Need A Dump...

[_x_FiReStOrM_x_]

Did a quick search, to no avail. Sorry if this has been covered, and my search skills are just lacking, but i could only find RB26 info.

Basically after a new dump pipe for RB20/25 standard exhaust housing (its a hiflow). Wanting a short dump if possible, similar to the factory one so i can reuse my front pipe, due to it having a flex pipe welded in which i wish to retain.

I fitted a cheap stainless split dump about 2 years ago, and immediately noticed it was harder to control boost steadily compared to the stock dump, but could never be farked refitting the stock one so i've just put up with it since. I am aware of the HPI bell mouth style ones which look like a good bit of kit, but $500 seemed a tad excessive to me. Is there any other options out there, what have you had luck with/ or are currently using, or should i go back to the standard dump (only @ 200rwkw)?

Opinions/info greatly appreciated guys! Cheers.

[GTSBoy]

Just Jap. Get the full length bellmouth** one, and take your flex joint out. Simply not needed on an inline engine. Goes all the way from turbo to cat.

** I'm just recommending the bellomouth because the dump Nazis here would scream at me for recommending the Just Jap full length split, which I have and think is better.

[_x_FiReStOrM_x_]

Haha, cheers for the reply mate. That's fair enough. The main reason i was wanting the flex was that the car has a hacka-tig-together 3" stainless import spec one piece exhaust, which has the cat flanges welded on in a stupid angle. The flex gives a couple of degrees of bend which helps it all bolt up nicely. I would rather not have to have the pipes cut, lengthened & rewelded for the sake of saving headaches, because the cat looks like its mounted slightly further back than stock, which the welded in flex pipe helps to reach. Kinda hard to explain in words. Crazy japs.

Though if thats what i ultimately have to do, it's almost worth spending the extra and just getting the HPI. Or if theres no gain to be had, back to stock.

Edited January 8, 2013 by _x_FiReStOrM_x_

[ARTZ]

i got one you can have with a screamer pipe attached if thats your thing

[B-Boi34]

I went with a Justjap 3inch bellmouth dump. They are pretty cheap & seems to do the job but yeah doesn't help if you need to keep the flex.

[_x_FiReStOrM_x_]

** I'm just recommending the bellomouth because the dump Nazis here would scream at me for recommending the Just Jap full length split, which I have and think is better.

At the risk of starting the usual shit flinging contest; why do you consider the split to be better, how much difference in terms of performance is there or is it purely for sound or ground clearance issues?

i got one you can have with a screamer pipe attached if thats your thing

Cheers mate, but i need to keep things a tad more inconspicuous due to the cops around here.

Looks like there's not too many options in the short dump pipes. Did anybody notice a big gain in performance from fitting just the dump alone? Mine was so long ago i cant remember.

Edited January 9, 2013 by _x_FiReStOrM_x_

[GTSBoy]

At the risk of starting the usual shit flinging contest; why do you consider the split to be better, how much difference in terms of performance is there or is it purely for sound or ground clearance issues?

I base it on my knowledge of gas flow (that's what I do) and also some wisdom imparted by a Garrett engineer on PF many many years ago. In fact, so many years ago that it was probably still AutoSpeed forums. Turbine dumps work best when they are not a great big gaping cavity, but are instead a smoothly expanding cone. OK, so that's hard to actually arrange in an engine bay where the dump has to bend downwards pretty well straight away, but teh split dumps come closer to that ideal than big ones do.

Most of the (valid) arguments brought against the split dumps here have centred on the flap fouling. Which is fair enough....the really cheap ones have had a history of doing that. But mine fit fine and has worked splendidly. Boost onset with my RB20 was a lot earlier, and sufficiently more steep that I had to back off the anti-creep in my pneumatic boost controller to stop it from just wheelspinning (which is the basic RB20 characteristic when you have boost wound up and the wastegate held shut.....nothing, nothing nothing, BOOST.) I haven't compared the dump against a stocker on the 25Neo because it didn't make sense to try to fit back the crappy old stuff.

[_x_FiReStOrM_x_]

That's really interesting stuff mate, thanks for that!

So it sounds like that would be a good way to go, i just need to weigh up whether its worth the $ of having the rest of the exhaust re-tig'd to match up to the front pipe, as opposed to just getting the bolt on HPI for $499. I cant seem to find the just jap full length split on their site though. :s

The only reason i'm going through this is that i need to remove the exhaust manifold to repair a couple of broken studs, so i figured now was as good as time as any to get rid of my china spec boostspikedump lol.

[wolverine]

I back to back tested a name brand split with a good bell mouth and the bellmouth outperformed the split by a whisker. I had no issues with fouling of the wastegate. I put down the slight improvement to having a larger area for gas expansion just outside the turbine for the gains observed. Probably the harder you push the car the more the split helps when there are more gases being wasted.

Given that the performance difference was minimal (in my case slightly less with a split) but the price difference is significant why pay more for it?

Either will do the job well enough.

[_x_FiReStOrM_x_]

Well this makes things harder lol.. J/k. Cheers Wolverine. The main problem i have is boost control is finicky at best compared to the stock dump. I wonder if my problem is that the w/g flap IS fouling on the dump.. doubt i would have checked that ages ago. You didn't happed to compare either aftermarket one to the stock pipe at all?

[wolverine]

No comparison to the stocker was tested.

It sounds like yours might be fouling but it still might be easier to get a bellmouth than frig around die grinding and then refitting and testing. I reckon you will come up trumps either way.

[_x_FiReStOrM_x_]

True. I will have the turbo off of the car during the process (exh mani has to come off) so i guess i can d/c the actuator and work the flap by hand for test fitting purposes. Still considering trying the stock one again too. Otherwise when i finally get pissed off enough, i'll throw the towel in and get a new complete turbo back system lol.

[GTSBoy]

Stock dump is a miserable thing. Better off making a temporary one out of playdough and spit than refitting one.

[_x_FiReStOrM_x_]

That... can be arranged.

Won't bother with the stocker then, it can be used as a toilet. I think i'll just pull the car apart and suss it out (see if w/g flap is fouling) before making the decision. Was hoping there was an easier solution but no such luck.

Thanks for the help guys. Muchly appreciated.

[Missileman]

like the title of this thread...

brb

[Kinkstaah]

I was in this situation (had a 'full' exhaust made which didnt have a dump in it...??) and ended up giving up and getting the HPI pipe.

Its nice and shiny, and for the most part it was less stressful. I'm just a lay person but when I held the stock one side by side with the HPI one it was pretty clear one would flow better than the other

[_x_FiReStOrM_x_]

Did you buy the HPI from Justjap? Is the $499 retail about the going rate at most stores, or is it available cheaper elsewhere?

[Kinkstaah]

I did get it from Just Jap due to impatience lol. I didn't actually FIND anything that was a stock dump replacement anywhere else, but my google fu is weak and I just wanted something I would know would fit. I'd much rather spend the extra $ for peace of mind, I didnt get a one piece front/dump simply because the guy didnt have a standard nissan turbo flange.

He didnt tell me this mind you Wasnt really the optimal way to go about getting a turbo back exhaust!

[D.I.Y. Mik]

The jjr split dump fouls on the coolant line on an rb20 so you have to move it.

If you go cheap be prepared for re welding the exhaust to fit.

[_x_FiReStOrM_x_]

Thanks for the opinions guys. I'm now almost leaning towards saving up for the HPI, just because of the whole 'no fuss fitment' thing.