Scoty

Following James's thread

I sent my downpipe to Hayward and Scott to have the splitter mod done to the downpipe, along with an order for a full 3 inch system.

I've just been informed by Ian at Hayward and Scott, that it will be with me tomorrow.

Pictures to follow.

Contact Ian on 01268 726034
E-mail : - sales@scoobyexhausts.com
Visit their website Hayward and Scott

Scoty

Thanks Ian,
Exhaust arrived this morning

First imperessions, very well made and designed.
Very quick service with a 2 day turnaround













Hayward and Scott also modified the downpipe to 3 inch all the way through, as it previously had a 2.5 inch reducer to allow fittment to a 2.5 inch centre section.

AndrewC

Did you provide the specifications for the splitter or was it something they had done before and already had 'in the bag' as it were?

Just interested to know why you've gone with the curved as opposed to a straight splitter?

Andrew...

Scoty

Just in from Ian at Hayward and Scott :-

jameswrx

iTrader: (4)

cool, andy f has a similar thing but welded to the exhaust housing on the turbo.

I would presume they had a turbo there to measure it up to as they done it like that so you shouldn't have a problem with fitting?

Scoty

James,

The splitter sticks out 3 cm from the downpipe flange, and need's to be able to fit a TD 05

What's your thought's on that? You have a WRX with a TD 05?

jameswrx

iTrader: (4)

3cm

you sure?, td05 depth is 22mm, more like 21mm after i tried fitting and brought the size down a bit.

Are you fitting yourself?, if so have a decent grinding tool ready

jameswrx

iTrader: (4)

forgot about the shape of your splitter.

it might be ok as the turbo is deeper where the splitter will go with that shape, i would presume they tried it on a turbo to get the right shape anyway, probably best to ring them and find out..otherwise like i say get a grinder ready!

Scoty

Andy also had the same concerns as you.
He thought it looked a bit big to fit the TD 05.

I told Ian (H&S) that I had a TD 05 turbo fitted on an MY98 UK car, prior to getting the mod done.

I have sent him an e-mail just now asking about the size of the splitter. He's quick to get back, so hopefully I might have an answer in the morning.

Unfortunately I dont have the facilities (garage, ramp, or jacks) so the car will have to go to the local garage to get the work done, so if the splitter needs trimed to fit, I'll speak to the garage and see what they can do.
Shouldn't be much of a problem though if it's needing 9mm taken off with a hack saw.

pat

Things move quickly in this old world... the prototype was made on Saturday and installed on my Legacy when I had the rest of my new system installed also.

Despite H&S being very busy, Ian agreed to make me a new 3" downpipe while I was there Top bloke! While it was being welded up, I attacked the guilotine with a sheet of 3mm stainless steel, and cut a section to install into the downpipe. It was then dutifully inserted into a vise and battered with a suitably blunt instrument (no, not my head, but I'm sure Ian would have been much happier if it had been ).

There are a couple of turbos there that I left to be used as patterns, one with an IHI exhaust housing and one with an MHI exhaust housing. To position the splitter, it is dropped into the pattern turbo and then a spare flange is marked up with the relevant positions. This flange is then bolted onto the downpipe, and the marks used to align the splitter within the downpipe. It's then spot welded in place and the downpipe is offered up to the relevant pattern turbo. If the fit is OK, then it's seam welded into place, otherwise it's adjusted as necessary.

I think I may have confused the issue slightly, because my Legacy has a turbo that looks like a TD05 but it's actually an IHI (it's a VF12), so the relevant splitter for it will be one for an IHI not for an MHI. I spoke to Ian about another splitter that he was doing for a car that's running a VF series hybrid, so told him to use the same pattern turbo again... it is possible that there was a bit of confusion and this one got made using the IHI pattern not the MHI one.

The reason for the curved design of the splitter is to try to reduce, as much as possible, any step change in exit diameter out if the turbine. The splitter extends down into the open neck so that both the wastegate gas and the turbine exist gasses are travelling in roughly the same direction before they merge again; it's not just about preventing the wastegate gas crossing the turbine exit at 90 degrees... it's more subtle than that

This is the first incarnation of the design, the evolution version will be somewhat more complex, but we didn't have sufficient time on Saturday to build one of those... it will also need a slightly different flange... having said that, this design does appear to work rather well on the Legacy

Cheers,

Pat.

bigsinky

sorry for being stoopid but i was told that a freer flowing exhaust would improve power somewhat. by spliting the neck are you not in some ways restricting the flow of exhaust again?

cheers

big sinky

Scoty

Thanks Pat

Ian told me they had done one of the splitter mod's to your downpipe at the weekend, so I understand now what might have happened.

I'll speak to Ian in the morning, and ask him if he can spare some time to fit the splitter suitable for a TD 05

[Edited by Scoty - 2/18/2003 10:06:30 PM]

pat

Big Sinky,

Any back pressure behind the turbo is a bad thing, so you are correct, a free flowing system will work best. There is more to it than just flow area though...

If you consider an open neck design, then the gas can expand to the full area, only to have to be squeezed back down to the size of the internal bore of the pipe. This expansion and contraction will add additional turbulence to the flow, and thereby actually flow less well than if it didn't have the chance to expand in the first place. So less area isn't always a bad thing.

What a splitter does is to allow an area for flow which is similar in size to the downpipe internal diameter, while at the same time preventing gas from the wastegate crossing the turbine exit flow at right angles and creating turbulence. The net effect of both the closer match between the area of the neck exposed to the turbine, and the reduction in turbulence will far outweigh the possible benefit of having a more open design... only if the downpipe was so large that it matched the exit area of the exhaust housing (it would need to be about 4" diameter) would the arguement about the diameter reducing lose its validity; but even under these circumstances, the benefit of a gradual increase in diameter coupled with the reduction in turbulence would still result in a net increase in flow. Oh the wonders of fluid dynamics

Hope this helps,

Pat.

Scoty

Ian's got back to me this morning to confirm this. He said I should grind 10mm off the end, and put an 8mm radius on each corner.
While I am not affraid to get my hand's dirty, I'll send it back down to Hayward and Scott to give them a chance to correct the splitter.
That way I know it will be done correctly

Scoty

7 Foot

Keep us posted with your progress. I am very interested on hearing how the car performs when you get it all bolted back together.

What are you expecting?

msgofaster

I think you will need to use a tighter radius pipe for your splitter, the radius you have there doesn't make the hole round, rather more egg shaped and that as a result will not allow expansion of hot gases and will loose you low end power.

I would also not run it down inside so far as this also reduces top end power.

This was all dyno prooven so maybe the fluid man can give the answer why

I would also back a flat splitter up the the curve for the WG gases to bounce off, then it will look the same as the WRcar turbo



Michael

Scoty

Michael,

You've been playing with different splitter shape and sizes for a couple of years now and you've found that.......

James also went for a straight splitter, as are a few people posting on his thread ( incase anyone missed it )

Pat, you say......

Guy's, what is the difference between reducing the step change in exit diameter out of the turbo and reducing the pre turbo exhaust gas pressure.
Which option will give the best gains.
I take it they are not two descriptions of the same thing

[Edited by Scoty - 2/23/2003 9:44:07 AM]

msgofaster

I have the results and know what does and doesn't work, it has been some thought and then action , not all book reading and study, I believe that the pressure drop pre turbo is better with a bigger pipe on the exit, hence the long tapper i found to be best, the splitter been curve is no different to a straight 3" bore, no whrre to releave to or expand.

Michael

Scoty

Thanks Michael

So as far as I understand it, the best splitter for a TD 05 turbo should be 3mm thick, sit 19mm right from the top left bolt hole on the downpipe, and 22mm right from the bottom left bolt hole on the downpipe, be straight, sit 12mm into the downpipe and 22mm into the turbo and have a small radius on the corners for the turbo around 8mm.

Also have any edge's grinded away where the mouth joins to the downpipe.

This will deliver fast spool up and mid range power that hits like a bomb

Scoty

Michael,

Just re-reading one of your post's.....

Are you saying here, to keep the curved splitter I have shown in the picture (but have it re-sized to fit the TD 05) and add an aditional flat splitter (sized 3mm thick plate 60mm X 34mm) to the back of the curved one so the WG gases will bounce off it

Or just replace the curved splitter with a flat straight 3mm thick plate 60mm X 34mm, sitting 19 and 22mm from the bolt holes respectively.

[Edited by Scoty - 2/23/2003 1:43:02 PM]

Deep Singh

The APS DP also has a straight rather than curved splitter.Not sure if that means anything....

Scoty

Thanks Deep

Straight splitter it is

msgofaster

Straight works best.

Michael

Scoty

Hello peeps

Not forgot about this. I was a bit late in getting the downpipe back to H&S, but it's away now, and will maybey get it back sometime this week.

Scoty

Here it is in all it's glory. Received this morning





Made to my exact spec.

Thanks for all the advice and keeping me right peeps

Deep Singh

Get on and fit it mate so you can tell us if it makes any difference!

Scoty

Just for you Deep

Got the car back on Wednesday after having the full system fitted with the splitter mod.

I only had about 10 seconds testing before it blew a pipe off the intercooler and split a hose on the turbo
So I don't have any proof at the moment that it has worked, but the car definately felt MUCH stronger, and very different to drive.(for the better)

Scott

Scoty

Sorry m8, probably not the best explaination above

I'm just in, and trying to eat some dinner

AlanG

That's because you're now overboosting Scoty.

Keep an eye on it.

Alan

Scoty

Lo Alan

Yeh, it cought me by suprise first time it happened. I expected the link to control the boost and therefore did'nt think it would go over 20psi.

Maybey the split turbo hose is causing the overboosting?