfectly but iv always wondered what it truly does over a big bellmouth...

The point is to stop the wastegate exit gas flow from splashing horribly across the turbine exit gas flow. If you can keep them separate, the idea is that the turbine exit gas gets a much more efficient expansion out into the dump, resulting in lower overall backpressure, or more to the point, more pressure drop across the turbine (meaning better power available to drive the turbine). The wastegate gases are then dropped in much further down where they don't interfere so badly.

If you were looking at a split dump I'd say look into the CES split dumps. Apparently these utilise a a longer split pipe, unlike the JJ ones etc and are supposed to effectively reduce back pressure on the waste gate flap (iirc).

So therefore I'd say the full split front, and not the just replace the stock dump.

The CES dump is possibly a bit nicer in the conical expansion of the turbine exit region than the cheapy is, but as far as I can tell, the return point for the wastegate flow is about the same distance down the dump. This is for the case of the split cheapy shown above. Any of the really short split cheapies, where they are intended to only replace the factory cast dump and mate to the original front pipe, are the ones that are not worth considering.

When I changed to my cheap split (JJR I think - many years ago now) I gained a good improvement in boost threshold, more stable boost control, and an increase in max boost that I then had to adjust out. That shows me that the wastegate flow was better (boost control improvement from less intereference between wastegate and turbine flows), that the overall pressure drop was lower (better boost threshold) and that the flow at high flow rates was better (increase in boost). Overall, it has been good.

The only open question is whether those changes would have been the same, less, or greater if I'd gone with a bellmouth dump. I don't have a comparison.

Most of these guys around here just write off the concept of the split dump though. I can't understand how they refuse to accept the idea of them, yet all agree that an external gate on a bigger turbo is a better idea. The ideas are related.

gtsttrk Mentor

gtsttrk

Posted
Posted

Does anyone have an example of a split that brings the WG flow back in basically where the the dump joins up with the cat? I've had a look around but haven't been able to find any that are produced like this.

jjman Mentor

jjman

Posted
Posted

never heard of such a design. N also could imagine why it would not exist as trying to merge the gas flow as it is also dealing with another change (going into a cat) could reduce efficiency of the design as opposed to merging it a bit further up the dump pipe- just like in the pic by the OP

gtsttrk Mentor

gtsttrk

Posted
Posted

never heard of such a design. N also could imagine why it would not exist as trying to merge the gas flow as it is also dealing with another change (going into a cat) could reduce efficiency of the design as opposed to merging it a bit further up the dump pipe- just like in the pic by the OP

Yeah I worded what I was asking very poorly, too much excitement from the granny lol :laugh:

Basically I was asking if anyone knew of a split like the one in the OP posted a pic of. Virtually all the ones I've seen either just replace the stock dump, or utilise the shorter split such as the JJ, CES etc.

Dose Pipe Sutututu Grand Master

Dose Pipe Sutututu

Posted
Posted

If you're not making loads of power and using the stock turbo especially, you're not really going to notice any real gains with the split, not to mention there's room for it to jam and give you headaches down the track.

Save the coin for a slab of beer and just get the bell mouth.

mrsr32 Rising Star

mrsr32

Posted
  • Author
Posted

Ok, so it looks like the latter is the better one of the 2. Had a hunt around for belmouths and there aren't any readily available. either way, its gotta be better than the stock dump. i'm interested in the gain i get vs my stock dump into 3"

gtsttrk Mentor

gtsttrk

Posted
Posted

I've used a JJ split before and didn't think that it was a bad little piece. Had it installed correctly and I definitely felt an increase at the RPM's that boost came on. The spool definitely seemed to come on earlier than when I was using a belmouth. Mind you, this could have just been a placebo. But the JJ split isn't bad for what you pay.

Just out of interest, has anyone used any of the CES products that I mentioned earlier? If you look at their website some of their products boat huge KW gains for what they are.

wolverine Grand Master

wolverine

Posted
Posted

If you're not making loads of power and using the stock turbo especially, you're not really going to notice any real gains with the split, not to mention there's room for it to jam and give you headaches down the track.

Save the coin for a slab of beer and just get the bell mouth.

This^^

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share
Go to topic listing


  • Similar Content

  • Latest Posts

    • The Bogan
      NC MX5

      By The Bogan · Posted

      Seat of the pants assessment of the new intake: The car is way less "doughy" when hitting the loud pedal, especially off idle when stopped or in traffic, I did use a cheapo lazer thermal thingo to measure the temp around where the pod filter got its air, it was between 55 - 60°C, in saying this the car was shut off and not moving, so the OEM intake pipe was not supplying any fresh air to where the pod was when the car was at least moving A weird bonus was induction noise on the throttle in the cabin increased a bit,  I was worried that I was actually going to lose some of that induction noise I love so much, outside though, when I got the daughter to do a WOT drive by pass for me, the induction noise has increased alot when on the throttle, not quite ITB doort, but well up there I'm extremely happy with the results and have been exploring the country roads in the region  As for house mods: 1.New front fence is up and is awesome, it really upgraded how the joint looks from the street, and the added security is nice 2. Electricians have replace some interior lights, and with more lighting in the garage, a few new motion detecting lights out the front above the garage, front room, and at the front door, which I have already found heaps helpful coming and going, also now has fancy pants CCTV all round the house The only hold point for power though is the solar and batteries due to supply issues, although this will happen over the next few weeks 3. I have done a heap of landscaping out the front and I'm almost ready to do a new small retaining wall with some nice blocks to replace the brick and cemented in rocks around the raised garden beds cemented in river stone "was the fashion at the time" the house was built. I currently have a pallet of retaining wall blocks and 2 bulka bags of 20mm blue metal to replace the wood chip that is in the raised garden beds around the house 4. I now have 3 big raised garden beds for out the back to grow some vegetables, about 70cm high, 200cm long and 100cm wide 5. My 2 compost bins are already pretty full with brown, green and kitchen waste from the landscaping I'vedone so far, but they will probably take a few months to break down, so anything else that gets chopped, trimmed, and kitchen waste will just start filling the base of the raised garden beds to about 30cm before I start throwing 40cm of good compost, and stuff, for the vegetables to grow in, I'll need a few ton of compost and soil, but the local supplier can sent me bulka bags of the stuff Basically the logs, wood chips and a few strategically placed rocks for drainage, will give the beds some good organic materials down low to break down over time, and they will hold moisture during the warmer months to save the water in my big arse water tank if we don't get alot of rain So, all in all, the car and house mods are going well, and I'm really enjoying being retired, I sleep in too 0700 and slowly plod around inside until I feel like actually doing anything, and only work in the yard for as long as want, which has actually been alot over the last few weeks,  although when you look at it, it seems that not a huge amount of work has been done,  until I look at the before I started the work pics Happy days and good times indeed 
    • Dose Pipe Sutututu
      new 1.5 LSD issues/concerns

      By Dose Pipe Sutututu · Posted

      This everytime 
    • DraftySquash
      Looking for someone with a R34 front bar

      By DraftySquash · Posted

      hahaha yeah. Plan is to get side skirts and probably just rear pods. But going to do them one-by-one. I've got a set that I really like from RHDJapen, but that one isn't shipped to AU. So need to find someone who can get it for me
    • MBS206
      new 1.5 LSD issues/concerns

      By MBS206 · Posted

      Here's an idea, answer the questions I asked you as they are trying to work out WHY the LSD will be binding up in a straight line.
    • MBS206
      Most women will agree that parking is the most taxing part of driving

      By MBS206 · Posted

      You haven't driven many modern cars then have you? Most of them have sfa steering feel with their stupid electric bullshit steering systems.
×
×
  • Create New...