Compound with VNT? (Now about which turbo's for compound setup)

[RadoTD]

I can get a VNT from a friend of mine for a good deal and I could run that on it's own, but.. it's big. He's going to get the model number for me so I can check some compressor maps, but it's an OEM turbo from a 5.7L Cummins.

So I was actually thinking of a way of running it along with my K14. I've attached a wonderfully drawn schematic of what I'm thinking.

Everything should be fairly self explanatory aside from the little yellow squares which are butterfly valves. I'm thinking of having one valve on the intake side so that the K14 can draw air without sucking it through the VNT's compressor. Once there is positive pressure between the VNT and the K14, that valve closes so that the K14 gets positive pressure fed through it.
Then on the exhaust side, leave the K14 wastegated at about 16psi and the vanes on the VNT to start closing at around 8-10psi and fully close at 16 or so. That butterfly valve on the exhaust would basically be a secondary wastegate.. does anyone know if the K14's internal wastegate would be sufficient?
In addition to that, I could have an air solenoid cut air flow from the VNT's vane controller. Then the exhaust behind the K14 would be fairly open and the VNT would never build positive pressure, so it would essentially just be running on just the K14. So with the flick of a switch, I could switch between 16psi spooling very quickly or who knows how many psi but not building it as quickly.

Could this work?




*edit - the turbo is a Holset HE351. Having trouble finding maps or just how big this thing is

[RadoTD]

Alright, so this thing isn't actually too stupid big. Not far off from an HX35...

For reference, a few that I've found, all dimensions in mm -

HE351
Compressor - 60/70
Turbine - 57/64

HX35
Compressor - 56/82
Turbine - 60/69

T3/T04E
Compressor - 58/75
Turbine - 52/60

T3
Compressor - 47/60
Turbine - 52/60


And here's a compressor map for it... not so far off by the looks of it! I'm a little low on flow, but I haven't found a turbo that I'm further towards the right side of

[OM617]

Alright, so this thing isn't actually too stupid big. Not far off from an HX35...

No. An HE351 is actually an HX40 turbo.
That turbo will not spool up on a 1.6L TDI, even with VGT technology and a compound to help spool it up.

I'm thinking of having one valve on the intake side so that the K14 can draw air without sucking it through the VNT's compressor. Once there is positive pressure between the VNT and the K14, that valve closes so that the K14 gets positive pressure fed through it.

That would significantly hurt performance since the additional airflow (what little it will provide) from the 351 will not be used by the engine to burn fuel. Also, it would not produce positive pressure since the valve would just be recirculating air back to the 351's inlet.

and the vanes on the VNT to start closing at around 8-10psi and fully close at 16 or so.

That defeats the entire point of using a VGT turbo. By the time your K14 is at 16psi you've got very little time to spool up that humungoid turbo before the engine shifts and you have to rebuild all that exhaust flow again.

Those turbos are a dime a dozen and dealerships throw them away. Don't pay more than $150-200 for one.
Also, the HE351Ve uses a CAN controlled electric motor to set vane position. You'll need a computer to control it.

The 351 is FAR FAR FAR too large for your engine and a very poor compound match. You need an HX30 for your low pressure side compound.

[Rabbit on Roids]

hx 25 even.. not like your looking at making 900 psi boost...

[RadoTD]

I want to put together the turbo system to be good for about 40psi of boost without just being a hot air pump. Not that I'll necessarily be using that all, but just in case, I want the option. It's a 1.9 AAZ as well, not the 1.6.

Any suggestions on the turbo setup then? Preferably something that can be had for a reasonable price and I don't mind going compound.
 Would a T3 be big enough? Old OEM T3's go on ebay for pretty cheap, so I'm thinking about one of those plus a rebuild kit.
Otherwise, a T3/T4 would make some sense; keeping the small tubine but getting a larger compressor. But then in terms of dimensions, it's compressor close to the size of the HE351... with no variable turbine.

The guy I can get it from said to run the HE351 on it's own. He got it to break in his Cummins 4BT because it spools very early (20+ psi before 1500rpm) on those engines.

[UnderPSI]

K14 and K26 would be worth over 300hp staged.

[Rabbit on Roids]

HE351's are garbage, they came on 6.7 cummins, and there are soo many cheap units on ebay because there all garbage.. idk why they are garbage, but thats what ive been told.

[RabbitJockey]

K14 and K26 would be worth over 300hp staged.

i would imagine if ur doing a compound youd want something bigger than both of those

[TDIMeister]

K14 and K26 would be worth over 300hp staged.

In a staged setup, the ultimate HP will be limited by the airflow capability of the LP (large) turbo.  I don't know from what application the K26 will be sourced, but if it's anything like one of the maps below, there's no chance in hell it'll make 300 HP.





Corrected mass flow of 0.2 kg/s (26.4 lb/min) will not support more than, and coming off a gasser engine with a high A/R turbine, will not spool worth a crap.  It'll make in the neighbourhood of 210 HP when maxing out the mass air flow of the K26, that is if your fueling supports it.

[TDIMeister]

I'm using a GT1749VB HP and GTA3776V LP, properly matched to make 400 HP in a 2.0 16V CR TDI.
http://forums.tdiclub.com/showthread.php?t=254284
http://forums.tdiclub.com/showthread.php?t=270527

Link to operating points matched on both compressor maps:
http://forums.tdiclub.com/showpost.php?p=2850784&postcount=134

[RadoTD]

Thanks for the info guys, I'll keep looking around trying to figure out what would be best. I'll properly look through various compressor maps when I have some time, although that K26 doesn't look great for a diesel due to how inefficient it becomes anywhere in the higher pressure ratio ranges.

What about the oh-so-common T3/T04E with my K14? Due to the exhaust running through the HP turbo first, having the T3 exhaust side might work to my advantage while getting the T4 compressor

Actually found this map for an HX30 and that seems like it might be well suited? Anyone know much about them? I like how high the pressure ratio's go.

[UnderPSI]

In that setup the K26 would be the low pressure turbo.

[RabbitJockey]

dave made 195whp with just a t3/t04e

[RadoTD]

TDI Meister - your car is nuts! A little out of my budget and goals, but I would love to build an engine like that!

The K26 seems a bit on the small side, but some Ford Thunderbirds came with a 60trim T3 that looks like it might be the ticket. Compressor map here. One thing that's nice is the 70% island is huge, it's got a good range of efficiency.

There's one on ebay where the seller says there are some cracks on the turbine housing. Is that something to be worried about? I'm keeping an eye on the auction to see if I can pick it up for cheap. I'd obviously put a full rebuild kit in it.
http://cgi.ebay.com/ebaymotors/Garrett-T3-turbo-ford-thunderbird-honda-60-63-/150467598316?cmd=ViewItem&pt=Motors_Car_Truck_Parts_Accessories&hash=item23089157ec#ht_500wt_1182

[TDIMeister]

I would avoid any Garrett T-series turbos, just because of the old tech.  I said it before and I'll say it again: turbines for gasser engines will not spool in a Diesel.  For the HP turbo in a series 2-stage setup, even a GT15 would suffice.  We are using a hybrid GT1749V for our build that targets 450 HP.  The HX30 map you posted above flows comparably with the GT3776V I'm using.