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Stock turbos for cheap parallel setup?
moroza Offline
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#1
Stock turbos for cheap parallel setup?
Due to some miscommunications, I may have ended up buying two stock turbos for an OM606. It occurred to me to make a cheap twin (parallel) setup using these, and two stock manifolds. Each manifold would be cut between the middle two runners, and capped off at the cut. One of these half-manifolds would go on the front three cylinders, the other on the back three, each with a stock turbo. I have to do custom intake and exhaust plumbing anyway, so the extra work there isn't much. I doubt this would be as good a solution as a compound setup, but would it gain anything over a single stock turbo? I expect there'd be a little more lag. How about increased power ceiling?
07-01-2020, 04:22 PM
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barrote Offline
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#2
RE: Stock turbos for cheap parallel setup?
Hy, k14 is a old machine and wasn't build to boost high... it was to give min EGP at 1 bar boost .
Basically it will not be as good as a single big turbo.
But u can try and post
FD,
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07-02-2020, 04:02 AM
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TwoMuchBoost Offline
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#3
RE: Stock turbos for cheap parallel setup?
Oh man... twin K14's would spool so slow and smokey; and that would be more work than I think you're estimating... two downpipes, two air intake/inlets + filters, two chargepipes + merge before intercooler, two wastegate brackets + diaphragm, twice as many opportunities for failures and boost leaks. That's assuming there's even room for all that, I'm trying to imagine two downpipes in that space and it's not computing lol. Yes, with two you get twice the airflow capability but it'll spool painfully slow as they're old turbo's with old technology. Simply put, there's a single turbo you can grab that will spool faster and probably make more power at the same time. My BorgWarner S251-SX was under $500 and is somewhat comparable power potential wise (400whp) and would definitely spool faster; I'm not utilizing the twin scroll housing it's got either so I expect that to improve further once I build a manifold. Then you have the billet S257 which isn't much more and flows 65lb/min... good for 500 to the tire with enough fuel.

As far as compounds go, you're right in that they're not suited at all unless you mean just one of the turbos on the manifold and purchasing a larger one to go over-top of it. But not both the K14's. Larger/low-press turbo should be roughly twice the size the small/manifold charger.

It's a really popular setup for the Cummins guys to put an S475 overtop the stock charger as a budget setup and it works well. Sizing that 1:2 ratio compressor wise to suit the stock K14 would put you at like an S362 or S366 but with a nice big hotside. If you could somehow fit a bigger turbine wheel into the stock K14 and port out the wastegate hole a little bit... I think that would be a slick setup for of 500-600 HP with stock-like spool.
(This post was last modified: 07-02-2020, 09:00 PM by TwoMuchBoost.)
07-02-2020, 08:57 PM
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JarrusJenkins Offline
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#4
RE: Stock turbos for cheap parallel setup?
(07-02-2020, 08:57 PM)TwoMuchBoost Wrote: Oh man... twin K14's would spool so slow and smokey; and that would be more work than I think you're estimating... two downpipes, two air intake/inlets + filters, two chargepipes + merge before intercooler, two wastegate brackets + diaphragm, twice as many opportunities for failures and boost leaks. That's assuming there's even room for all that, I'm trying to imagine two downpipes in that space and it's not computing lol. Yes, with two you get twice the airflow capability but it'll spool painfully slow as they're old turbo's with old technology. Simply put, there's a single turbo you can grab that will spool faster and probably make more power at the same time. My BorgWarner S251-SX was under $500 and is somewhat comparable power potential wise (400whp) and would definitely spool faster; I'm not utilizing the twin scroll housing it's got either so I expect that to improve further once I build a manifold. Then you have the billet S257 which isn't much more and flows 65lb/min... good for 500 to the tire with enough fuel.

As far as compounds go, you're right in that they're not suited at all unless you mean just one of the turbos on the manifold and purchasing a larger one to go over-top of it. But not both the K14's. Larger/low-press turbo should be roughly twice the size the small/manifold charger.

It's a really popular setup for the Cummins guys to put an S475 overtop the stock charger as a budget setup and it works well. Sizing that 1:2 ratio compressor wise to suit the stock K14 would put you at like an S362 or S366 but with a nice big hotside. If you could somehow fit a bigger turbine wheel into the stock K14 and port out the wastegate hole a little bit... I think that would be a slick setup for of 500-600 HP with stock-like spool.

I would have thought any s400 blowing into the stock HX35/HE351 would be way too big... same as using an s300 into a stock K14.

(fun fact the K14 was also a stock turbo option for a Peugeot XUD9TE 1.9litre turbo diesel... so yeah K14 for a 605/606 is way too small)
07-05-2020, 04:54 PM
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TwoMuchBoost Offline
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#5
RE: Stock turbos for cheap parallel setup?
The reason the S475 is chosen is because it supports a ton of power and is the cheapest bang for your buck. They came stock on Detroit diesels so you can grab them for under $600 and it flows 1000+hp worth of airflow. You can get an S472 or S467 as well but not as cheaply. My S251 flows right around 50 lbs/min and the HX35 has a 54 or 56mm compressor. S475 flows around 105-110 if I remember correctly so they're actually right around that 2:1 ratio. The trick is sizing the exhaust housings, wheels, and gating correctly to not have drive pressure out of whack.

My 606 engine didn't come with the turbo so I never ran the stock one admittedly. The K14 can make a solid 250-300 hp can't it? I'd like to guestimate 30-35lb/min out of that turbo... so something in the 65-75ish lb/min range (like an S300) wouldn't be out of line but maybe I'm way off with the K14 size. My main concern is I've noticed most of the people I've seen do Benz compound setup go too closely sized with the turbo's and have poor results. This isn't a set of "towing compounds" for a Cummins that only operates between 1200-3000RPM, we have a huge RPM operating range (ie. 5,500 RPM redline and we still want boost at 2,000 RPM) so we end up needing map width more than gigantic pressure ratio. You need the manifold charger to light instantly and just not run off it's compressor map before the big one lights... we don't need 150psi of boost like the Cummins, just 45-60 or so but over a giant operating range. Also, from what I've been told by countless pulling competitors, you only get about 75% of the big turbo's actual flow capability in a compound setup so you have to size bigger; so in a compound setup you can expect 800+ out of a S475 vs 1000+ in a big single setup.
07-06-2020, 11:19 AM
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Petar Offline
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#6
RE: Stock turbos for cheap parallel setup?
@JarrusJenkins The K14 on the Peugeot  and the one on the 606 and completely different. The turbine is a bit bigger on the 606, and the compressor is much bigger, in fact it is similar in size to the K24, if not the same. It is sized ok for a stock engine, a bit small on the top end, but I guess that was intentional since the low end was the priority
(This post was last modified: 07-06-2020, 09:17 PM by Petar.)
07-06-2020, 09:16 PM
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moroza Offline
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#7
RE: Stock turbos for cheap parallel setup?
I openly declare that I'm a newbie when it comes to forced induction. I've only owned a couple of turbo vehicles - an 83 Mitsubishi truck and a 96 Passat TDI - and most of the technical discussion here is over my head. Of course, I have a lot of studying to do. For now, I was hoping to get a simple general opinion, and I'm gathering that that opinion, from people qualified to have it, is No.

Anyway, it looks like I only bought one stock turbo after all. My plans are to run a mildly turned-up stock setup, perhaps 200whp, and be happy with that for a while.
07-06-2020, 09:37 PM
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