Unorthodox turbo ideas

[Runt]

Okay, I've been bouncing these ideas around for a long time, since I was dealing with american gasser stuff.
I've read that this turbo and that turbo are too small, and this turbo and that turbo are too big, etc.
Some have mentioned using the holset hx/hy35 but that they are difficult to spool on any but the biggest, wildest TDs.  In the past, I knew of a few of these that were used on gasser engines, and one example seems particularly suited to this discussion.  The vehicle was a 4.0l gasoline explorer, and the hx35 was found to perform alright, but wouldn't spool until almost 3000 rpm, and would only make 5ish psi, if memory serves.  So the owner blocked off one side of the split turbine housing, and forced all exhaust into the other side.  Viola!  Spool was 1700, boost was wastegate limited around 12psi.  (those of you who know them will wonder, as I did, how long a 4.0l ford will last at 12psi, but... his truck, his choice.) His idea was to rig an external wastegate to dump exhaust from the primary (open) side of the split housing to the secondary side once it was spooled, but I lost touch with him before he did so.  I haven't looked at the maps for an hx in a while, but I can't help but wonder if that would perhaps be applicable in our world of VW's.  I've a few things to do before it gets time to put a bigger turbo on mine, headgasket, injectors, ip, exhaust, and cleanup, but if noone tries it before then, I probably will since I currently have the hx35 with the smallest exhaust housing in my hands.  For now I'm focused on stopping and steering, then comes speeding up.

[gilligan5000]

My guess would be that your EGTs would just go through the roof and melt somthing...whatever the weakest link is.  Stock turbos can raise EGTs to 1100F ~ish on a hard pull...aluminum melts at 1220F.  Not enough wiggle room to even consider restricting flow.  Sorry to be Debby Downer

[Kantdrivefast]

...aluminum melts at 1220F.  Not enough wiggle room to even consider restricting flow.

Which isn't the same as 1200F through the exhaust manifold. Hence why mine (and several others) engines still run after hitting 1200F

[Rabbit on Roids]

ive heard of people running 1600+ EGT temps. they didnt have molten chunks of piston going out the tail pipe. the only engine that i have seen actually melt down from too much heat, is an old 6.2 chevy, and it was stuck in the mud. needless to say, by the time we got it up to the road, the driver had held it at wide open throttle long enough that the manifolds were glowing and it was shooting chunks of (precup, piston, injector tip, what have you) out the exhaust. it must have been wide open for 10 minutes or longer, with a load on it. it takes quite a bit to burn an IDI down. and chevys are known to have cooling problems too. your pistons dont instantly melt as soon as you hit 1220*f. they have to warm up to that temp also, and that doesnt happen instantly. the piston has to be that hot, not the exhaust.

if there is anything IN the engine that gets that hot, there will definitely be oil smoke coming back OUT of the engine.

[RabbitJockey]

yeah i've heard of na engines running into the 1600s as well.  but basically what you're describing is a "quick spool valve" you blocks off one side of a dual scroll turbo which cuts the a/r in half making the turbo spool up faster. then as boost builds and back pressure builds and more flow is needed, the quick spool valve begins to open allowing the exhaust to flow through the other side of the turbine housing, thus giving the top end flow.  similar idea to a vnt.  powered by spearco posted the thread before.  i actually read about a turbo camaro with a rear mount turbo that did a similar setup to this with great success.

heres one for 250 http://performancemetalwerkz.webs.com/apps/webstore/

and heres the old thread discussing the 500 dollar one http://www.vwdiesel.net/forum/index.php?topic=22893.0

[rabbitman]

If I had the turbo and 250 bucks I'd do it, better low end boost while still flowing enough for low rpm and then you'd get good high end flow/boost.

[Runt]

Okay, so maybe my ideas aren't so unorthodox.  That probably means they are not too bad.  Neat to see that the part is available, although not the way I was going to build it myself.  I'll probably either buy that one or copy it at first though, as my idea requires about 2-1/2 or 3 inches in length to make a nice smooth transition from full width to single scroll.  If I like the way the thing runs, I'll work on packaging the longer unit then.  I also had an idea of making the valve actuate by exhaust pressure, therefore opening up as soon as the turbine becomes a restriction.  That is easier to do with my idea.  Thanks, Trev0rbr, for the links.  I guess maybe I'll be doing a turbo swap soon.  The dodge cummins guy that keeps trying to buy it from me, but hasn't shown up with cash, is gonna be ticked!   

[Powered by Spearco]

Just a word of caution, the PerformanceMetalWerkshop web site seems kind of sketchy, due to theres now contact info.
Can anyone confirm this is a ligit site?

[Rabbit on Roids]

why doesnt the OP just get a proper sized VNT? wouldnt it outperform some spool valve equipped HX?

[Runt]

A properly sized vnt might outperform the hx35, but then I'm not sure that it would.  The holsets do have a rather advanced design on the compressor side, as I understand it.  When I could find maps, they were somewhat broader and covered a larger area than most turbos, iirc.  As many have discovered, controlling te vnt can be difficult to do manually, and one of my favorite things about these cars is simplicity, so I'll be using no electronics in my setup.  Also, the vnt can spool low enough to cause low rpm rod failure, as is frequently discussed, whereas I thik that the holset might not.  Actually, my gut feeling is that using one port in the split turbine would spool and run quite well, opening the second port would just serve to prevent the turbine from becoming a restriction, and thus  reduce egts.  My doubts about this setup arise more on the inlet (compressor) side, as I think it may be oversized for my use.
I have the hx  already, and a vnt is money I could spend elsewhere.  Unless someone feels like donating one for experimentation, as I think I have a simple clean, non electronic, solution for the vane control that does not require connecting the throttle directly to the vane lever.

[Rabbit on Roids]

A properly sized vnt might outperform the hx35, but then I'm not sure that it would.  The holsets do have a rather advanced design on the compressor side, as I understand it.  When I could find maps, they were somewhat broader and covered a larger area than most turbos, iirc.  As many have discovered, controlling te vnt can be difficult to do manually, and one of my favorite things about these cars is simplicity, so I'll be using no electronics in my setup.  Also, the vnt can spool low enough to cause low rpm rod failure, as is frequently discussed, whereas I thik that the holset might not.  Actually, my gut feeling is that using one port in the split turbine would spool and run quite well, opening the second port would just serve to prevent the turbine from becoming a restriction, and thus  reduce egts.  My doubts about this setup arise more on the inlet (compressor) side, as I think it may be oversized for my use.
I have the hx  already, and a vnt is money I could spend elsewhere.  Unless someone feels like donating one for experimentation, as I think I have a simple clean, non electronic, solution for the vane control that does not require connecting the throttle directly to the vane lever.

how many people have a VNT on there car and have electronics hooked to them? if its on an IDI, maybe 1 or 2.. 99% of VNT users have mechanical controllers rigged up. works off boost pressure and throttle position. and how many people have you ACTUALLY seen bend rods from boost too early? ive personally seen ZERO problems bending rods from the boost of a VNT. sure, in theory its possible, but has it really happened yet?

and people are not connecting there throttle DIRECTLY to the VNT. maybe you should do some more reading before you discard a great idea. if spool valves were a great idea, why doesnt everyone use then? why dont they come on new cars?

as for VNT's, everybody is using them, and they do come on most new diesel pickups and other cars as well. i just think the spool valve would have caught on better had it been a good idea.

[truckinwagen]

you know RoR, that is exactly the argument that was made against water/meth injection. about a year before everyone started using it, and it started coming on factory cars.

[Rabbit on Roids]

i still dont see how water inj is a bad thing tho? its cleaning your engine, and making it run cooler..

[truckinwagen]

I didnt say it was bad(it is actually very god in many ways), just that the argument you just used against the spoolvalve was the same used against water injection.

and look how useful water injection has turned out to be now that people tried it.

I see no reason to doubt something before it has been tried, who knows, maybe the HX with a spoolvalve will work wonders.