Well done for giving it a go, that sheet looks thicker than 3mm?

I look forward to hearing what difference it makes.

Andrew...

A sump plug will fit the lambda boss.....

Hi James I'm not the most tech guy in the world so...

what are you hoping the results will be from this procedure, interesting stuff keep it up.


dazza

The downpipe doesn't look open neck? I cannot help thinking you have just restricted the flow of the wastegate gases.. which will also still cause turbulance when entering the flow of exhaust gases down the righthand side of the pipe and restrict the flow away from the turbo?

Have you had the downpipe on the car without the splitter, then fitted the splitter so you can get a comparison of before and after?

Keeping an open mind.. just my opinion..

Feel you should do with and without spliter comparison either with Rolling road or at least drive it with and without.

JGM :)

hi daz, hopefully it should give me better low end power and midrange torque.

i had a hks downpipe on but it's a closed neck like the standard one, i'm using the standard one at the mo because of the mot recently. Going back to the standard d/p showed how bad it is standard, the low end responce and power is crap with the standard d/p.
The hks is 100 times better than standard for turbo spool up and low end responce. The open neck d/p is better than the hks for spool up and low end and the splitter mod I done today is supposed to be better still so hopefully it should be good.

I'll let you know.

James

When you say std D/P do you mean with a cat, for the MOT? If that's the case then yes it will be crappier than a de cat d/p.

I guess after the trouble you've gone to that you've smoothed the internal lip and the new welds?

F

I have made my own down pipe and it has an open neck , but on my downpipe the neck is open to the full size of the turbo/wastegate outlet and then narrows to just under 4" about 10" down from the top ,it then continues at just under 4" allthe way to the centre section will this pipe be any good or should i have devided the neck? i have yet to fit it so any ideas would be greatly recieved so i could alter it before i fit it , sorry to hijack but it's on the same theme.

webster,

yours is ideal for the splitter mod with the pipe you described, it's how i would of liked mine but the guy said it would still be an improvement over the normal open neck the way i've done it.

As said before the splitter goes into the turbo housing up against the turbo and sits between the wastegate and exhaust turbine splitting the gases as they exit

james

Hi James I'm planning on having thsi done next week.Remember I'm a non techie aand then try and expain.I understand that the plate should be 3mm thick and for my turbo should extend 27mm into the turbo housing(according to Mike South).How do I centre it in the mouth of the DP.
Many thanks,Deep.

cool, nothing like experimantation.

I'm just getting into all the tuning bits etc so some of the stuff I'll probably ask may be a bit anal for you guys so please be a bit patient with me.

Just a couple of small things, whats this open neck / closed neck jobbies.

cheers

dazza.

( they say you learn summat new everyday...



...they abviously visted ScoobyNet)

V30 turbo for that size isn't it? sti7?, from reading what michael said.

looking at the third picture down, look at the two holes top and bottom to the left of the plate. On mine to get the position it was 19mm to the right (from centre of top hole) and 22mm to the right (from centre of bottom hole).
This may be different for your car but you'll have to ask Michael, think it's the same though.

James

dazza, i'm learning too mate, i'm just an enthusiastic car owner trying a new mod thats all.

The open neck/closed neck is:

open (like above), if you look at the third pic down the whole area there that bolts(5 bolts) to the exhaust side of the turbo is 'open' allowing greater flow from both exhaust turbine and wastegate gases..

..'open' wont mean anything to you without knowing that closed means the same area in pic 3 is closed off apart a hole the size of the exhaust bore on the right hand side of the plate, basically think of pic 3 as a solid plate apart from a hole just for the exhaust pipe. This gives the wastegate a harder route to flow and also disrupts the turbine flow when the wastegate gases have to interrupt the flow of turbine gases by moving to the right into their path. The turbo has(on my car) a 22mm resess where the gases from the wastegate can hit the plate of a closed neck d/p and go down the exhaust on the right.

open neck therefore allows better flow, it tends to be noticed at lower revs allowing better responce and turbo spool up(boost comes in earlier)

closed neck is on the standard d/p and some aftermarket d/p's like hks.

James

Okay, right I'm think i'm with you now James.

The open d/p is obviously the best option so I presume that by welding in the spliter between the two ports will aid the joining airflows smoothening things out and making improvements in gas flow.

Are there any dissadvantages with the open neck.

cheers

dazza

Thats the theory!

re disadvantages: don't think so really, they are i believe at a slight low end torque dissadvantage compared to a 'twin dump' d/p(two seperate pipes, exhaust and wastegate meeting further down the d/p. But they are far supperior compared to the standard d/p for flow.

hopefully though with the splitter mod the open neck should get back the torque the twin dump offers and have better flow than the twin dump.
Remember that the twin dump is not going to flow that well IMO because it's twin dump position is not up against the exh turbine and wastegate but 22mm away allowing the gases to mix up before they make their way down the two pipes of the twin dump d/p thus disprupting flow.

james

Arr right see what you mean, you've just answered another question about twin dump's, basically then the design flaw if I understand this right of the twin dump is that you still have the 2 airflows mixing together directly at exit of the turbo, as with an open d/p and then (22mm) it splits to 2 pipes. ( is that right).

If so then the pefect soloution would be to put the spliter in to a twin dump.

Is this right or am I drinking to many Grolsch...


dazza

Thanks James.I take it from that you mean that the splitter is not at a right angle to the mouth but slants somewhat.Have I got that right? I c'ant find Mikes original thread.When he quotes 27mm for my VF30,does he mean that 27mm should project above the mouth of the DP and whatever length into the DP to allow welding.Also what is the dimension of the splitter from welding point to welding point ie its width.Sorry about so many questions but I'm planning to have this done on Wednesday so need all the info.
Many thanks,Deep.
ps I heard somewhere that the JDM STi8 has this in its DP as standard.

Sorry,I've just seen you state the width in your first post!
Did you do the other stuff that Mike recommends on his site ie machining away the internal lips and gasket face?

As i'm not fitting til i get a bolt for the o2 sensor hole, i'll be getting a new gasket and drawing round the inside and yes doing some smoothing of lip and welds

If you look at Michael's website, he expands the 'open neck' much further down into the pipe than even scoobysport/H&S do/did. The d/p you've started with reduces down very quickly from the open neck.

I'd be intersted to see how yours functions, but suspect it wont be optimal - has Michael seen these photo's and commented?

Richard

yeah i'm aware of this and I asked Michael what he thought last week. He reckoned it would be beneficial.

Also like I said bare in mind the plate is only 12mm inside the d/p and the splitter is in the area at the back of the turbo not in the d/p, so if you think what is in the actual d/p it is very minimal area and the point is the split from turbo to d/p not the split in the d/p

James

I think TSL do a bolt for the downpipe but there site is down at the minute..

Dan:D:D

yeah i know, think £12 for a bolt is a bit excessive though.

I'm going to get one from an agricultural engineer tommorrow, they were shut yesterday.

Might get a few more and sell em for a fiver lol

james you're a star mate.Thanks for reposting the piccies with dimensions.Yes I have a VF30.Do you have Mikes email so I can confirm with him that the orientation from the bolts is the same as yours.
Thanks for taking the time out,Deep.

No worries, his email is msgofast@bigpond.net.au

Thanks

Hi Michael.Was about to email you about the position in relation to my turbo,thanks for answering that.Should get the mod done on Wednesday.Why is that lip there in the first place?

The lip is there as from the outside it all looks like a nice fit , but the inside is where it's at , they have just slipped 3" inside the tappered part and that is the result, some grinding and it will all smooth over easy.

To gring this stuff you can buy carbide Burrs from your local engineers supplys that fit a die grinder and can spin at 10,000rpm , use some lube like WD40 so they last a long time and you would rip that lip of in 45 sec easy.

Michael

Cheers Michael, going to fit this weekend so plenty of times to smooth things out.

James

FWIW I have done a similar mod but fitted it into the turbine housing. This way I made a smooth curved transition from the turbine to the downpipe. The CSA increases gradually from the turbine exit into the downpipe. The wastegate gasses do not rejoin until 400mm+ down the downpipe (Falkland twin dump)

Any interest then I can post up pict later tonight. :)

Andy

If you need to blank the hole quickly get to a breakers and find a spark plug from any pinto engine.