Super CT26

**Bush65** · 20th July 2011, 10:03 AM

Originally Posted by c.h.i.e.f

Thanks for the input bush good to see you posting on the site again takes a bit of the pestering that we give dougal about info on turbo's .... I didn't know BW made turbo's for caterpillar I thought they were cat turbo's as they hav stamped on them but it makes sense a specific manufacturer making them...holset are in buisness with cummins and hav released there new range and technologies in a article I was browsing what's your opinion on them ? well with a compound setup I hav been told they are useless for our motors and would be undrivable on road due to lag (as dougal stated "rice burner" terminology) but I cannot see how this is the truth and seeing what dougal has said about vnt having problems has anyone done a comparison between a vnt and a compound setup ?

Sorry if I wasn't clear about the Caterpillar turbos. BW sell a lot of cores, etc for their turbos and CAT use these with a custom housing/cover - I don't know if BW make the housing/cover, but it ensures customers by replacement turbos from CAT.

Holset is an old british turbo manufacturer that was spun off from another company, the details of which are now dim in my memory. They have been owned by Cummins for some years now. You can download (from holset web site) their newsletters, which often have good articles, but I haven't looked at any for some time. I remember an old article that was about compound and modulated compound turbos, so that may be the technology you are referring to - so called modulated turbos operate as compound (or 2 stage) at low end then at the high end (as exhaust manifold pressure increases) some of the exhaust flow into the turbine of the high pressure turbo is modulated by diverting (bypassing) it to the low pressure turbine.

BW have been doing similar (modulated and compound sets) for a good few years for many of the current model euro diesels (eg 3.0 litre V6 in disco 4).

The following pics were pinched from the Holset article and joined as one. They show what happens when the compressor outputs are combined like this note the top pic shows the compressor maps for the 2 compressors alone, overlaid by the output when operating as a compound set - pressure ratio of each are multiplied to obtain PR of the compound set.

**def-90** · 20th July 2011, 06:39 PM

so not much of an update but a few bits

a couple of pics of the ordinary turbo manifold fpor the TB28 and the one we dodged up to accept the CT, abit of ghetto fab that'll do me until i get some headers made

ground the internal kinda fins back a little to open it up a little

manifold sitting in place

turbo sitting in place

started cutting out the front fenders besides the head light s to fit my ricer intercooler (hope its not to big to create lag or too much pressure drop) and workin gout the front end, i'll prolly move the radiator back another 30-40mm as its 90mm from the fan and will make the intercooler fit alot easier, put a few new gauges in and we started work on my mates 120 isuzu to get his td05? suzi turbo on.

question to dougs and the like, for the dump pipe i was going to 'massage' some 4" pipe to the exhaust flange then reduce to 3" probably after the 180deg bend, will that be ok or should i fab 3" right up to the flange a splay it out ?

**Dougal** · 20th July 2011, 07:31 PM

Aha, that's the IHI manifold. It's quite a good one with the split pulses so as long as the bonnet shuts you're good to go.
I don't think you need 4" at the dump, 3" is heaps, the outlet of the turbine is only about 2".

I have the IHI manifold too, but mine has had the neck cut off and flipped. Now a low mount.

**def-90** · 20th July 2011, 08:00 PM

ok so u think they are a ok manifold? they just seem smaller internally then the standard manifolds i was contimplating cutting up. i know 3" is more then sufficient but for ease i can massage a 4" pipe to meet the exhaust flange but then it won't really straighten till it does a 180deg where i can fit the reducer, just curious if this will impede p[erformance?

just easier then cutting and welding a 3" pipe to meet the exhaust flange?

**def-90** · 20th July 2011, 08:34 PM

oh yeah there will be some bonnet massaging too, i didn't check that when we dummied it up at the start, we could have angled the flange abit to clear the bonnet, but oh well thats cool...

**rick130** · 20th July 2011, 09:13 PM

Originally Posted by def-90

ok so u think they are a ok manifold? they just seem smaller internally then the standard manifolds i was contimplating cutting up.
[snip]

At a guess the smaller ID branches would be designed to keep heat and gas velocity higher for better spooling of the turbine than would be preferred for an NA manifold, particularly if using a split pulse arrangement.

**rar110** · 21st July 2011, 04:21 AM

Is that type of manifold for an IHI RHB5 or RHB6 size turbo?

**Dougal** · 21st July 2011, 06:40 AM

Originally Posted by rar110

Is that type of manifold for an IHI RHB5 or RHB6 size turbo?

That's the RHB6. The 5's weren't used on these engines.

The side wall thickness in these manifolds is enough to drill and tap for an EGT probe sideways in the neck just below the turbo mount flange.
For the dump-pipe, just keep it smooth. You can worry about polishing once everything is up and running.

**def-90** · 21st July 2011, 06:40 PM

so had a little crack today and whipped some ghetto fab dump pipes
mine was slapped up with a 4"to 3" reducer and just massaged the 4" section to fit the exhaust flange, again it wont be a long term answer just something quick to get me by

and dougs do u think this will a ok place for my egt probe? its a long sucker

and a quickie of my ricer intercooler

and my mates dump pipe, we made it out of a 4" doughnut, down to 3.5" down to 3" we worked out after making it it was somewhat ordinary, ah well will do for now. give some feedback on this bucket dump pipe to dougs.

**Dougal** · 21st July 2011, 07:16 PM

Looks like it's all coming together. Since you're running the exhaust out that direction you could actually spin the turbo around and put the compressor side to the front.

For the EGT probe, it's gotta go in the manifold. In the exhaust after the turbo is a guessing game as you don't know how much heat the turbo has taken out of the exhaust gases.

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