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+--- Thread: VGT vs. Disco Potato (/showthread.php?tid=917)
VGT vs. Disco Potato - CID Vicious - 12-07-2009
Was going around G-Pop Shop and was curious to see if any VGT turbos were to be had...no luck.
However, I did happen upon a blast from the ricer past...the Garret GT2860RS, also know as the 'Disco Potato' turbo. On a 2.0l ricer motor, this was good for about 275 wheel horsepower, similar torque, and virtually nonexistent lag. For about a grand for a brand new modern turbo, with no messing around with VGT actuators, it might not be a bad option.
Question is, does anyone know of anyone using them on OM617s?
This might be a good option to those (like me) who are a little phobic about plunking down 500 bones for a used turbo that could end up being a paperweight. Granted, the DP is twice that figure, but it's also new and a known quantity. T25 flange, choice between .64 or .86 turbine for the same price, compact...
Pertinent question: are the VGT turbos ball bearing or standard? Standard are easier to rebuild and cheaper, might make the idea of a used VGT seem more appealing to me. Although, factoring in purchase price, rebuild kit, labor...getting close to DP price territory.
I know that VGTs are 'superior' in the technical sense, but let me put it this way: an LS1 or a SBC? Well, the LS1 is superior, but ~300hp and up can be had by either. I have a feeling the VGT/DP thing will be similar, the VGT might be better but it's a bit more of a headache to get working properly, whereas the DP isn't any more complicated to setup than a watercooled T3. VGTs are cool but perhaps this is another, parallel path to explore.
I didn't know these had come down to a reasonable level, back when I had my SE-R these were 2500 F-N bucks
. Didn't matter, wasn't willing to risk tearing the transmission in half anyway, even stock SR20DETs can break 'm easy if they're run too hard. But at not much more than a new T3...hmm...Anyway, I turn this over to y'all...
RE: VGT vs. Disco Potato - winmutt - 12-07-2009
I assume this is the ball bearing? The VNT are all journal based. I had talked to a Garrett employee who had made a bb one from the "spare parts bin". Who here doesnt wish they had such a bin? I believe the VNT will still provide more boost early on with the downside of moving parts and vane control.
RE: VGT vs. Disco Potato - Kiwibacon - 12-07-2009
A disco potato would have almost nothing until ~2500rpm on a 3 litre diesel.
If you're after all out power it'd be fine, but drivability will be compromised.
RE: VGT vs. Disco Potato - ForcedInduction - 12-07-2009
I believe VNTs aren't BB because they are all made for diesels. Since diesels are always in high boost, BB wouldn't last nearly as long as journal bearings since the bearings are always in physical contact with the rolling surface.
There wouldn't be much advantage to a BB VNT anyways.
1- A normal VNT can already accelerate right along the surge line.
2- BB have higher drag at high RPMs which means even higher backpressure above the vanes restricting free flow.
RE: VGT vs. Disco Potato - CID Vicious - 12-08-2009
Kiwi, I can't argue with the assertion that there'd be no action until 2500rpm, but that's not the result with a much smaller displacement SR20DET. I know that diesel exhaust is cooler, but a liter of displacement would, I'm assuming, make up quite a bit of the difference. The turbo is known for it's supercharger-like response, so I'm not picturing having a ton of lag, though I'm just guessing.
The best thing, thinking as if we were 'Super Turbo Diesel Magazine', would be to take, say, Forced's car, which is already a fairly familiar setup by now, and swap in a DP and see what the dyno says. Compare apples to apples in the real world. Bench racing only goes so far when determining these things, mods that work wonders on some motors do absolutely nothing on others, and it's not until you put it to the test that it works.
I wonder if G-Pop would be interested in loaning us one for a dyno pull? Or if there was some way to find a used one sitting on someone's garage shelf to test and give back.
My tach doesn't work, but 2500 rpm doesn't scare me too much, the stock setup doesn't seem to have any kind of TDI-style instant boost stock, for sure. The top end, as you say, would probably make up for the (at this point perceived) lack of low end. I sold my VTEC Civic to buy the 240D, so I'm not afraid of a little delayed gratification - that top end rush was simply addicting. I sometimes wonder if I quite made the same choice, but I had the feeling I was just going to get in trouble with it.
RE: VGT vs. Disco Potato - Kiwibacon - 12-08-2009
(12-08-2009, 02:54 AM)CID Vicious Kiwi, I can't argue with the assertion that there'd be no action until 2500rpm, but that's not the result with a much smaller displacement SR20DET. I know that diesel exhaust is cooler, but a liter of displacement would, I'm assuming, make up quite a bit of the difference. The turbo is known for it's supercharger-like response, so I'm not picturing having a ton of lag, though I'm just guessing.
There are plenty of people running these turbos on larger diesels, like Nissans TD42 (4.2 litre) and they don't get boost until close to 2000rpm. They're over twice the SR20 displacement.
These guys are talking 3500rpm for max boost with a disco potato on an SR20.
http://www.nissansilvia.com/forums/index.php?showtopic=75670
RE: VGT vs. Disco Potato - CID Vicious - 12-08-2009
What kind of power gains are they seeing? If it'll feed a 4.2l motor, it's got plenty of capacity for severe output from a 617.
Jeemu's car was called a 'dyno queen' because of his curve and where the power started, but I'll bet he'll still toast any VGT'd car you can find. The VGT would be a more pleasant daily driver, for sure, but faster?
I'm thinking 10mm elements in the M pump (assuming this doesn't turn out to be a dead end) and a DP would put a smile on many of our faces, and would toast a Holset for driveability at the same time.
RE: VGT vs. Disco Potato - Kiwibacon - 12-08-2009
(12-08-2009, 03:33 AM)CID Vicious What kind of power gains are they seeing? If it'll feed a 4.2l motor, it's got plenty of capacity for severe output from a 617.
Jeemu's car was called a 'dyno queen' because of his curve and where the power started, but I'll bet he'll still toast any VGT'd car you can find. The VGT would be a more pleasant daily driver, for sure, but faster?
I'm thinking 10mm elements in the M pump (assuming this doesn't turn out to be a dead end) and a DP would put a smile on many of our faces, and would toast a Holset for driveability at the same time.
The 4.2's rev a lot slower than a 617, hence the total airflow isn't much different.
A disco potato should be good for over 200hp on a diesel with no smoke. However it depends how much boost you're running and what VE your motor has.
RE: VGT vs. Disco Potato - awsrock - 12-08-2009
I paid $50 for my GT2256v..it was supposedly "bad"..
Anyway, if you are looking to spend $500, there are a LOT of good VGT/VNTs out there that can be had for half of that..heck, the only 2359v I know of on ebay is going for $549.
Not sure about the Holset models...but they can probably flow the same, if not more than the DP and since they are designed for diesels, will probably be much more responsive. An HX35 is good up to 280hp, and an HY35, while possibly providing slightly less power, would spool much quicker.
RE: VGT vs. Disco Potato - ForcedInduction - 12-08-2009
Lets not forget that you can get a nearly new HE351VE for $150 all day long. There are 11 of them on eBay right now starting at $95.
http://motors.desc.shop.ebay.com/items/?_nkw=vgt*&_sacat=6030&LH_TitleDesc=1&_trksid=p4506.m270.l1313&_dmpt=Motors_Car_Truck_Parts_Accessories&_odkw=vgt*&_osacat=6030
RE: VGT vs. Disco Potato - CID Vicious - 12-08-2009
Hmmm...seems like I'd overestimated what a VGT would end up going for. Unless one were to find a DP pretty cheap it looks like a VGT is, indeed, the better way to go. And since they're journal bearing designs they can't be all that hard to rebuild if I end up getting a bad one.
Worth having the discussion, I suppose...